Search for Uranium

In the United

By VINCENT E. McKELVEY

A CONTRIBUTION TO THE GEOLO<

States

JY OF URANIUM

GEOLOGICAL SURVEY BUL LE TI N 103 0-A

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of the 

Commission

UNITED STATES GOVERNMENT PRINTING OFFI CE, WASHINGTON : 1955
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 25 cents (paper cover)
CONTENTS

The letters in parentheses preceding the titles are those used to designate the separate chapters.

(A) Search for uranium in the United States, by V. B. McKelvey_ _

(B) Stratigraphy of parts of De Soto and Hardee Counties, Florida, by

Page 

1

M. If. Bergendahl..________________ 65

(C) Uranium deposits at base of the Shinarump conglomerate, Monument

Valley, Arizona, by I. J. Witkind________ .___________ 99

(D) Accuracy of ore-reserve estimates for uranium-vanadium deposits on

the Colorado Plateau, by A. L. Bush and H. K. Stager__ __ ___ 131

(E) Study of radioactivity in modern stream gravels as a method of prospecting, by R. T. Chew, III.__________.___________ 149

(F) Geology and monazite content of the Goodrich quartzite, Palmer area,

Marquette County, Michigan, by R. C. Vickers. --- - 171

(G) Wall-rock control of certain pitchblende deposits in Golden Gate 

Canyon, Jefferson County, Colorado, by John W. Adams and 

Frederick Stugard, Jr_________________________ 187

(H) Uranium in black shale deposits, northern Rocky Mountains and 

Great Plains, by W. J. Mapel

(I) Reconnaissance study of uranium deposits in the

water County, Wyoming, by Donald G. Wyant, William N. Sharp,

and Douglas M. Sheridan_________.

(J) Stratigraphy of the Morrison formation in part of northwestern New

Mexico, by V. L. Freeman and L. S. Hilpert.

Red Desert, SweBt-

(K) Uranium deposits in oolitic limestone near I 

County, Wyoming, by R. R. Guilinger and P. 

(L) Uranium and copper deposits, Coyote district,

/Tayoworth, Johnson

K. Theobald, Jr__ 335

Mora County, New

Mexico, by C. M. Tschanz_________.

(M) Description of indicator plants and methods of botanical prospecting

for uranium deposits on the Colorado Plateau, ay Helen L. Cannon. 399

(N) Geology and uranium deposits of the Caribou area, Boulder County,

Colorado, by F. B. Moore, W. S. Cavender, and E. P. Kaiser____ 517

211

237

309

343

Contributions t0 the 

Geology of Uranium 

1955

GEOLOGICAL SURVEY BULLETIN 1030

This bulletin was printed as separate chapters A-N

These reports concern work done on behalf 

of the U. S. Atomic Energy Commission 

and are published with the permission of 

of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON ; 1957

CONTENTS

Page

Abstract______________-_-__----_____-_-____^____ _ 1

Introduction_____________________________________________________ 1

Acknowledgments. ___________________________ ___^ _________________ 2

Common uranium minerals__-______--____________._________________ 2

Types of uranium deposits_________________________________________ 3

Uraniferous igneous rocks_____________________________________ 4

Uranium-bearing pegmatites____________________________________ 5

Hydrothermal vein deposits___________________________________ 5

Replacement deposits._________________________________________ 6

Tuff and tuffaceous sediments___________________________________ 7

Uraniferous coal and associated carbonaceous shale_______________ 7

Uranium-bearing continental sandstone and conglomerate-_________ 8

Uraniferous asphaltite and related substances.____________________ 12

Uranium deposits in limestone__________________________________ 13

Uraniferous aluminum phosphate deposits ________________________ 14

Uraniferous black shale_______-_______________._________________ 14

Uraniferous phosphorite._______________________________________ 16

Uraniferous placers--___--_-_-_---___________-_______-__-__---- 17

Summary of the geology of uranium. ____________________________ 18

Methods of prospecting for uranium.________________________________ 20

Geologic prospecting.__________________________________________ 20

Geophysical prospecting._______________________________________ 20

Botanical prospecting._________________________________________ 21

Geochemical prospecting.______________________________________ 22

Physical exploration.__________________________________________ 23

Selection of areas for prospecting___________________________-____ 23

Distribution of uranium deposits in the United States._________________ 24

Uranium vein and replacement deposits._________________________ 24

Uranium deposits in tuffaceous rocks___________________________ 28

Uranium deposits in limestones_-________________________-_-----_ 29

Uranium deposits in sandstones.________________________________ 29

Uraniferous asphaltite deposits....______________________________ 33

Uraniferous coal and continental carbonaceous shale.______________ 36

Uraniferous phosphorites_______________________________________ 37

Uraniferous marine black shales.________________________________ 37

Uranium-bearing placers______-____________-___-___-_-_-----_ 40

Outlook for future discoveries-___-_____-______-_______-___------ 40

Conclusions....___________________________________________________ 44

References cited___________________________________________________ 45

Index._________________________________________ 61

in
IV CONTENTS

ILLUSTEATIONS

Page 

FIGURE 1. Vein and replacement deposits of uranium in the United States. 26

2. Uranium deposits in tuffaceous rocks, sandstones, and limestones in the United States.____________________________ 30

3. Uraniferous asphaltite, coal, and continental carbonaceous

shale deposits in the United States_______________________ 34

4. Uraniferous marine phosphorites and black shales in the United

States.________________________________ 38

5. Placer deposits of monazite, zircon, and radioactive black

minerals in the United States.__________________________ 42
A CONTRIBUTION TO THE GEOLOGY OF URANIUM

SEARCH FOR URANIUM IN THE UNITED STATES

By V. E. MCKELVEY

ABSTRACT

The search for uranium in the United States is the most intensive ever made 

for any metal during our history. The number of prospectors and miners involved is difficult to estimate, but some measure of the size of the effort is indicated by the fact that more than 500 geologists are employed by government and 

industry in the work a number comparable to or larger than the total number of 

geologists engaged in the study of all other minerals together except oil. The 

largest part of this search has been concentrated in the Western States. No vein 

deposit of major importance by world standards has been discovered, but the 

search has led to the discovery of important minable deposits in sandstones on 

the Colorado Plateau, Wyoming, and South Dakota and in coals in South 

Dakota; of large, low-grade deposits of uranium in phosphates in both the 

western and Florida fields, in black shales in Tennessee, and in coals in the 

Dakotas, Wyoming, Idaho, and New Mexico; and of some promising occurrences 

of uranium in vein deposits. Despite the fact that many of the districts considered favorable for deposits of uranium have already been examined, the 

outlook for future discoveries is bright, particularly for uranium in sandstone 

and vein deposits in the Rocky Mountain States.

INTRODUCTION

The search for uranium in the United States is the most intensive 

ever made for any metal during our history. Although the number of 

uranium prospectors is difficult to estimate, more than 500 geologists 

are employed by government and industry in the work a number 

comparable to if not larger than the total number of geologists engaged in the study of all other metals together.

The results of this search have far exceeded expectations, for it 

has led to discoveries of numerous large deposits of uranium minable 

now as well as extensive resources in lower grade deposits that insure 

our future. It is not possible to describe these results in detail here, 

but it is the purpose of this report to summarize briefly the information on the common uranium minerals; the kinds of deposits in which 

uranium is found; the methods used in the search for uranium; the 

important deposits found in this country thus far; the outlook for 

future discoveries; and the recent literature on the geology of uranium 

deposits in the United States.

1
2 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ACKNOWLEDGMENTS

This account is mainly a review of work done by many other 

geologists.. Beyond the acknowledgment implied by the references 

themselves, I wish to acknowledge my debt to my associates on the 

Geological Survey and to friends in the Atomic Energy Commission 

and other organizations engaged in the study of uranium for background information, much of it unpublished, that contributed directly or indirectly to this report. Rosemary Bobbins and R. W. 

Schnabel helped compile the maps showing the distribution of various types of deposits; Ralph S. Cannon made many constructive suggestions on the first draft of this paper, which constituted the text of 

a talk presented before the American Association of Petroleum Geologists at Casper, Wyoming, in April 1953 and St. Louis, Missouri, in 

April 1954; J. H. Eric, G. N. Pipiringos, M. R. Klepper, R. D. Nininger, W. S. Twenhofel, G. W. Walker, K. G. Bell, and R. M. Garrels 

made suggestions that greatly improved the final manuscript; and 

A. P. Butler, R. P. Fischer, and L. R. Page collaborated with me in 

1951 on the preparation of an unpublished report on domestic resources of uranium and thorium somewhat similar in scope to this 

one.

This paper was prepared as part of a program that is being conducted by the U. S. Geological Survey on behalf of the Division of 

Raw Materials of the U. S. Atomic Energy Commission.

COMMON URANIUM MINERALS

Uranium is found in a great variety of minerals (Frondel and 

Fleischer, 1952, 1955). Nearly 100 species may be listed as uranium 

minerals, and we may list more than 200 if we count all the minerals in 

which uranium occurs commonly but is not an essential constituent. 

Most uranium minerals are black or bright shades of green, yellow, 

and orange. These are most accurately identified and their uranium 

content determined by laboratory methods (George, 1949; Rodden 

and Tregoning, 1950; Grimaldi and others, 1954), but two criteria 

either singly or together aid in identifying them in the field. First, 

along with thorium and some potassium minerals, uranium minerals 

are radioactive and generally can be detected and measured by a Geiger 

or scintillation counter (Senftle and McMahon, 1949; Brownell, 1950; 

Wright, 1953, 1954a). Second, some uranium minerals, particularly 

the brightly colored ones, fluoresce under the ultraviolet lamp. The 

precipitate formed by evaporating a sulfuric acid solution of uranium 

minerals also fluoresces, as does a bead formed by the fusion of 

uranium minerals with sodium or lithium fluoride (Bain, 1950, 

p.278).
SEARCH FOR URANIUM IN THE UNITED STATES 3

The uranium minerals may be- classified, according to the other elements combined with the uranium, as oxides, vanadates, phosphates, 

arsenates, carbonates, sulf ates, silicates, niobates, tantalates, titanates, 

and other minerals in which uranium occurs as a minor constituent.

The common uranium oxides are uraninite and its collof orm variety, 

pitchblende. These oxides are black or brown and have specific 

gravities of 5 to 9. For the most part they are formed through igneous 

and hydrothermal processes. The common uranium phosphates are 

autunite (yellow) and torbernite (green). These minerals are generally formed by weathering, and their presence suggests that primary 

uranium minerals may be found at depth. Two uraniferous vanadates carnotite and tyuyamunite are important constituents of 

uranium deposits on the Colorado Plateau. Both are a bright mustard 

or canary yellow.

Most uranium carbonates and sulf ates are so soluble that they are 

not common in nature except as occasional efflorescences in dry regions. 

Schroeckingerite (greenish yellow) is one of the most impqrtant 

carbonates, and zippeite (yellow) is one of the most common sulfates^ 

Of the uranium silicates, uranophane (yellow) is the most common. 

The rare earth niobates such as pyrochlore, euxenite, samarskite, and 

fergusonite contain variable amounts of uranium. They are darkcolored or black minerals and are not found in large amounts. Brannerite and davidite are the uranium titanates. Both are black and 

neither is common, though they do constitute the ore minerals in a 

few im'portant deposits.

Of all these uranium minerals, only uraninite, pitchblende, davidite, 

brannerite, carnotite, tyuyamunite, autunite, torbernite, uranophane, 

and Schroeckingerite generally form minable deposits under present 

economic conditions. The other uranium minerals, however, are commonly associated with uranium ores and are useful as clues to the 

possible presence of uranium deposits.

Among the minerals that may contain minor amounts of uranium, 

the most important are carbonate-fluorapatite, fluorite, monazite, 

zircon, and some carbonaceous materials. Carbonate-fluorapatite generally contains no more than 0.03 percent of uranium; fluorite and 

monazite may contain as much as a few tenths of a percent of uranium; 

and zircon and certain carbonaceous materials, such as thucholite, may 

contain several percent of uranium.

TYPES OP URANIUM DEPOSITS

Before discussing the characteristics of the various types of uranium 

deposits, it is appropriate to mention some economic considerations 

by which the value and importance of the various types may be gaged.
4 CONTKIBUTIONS TO THE GEOLOGY OF URANIUM

High-grade uranium deposits over the world are those that contain 

about 0.5 percent or more of uranium in the ore or in easily formed 

mechanical concentrate. Under certain conditions, the Atomic Energy 

Commission will buy ores containing 0.1 percent uranium, so that we 

may consider deposits of this grade minable in this country, if they 

are easily accessible (U. S. Atomic Energy Commission and U. S. 

Geol. Survey, 1951, p. 94-102). As with other ores, we might apply 

the rule of thumb that if a metal can be recovered as a byproduct of 

another constituent its concentration need only be one-tenth as much 

as it would need to be otherwise. As a rough generalization, we may 

thus consider that deposits that might yield uranium as a byproduct 

need contain only about 0.01 percent uranium under present economic 

conditions in this country.

Uranium is concentrated by a wide variety of processes in a wide 

variety of deposits (Bain, 1950; Everhart and Mathez, 1951; C. F. 

Davidson, 1951; Everhart, 1954a, 1954b; Nininger, 1954). Like other 

metals, uranium is transported and acted upon by igneous, weathering, 

and sedimentary processes, but it is also concentrated at times by each 

of these processes. This diversity of origin and occurrence of uranium 

is one of the fascinating features of uranium geology, but it makes 

the description and classification of uranium deposits difficult. Thus, 

on the one hand, the various types of deposits grade into one another so 

subtly and completely that it is difficult to segregate them descriptively ; on the other hand, positive criteria by which one may identify 

the process responsible for the formation of many individual deposits, 

including some of the more important ones, are lacking or may not 

have been recognized. For these reasons, the various types of uranium 

deposits are grouped here simply by the type of rock in which the 

uranium is found.

UBANIFEBOUS IGNEOUS BOCKS

Nearly all igneous rocks contain traces of uranium (Evans and 

Goodman, 1941), and moderate concentrations occur, along with many 

other elements enriched in pegmatites (Coats, TEI 330, p. 87 x ), in 

some silicic types, and particularly in late-stage differentiates of alkalic or silica-alkalic magmas (Larsen, TEI 490, p. 255-259). Few 

of the silicic rocks contain more than 0.001 to 0.002 percent uranium, 

but some of the silica-alkalic rocks, such as the pyrochlore-bearing 

albite-riebeckite granites of Nigeria (Mackay and Beer, 1952) and the

1 U. S, Geological Survey reports TEI 330, TEI 390, TEI 440, and TEI 490 include progress reports on nearly every current Survey project to the field of uranium, geology. For 

the sake of brevity, these reports are listed only once in the bibliography, with the U. S. 

Geological Surveyi shown as author, rather than by the author of the various: sections to 

which reference will be made. References to individual sections will be given as above.
SEARCH FOR URANIUM IN THE UNITED STATES 5

quartz-bostonite dikes in the Colorado Front Kange (Phair, 1952), 

contain 0.005 to 0.02 percent. Among the volcanic rocks, the glassy 

phases seem to be most uranif erous (J. A. S. Adams, written communication, 1953).

The uranium in some of the igneous rocks is mainly in accessory 

minerals like pyrochlore, xenotime, monazite, zircon, sphene, and 

apatite (Larsen and others, 1952; Larsen, TEI 490, J>. 255-259), some 

of which might be concentrated and recovered by mechanical means. 

In others, however, an appreciable amount is in an acid-soluble form 

(Hurley, 1950; C. F. Davidson, 1951; Harrison Brown and others, 

1953) that might be recovered by leaching. The potential tonnage of 

uranium in igneous rocks, particularly the plutons, is enormous.

TJEANIUM-BEARING PEGMATITES

Many granitic pegmatites contain minor amounts of uraninite and 

other radioactive minerals (Page, 1950; Lang, 1952). According to 

Page, uraninite is closely associated with muscovite and biotite; betafite with biotite; euxenite and monazite with beryl; and samarskite 

with columbite and fergusonite. Calcite and calcite-fluorite pej^matites in the Grenville region of Ontario also contain minor amounts of 

uraninite (Ellsworth, 1932), and Lang (1952, p. 15) reports a uranium-bearing diorite pegmatite in the Northwest Territories. Some 

pegmatite dikes contain spectacular crystals of uranium minerals!, but 

few have minable tonnages that contain more than 0.01 percent of 

uranium. Recently, however, a minable uraiiinite-bearing pegmatite 

was discovered in the Colorado Front Eange that appears to contain 

about 0.1 percent uranium (Sims, TEI 490, p. 138).

Uraninite-bearing migmatite rocks have been found recently in the 

Charlebois Lake district (Mawdsley, 1952) and other areas in Saskatchewan (Lang, 1952). Large volumes of some of the migmatite 

rock contain 0.01 percent or more of uranium.

HYDBOTHEKMAL VEIN DEPOSITS

Of the hydrothermal vein deposits, three overlapping types are the 

most important: nickel-cobalt-native silver-pitchblende veins (Bastin, 

1939; Everhart and Wright, 1953); pyrite-galena-pitchblende veins 

(Everhart and Wright, 1958); and uranif erous fluorite veins (Wilmarth and others, 1952). A fourth type, high-temperature uraniumtitanate veins (Nininger, 1954, p. 55-56; Pabst, 1954), and a fifth, 

high-temperature uraninite veins (Stevenson, 1951) may be mentioned 

also, though they are not common.

The nickel-cobalt-silver-pitchblende veins may contain important 

amounts of several base and precious metals, chiefly copper, nickel,

335911° 55 2
CONTRIBUTIONS TO THE GEOLOGY CF URANIUM

and

deposits

cobalt, silver, lead, and bismuth. They are 

carbonate than a quartz gangue, and commonly 

tary and volcanic host rocks. The pyrite-ga 

may contain minor amounts of lead, copper, 

but consist chiefly of pitchblende, galena, qua 

rite; felsic intrusives are generally the host ro< 

monly contain conspicuous hematite stains, 

either type, though it is more abundant in th 

blende veins, and it forms the chief mineral in t 

veins. The uranium in some of the latter 

blende grains disseminated in the fluorite, but 

mineral has been recognized. The nickel-cobalt 

the Great Bear Lake, Canada (Kidd and Hay 

others, 1950), Joachimsthal, Czechoslovakia 

Shinkolobwe, Belgian Congo (Thoreau and Te 

are examples, have been by far the most import 

of the past (Merritt, 1949). They have larg( 

contain more than 0.1 percent of uranium, 

uranium ores that yield large tonnages containing 

of uranium. The pyrite-galena-pitchblende 

Urgeirica, Portugal (Everhart and Wright, 

Saskatchewan (Robinson, 1950), districts are t 

amples, generally yield smaller tonnages of ore 

percent of uranium. The uraniferous fluorite 

less than 0.1 percent of uranium.

When oxidized, the vein deposits of uranium 

secondary uranium minerals like autunite, 

ingerite, either formed in situ or deposited in 

nearby (Stugard, and others, 1952). Secondary 

common. The weathering process tends to di 

the lodes, rather than to concentrate it furthe 

deposits, therefore, are less uraniferous than 

they were derived. They generally contain

and

to

less

uranium, and in some the uranium may be 1< 

leaving a residual radioactivity due mainly 

of the more insoluble disintegration product 

1953). Such radioactivity is of interest becaui 

sfble presence of higher grade deposits at deptl

REPLACEMENT DEPOSIT!

Disseminated replacement deposits of uranium 

vicinity of pitchblende veins, but other replacement deposit: 

Uranium-bearing thorianite replaces metamorphosed

more likely to have a 

occur in metasedimenena-pitchblende veins 

several other metals 

tz or jasper, and py- 

;ks. Both types comluorite may occur in 

i pyrite-galena-pitchle uraniferous fluorite 

occurs as pitchin others no uranium

-silver veins, of which 

ock, 1935; James and 

(Zuckert, 1926), and

 donck, 1933) deposits 

,nt uranium producers 

tonnages of ore that 

they are the only 

0.5 percent or more 

veins, of which the 

953), and Goldfields, 

le most important exthat contain 0.1 to 0.5 

eins generally contain

are characterized by 

torDernite, and schroeckcracks in other rocks

enrichments are un- 

,perse the uranium in 

r; most oxidized vein 

;he lodes from which 

ss than 0.2 percent of 

ached out altogether,

the lagging behind

(Phair and Levine, 

e it indicates the posare common in the 

are rare, 

trachyte near
SEARCH FOR URANIUM IN THE UNITED STATES 7

Birch Island, British Columbia (F. C. Armstrong, written communication, 1953). Pitchblende replaces pre-Cambrian carbonaceous slate 

and schist in the Bum Jungle district of Australia (Sullivan and 

Matheson, 1952), pre-Cambrian Franklin limestone in Warren 

County, N. J., and the upper Jurassic Todilto limestone at Grants, 

N. Mex. (Towle and Kapaport, 1952). The origin of the deposits 

in the Todilto is uncertain, but the association of uranium with fractures and replacement deposits of fluorite (Bucher, 1953) implies a 

hydrothermal origin. Carbonatites in the Halliburton-Bancroft area 

of Ontario contain pyrochlore of replacement origin. Pitchblende, 

carnotite, and other uranium minerals replace logs, clay galls, and 

bones in sandstone ores; but, as is discussed more fully below, the 

origin of such deposits is in dispute.

TUFF AND TUFFACEOUS SEDIMENTS

Many tuffs and tuffaceous sedimentary rocks of Tertiary age in 

the Western United States contain autunite, carnotite, and other secondary minerals on fractures and bedding planes (Hewett, 1923,1925; 

Walker, 1953; Walker and Levering, 1954). Perhaps some of these 

deposits have a hydrothermal origin (Duncan, 1953b), but it seems 

more likely that the uranium has been derived from the enclosing' tuffs 

(which may contain 0.001 to 0.002 percent uranium) during the course 

of their devitrification, as suggested by Gill and Moore (1955) for 

the carnotite-bearing tuffaceous sandstone recently found in South 

Dakota. The uranium in such deposits is irregularly distributed. 

With a few exceptions, known occurrences are small, and minaide 

thicknesses generally contain less than 0.2 percent of uranium.

TJRANIFEROUS COAL AND ASSOCIATED CAEBONACEOTJS SHALE

Most coal and associated carbonaceous shale beds are essentially 

nonuraniferous. In recent years, however, several coals and carbonaceous shales have been found in the Western States that contain 

0.005 to about 0.1 percent of uranium, and in the summer of 1954 important, minable deposits containing 0.2 percent or more were found in 

northwestern South Dakota and adjacent areas (Gill, TEI490, p, 149- 

155). The uranium in the lower grade deposits seems to be in organo-uranium compounds or complexes, perhaps uranyl humates 

(Breger and Deul, TEI 330, p. 121; TEI 490, p.. 171; Schopf and 

Gray, 1954) and is irregularly distributed in the coal. The largest 

amounts seem to be in carbonaceous shales, high-ash lignites, and subbituminous coals. Secondary minerals, such as meta-autunite and 

metatynyamunite, are found in some of the higher grade deposits.
8 CONTRIBUTIONS TO THE GEOLOGY OJ URANIUM

basie

Denson, Bachman, and Zeller (work describe* I 

1952) found* in their studies of the South Dakoti 

places only the first lignite bed just below the 

formation, which unconformably overlies the coal 

is uraniferous. Traced laterally, a given bed, 

is the first bed below the unconformity at the 

is found to be nonuraniferous down dip where it 

lignite higher in the section (Gill, TEI-390, p. 

uranium content of a given layer is generally 

Concentrations of uranium also are found whe 

tersected by faults or through-going joints, 

evidence, Denson, Bachman, and Zeller concluded 

in the lignite was derived from the White Riv 

overlying Miocene Arikaree formation by perco 

Because the White River formation contains al 

known to be slightly uraniferous in some other 

lated that the uranium was derived from the 

volcanic ash. Application of this hypothesis t( 

deposits has given rewarding results in several areas

In view of the fact that the uranium can b 

from uranium-bearing solutions (Moore, 1954), 

tuff for example, decaying arkosic rocks or e 

lutions might yield uranium to lignites 

the uranium in a coal bed cut by a shear zone at 

at the foot of the Colorado Front Range is thoi 

rived from hydrothermal solutions (L. R. Page, 

1952).

in Vine and Moore,

lignites that in most 

Oligocene White River 

-bearing series there, 

uraniferous where it

of the White River, 

s overlain by another 

131). Moreover, the

highest at the top. 

e lower beds are inFrom this and other 

that the uranium 

5r formation and the 

ating ground waters, 

undant volcanic ash, 

ocalities, they postudecomposition of the

the search for other

URANIUM-BEARING CONTINENTAL SANDSTONE AND 

CONGLOMERATE

Uranium-bearing continental sandstones and ( 

the largest known uranium source in this country 

known in the world the Colorado Plateau and 

South Africa, respectively. The subsequent discussion 

on deposits in these districts.

The Colorado Plateau deposits have been traditionally 

tite deposits because of the brightly colored camotite 

dized minerals that characterize them near the surface 

1950) i Recently, however, deeper mining and 

that carnotite is only a shallow oxidation product 

of pitchblende and other dark uranium and vanadium 

characterize many of the deposits at depth (Rai 

and others, 1952; Weeks and others, 1953; Weeks 

1954). These minerals, along with hydromica,

adsorbed by lignite 

other sources besides 

en hydrothermal soThus,

the old Leyden mine 

ight to have been deoral communication,

and other adsorbents.

onglomerates include 

and the largest 

the Witwatersrand of 

focuses mainly

called carnoand other oxi- 

(Fischer, 1937, 

drilling have shown 

of the weathering 

minerals that 

or, 1952; Rosenzweig 

and Thompson, 

pyrite, and other sul-
SEARCH FOR URANIUM IN THE UNITED STATES 9

fides, fill pore spaces in tuffaceous, arkosic, and quartzose sandstones 

and conglomerates and also replace clay galls, logs, and other wood 

fragments. In addition to woody carbonaceous matter, some of the 

deposits contain uraniferous asphaltic pellets and lenses (Gott and 

Erickson, 1952) and a harder form of uraniferous "carbon," insoluble in organic reagents (I. A. Breger, oral communication, 1953),: 

Uranium, vanadium, copper, or silver may be the dominant metal in 

the deposits, and minor amounts of molybdenum, cobalt, nickel, lead, 

zinc, selenium, and arsenic are also present in many of them (Riley 

and Shoemaker, 1952; Shoemaker, ETI-490, p. 58-78). Quartz 

overgrowths are abundant on the sand grains, particularly along the 

edges of the ore bodies and in the wall rocks (Waters and Granger, 

1953). In some deposits, the ore seems to be localized near or to replace carbonate cement (Sharp and others, TEI-440, p. 64; Gott and 

others, TEI-440, p. 67).

The ore deposits are tabular masses, generally elongated in the 

direction of the long axes of the sandstone or conglomerate lenses in 

which they occur. The lenses are interpreted as fossil stream-channel 

deposits. Near the ore, associated mudstone lenses are generally 

green or gray instead of red; and in the oxidized deposits, the sandstone in many places has a freckled appearance instead of its usual 

uniform reddish-brown color (Weir, 1952). Ore has been produced 

from about 20 formations on the Plateau, ranging in age from Permian 

to Tertiary, but the principal sources have been the Triassic Moenkopi, 

Shinarump, and Chinle formations, the Jurassic Entrada, Summerville, and Morrison formations (including the Salt Wash, Todilto, 

Eecapture, Westwater Canyon, and Brushy Basin members of the 

Morrison formation) (Riley and Shoemaker, 1952; T. W. Mitcham, 

unpublished chart, 1954; Finch, 1955). Over large areas, however, 

known minable deposits are restricted to one favorable zone or layer, 

a few feet or a few tens of feet in thickness. Within this zone, the 

distribution of ore is confined mainly to the channel sandstones and, 

within them, is localized in zones where their thicknesses increase, 

where mudstone partings or fine debris are present, and at channel 

bends and other places where logs and other carbonaceous matter 

are abundant (Weir, 1952; Stokes, 1952, 1954; Finch, 1953). The 

deposits commonly extend across the bedding to form concretionlike 

structures called "rolls" by the miners. In a few areas the deposits 

are localized along joints or faults (Coffin, 1921, p. 162, 170, 21£; 

Benson and others, 1952; Waters and Granger, 1953, p. 10), and it has 

been suggested (E. V. Eeinhardt, talk at San Francisco meeting of the 

American Mining Congress, Sept. 21, 1954) that the rolls also represent ore disseminated from solutions moving along a joint, the
10 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

position of which is now obscure. Many of the deposits in the Black 

Hills seem to be localized on structural terraces (Gott and others, 

TEI-440, p. 66). Despite these exceptions, the sandstone ores as a 

rule show no obvious relation to local structures other than the sedimentary ones. In contrast to most of the deposits in sandstone and 

conglomerate, those in the Todilto limestone seem to be concentrated 

along fractures (Bucher, 1953; Gilkey, 1953).

The regional distribution of the deposits has been correlated both 

with tectonic and with sedimentary features. Within any given 

formation, the deposits are most conspicuous in areas where channel 

deposits are well sorted but intertongue or are interbedded with 

mudstones (Craig and others, 1951; D. F. Davidson, 1953a; Masters, 

1953; Gott and others, TEI 440, p. 66; Mullens and Freeman, 1954), 

or are near the margins of deposition of the formation (Mullens, TEI 

390, p. 23; Finch, 1953). The host sediments have a high mean 

permeability, are characterized by large variations in permeability, 

and are only fair to poor in regional transmissive capacity (Jobin, 

TEI 490, p. 48). In some areas deposits are common in the vicinity 

of (though not adjacent to) the alkalic laccolithic intrusives (Rjley 

and Shoemaker, 1952; Reinhardt, 1952; Shoemaker, written communication, 1951) such as those comprising the La Sal and Carrizzo 

mountains, and in some areas they seem closely related to early 

Tertiary faulting associated with the collapse of salt anticlines (Cater, 

1954; Shoemaker, written communication, 1951). As a result of these 

controls, singly or together, many of the most important deposits of 

the Plateau are clustered together in "mineral belts" that have considerable regional continuity. Of these, the Uravan mineral belt is 

the best defined (Fischer and Hilpert, 1952), but three others have 

been recognized recently in Utah and Arizona (Finch, 1953). Recognition of these belts has aided considerably in exploration for new 

deposits.

Individual deposits on the Plateau range from a few pounds to more 

than a million tons in size. Their uranium content is generally in the 

range of 0.1 to 0.5 percent.

The Witwatersrand ores consist mainly of pyrite, uraninite, thucholite, gold, sericite, chloritoid, and chlorite and minor amounts of 

cobalt, copper, nickel, lead, and zinc sulfides (Young, 1917; Eeinecke, 

1927; Davidson and Bowie, 1951; C. F. Davidson, 1952,1953). These 

minerals are in pore spaces in coarse sandstones and conglomerates, 

the grains of which contain abundant quartz overgrowths.

The ore-bearing strata have considerable lateral continuity, but ore 

tends to be concentrated in elongated paystreaks, which are roughly 

parallel but form a braided pattern, interpreted by Leopold Reinecke
SEARCH FOR URANIUM IN THE UNITED STATES H

and Douglas Johnson (Keinecke, 1940, p. 127) as channels on a gigantic 

piedmont alluvial fan. The Witwatersrand system is about 25,000 

feet in thickness, but ore is confined to a dozen or so thin conglomerates, mostly in the upper half of the system (McLean, 1954). Of 

these, only one or two are prominent ore-bearers in any given area 

(Reinecke, 1940, p. 120). Within these layers ore seems most 

abundant where the conglomerates are thickest and where the pebbles 

are coarsest and best sorted.

Small, scattered intrusives of a variety of types have been reported 

from the Rand. They range in composition from basic to acid to 

alkalic types, but the most common are altered diabase dikes. Few 

have any evident relation to ore. Thin quartz veinlets are not uncommon, and some of them contain gold (Young, 1917"), and one high 

in the system contains pitchblende (C. F. Davidson, 1953). Such 

phenomena, however, comprise a minor part of the Rand picture. 

Likewise the ores seem unrelated to fractures and faults, although a 

few faults are mineralized where they cross ore-bearing horizons.

The Witwatersrand ores have greater lateral continuity and are 

lower in uranium content than the Plateau ores. The ores in the two 

fields differ somewhat in the assemblage of dominant metals chiefly 

the presence of gold and the absence or paucity of vanadium, copper, 

and silver in the Rand ores and the reverse with respect to the Plateau 

ores. Neverthless, the descriptions above reveal that the deposits of 

the Witwatersrand and the Colorado Plateau have many features in 

common. The origin of both ores has been hotly debated for decades 

and is still in dispute. Essentially the same hypotheses of origin, or 

variants of them, have been presented for ores in both regions: (1) 

placer concentration of the chief ore metals, followed by recrystallization and some redistribution of them (Bain, 1952; Young, 1917; 

Reinecke, 1927); (2) precipitation from solution at time of deposition 

of enclosing sediments, followed by recrystallization and some redistribution (Fischer, 1937; Gruner, 1951; MacGregor, 1953); (3) 

derivation from volcanic tuffs or other sediments associated with the 

ore, as the result of weathering and ground-water action, after the 

enclosing rocks were deposited (Lindgren, 1913, p. 368; Koeberlin, 

1938; Proctor, 1953; Gruner, 1954); (4) derivation from petroleum 

or petroleum source beds (Gott and Erickson, 1952); and (5) precipitation from hypogene solutions, possib]y injected into circulating 

ground waters, after the enclosing rocks were deposited (Dodd, 1950; 

Waters and Granger, 1953; Cater, 1954; Graton, 1930; Davidson, C. F., 

1953; Shoemaker, written communication, 1951; Kerr and Lapham, 

1954).
12 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The supporters of the syngenetic and penesyngenytic hypotheses 

Include most of the exploration geologists in both areas who are best 

acquainted with the habits of the ores. This attests to the close relation the ores bear to sedimentary rather than to tectonic and igneous 

features. The epigeneticists admit this relationship but believe that 

these sedimentary features merely controlled the movement of ore 

solutions and the deposition of metals derived from other sources after 

the enclosing rocks were deposited. Without reviewing the arguments 

for any of these hypotheses it may suffice to say that recent age determinations of the Plateau ores show that the uranium there was deposited during the Late Cretaceous or early Tertiary, long after the 

deposition of the host rocks (Stieff, Stern, and Milkey, 1953). Very 

likely, therefore, the ore was derived from dispersed sources in the 

sedimentary pile or from hypogene solutions. According to Stieff, 

Stern and Milkey, the first possibility appears less probable because 

in such a redistribution, the common lead found in the ores would 

have had to be transported and redeposited with, the uranium and the 

previously formed radiogenic lead carried away or deposited elsewhere.

Regardless of the origin of the sandstone ores, the knowledge already 

gained about their habits not only helps guide exploration for ore in 

known districts but aids in the search for new districts as well. Basic 

to the exploration for individual deposits in known districts are the 

facts that (1) the deposits in a given area are confined to certain zones 

and (2) within these zones, to the vicinity of the boundaries between 

permeable and impermeable parts. Of value in the search for new 

districts are the facts that, with few exceptions, the deposits have 

been found only in lenticular elastics, generally of fluviatile origin, 

and, as C. F. Davidson (1953) points out, the old granitic rocks over 

which these deposits lie in several districts "have undergone domal 

uplift since the covering blanket of sediments was deposited, due presumably to intrusion of 'younger' granites which are not always 

exposed."

TJRANIFEROUS ASPHALTITE AND RELATED SUBSTANCES

Uranium, in places in the form of free, evenly disseminated grains 

of uraninite, commonly occurs in asphaltites; in hard, lustrous hydrocarbons called thucholite (Ellsworth, 1928); and in similar appearing 

substances, here referred to as "asphaltite," that contain little or no 

hydrogen (I. A. Breger, oral communication). These substances occur 

in some uraniferous veins and pegmatites, and in many sandstone 

deposits and certain reservoir rocks in oil fields (Davidson and Bowie, 

1951; Faul and others, 1952; Gott and Erickson, 1952; Barthauer and 

others, 1953). Davidson and Bowie (1951) and others believe that the
SEARCH FOR URANIUM IN THE UNITED STATES 13

thucholite in many pegmatites, veins, and in the Witwatersrand originated from the polymerization of migrant natural gases by radiation 

from uranium-bearing minerals already in those deposits. On the 

other hand, the facts that "asphaltite" occurs in oil-stained pore spaces, 

that the uranium is so uniformly distributed that it must have been 

in the organic matrix while the latter was in a fluid state (Pierce, 

TEI 490, p. 274), and that the "asphaltite" contains an assemblage 

of other metals similar to that found in smaller concentrations in oil 

in nearby pools (Erickson and others, 1953) led Gott (TEI 390, p. 257) 

to the conclusion that the uraniferous "asphaltite" in several occurrences in the United States is a residual petroleum, not a polymerized 

natural gas. If this is true, it is possible that petroleum fluids may 

transport uranium to sites of ore deposition (Gott and Erickson, 1952), 

particularly in sandstone-type deposits. The uranium content of 

crude oils ranges from a fraction of a part per billion to a few thousand parts per billion (Erickson and others, 1953; Breger and Deul, 

TEI 490, p. 171). According to Breger and Deul most of it seems 

to be in asphaltenes.

URANIUM DEPOSITS IN LIMESTONE

Most carbonate rocks are nonradioactive (Beers and Goodman, 

1944), and the few that do contain uranium are probably of diverse 

origins. The only limestones that have yielded commercial amounts 

of uranium are the Upper Jurassic Todilto limestone near Grants, 

N". Mex., and one at Tyuya Muyun, Russia. As mentioned previously, 

the Grants deposits seem to be replacements along fractures, are associated with fluorite, and are probably of hydrothermal origin. The 

Tyuya Muyun deposit is also associated with fractures (Mninger, 

1954, p. 80). Carnotite and uranium-bearing fluorite are sparsely disseminated in limestone adjacent to a thin uraniferous black shale in 

the Spergen limestone of Mississippian age in Missouri (Muilenberg, 

1949) and are thought to have been leached from the black shale by 

ground water (Gott and others, 1952). Alternatively, it seems possible that the uranium in both the limestone and the shale, as well as the 

fluorite, were derived from hypogene solutions. Small amounts of 

uranium in slightly petroliferous and phosphatic clay galls in the 

Cambrian Milton dolomite of Keith (1923) in Vermont and in algal 

limestone in the Tertiary (Upper Eocene) Uinta formation in Utah 

may be syngenetic (Gott and others, 1952). Uranium in algal, chalcedonic limestone in the Miocene ( ?) Browns Park formation at Miller 

Hill, Wyo., appears to be most concentrated where the limestone is 

fractured, and brecciated and to have been derived from adjacent 

tuffaceous sediments (Vine and Prichard, TEI 390, p. 91).

335911° 55 3
14 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIFEROUS ALUMINUM PHOSPHATE DEPOSITS

Uraniferous aluminum phosphate minerals originate as a result of 

the weathering of phosphorite in a tropical or subtropical climate. 

Examples are those in Florida (Cathcart and others, 1953), Senegal 

(Guntz and Arene, 1953; Capdecomme, 1953), and Nigeria (Davidson 

and Atkin, 1953). The form of the uranium in these deposits is 

unknown. A few particles of autunite have ben identified by Z. A. 

Altschuler and C. E. Boudreau in the Florida deposits (written communication, 1949), but the bulk of the uranium seems to be in the 

phosphate minerals, where it probably substitutes for calcium.

In Florida, the aluminum phosphate deposits compose the upper 

(near surface) part of the Pliocene Bone Valley formation. The 

aluminum phosphate zone averages about 6 feet in thickness but 

ranges from less than 1 foot to 60 feet in thickness. It is generally 

thickest on topographic highs. From 70 to 80 percent of the zone 

consists of quartz sand; the remainder is composed of minus 150-mesh 

particles of wavellite, crandallite (pseudowavellite), carbonate-fluorapatite, and kaolin easily separable from the sand by washing. Crandallite is most abundant in the lower part of the zone, and wavellite 

in the upper (Altschuler, TEI 330, p. 171-174). The uranium content of the fine fraction ranges from 0.01 to 0.02 percent or more and is 

highest near the base of the zone where crandallite first appears 

(Altschuler, TEI 330).

The aluminum phosphate deposits in Florida, and presumably the 

other fields as well, contain enormous tonnages of uranium. In 

Florida this material is now stripped as overburden and discarded, 

but because the fines contain 15 to 30 percent of P2O5 and a similar 

amount of A12O3 , it is possible that this material may eventually be 

utilized. If so, uranium probably will be recovered as a byproduct of 

phosphate or alumina production, or both.

URANIFEROUS BLACK SHALE

Many marine bituminous black shales contain 0.005 to 0.02 percent 

of uranium (Beers, 1945; Russell, 1945; McKelvey and Nelson, 1950; 

Gott and others, 1952). Examples include the Upper Cambrian 

alum shale of Sweden (Westergard, 1944a, 1944b) and the Chattanooga shale of Tennessee (Conant, 1952; Swanson, 1953). The uranium in these shales is in acid-soluble form, but it probably does not 

occur in a distinct uranium mineral. In the Chattanooga shale it is 

concentrated in pyrite-organic-matter complexes (Bates and others, 

1954). The largest amounts of uranium (as much as 0.5 percent) 

in the alum shale are in nodules and lenses of dark bitumen, called 

kolm. Though the megascopic nodules of kolm do not contain an
SEARCH FOR URANIUM IN THE UNITED STATES 15

appreciable proportion of the total uranium in the alum shale, the 

uranium content of the shale increases as the total equivalent thickness of kolm increases (Josef Eklund, oral communication, 1952). 

Microscopic kolm-like particles are also present, and though their 

uranium content and abundance is unknown, it is possible that the 

increase in the amount of megascopic kolm may reflect an increase 

in megascopic kolm. If this is true, the microscopic kolm-like particles may be the uranium carriers in the shale itself. In the Miocene nodular shale in California and the Pennsylvanian Cherokee 

shale equivalents in Oklahoma the uranium may occur both in phosphate and carbonaceous mattesr (Whitehead, 1952). Brown and Keller (1952) report that the uranium in a black shale in the Spergen 

limestone of Mississippian age in Missouri is in the fine clay fraction, not in the organic matter.

Though nearly all marine black shales contain slightly more uranium than the average sedimentary rock, only a small percentage of 

them contain more than 0.005 percent. The distinguishing characteristics of the uraniferous shales are not known in full, but it can 

be said at least that as a group they are sapropelic, rather than 

humic. They are highly carbonaceous (Burton and Sullivan, 1951) 

and bituminous, high in sulfides, noncalcareous, generally somewhat 

phosphatic (or contain phosphatic nodules in the section); they accumulated slowly (their net accumulation apparently proceeded at the 

rate of only 1 foot per 200,000 to 1,000,000 years, compared to 1 foot 

per 700 years for other shales), almost certainly under anaerobic 

conditions. The richest parts of the alum shale in Sweden were 

deposited in embayments in the Late Cambrian sea (Josef Eklund, 

oral communication, 1952), and the uranium in the most uraniferous 

shale known in this country, the Permian (?), Pennsylvanian, and 

Mississippian (?) Hartville formation in Wyoming, seems also to 

have been concentrated near the margin of deposition of that shale. 

Older shales, as a group, appear to be more uraniferous than younger 

shales (Russell, 1945).

Very likely the uranium in black shales is extracted from the sea 

by plankton, either alive or dead. Some marine algae concentrate 

minor metals (Black and Mitchell, 1952) and dead plankton is reported to be an effective adsorbent for uranium (E. W. Steel and 

E. F. Gloyna, written communication, 1953) and other metals (Harvey, 1945; Krauskopf, 1952)., The reason uranium is more concentrated in some black shales than in others, however, is unknown. It 

has been suggested that high concentrations may form in restricted 

areas bordering granitic terranes (Glebov, 1941; Str0m, 1948), but 

this alone does not explain the marked differences often found in the
16 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

uranium content of two adjacent layers nor the uranium content of 

such widespread formations as the Chattanooga shale. It seems more 

likely that the controls have to do with the pH, redox potential, 

and other physicochemical factors that affect the precipitation of 

uranium in the sea. Because some uraniferous shales have a demonstrable capacity to adsorb uranium (Tolmachev, 1943) and because 

uranium is irregularly distributed in some nonmarine carbonaceous 

shales, where it appears to have been adsorbed from percolating 

waters, it is not unlikely that uranium can be adsorbed by black shales 

long after their deposition, or at least until compaction materially 

reduces their perviousness. The uniformity of the distribution of 

uranium in the marine shales suggests, however, that this has not 

been the dominant process in the concentration of uranium in them. 

Black shale formations contain some of the world's largest uranium 

resources. Despite their low uranium content they may eventually 

yield uranium as a coproduct of the production of oil and sulfur, 

potassium, phosphate and minor metals.

URANIFEROUS PHOSPHORITE

Marine phosphorites commonly contain 0.005 to 0.03 percent of 

uranium (McKelvey and Nelson, 1950; Davidson and Atkin, 1953). 

Important examples include the phosphorites in the Permian Phosphoria formation in the Western States (Thompson, 1952, 1953), the 

Pliocene Bone Valley formation of Florida (Cathcart and others, 

1953), and the Upper Cretaceous-Lower Eocene deposits of North 

Africa (Hebert, 1947; Guntz, 1952; Lenoble and others, 1952). Although traces of secondary uranium minerals have been found in the 

Moroccan (Arambourg and Orcel, 1951) and Phosphoria deposits, 

the uranium in the phosphorites seems to be mainly in the mineral 

carbonate-fluorapatite, where it probably substitutes for calcium 

(Altschuler and others, 1954). The uranium content of the rock 

generally increases as the phosphate content increases, but deposits 

or beds richest in phosphate are not necessarily richest in uranium, 

and in the Phosphoria formation the most uranif erous samples known 

are not the most phosphatic. Some of the departures from the general rule that uranium increases as the P2O5 content increases may 

be due to the inverse relationship uranium bears to the CO2 content. 

In the Phosphoria formation the uranium content generally falls 

off sharply as the CO2 content rises above 2 percent, regardless of 

the phosphate content. It is interesting to note that the weakly 

phosphatic black shales in the Phosphoria contain little or no uranium.

Phosphatic nodules in certain black shales, such as those of Pennsylvanian age in Kansas and Oklahoma (Runnels and others, 1953),
SEARCH FOR URANIUM IN THE UNITED STATES 17

are uraniferous, generally more so than the enclosing black shale. 

Phosphatic nodules on the present sea-bottom ®ff the coast of 

California contain about the same quantity of uranium as older phosphorites (Emory and Dietz, 1950). Some fossil bones and teeth are 

also uraniferous and the uranium content seems to be greater in older 

than in younger specimens (Jaffe and Sherwood, 1951). In the 

Phosphoria formation, however, beds composed mainly of phosphatic 

shells, fish scales, and other organic fragments are less uraniferous 

than other kinds of phosphatic materials.

The concentration of uranium in phosphorite takes place by ion 

exchange (Neuman and others, 1949 a, b, c; Moore, 1954) or other 

chemical adsorption processes. It may thus be deposited at essentially the same time as the phosphorite or at any "time thereafter. 

The uniform distribution of uranium in the marine phosphorites, 

as well as the presence of uranium in phosphorite on the present sea 

bottom, suggests that the uranium in most of those deposits is adsorbed from the sea water at the time of deposition or before burial. 

The increase of the uranium content of bones and teeth with age 

indicates that an appreciable part of the uranium in them is adsorbed 

from ground-water solutions, possibly long after the bones were deposited. The fact that the uranium content of phosphorite particles 

in the Pliocene Bone Valley formation of Florida is appreciably 

higher than in the underlying Hawthorne formation, from which the 

Bone Valley was derived by submarine reworking of the Hawthorne 

and its weathered debris, suggests that the Bone Valley particles 

adsorbed more uranium from sea water during their second exposure 

to it.

In summary, the uranium content of phosphorite deposits is not 

wholly predictable, but as a general rule appreciable amounts are 

found only in noncalcareous marine phosphorites that contain more 

than 25 percent P2O5 (in the rock or in the concentrate of phosphatic 

particles). Residual deposits derived from the weathering of phosphatic limestones are not likely to be appreciably uraniferous unless 

they have been exposed later to sea water or other uranium-bearing 

solutions.

URANIFEROUS PLACERS

Because the common uranium minerals are relatively soft and are 

soluble in the zone of weathering, most uranium minerals are not concentrated in placers (C. F. Davidson, 1953). Exceptions are found, 

however (Steacy, 1953), particularly in placer concentrations of some 

of the accessory uranium-bearing minerals of igneous rocks and 

pegmatites for example, monazite, zircon, and the "radioactive 

blacks" euxenite, brannerite. uranotliorite, samarskite, and ferguson-
18 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ite which contain variable, but in places appreciable amounts of 

uranium. The relatively small size of the known placer deposits, 

particularly the "radioactive blacks," combined with the refractory 

nature of these uraniferous minerals, have not made them important 

sources of uranium anywhere.

SUMMARY OF THE GEOLOGY OF URANIUM

From the previous description of the various types of uranium deposits, it may be seen that uranium is a chemically active and mobile 

metal. In magmatic processes some of it combines with other elements 

and crystallizes mainly as accessory minerals, particularly in latestage differentiates such as silicic and silica-alkalic igneous rocks and 

pegmatites,, Some, however, is concentrated with other metals in 

late-stage solutions and is transported away from the magma by 

hydrothermal solutions and deposited, generally as pitchblende, in 

veins and possibly in pervious or carbonaceous sedimentary formations.

During the weathering of these primary concentrations, insoluble 

minerals (mainly the accessory minerals of igneous rocks and pegmatites) are freed from their matrix and some of them may eventually 

be concentrated in placers. However, most of the primary uranium 

is oxidized, taken into solution in the form of sulfates, carbonates, 

and other relatively soluble salts, and ultimately transported to the 

sea, either in solution or adsorbed on clay and organic matter (Fredrickson, 1948). The dispersal of primary concentrations may be 

interrupted by the formation of secondary concentrations along fractures and in cavities in almost any kind of rock where uranium salts 

are precipitated because of evaporation, or changes in the pH or 

redox potential of the ground-water solution. Uranium may also be 

adsorbed by carbonaceous materials peat, certain coals, carbonaceous shale and plant fossils or by phosphatic materials such as 

bone, phosphorite, or monazite.

Holland and Kulp (1954) reason that the bulk of the uranium 

brought to the sea in solution is deposited on the shelves, probably 

because it is removed by organisms. Available data are not adequate 

to prove or disprove this hypothesis, but at least it is true that the 

highest concentrations in sediments are formed on the shelf or near 

its margin, probably as the result of the upwelling of cold, deep 

carbon dioxide-rich waters. These waters, rich in phosphate and 

other nutrients, not only nourish large growths of plankton and other 

organisms (Hentschel and Wattenburg, 1930) whose death and decay 

may produce anaerobic bottom conditions (Brongersma-Sanders,
SEARCH FOR URANIUM IN THE UNITED STATES 19

1948), but they are the source of the phosphate and the minor metals 

deposited in this environment (McKelvey arid others, 1953).

The association of uranium with carbonaceous materials deserves 

special summary. Carbonaceous matter is associated with many of 

the types of uranium deposits already mentioned even with some of 

the vein and pegmatite deposits, as well as with many asphaltites, 

isolated carbonized fossil plants, sandstone deposits, and many petroleums. In addition, radioactive decay products of uranium are 

found in many natural gases and oilfield brines (Gott and Hill, 1953). 

The significance of this association is not completely known. It 

seems definite that some carbonaceous matter is in some way a precipitator of uranium (Tolmachev, 1943; Frederickson, 1948; Moore, 

1954) and that some plants concentrate uranium, at least in small 

amounts (Cannon, 1952). In addition, it is possible that radiation 

stemming from uranium in sediments generates petroleum from associated organic matter (Whitehead and others, 1951), that it also 

polymerizes migrant methane into the carbonaceous substances found 

in some pegmatite and vein deposits (Grip and Odman, 1944; Davidson and Bowie, 1951), and that petroleum fluids may sometimes 

transport uranium to sites of ore deposition (Gott and Erickson, 1952). 

In some places, the association may simply indicate that uranium compounds are more stable under reducing conditions such as generally 

prevail in environments where carbonaceous matter is also stable.

The progressive migration of uranium from its primary concentrations to sedimentary rocks involves a progressive dispersal of 

uranium from each phase of the cycle to the next. This is reflected 

in a change, roughly by a factor of five, in the maximum grade of 

uranium of deposits formed during each phase. Thus the uranium 

content of pitchblende deposits ranges from about 0.1 to 1.0 percent; 

that of deposits formed during weathering, from 0.02 to 0.2 percent, 

and that of most sedimentary deposits is less than 0.03.

The relationships described in the uranium cycle have a special 

bearing on prospecting for they constitute the geologic machinery that 

produces a metallogenic province. Thus, in a region in which uranium 

is abundant in igneous rocks, pitchblende deposits may be expected 

also in hydrothermal vein deposits within the igneous rocks or in associated basement rocks, in continental sandstones overlying the 

plutons, and perhaps in carbonaceous rocks also. Secondary uranium 

deposits may be found in volcanic ash, in lignites and carbonaceous 

shales, and in rocks in many other geologic environments. Discovery 

of any one of these types is suggestive of the presence of one or more 

of the other types in the region.
20 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

METHODS OF PROSPECTING FOR URANIUM

The methods used to search for uranium deposits are (1) geologic, 

(2) geophysical, (3) botanical, (4) geochemical and (5) physical exploration. Many uranium deposits, and deposits of other minerals 

too, have been discovered by accident, but unfortunately it is not yet 

possible to systematize an accidental prospecting method!

GEOLOGIC PROSPECTING

Geologic prospecting is based on the recognition of uranium minerals or on the recognition of geologic features commonly associated 

with uranium deposits. This is the method that the amateur uses 

when he picks up a bright-yellow or green mineral, and it is also the 

method that the geologist uses when he stops to examine a quartzhematite vein or a particular type of rock that he knows is commonly 

associated with uranium. Success in geologic prospecting is proportional to the prospector's knowledge of ore habits and guides and 

to his industry, luck, and optimism. It is safe to say that few deposits have been found by pessimists.

GEOPHYSICAL PROSPECTING

The radioactivity of uranium minerals may be detected by use of 

Geiger and scintillation counters (Wright, 1953, 1954a; Brownell, 

1950; Wilson and others, 1954). Their use gives the prospector an 

unusual advantage, for these instruments can detect the presence of 

radioactive minerals even if they are concealed from sight by a few 

inches or so of soil or rock. Geiger counters and scintillation counters 

have been developed in various shapes and sizes, suitable for use by 

the prospector on the ground, for carborne (Nelson, 1954) and airborne (Stead, 1950; Stead and Da vis, 1952) reconnaissance, and for 

drill-hole logging (Faul and Tittle, 1951; DiGiovanni, and others,

1953). The scintillation counter is much more sensitive than the 

Geiger counter and therefore will detect much less intense radioactivity. For this reason, scintillation counters have now largely displaced 

Geiger counters in airborne reconnaissance. Light planes, such as 

those used by the Atomic Energy Commission, are used to search for 

specific deposits in broadly favorable areas (Tavelli, 1951; Foote,

1954). They fly at an altitude of about 50 feet and are equipped with 

scintillation counters that detect almost all abnormal radioactivity 

that field Geiger counters detect on the ground. Larger planes, like 

the Geological Survey's DC-3, are used for quick reconnaissance of 

large regions (Stead, 1950; Balsley, 1952). The Survey's plane is 

flown at an elevation of about 500 feet along traverse lines about a
SEARCH FOR URANIUM IN THE UNITED STATES 21

quarter of a mile apart, and it continuously records both radioactivity 

and magnetic measurements.

Of course, all of these instruments are applied mainly to the* direct 

search for ore, that is, the search for a radioactivity anomaly that 

represents an individual uranium deposit, or an area of above-average 

radioactivity in which ore deposits might be found (Gross, 1952). 

Complications arise, however, from the fact that most of the radioactivity detected comes not directly from uranium itself but from its 

radioactive decay products. These decay products, such as radon 

and radium, sometimes get separated from the parent uranium but 

even then they may reveal the presence of uranium nearby. For 

example, small pips are observable on the gamma-ray logs of barren 

holes drilled down dip from many ore-bodies on the Colorado Plateau 

and therefore can be used in locating the ore itself (Bell and Rogers, 

1950); in addition, the level of radiation in an ore-bearing zone in 

some areas is much higher in the general vicinity of ore than elsewhere (Hinckley, 1952; Teichman, 1952). Similarly, the air in some 

mines is radioactive even though no radioactive minerals are observable in the mine walls (Dunning, 1950), and some natural gases and 

brines are radioactive even though no uranium or thorium deposits 

are known in the reservoir rocks (Gott and Hill, 1953). Such radioactivity is most likely due to the presence of radon, a highly radioactive gas formed as one of the disintegration products of uranium. 

Its presence indicates that uranium may be nearby, though of course 

in unknown quantities. Radioactivity anomalies arising from other 

daughter products of uranium have been found also in alluvium downstream from uranium deposits in South Dakota (R. S. Cannon, 1953) 

and on the Colorado Plateau (Chew, 1954). Like placer gold, these 

dispersed decay products provide useful clues to the presence and 

location of lode deposits.

Some of the more conventional geophysical exploration methods 

resistivity surveys (Davis, 1951), refraction seismic surveys (Wantland and Casey, 1952), and electric logging (Black, TEI-330, p. 71) 

h ave been tried experimentally on the Colorado Plateau. These methods do not indicate the presence of uranium any more than they do 

oil, but they show some promise in locating structures, such as buried 

channels, favorable for the occurrence of uranium.

BOTANICAL PROSPECTING

Two methods of botanical prospecting have been developed recently 

to the point where they can be used in the search for some uranium 

depostis (H. L. Cannon, 1952, 1953, 1954, 1955). One method is

335911° 55 4
22 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

based on the fact that certain plants, like juniper and saltbrush, take 

up uranium from the soil if any appreciable amounts are present. 

Samples collected from these uranium absorbers in the vicinity of 

near-surface ore deposits contain two or three parts per million or 

more of uranium. The other principal method is based upon the fact 

that certain plants require for their growth large amounts of selenium 

(Beath, 1943), others require large amounts of sulfur, and others require plant nutrients that are not released from the soil except where 

large amounts of acids are present, as is the case in the vicinity of 

sulfide ore bodies. These plants are therefore indicators of selenium, 

sulfur, or other substances, and inasmuch as these substances are commonly associated with uranium, particularly in the ores of the Colorado Plateau, they may indicate the presence of uranium too. Prospecting by this method consists first of mapping the distribution of 

the sulfur and selenium indicator plants and then of drilling in the 

vicinity of the greatest concentration of these indicator plants. 

Botanical prospecting can be used only where the ore lies at depths 

of less than about 50 feet; and, furthermore, the indicator plant 

method can be used only where the indicated elements are known to be 

associated with uranium in the ore.

GEOCHEMICAL PROSPECTING

Geochemical prospecting techniques, in which the metal content of 

soil or runoff is analyzed as a possible clue to the presence of concealed ore bodies, are now widely used in the search for many other 

metals, but they have not been much used in the search for uranium 

deposits, mainly because suitable field tests for trace amounts of 

uranium have not been available. If a quick, simple field test for 

determining small quantities of uranium, particularly in natural 

waters, can be developed, this method should have wide usefulness 

(Philip Fix, written communication, 1954). The average uranium 

content of natural waters is less than 1 part per billion. Generally, 

larger amounts are found only in the vicinity of uraniferous deposits 

or in waters draining tuffaceous terranes.

The determination of radioactive daughter products in stream sediments is an indirect geochemical prospecting method that offers some 

promise. Soil or water analysis of other metals such as copper, 

vanadium, and selenium that are known to be associated with 

uranium in certain districts provide another indirect geochemical 

prospecting method that may prove useful in some areas (Gott and 

others, TEI440, p. 69).
SEARCH FOR URANIUM IN THE UNITED STATES 23

PHYSICAL EXPLORATION

Most of the methods described thus far are rather inexpensive to 

use. Some require special equipment and knowledge but, with the 

exception of aerial reconnaissance, their cost is measured largely in 

terms of the time of the person applying them. If any of these 

methods or a combination of them does point to a local concentration 

of uranium, the lead is followed by physical exploration that is, 

drilling, trenching, test-pitting, or driving underground workings 

such as shafts or adits. In contrast to the other methods, all methods 

of physical exploration are expensive. For this reason only promising prospects are tested by drilling or other means, and when any of 

these methods are used they should be supported and guided by as 

full a knowledge of the geology of the district as can be had. On the 

other hand, when prospecting has developed a promising lead, such 

as an outcrop of ore or a favorable geologic association or structure, 

there is no substitute for physical exploration of one type or another 

to determine the extent, grade, and tonnage of the ore.

SELECTION OF AREAS FOR PROSPECTING

The selection of areas in which to use these methods deserves some 

comment. Two approaches may be distinguished, one the observational or, "uranium is where you find it" approach, the other the 

analytical or "uranium is where it ought to be" approach. It will be 

no surprise to economic geologists to learn that most of the producing 

uranium districts in the world were found through the "uranium is 

where you find it" approach, as were also some of the recent discoveries 

in this country, such as the Grants, N. Mex.; Marysvale, Utah; and 

Boulder, Mont., districts. Inasmuch as our understanding of the occurrence of uranium minerals or of the geology of this country is still 

sketchy the observational approach will continue to have an important 

place in prospecting for some time to come. Geologists of the Atomic 

Energy Commission and the Geological Survey have done a good deal 

of observational prospecting, not only by way of field reconnaissance 

but also by way of testing samples in museum collections; old drill 

cores; seismic shot holes; samples of all kinds of ores, concentrates, 

and tailings solicited from mining companies; and samples submitted 

by the public (see Butler, 1952, for localities checked by the Geological 

Survey). It will pay both the prospectors and geologists to continue 

to look for uranium wherever and whenever they have opportunity, 

regardless of whether or not the specific area is supposed to contain 

uranium deposits.

The analytical approach has yielded important results in the search 

for uranium, mostly by the application of simple empirical relation-
24 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ships the reasoning that if one phosphate rock is found to contain 

uranium, other similar phosphate rocks may contain it also. By 

examining rock associations similar to those already described, many 

previously unknown occurrences of uranium have been found in this 

country, particularly in phosphate rocks, lignites, and black shales. 

Geological theory, little used in the past simply because it was not well 

advanced, is now being applied successfully in the search for deposits 

in previously known districts, such as the Colorado Plateau, and in 

the search for new districts as well. Thus the discovery of the high 

grade uraniferous lignite deposits in South Dakota by J. R. Gill is 

a direct result of geologic prospecting guided by an understanding of 

ore habits and genesis. We may confidently expect the scope and 

power of the analytical approach to increase markedly in the future 

as the body of data on the occurrence and geochemistry of uranium 

increases.

Nearly all of the prospecting methods described can be used with 

both the observational and analytical approaches. The most effective 

prospecting, of course, makes use of all knowledge and tools available 

and appropriate to the specific problem.

DISTRIBUTION OF URANIUM DEPOSITS IN THE 

UNITED STATES

The search for uranium in the United States has disclosed the 

presence of many small vein deposits, of large minable reserves in 

sandstone-type deposits, and tremendous low-grade resources of uranium in lignites, phosphorites, and marine black shales. The distribution of uranium in these and other deposits is shown on figures 

1 to 5, and the more important of them are discussed in the following 

pages. In this discussion, the deposits are grouped according to the 

type of rock in which they occur, even though all deposits in some of 

the groups are not of the same origin. Inasmuch as no highly uraniferous igneous rocks or large uraniferous pegmatites have been found 

in this country, no attempt has been made to summarize the scattered 

data on their occurrence and they are omitted from the discussion that 

follows.

URANIUM VEIN AND REPLACEMENT DEPOSITS

Many uranium-bearing veins and related deposits have been found 

in recent years in the United States (fig. 1), though only a few have 

yielded any production. Nearly all are fracture fillings in igneous or 

metamorphic rocks but a few such as the Thomas Eange fluorspar
SEARCH FOR URANIUM IN THE UNITED STATES 25

pipes and the Placerville thucholite deposits are in breccia and fault 

zones in carbonate rocks. A few consist of uraniferous fluorspar deposits, but most are metalliferous quartz-sulfide deposits, mainly of 

the simple type, high in lead, copper, silver, or gold. Some have relatively complex mineral assemblages, but only the Blackhawk district 

in New Mexico seems to have the pitchblende-nickel-cobalt-native silver association that characterizes the world's principal uranium veins 

(Gillerman, 1952a); this deposit, however, has no important known 

reserves. Most of the metalliferous deposits shown on figure 1 contain 

pitchblende, but only secondary minerals have been found in the 

Majuba Hill, Goodsprings, Yellow Canary, St. Peters Dome, St. Kevin, 

Katherine and Michael, Silver Lady, Buckeye, and White Signal 

districts. Pitchblende probably will be found on deeper exploration 

in these areas, though possibly not in minable quantities.

The most important of the vein deposits are those at Marysvale, 

Utah.; in the Colorado Front Eange; and near Boulder, Mont. 

The deposits at Marysvale, discovered by a prospector in 1948, are 

found in steeply dipping quartz veins along the margin of a quartz 

monzonite intrusive (Gruner and others, 1951; Kerr and others, 1952). 

The walls are extensively pyritized and altered to clay minerals, The 

uranium occurs in autunite, schroekingerite, torbernite, uranophane, 

and other secondary minerals near the surface, but it occurs in pitchblende at depth. Marysvale has been a rather consistent though small 

source of uranium since its discovery, and it promises continued 

yield in the future.

The Front Eange of Colorado (deposits 16-21, fig. 1) is the only 

area in the United States where any significant tonnage of pitchblende was mined from hydrothermal veins prior to World War II. 

Production in recent years has been negligible, but many new occurrences of uranium have been found as a result of the activities of Survey geologists and prospectors (King and others, 1952, 1953; Sims, 

TEI 440, p. 75-88; TEI 490, p. 135), and a few deposits are now 

coming into production. In the Jamestown district, uraninite is 

disseminated in fluorite in fluorite veins and breccia zones (Phair 

and Shimamoto, 1952). At the Copper King mine pitchblende occurs 

in quartz-siderite veins that cut deposits of iron, copper, and zinc 

sulfides, associated with a skarn zone in granite (Derzay and Baker, 

1953; Sims and Phair, 1953). The most important deposits in the 

Front Eange are in the Central City (Armstrong, 1952; Moore and 

Butler, 1952), Lawson-Dumont (Harrison and Leonard, 1952), Caribou-Grand Island (Ridland, 1950; King, 1952; Moore and Cavender, 

1952), and Ealston Buttes areas (J. W. Adams; Sheridan and Maxwell, TEI 490, p. 139 and others, 1953). At most localities in these
26 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

r~~~» -J-r _j__J

». V -r-

' a* I

^

' --_ CM op ^ i 

, 4 ~~ -4---- ._..5O
FIGURE 1. Vein and replacement deposits of uranium in the United \8tates, mainly in 

12,15, and 18 are uraniferous fluorspar veins or pipes; the remainder are metallife

and references to them are listed below.

1. Spokane molybdenite mine, Lincoln County, Wash. (King and others, 20. 

1952)

2. Wellpinit, Stevens County, Wash. (Weis, TBI 490, p. 219) 21.

3. Coeur d'Alene district, Shoshone County, Idaho (Thurlow and

Wright, 1950) 22.

4. North Fork-Shoup district, Lemhi County, Idaho (Trites and Tooker,

195.3 ; Weis, TEI 490, p. 218) 23.

.5. Boulder-Clancy area, Jefferson County, Mont. (Klepper, 1950; Becraft,

1953; Roberts and Gude, 1953, 1954) 24.

6. Moonlight claims, Humboldt County, Nev. (Williams and Davis,

1953) _ 25.

7. Stalin's Present mine, Pershing County, Nev. (Kaiser and Page, 1952; 26. 

Anderson and Wadell, 1952) 27.

8. Reese River district, Lancler County, Nev. (Sharp and Hetland, 1954) 28.

9. Bast Walker River area, Lyon County, Nev. (Staatz and Bauer, 1953)

10. Majuba Hill, Pershing County, Nev. (Thurston and Trites, 1952) 29.

11. Goodsprings district, Clark County, Nev. (Behre and Barton, 1954)

12. Thomas Range district, Juab County, Utah (Staatz and Bauer, 30. 

1951a, 1952) 31.

13. Sheeprock Mountains, Juab County, Utah (Taylor, TBI 390, p. 215) 82.

14. Yellow Canary claims, Daggett County, Utah (Wilmarth, 1953) 33.

15. Marysvale, Piute County, Utah (Gruner and others, 1951; Kerr and

others, 1952) 34.

16. Staats Fluorspar mine, Beaver County, Utah (Wilmarth and others, 35. 

1952 ; Taylor, TEI 390, p. 215) 36.

17. Silver Cliff Mine, Niobrara County, Wyo. (Wilmarth and Johnson, 37. 

1954)

18. Copper King Mine, Larimer County, Colo. (Derzay and Baker, 1953; 38. 

Sims and Phair, 1953) 39.

19. Jamestown district, Boulder County, Colo. (Phair and Shimamoto, 40. 

1952) 41.

Caribou-Grand I

King, 1952; M

Ralston Buttes 

others, 1953) 

Central City dis

and Butler, 19

Lawson-Dumont 

Leonard, 1952

Alma district, P

wald and Piers

St. Peters Dome, 

St. Kevin distric

Red Mountain, 

Lower Uncompa

Pierson, 1953) 

Placerville thuc

1951 ; Wilmar

Silver Lady claim

Buckeye claims, 

Katherine and M

Hillside mine, Y

others, 1951)

Kitten No. 1 cla

Black Dike claim

Sure Fire claim, 

White Signal d

Granger and B

Blackhawk distr

Huron River are

Franklin limesto

Phillips pyrite m

TEI 390, p. 19
28 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

areas uranium occurs as pitchblende in small pods or shoots in quartzpyrite or quartz-carbonate lead-zinc-silver veins that cut pre-Cambrian 

granite, gneiss, or schist. Some of these districts have a zonal dis^ 

tribution of minerals, and Leonard (1952) has found recently that 

pitchblende generally occurs in a zone intermediate between the central zone, characterized by pyritic gold ores, and the peripheral zone, 

characterized by lead-zinc-silver ores. This relation has already aided 

in the discovery of additional occurrences of uranium there, and it 

may help in other districts as well. Another useful guide to the 

search for pitchblende deposits in the Front Range is the occcurrenoe 

of Tertiary bostonite dikes. These are highly radioactive, and many 

of the pitchblende deposits seem to be genetically related to them 

(Phair, 1952).

The pitchblende-bearing veins in the Boulder area, Jefferson 

County, Mont., were discovered by a local prospector in 1949, and since 

then uranium has been found at several localities between Boulder 

and Clancy (Klepper, 1950; Becraft, 1953, Eoberts and Gude, 1953, 

1954). Small quantities of ore have been mined at the Free Enterprise and Woodrow Wilson mines, and prospects for future discoveries elsewhere in the region seem good. The pitchblende occurs alone 

or with a little silver and pyrite in chalcedonic veins and with leadzinc-silver ore in quartz veins. With one exception the veins cut 

quartz monzonite and related intrusive rocks of the Boulder batholith.

None of the domestic vein deposits is known to contain large reserves of minable ore. It is significant, however, that the uranium 

minerals in most of them have been discovered since 1944, ^hen the 

first serious uranium prospecting began. It is not unreasonable to 

suppose that further exploration of some of them will yield minable 

reserves and that new finds in other areas will result from additional 

prospecting.

UKANIUM DEPOSITS IN TUFFACEOUS BOCKS

As shown in figure 2, several deposits of secondary uranium minerals have been found in tuffaceous rocks in the Western States. In 

some of these deposits those in the Rosamond and Rajidsburg 

districts of California for example the uranium occurs along fractures or bedding planes, but in others it is concentrated along ancient 

stream channels, much as in the sandstone deposits. Carnotite or 

uranophane is the uranium-bearing mineral in several of the desposits, 

but uranium phosphates are characteristic of many of the deposits, 

particularly those in California. Most of the known deposits in 

tuffaceous rocks are small and of low grade. Additional prospecting 

is sure to reveal similar occurrences elsewhere, but, judging from
SEARCH FOR URANIUM UST THE UNITED STATES 29

known occurrences, it seems unlikely that many deposits of this type 

will produce large tonnages of ore minable under present economic 

conditions. Of more promise in the long run is the possibility that 

uranium can be extracted by mass leaching methods from the tuffs that 

have "exuded" these small concentrations of secondary minerals.

URANIUM DEPOSITS IN LIMESTONES

Only a few uranium deposits of any kind have been found in limestones in the United States (fig. 2), and only those in the Todilto 

limestone near Grants, N. Mex., have yielded ore. The deposits at 

Miller Hill, Wyo., discovered by Geological Survey through aerial 

reconnassiance in 1952, contain 0.1 to 0.4 percent uranium, but known 

deposits are small. Despite the paucity of uranium deposits in limestones, the importance of the deposits in the Todilto would seem to 

justify further search for uranium in similar limestones elsewhere 

in the Western States.

URANIUM DEPOSITS IN SANDSTONES

Although other deposits in this country offer promise as future 

sources of uranium, our most important production has been and 

continues to be from the sandstone-type deposits of the Colorado 

Plateau (fig. 2). Resources in these deposits have supported a steadily increased production that has made the United States one of the 

world's leading producers of uranium since 1951 (U. S. Atomic Energy 

Commission, 1951, p. 8; Johnson, 1954). Equally important is the 

fact that most of the discoveries of minable ore outside of the Colorado 

Plateau, such as those in the Black Hills area, are also of the sandstone type.

As the general geology of the Colorado Plateau deposits has already been described, it is necessary here to discuss only the new developments and findings in the field. The uranium deposits on the 

Plateau are scattered over an area of more than 50,000 square miles 

in Colorado, Utah, Arizona, and New Mexico (Fischer, 1937, 1950; 

Shoemaker and Luedke, 1953), and ore is now being produced from 

about 550 mines (Winpf en, 1954). Before World War II the principal 

production and known reserves came from carnotite ores in the area in 

western Colorado, since defined as the Uravan mineral belt (Fischer 

and Hilpert, 1952). Diamond-drill exploration, guided by the concept 

of the mineral belt and also by criteria for defining ground favorable 

for the occurrence of ore (Weir, 1952, Stokes, 1953), has greatly increased the size of the reserves in this area and made possible much of 

the increase in production from the Plateau since the war.

335911° 55 5
30 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM
FIGUEE 2. Uranitim deposits in tuffaceous rocks, sandstones, and limestones in the Unite

tions and localities and references to them are listed 

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

TUFFACEOUS ROCKS

Oligocene Chadron formation, Slim Buttes, Harding County, S. Dak. 21.

(Gill and Moore, 1954) 

Oligocene Chadron and Brule formations, Scenic, Pennington County, 22.

S. Dak. (Moore and Levish, 1955) 

Pliocene (?) rocks, Splitrock, Natrona County, Wyo. (Love, TEI, 390, 23.

p. 66) 

Virgin Valley opal district, Humboldt County, Nev. (Staatz and 24.

Bauer, 1951b) 

Tertiary rhyolite tuff, Atlanta mine, Lincoln County, Nev. (Hewitt, 25.

1923) 

Tertiary welded tuff, Coaldale, Esmeralda County, Nev. (Duncan,

1953b) 26. 

Tertiary (?) rhyolite tuffs, Sloan, Clark County, Nev. (Hewitt, 1923;

Behre and Barton, 1954) 27. 

Tertiary tuffs and flows, Randsburg. Kern Countv. Calif. (Walker and

Lovering, 1954) ... ^ 

Miocene Rosamond series of Hersey, Rosamond district, Kern County,

Calif. (Walker, 1953) 29. 

Tertiary tuff, Aguila, Ariz. (Hewitt, 1925) 

Jurassic Sundance formation, Mayoworth area, Johnson County, Wyo. 30.

(Love, 1954b)

LIMESTONES 31.

Miocene (?) Browns Park formation, Miller Hill, Carbon County, qo 

Wyo. (Love, 1953)

Miocene(?) Browns Park formation, Saratoga area, Carbon County, 33 

Wyo. (Stephens, TEI 490, p. 131)

Eocene Uinta formation. Myton area. Dnsfhpne County, Utah (Gott 34 

and others, 1952)

Limestone and sandstone of the Jurassic Todilto limestone, and 35. 

Brushy Basin and Westwater Canyon members of Morrison formation, McKinley County, N. Mex. (Towle and Rapaport, 1952; »« 

Bucher, 1953) 37'

Permian Hueco limestone, El Paso and Hudspeth Counties, Tex. 

(Eargle, TEI 490, p. 133J

Lower Cretaceous Edwards limestone, King Mountain area, Upton

County, Tex. (Eargle, TEI 490, p. 132) 38

Spergen limestone of Mississippian age, Bugsen's Quarry, St. Genevieve County, Mo. (Muilenberg, 1949; Gott and others, 1952) 39

Cambrian Milton dolomite of Keith (1923), Chittendon County, Vt.

(Gott and others, 1952) 40.

SANDSTONES

20. Pennsylvanian Pottsville formation and Upj 

Ridge member of the Catskill formation, $ 

County, Pa. (Klemic and Baker, 1954)

er Devonian Cherry 

auch Chunk, Carbon 42.

Upper Huronian(

quette County, M

Permian sandston

330, p. 203) 

Permian Garber s

Okla. (Beroni, T

Triassic Chinle fo

490, p. 220) 

Cretaceous Lako

County, S. Dak

Gott and others

Cretaceous Fall R

area, Crook Cou

Eocene Wasatch f

Wyo. (Love, 195

Eocene Wind Riv

(Love, 1954a) 

Eocene Tepee Tr

Wyo. (Love, TE

Eocene sandstone, 

p. 180) 

Eocene Green Ri

Wyo. (Sheridan 

Miocene (?) Brow

Wyo. and Moffa

Oligocene( ?) Trou

Middle Park, Gr

Penusyl-vanian an

County, Colo. (W

Jurassic Morrison 

Colo. (Beroni an

Tertiary sandston

Various formatio

Chinle and the 

orado Plateau, 

1950; Shoemak

Cretaceous Dakot

(Stugard, 1952

Triassic Chinle fo

Utah (Proctor, 

Hack's Canyon, M

Pre-Cambriau Dri

Ariz. (Kaiser, 

TEI 490, pp. 1

Upper Cretaceous 

County, N. Mex
32 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Of greater long term importance, however, has been the discovery, 

mainly by private prospectors, of important deposits, some containing 

a million tons or more of ore (Johnson, 1954; Merritt, 1954), in new 

districts or other areas previously not known to contain minable ore. 

The largest single producer on the Plateau now is the Mi Vida mine 

near Moab, Utah (Dix, 1954; Meyers, 1953; Gruner and others, 1954). 

The deposit there was completely unknown until late in 1952 in fact, 

the Chinle formation in which it occurs was not even known to contain 

ore in that area. Other important deposits have since been found in 

the Moab area (Everhart, 1954a), The Happy Jack mine in the 

Shinarump conglomerate in White Canyon, Utah, was known only as 

a prospect until about 1950, but it has since been found to contain large 

reserves of copper-uranium ore and is now an important producer 

(Dodd, 1950; Miller, 1953). Important deposits also have been found 

recently in the White Canyon area (Benson and others, 1952; de 

Vergie, 1953). New discoveries, mainly of vanadium-uranium ore, 

also have been made in the Temple Mountain and other areas in the 

San Rafael Swell and Green River districts (Reyner, 1950; Finch, 

1953). The Grants, N. Mex., district is another recent discovery. The 

best known deposits there are tyuyamunite-pitchblende ores in the 

Todilto limestone (Towle and Rapaport, 1952), but other deposits of 

equal or greater importance have been found in the area in the Westwater Canyon and Brushy Basin members of the Morrison formation 

and in the Dakota sandstone as well (Mirsky, 1953; EverhaTt, 1954a; 

Wright, 1954b; Argall, 1954). The Lukachukai district in Arizona 

is another important new area (Masters, 1953). Exploration there 

by AEC has disclosed the presence of enough ore to justify a new 

mill at Shiprock. Important or promising deposits have also been 

found in the Monument Valley and Cameron areas of Arizona (Finch, 

1953; Williams and Barrett, 1953) and the Henry Mountains area of 

Utah (Bain, 1952). These new discoveries have not only helped bring 

the Colorado Plateau to a position of prominence as one of the 

world's large sources of uranium but they have stimulated the additional prospecting that will help maintain or further extend this 

position.

The South Dakota deposits, found by a prospector in June 1951, 

occur in the Fall River and Lakota sandstones and much resemble the 

Colorado Plateau deposits in shape and size. Since the first discovery 

in the Craven Canyon Area in Fall River County in the southern 

Black Hills, uranium has been found near Devil's Tower and in other 

places around the northern Black Hills by prospectors, mining companies, and the Atomic Energy Commission, in large part by means 

of airborne reconnaissance (Foote, 1954). The Commission has es-
SEARCH FOR URANIUM IN THE UNITED STATES 33

tablished a buying station at Edgemont, and extensive diamond-drill 

exploration is in progress.

The Pumpkin Buttes deposits, Wyoming, were found in the fall of 

1951 in the Wasatch formation as the result of Geological Survey airborne reconnaissance (Love, 1952; Troyer and others 1954). Some 

of the uranium there occurs in small masses, a few inches to a few feet 

in diameter, that contain as much as 15 percent of uranium. These 

deposits, now called the "pumpkin type," are too small to be minable 

on a significant scale. Disseminated-type deposits have been discovered since that more nearly resemble those in South Dakota and the 

Colorado Plateau, and a few of these are now in production. Kelict 

uraninite in association with pyrite has been discovered in disseminated-type deposits at two localities (Sharp and others TEI 490, 

p. 119).

Ore is also being mined from newly discovered sandstone deposits 

in the Gas Hills (Love, 1954a; Thomas, 19.54) and at Crooks Gap 

(Stephens, TEI 490, p. 120) in the Wind River Basin of Wyoming 

and in the Poison Basin in Wyoming and Colorado (Vine and Prich* 

ard, 1954). The ore in the Gas Hills is in the upper, coarse-grained 

part of the Eocene Wind River formation; it contains uraninite in 

addition to secondary uranium minerals. The Crooks Gap deposits 

are mainly in the lower part of the Eocene Wasatch(?.) formation j 

uranophane is the principal mineral. All known deposits in the Poison Basin area are in the Browns Park formation of Miocene age. 

Because of these discoveries and the discovery of uranium minerals 

at several other localities in Wyoming, the outlook for future discoveries of minable ore in Tertiary and Cretaceous fluviatile, rocks in 

Wyoming, Montana, and adjacent States is bright indeed.

Several pitchblende deposits are now being mined from the preCambrian Dripping Springs quartzite in southeastern Arizona. The 

deposits occur mainly in the upper member of the formation, but 

within that unit their distribution is controlled by fractures and proximity to diabase intrusives (Granger and Raup, TEI 490, p. 112-116).

Other sandstone-type deposits have been found elsewhere in the 

United States (fig. 2), but none of them has yielded ore. In view 

of the widespread occurrence of uranium in sandstone deposits in this 

country as well as the current prospecting enthusiasm, the prospects 

for additional discoveries of this type of ore seem bright indeed.

TTEANIFEEOUS ASPHALTITE DEPOSITS

The distribution of uraniferous asphaltites and related substances 

is shown in figure 3. The only deposits being exploited are those in 

the San Rafael district, where the asphaltite is a major constituent
34 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM
FIGURE 3. Uraniferous asphaltite, coal, and continental carbonaceous shale deposi

bearing formations and localities and references to them 

ASPHALTITE

1. Gilsonite, Uintah County, Utah (Erickson and others, 1953)

2. Elaterite, Duchesne County, Utah (Erickson and others, 1953)

3. Asphaltite in Upper Triassic Shinarump conglomerate, San Rafael 

Swell district, Emery County, Utah (Gott and Erickson, 1952)

4. Asphaltite in Upper Jurassic Westwater Canyon sandstone member 

of Morrison formation, Poison Creek, McKinley County, N. Mex. 

(Gott and Erickson, 1952)

5. "Asphaltite" in Panhandle gas field, Amarillo, Tex. (J. W. Mytton in 

Erickson and others, 1953; Pierce, TEI 490, p. 274)

6. "Asphaltite" in Permian Hennessey, Garber, and Wellington formations, Wichita Mountains, Okla. (Hill, TEI 330, p. 201 Hill, 1954)

7. Asphaltic material in Mississippian Pitkin limestone and Pennsylvania Atoka formation, northern Arkansas (Beroni, TEI 490, p. 217)

COAL

8. Paleocene Ft. Union formation, North and South Dakota and Montana (Gill, Schopf and others, TEI 330, p. 123-138 ; Gill, TEI 390, 

p. 131; Moore, TEI 390, p. 123; Gill, TEI 490, p. 149-155)

9. Eocene Wasatch formation, Red Desert area, Sweetwater County, 

Wyo. (Masursky, TEI 330, p. 140 ; Masursky and Pipiringos, TEI 

390, p. 139-143)

10. Upper Cretaceous Bear River formation, Booneville County, Idaho 

(Vine and Moore, 1952 ; Vine, TEI 330, p. 117)

11. Tertiary lignite, Gamma property, Churchill County, Nev. (Gott and 

others, 1952)

12. Upper Cretaceous Straight Cliffs sandstone, Webster Mine, Iron County, 

Utah (Zeller, TEI 390, p. 117)

13. Pleistocene peat, Pettit property, Davis County, Utah (Duncan, 1953c)

14. Upper Cretaceou

son County, C

15. Fireflex Mine, S

16. Pliocene (?) and 

County, Calif. 

17. Upper Cretaceou

N. Mex. (Bach

18. Pennsylvanian ( 

19. Tertiary Ft. U

and others, 1

20. Upper Eocene B

330, p. 117)

21. Pliocene Salt L

(Duncan, 195

22. Cretaceous Dako

P. 117)

23. Cretaceous Dak

390, p. 117)

24. Cretaceous Dak

P. 117)

25. Pre-Cambrian sl

Colo. (Pierson 

26. Pennsylvanian P

County, Colo. 

27. Cretaceous Dak

others, 1951)

28. Cretaceous Dako

sky, 1953)
36 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

of the sandstone deposits in Triassic formations (Gott and Erickson, 

1952; Finch, 1953). Numerous occurrences of uraniferous hard "asphaltite" pellets have been found recently in well cuttings in the 

Panhandle gas field in Texas, in many other gas fields in Kansas, 

Oklahoma, Texas, and New Mexico (Faul and others 1952; Gott, 

TEI 390, p. 256-258) and in outcrops of Permian age along the flanks 

of the Wichita Mountains (Hill, TEI 330, p. 202). The "asphaltite" 

pellets contain 1 to 10 percent uranium and seem to be the source of 

the radon in the gas fields in that area. None of the known deposits 

appears to be of commercial importance.

UBANIFEBOUS COAL AND CONTINENTAL CARBONACEOUS SHALE

Many uraniferous coals and carbonaceous shales (fig. 3) have been 

found in the United States since the first occurrence was discovered 

in 1945 in the Eocene Wasatch formation on the Red Desert of Wyoming. Most of these deposits are too thin, low-grade, or small to be 

of importance now or in the future, but recently several large deposits 

containing 0.2 percent or more uranium have been found in South 

Dakota and adjacent areas in North Dakota and Montana. These 

deposits are mainly in the Paleocene Ft. Union formation in areas 

previously known to contain low-grade uraniferous lignites. Generally, the uraniferous beds are high ash lignite or carbonaceous sandstone or shale. Their discovery suggests not only that similar deposits 

may be found elsewhere in the Dakota lignite field but that minable 

patches of high-grade uraniferous coal may be found in other coal 

fields now known to be weakly uraniferous only.

Carbonaceous shale in the Cretaceous Dakota sandstone near 

Gallup, N. Mex., is being mined as uranium ore on a small scale now 

(Mirsky, 1953). Carbonaceous shale in small pockets in the Pennsylvania Paradox member of Hermosa formation in Colorado, the 

Pliocene Salt Lake formation in Idaho, and the Cretaceous Bear 

River formation in Wyoming contains as much as 0.1 percent of 

uranium, or slightly more. It is not known yet whether any of 

these deposits contains minable amounts of shale of this grade, but 

it is reasonable to expect that some uranium, but probably not a great 

amount, will be derived from deposits of this type.

The most important low-grade coals are the Red Desert deposits 

and those in the Paleocene Ft. Union formation in the Dakota-eastern 

Montana field. The uranium in lignites and coals in these areas is 

irregularly distributed, as it is elsewhere, but large tonnages in both 

fields contain 0.01 to 0.03 percent of uranium in the ash. These deposits will yield uranium only if it can be derived as a byproduct of 

other operations, such as the manufacture of steam power.
SEARCH FOR URANIUM IN THE UNITED STATES 37

UEANIFEEOTTS PHOSPHORITES

The most important uraniferous phosphorites in the United States 

(fig. 4) are those in the Pliocene Bone Valley formation in Florida 

and the Permian Phosphoria formation in the Western States. Both 

contain huge quantities of phosphate averaging 0.01 to 0.02 percent 

of uranium. Even though the content is small, extensive research 

sponsored by the Atomic Energy Commission has made it possible 

to recover uranium as a byproduct of the manufacture of triple superphosphate fertilizer (Wimpfen, 1951; Euch, 1954). Production from 

the Florida field began late in 1952, and three additional recovery 

plants have been added since then. Uranium may soon be obtained 

from the western phosphorites by the same process, but no large production is anticipated immediately from this source because the 

western triple superphosphate industry is still comparatively small.

The aluminum phosphate zone in the upper part of the Bone Valley 

formation in Florida also contains huge amounts of uranium in concentrations slightly higher than that in the underlying carbonatefluorapatite mined for fertilizer. Research sponsored by the Atomic 

Energy Commission on the extraction of uranium and other coproducts such as aluminum and phosphorus has already led to development 

of recovery processes that are now being tested on a pilot-plant scale 

(U. S. Atomic Energy Commission, 1954, p. 7).

Recent aerial radioactivity surveys have disclosed the presence of 

uraniferous phosphorite in several areas outside the Bone Valley field 

(Moxham, 1954). These localities have not yet been explored, but 

ground examination in one of them showed the presence of leached 

phosphatic rock similar to that in the Bone Valley field. Additional 

reconnaissance of this type may lead to the discovery of other deposits 

elsewhere on the Atlantic or Gulf Coastal Plains.

UEANIFEEOUS MAEINE BLACK SHALES

The most important uraniferous black shale yet discovered in the 

United States is the Devonian and Mississippian Chattanooga shale of 

Tennessee (fig. 4). The upper part of this formation contains vast 

quantities of uranium in concentrations of 0.01 percent or slightly less 

Despite extensive research, the mineralogy of the uranium in the shale 

is not yet known, but most of the uranium seems to be concentrated in 

pyrite-organic matter complexes (Bates and others, 1954).

The highest percentage of uranium in black shale thus far discovered in the United States is in the Permian (?) Pennsylvanian and 

Mississippian (?) Hartville formation in southwestern Wyoming. 

This shale contains 0.019 percent of uranium (Duncan, 1953a), but 

it is thus far known to be appreciably uraniferous only in the sub-
38 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

A--, .>

Jf I «f 'I

r-0 « f m
FIGUKE 4. Uraniferous marine phosphorites and black shales in the United Sta

listed below.

PHOSPHORITES

1. Permian Phosphoria formation, Montana, Idaho, Wyoming, and Utah 

(McKelvey and Nelson, 1950 ; Thompson, 1952, 1953 ; Swanson and 

others, 1953)

2. Pennsylvania nodular black shales in the Coffeyville, and Port Scott 

formations, the Bourbon group, Hushpuckney shale member, and 

Stark shale member (Moore, 1932) in Kansas and Oklahoma (McKelvey and Nelson, 1950 ; Runels and others, 1953)

3. South Carolina phosphate field, Charleston County (D. F. Davidson, 

1951)

4. Pliocene Bone Valley formation, Florida (Butler, 1952 ; Cathcart and 

others, 1953).

BLACK SHALES

5. Mississippian and Pennsylvanian (?) Heath shale member of Flat Willow formation, Fergus County, Mont. (Duncan, 1953a)

6. Permian (?) Pennsylvanian and Mississippian (?) Hartville formation, 

Wyoming and Nebraska (Duncan, 1953a)

7. Cretaceous Shar

Dakota (Tour

8. Pennsylvanian 

pita, Mora C

390, p. 81-90

9. Pennsylvanian 

10. Shale in the D

(McKelvey an

11. Shale in Spers

Missouri (Go

12. Devonian Moun

13. Upper Devonia

(Beers, 1945)

14. Devonian and 

Stratton, 194

15. Devonian and 

bama (Russel
40 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

surface where it has been penetrated by oil wells the black shale 

facies passes into limestone facies before the Hartville crops out on 

the Hartville dome. Whether further reconnaissance will disclose a 

locality at the surface where uraniferous shale crops out remains to 

be seen.

Copper and uranium deposits in the Coyote district, near Guadalupita, N. Mex., are associated with lenticular carbonaceous marine 

beds (Tschanz, TEI 390, p. 81), but they have more features in common with the sandstone deposits than they do with other marine black 

shales. The uranium, which occurs as metatyuyamunite and uraninite, and in other forms not yet identified, is irregularly distributed 

and is present in sandstones, arkose, and limestone beds as well as in 

carbonaceous shale. The importance of this deposit is not yet known. 

Several other marine black shales, mainly of late Paleozoic age, and 

mainly in the mid-continent region, are also uranif erous (fig. 4), but 

none discovered yet equals the Chattanooga in extent and potential 

resources.

No uranium has yet been produced from black shales in this country, 

but the Atomic Energy Commission is sponsoring research on lowcost mining and processing methods on the Chattanooga shale that 

may make the production of uranium, along with such coproducts as 

phosphate, oil, and potash, possible in the foreseeable future (Barr, 

1953; Euch, 1954).

URANIUM-BEARING PLACERS

The only placer deposits in the United States (fig. 5) likely to yield 

uranium are those of radioactive black minerals in central Idaho 

(Mackin and Schmidt, 1953; Schmidt, TEI 490, p. 205). Production 

of uranium from these deposits is contingent upon the solution of 

extraction problems. Monazite in other placer deposits in central 

Idaho is of interest chiefly for its rare-earth content, and it is not 

likely that the 0.1 percent of uranium it contains will be recovered. 

Monazite in alluvial placers in the Southeastern States contains 0.3 to 

0.4 percent uranium (Mertie, 1953); although these deposits are widely 

distributed in two extensive northeastward-trending belts, individual 

deposits of minable grade are small.

OUTLOOK FOR FUTURE DISCOVERIES

The outlook for future discoveries of uranium deposits in the United 

States seems bright. The numerous occurrences of uranium in veins, 

tuffaceous rocks, lignites, and sandstone-type deposits in the Kocky 

Mountain States led L. K. Page (oral communication, 1950) to suggest 

that this area constitutes a uranium province of major importance.
SEARCH FOR URANIUM IN THE UNITED STATES 41

Subsequent discoveries tend to confirm this view. We may confidently 

expect, therefore, that additional discoveries of primary and secondary 

deposits of all types will be made in this general area.

The numerous occurrences of pitchblende veins in the Western 

States have about the same relation to the occurrence of larger, minable deposits as smoke does to fire. It is well known that for every 

large oil field there are scores of smaller ones, and the same relationship holds with respect to mineral deposits. Further exploration in 

the vicinity of the known occurrences (fig. 1) seems sure, therefore, 

to reveal some minable deposits, and additional prospecting in granitic 

and metamorphic terranes may well turn up important new districts.

The possibilities for discovering additional important sandstone 

deposits seem particularly promising, both within the Colorado Plateau and elsewhere in the Western States. It seems well worth while 

to examine all lenticular permeable formations in the western area, 

whether they are known to contain ore or not. The oldest formation 

of this type in any given district, particularly the parts where per- 

^eable facies interfinger with impermeable ones, seem especially 

promising. Kecognizing the possibility that the sandstone ores may 

have a hydrothermal source, it seems well also to investigate older 

carbonaceous rocks in areas of known sandstone-type deposits on the 

chance of turning up a Rum Jungle type of deposit.

Just plain looking has led to most of the discoveries of recent years, 

but the backlog of information now available on the habits of the 

sandstone ores seems sufficient to support a deductive approach to 

prospecting in the future that might be much more fruitful than the 

uranium-is-where-you-find-it approach of the past. The principal 

basis for such prospecting in the search for sandstone ores must be 

the analysis and understanding of sedimentary facies and transmissibility relationships. The basic geologic problem is thus one not unlike 

that encountered in the search for oil in fact the problem is one more 

likely to be solved by men with training in petroleum geology, using 

the oil companies' regional geological approach, than that it is by 

men whose experience is limited to mining geology. In this connection, one may ask if it is possible that a modification of some of the 

principles and methods currently being developed by the oil industry 

in the investigation of hydrodynamic gradients might find application 

in the search for sandstone ores or at least in the definition of favorable 

ground.

The recent discovery of minable uraniferous lignite beds in the 

South Dakota field strongly suggests that similar deposits may be 

found elsewhere. Particularly promising are the fields already known 

to contain weakly uraniferous beds and, within them, geologic settings
42 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM
FIGURE 5. Placer deposits of monasite, zircon, and radioactive black minerals in 

to localities are listed below.

1. Western zircon and monazite placers (Skidmore, J. H., written com- 4. Monazite in p

munication, 1944 ; Chesterman and Main, 1947) Mich. (Vicker

2. Central Idaho monazite, zircon, and "radioactive black" placers (Staley, 5. Zircon in Mioce

1948; Trites and Tooker, 1953; Mackin and Schmidt, 1953) Va. (Laughlin

3. Monazite in Cambrian Deadwood formation, Bald Mountain, Sheridan, 6. Southeastern m

and Big Horn and Carbon Counties, Wyo. (McKinney, A. A. and (Mertie, 1953

Hoist, H. W., written communication, 1853) 7. Florida monazit
44 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

that might have favored the percolation of uranium-bearing ground 

water through or adjacent to carbonaceous beds. As Denson, Bachman, and Zeller (see Vine and Moore, 1952) have pointed out, the 

highest bed beneath a sequence of tuff is likely to be uraniferous, 

especially where this bed is overlain by pervious rocks.

The prospects for discovering additional phosphorite fields are more 

limited than for other types of deposits, but they are good on the Gulf 

Coastal Plain, where exposures are poor and the subtropical weathering has leached the deposits at the surface and destroyed their distinguishing characteristics.

Despite the fact that rather extensive sampling already undertaken 

has not uncovered a uraniferous marine black shale in this country 

that contains 0.02 percent of uranium or more, it is not unreasonable 

to suppose that one or more such deposits exist in the United States. 

Recalling the facts that the most uraniferous parts of the alum shale 

in Sweden lie in marine embayments and that the shale in the Hartville formation in Wyoming passes into calcareous facies before it 

reaches the surface in the Hartville uplift, further search for uranium 

in black shales might be directed along the margins of black shale 

facies.

CONCLUSIONS

The 10 years of intensive search for uranium in this country have 

led to discoveries of sandstone deposits on the Colorado Plateau and 

elsewhere that have supported a several-fold increase in production, 

to the discovery of important minable deposits in lignites and of many 

occurrences of uranium in ore-grade concentrations in veins (mostly 

of insufficient volume to be mined), and to the discovery of large but 

low-grade resources of uranium in the lignites, black shales, and 

phosphorites. The increase in production from the Colorado Plateau 

speaks for itself, but I may add that production there is likely to increase and to continue at a high level for many years to come.

The results of the current prospecting boom create a bright outlook 

for future discoveries of other minable sandstone, lignite, and vein 

deposits. But even if higher grade ores do not materialize, the large 

low-grade deposits already discovered insure our future. These deposits will yield uranium now only at a high price, but the important 

thing is that they contain virtually unlimited resources that can be 

made available now if emergency needs demand, or later when higher 

grade deposits are exhausted. In this connection, Jesse C. Johnson 

(1954), Director of the Raw Materials Division of the Atomic Energy 

Commission, recently predicted that supplies of uranium obtainable 

from high-grade deposits would be adequate to support a large nuclear 

power industry well into the period when its efficiency in utilization
SEARCH FOR URANIUM IN THE UNITED STATES 45

of raw materials has reached an advanced stage, at which time it could 

afford to utilize higher priced uranium extracted from the low-grade 

deposits. The reasonableness of this prediction is perhaps more readily realized if we recall that one pound of uranium is considered the 

potential power equivalent of 1250 tons of coal. The uranium in a 

ton of black shale, phosphorite, or uranif erous lignite is thus roughly 

the potential power equivalent of 250 tons of coal. The concern expressed in recent years in many quarters over the adequacy of power 

supplies may therefore be postponed until the far distant future, for 

the resources of uranium in the United States in known low-grade 

deposits (shale, phosphate, and lignite) have far more potential 

power equivalent than all other types of our mineral fuels added together. And in the world as a whole, "the energy potentially available in * * * reserves of minable uranium has been estimated as between 20 and 25 times the energy from world reserves of oil, gas, and 

coal" (Smyth, 1954).

REFERENCES CITED

A strong attempt has been made to cite only references that are 

available to the public; the exceptions are indicated as unpublished 

reports. Many of the other papers cited are not published, but are on 

"open file." The largest group of these, released by the Technical 

Information Service of the Atomic Energy Commission at Oak Ridge, 

Tenn., are available in numerous public libraries all over the country. 

A list of these libraries is printed in each issue of Nuclear Science 

Abstracts and is also published in U. S. Geological Survey Circular 

281, p. 8, and Bulletin 1019-B, p. 78-79. The location of open file 

reports released directly by the U. S. Geological Survey is also indicated in Circular 281 and Bulletin 1019-B.

An effort has been made also to restrict references to those of recent 

date. Those that contain numerous references to earlier reports are 

indicated by an asterisk (*). The bibliographies by Alien (1953); 

Cooper (1951; 1952; 1953a; 1953b; 1954; 1955); Croxton (1951); 

Curtis and Houser (1953); and Wallace and Smith (1955), and 

Nuclear Science Abstracts will be particularly helpful in this regard.

Adains, J. W., Gude, A. J., 3d, and Beroni, E. P., 1053. Uranium occurrences in

the Golden Gate Canyon and Ralston Creek areas, Jefferson County, Colo.:

U. S. Geol. Survey Circ. 320. 

*Allen, R. E., 1953, Uranium and its compounds, a bibliography of unclassified

literature: U. S. Atomic Energy Cornrn. TID-3041, Tech. Inf. Service, Oak

Ridge, Tenn. 

Altschuler, Z. S., Clarke, U. S., Jr., and Young, E. J., 1954, Uranium in apatite:

Geol. Soc. America Bull., v. 65, p. 1225 (abs).
46 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Anderson, T. P., and Wadell, G. G., 1952, Examination of the Stalin's Present 

mine, Pershing County, Nevada: U. S. Atomic Energy Comm. RMO-927, 

Tech. Inf. Service, Oak Ridge, Tenn.

Ararnbourg, C., and Orcel, J., 1951, Observations prelirninaires sur la presence 

d'un vanadate d'urane dans les gisements de phosphates du Maroc: Acad. 

des Sci. Paris, Comptes Rendus, v. 233, p. 1635.

Argall, G. O., Jr., 1954, Why Anaconda's uranium, mines are unique: Mining 

World, v. 16, no. 10, p. 54-59.

Armstrong, F. C., 1952, Pitchblende deposits on Quartz Hill, Central City district, Gilpin County, Colo.: (abs.), Geol. Soc. America Bull., v. 63, p. 1232.

Axelrod, J. M., Grimaldi, F. S., Milton, C., and Murata, K. J., 1951, The uranium 

minerals from the Hillside mine, Yavapai County, Ariz.: Am. Mineralogist, 

v. 36, p. 1-22.

Bachman, G. O., and Read, C. B., 1951, Results of recent reconnaissance investigations of uranium in coal, black shale, and related deposits in Sandoval 

and Rio Arriba Counties, N. Mex., U. S. Geol. Survey unpub. Trace Elements 

Memo. Rept. 309.

*Bain, George W., 1950, Geology of fissionable materials: Econ. Geology, v. 45, 

p. 273-323.

* 1952, Uranium deposits in southwestern Colorado Plateau; U. S. Atomic

Energy Cornm. RMO-982, Tech. Inf. Service, Oak Ridge, Tenn. 

Balsley, J. R., 1952, Aeromagnetic surveying, in Landsberg, H. E., Advances in

Geophysics: New York, Acad. Press, p. 313-349. 

Barr, J. A., 1953, Significance of uranium occurrence in the Chattanooga black

shales of Tennessee and the southeastern United States: Address delivered

before the Southeastern Section of the Geol. Soc. America, Nashville, Tenn.,

April 3,1953. 

Barrett, D. C., 1954,-Buckeye No. 1, 5, and 9 claims, Kern County, Calif.: U. S.

Atomic Energy Comm., unpub. Prelim. Reconnaissance Rept. SC-SL-29. 

Barthauer, G. L., Rulfs, C. L., and Pearce, D. W., 1953, Investigation of thucholite :

Am. Mineralogist, v. 38, p. 802-814. 

Bastin, E. S., 1939, The nickel-cobalt-native silver ore type: Econ. Geology, v. 34,

p. 1-40. 

Bates, T. F., Strahl, E. O., Short, N. M., Silverrnan, E. N., and Camilli, E., 1954,

Mineralogy and petrography of the Chattanooga shale: Geol. Soc. America

Bull., v. 65, p. 1230. 

Beath, O. A., 1943, Toxic vegetation growing on the Salt Wash sandstone member

of the Morrison formation: Jour. Botany, v. 30, p. 698-707. 

Becraft, G. E., 1953, Preliminary report on the Comet area, Jefferson County,

Mont.: U. S. Geol. Survey Circ. 277.

*Beers, R. F., 1945, Radioactivity and organic content of some Paleozoic shales: 

Am. Assoc. Petroleum Geologists Bull., v. 29, no. 1, p. 1-22.

*Beers, R. F., and Goodman, Clark, 1944, Distribution of radioactivity in ancient

sediments : Geol. Soc. America Bull., v. 55, p. 1229-1254. 

Behre, C. H., Jr., and Barton, P. B., Jr., 1954, Interpretation and valuation of

uranium occurrences in the Bird Spring and adjacent mining districts,

Nevada: U. S. Atomic Energy Comm. RME-3091, Tech. Inf. Service, Oak

Ridge, Tenn. 

Bell, H., and Bales, W., E., 1955, Uranium deposits in Fall River County, S. Dak.:

U. S. Geol. Survey Bull. 1009.
SEARCH FOR URANIUM IN THE UNITED STATES 47

Bell, K. G., and Rogers, A. S., 1950, Experimental gamma-ray logging of drill 

holes in the Calamity area, Mesa County, Colo.: U. S. Geol. Survey unpub. 

Trace Elements Inv. Kept. 84.

Benson, W. E., Trites, A. F., Jr., Beroni, E. P., and Feeger, J. A., 1952, Preliminary 

report of the White Canyon area, San Juan County, Utah : U. S. Geol. Survey 

Circ. 217.

Beroni, E. P., and King, R. U., 1950, The Mike Doyle carnotite deposit, El Paso 

County, Colorado: U. S. Geol. Survey TEM-133, U. S. Atomic Energy Comrn., 

Tech. Inf. Service, Oak Ridge, Tenn.

Beroni, E. P., McKeown, F. A., Stugard, F., Jr., and Gott, G. B., 1953, Uranium 

deposits of the Bullocb group of claims, Kane County, Utah: U. S. Geol. 

Survey Circ. 239.

Black, W. A. P., and Mitchell, R. L., 1952, Trace elements in the common brown 

algae and in sea water: Jour. Marine Biol. Assoc. of the United Kingdom, 

v. 30, p. 575-584.

Brongersma-Sanders, M., 1948, The importance of upwelling water to vertebrate 

paleontology and oil geology : Verhandelingen der Koninklijke Nederlandsche 

Akademie van Wetenschappen, Afd. Natuurkunde, Tweede Sectie, Deel 

45, n. 4

Brown, H., Blake, W. J., Chodas, A. A., Kowalkowski, R., McKinney, C. R., Neuerburg, G. J., Silver, L. T., and Uchiyama, A., 1953, Leaching studies of interstitial materials in igneous rocks: Geol. Soc. America Bull., v. 64, p. 1400.

Brown, J. H., Jr., and Keller, W. D., 1952, Uranium in the clay of a black radioactive shale: Science, v. 16, p. 632-633.

Brownell, G. L., 1950, Radiation surveys with a scintillation counter: Econ. 

Geology v. 45, p. 167-174.

Bucher, W. H., 1953, Fracture studies in the Zuni and Lucero Uplifts, New 

Mexico: Columbia Univ. Ann. Rept. for June 15, 1952 to April 1, 1953, pt. 

1, U. S. Atomic Energy Comm., RME-3042.

Burbank, W. S., and Pierson, C. T., 1953, Preliminary results of radiometric reconnaissance of parts of the northwestern San Juan Mountains, Colorado: 

U. S. Geol. Survey Circ. 236.

Burton, V. L., and Sullivan, G. R., 1951, Carbon content and radioactivity of 

marine rocks: Am. Geophys. Union Trans., v. 32, p. 831-884.

Butler, A. P., Jr., 1952, The Geological Survey's work on the geology of uranium 

and thorium deposits: U. S. Geol. Survey TEI-207, U. S. Atomic Energy 

Comm., Tech. Inf. Service, Oak Ridge, Tenn.

 Cannon, H. L., October 1952, The effect of uranium-vanadium deposits on the 

vegetation of the Colorado Plateau: Am. Jour. Sci., v. 250, p. 735-770.

 1953, Geobotanical reconnaissance near Grants, New Mexico: U. S. Geol. 

Survey Circ. 264.

 1954, Botanical methods of prospecting for uranium : Mining Engineering, 

v. 6, p. 217-220.

 1955, Methods of botanical prospecting for uranium deposits on the

Colorado Plateau : U. S. Geol. Survey Bull., in preparation. 

Cannon, R. S., Jr., 1953, Radioactivity of alluvium downstream from uranium

deposits: U. S. Geol. Survey unpub. Trace Elements Memo. Rept. 225. 

Capdecomme, L., 1953, Etude mineralogique des gites de phosphates alumineux

de la region de Thies (Senegal) : 19th Int. Geol. Cong. Comptes Rendus, v.

11, p. 103-118, Algiers.
48 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Cater, F. W., Jr., 1954, Geology of the Bull Canyon quadrangle, Colorado: U. S. 

Geol. Survey Geologic Quadrangle Maps of the United States.

Cathcart, J. R., Blade, L. V., Davidson, D. F., and Ketner, K. B., 1953, The geology 

of the Florida land-pebble phosphate deposits: 19th Int. Geol. Cong., Algiers, 

Coniptes rendus, v. 11, p. 77-91.

Chesternian, C. W., and Main, F. H., 1947, Reconnaissance investigations for 

trace elements in Utah, Colorado, Nevada, California and Oregon, preliminary report: U. S. Geol. Survey unpub. Trace Elements Investigations 

Rept. 24.

Chew, R. T., 1954, Preliminary report on the study of radioactivity in modern 

stream gravels: U. S. Geol. Survey unpub. Trace Elements Memo. Rept. 629.

Coffin, R. C., 1921, Radium, uranium, and vanadium deposits of southwestern 

Colorado : Colorado Geol. Survey Bull. 16.

Conant, L. C., 1952, Origin of the Chattanooga shale: U. S. Geol. Survey unpub. 

Trace Elements Inv. Rept. 237; Nuclear Sci. Abs., v. 6, no. 20, p. 709-710.

*Cooper, M.. 1951, Preliminary bibliography on uranium and thorium and radioactive carbonaceous deposits: U. S. Atomic Energy Comm. RMO-835, 

Tech. Inc. Service, Oak Ridge, Tenn.

* 1953a, Bibliography and index of literature on uranium and thorium and 

radioactive occurrences in the United States Part 1, Arizona, Nevada, and 

New Mexico: Geol. Soc. America Bull., v. 64, p. 197-234.

* 1953b, Bibliography and index of literature on uranium and thorium and 

radioactive occurrences in the United States Part 2, California, Idaho, 

Montana, Oregon, Washington, and Wyoming: Geol. Soc. America Bull., 

v. 64, p. 1103-1172.

* 1953c, Selected bibliography on uranium exploration and geology of uranium deposits: U. S. Atomic Energy Comm. RMO-4007, Tech. Inf. Service, 

Oak Ridge, Tenn.

* 1954, Bibliography and index of literature on uranium and thorium and 

radioactive occurrences in the United States Part 3, Colorado and Utah: 

Geol. Soc. America Bull., V. 65, p. 467-590.

* 1955, Bibliography and index of literature on uranium and thorium and

radioactive occurrences in the United States Part 4: Arkansas, Iowa, 

Kansas, Louisiana, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, 

South Dakota, and Texas: Geol. Soc. America Bull., v. 66, p. 357-366. 

Craig, L. C., Holmes, C. N., Cadigan, R. A., Freeman, V. L., Mullens, T. E., and 

Weir, G. W., 1951, Preliminary report on the stratigraphy of the Morrison 

and related formations of the Colorado Plateau region: U. S. Geol. Survey 

TEI-180, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.; 

U. S. Geol. Survey Bull. 1009-E, 1955.

*Croxton, F. E., 1951, Uranium and its compounds: a bibliography of unclassified literature: Carbide and Carbon Chemical Company, K-295 pt. 2, K-25 

Plant, Oak Ridge, Tenn.

*Curtis, Diane, and Houser, Shirley S., 1953, Bibliography of U. S. Geological 

Survey Trace Elements and related reports: U. S. Geol. Survey Circ. 281.

*Davidson, C. F., 1951, The distribution of radioactivity: Min. Mag., London, 

v. 85, p. 329-340.

*1952, On the hydrothermal origin of the Rand gold ores: 19th Int. Geol. 

Cong., Res. des communications, p. 82-83, Algiers.

* 1953, The gold-uranium ores of the Witwatersrand: Min. Mag., v. 88,
SEARCH FOR URANIUM IN THE UNITED STATES 49

*Davidson, C. F,, and Atkin, D., 1953, On the occurrence of uranium in phosphate 

rock: 19th Int. Geol. Cong. Conaptes Rendus, v. 11, p. 13-31.

*Davidson, C. F., and Bowie, S. H. U., 1951, On thucholite and related hydrocarbon-uraninite complexes, with a note on the origin of the Witwatersrand 

gold ores: Geol. Surv. Great Britain Bull. 3, p. 1-19.

Davidson, D. F., 1951, Uraniferous phosphate rock near Charleston, Charleston 

County, S. C.: U. S. Geol. Survey unpub. Trace Elements Memo Rept. 246.

* 1953a, Distribution of coarse- and fine-grained rocks in the Wasatch 

formation and their relationship to uranium deposits, Powder River Basin, 

Wyo.: U. S. GeoL Survey TEM-676, U. S. Atomic Energy Cbmm., Tech. Inf. 

Service, Oak Ridge, Tenn.

1953b, Reconnaissance for uranium in the Powder River basin, Wyoming:

U. S. Geol. Survey TEM-677, U. S. Atomic Energy Comrn., Tech. Inf. Service,

Oak Ridge, Tenn. 

Davis, W. E., 1951, Electric resistivity investigations of carnotite deposits in the

Colorado Plateau: U. S. Geol. Survey TEM-232, U. S. Atomic Energy Cornm.,

Tech. Inf. Service, Oak Ridge, Tenn. 

Derzay, R. C., and Baker, K. E., 1953, Results of exploration at the Copper King

mine, Larimer County, Colorado: U. S. Atomic Energy Cornm., RME-4018,

Tech. Inf. Service, Oak Ridge, Tenn. 

DiGiovanni, H. J., Graveson, R. T., and Yoli, A. H., 1953, Scintillation unit for

drill-hole logging: Nucleonics, v. 11, p. 34-39. 

Dix, J. P., Jr., 1954, The uranium deposits of Big Indian Wash, San Juan County,

Utah: U. S. Atomic Energy Comm., RME-4022 (revised), Tech. Inf. Service,

Oak Ridge, Tenn. 

Dodd, P. H., 1950, Happy Jack mine, White Canyon Utah: U. S. Atomic Energy

Comm., RMO-660, Oak Ridge, Tenn. 

Duncan, D. C., 1953a, Reconnaissance investigations for uranium in black shale

deposits of the western states during 1951 and 1952: U. S. Geol. Survey

TEI-381, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

 1953b, A uranium-bearing rhyolitic tuff deposit near Coaldale, Esmeralda 

County, Nevada: U. S. Geol. Survey Circ. 291.

 1953c, Results of reconnaissance for uranium in non-marine carbonaceous

rocks in parts of California, Idaho, Nevada, Oregon, Utah, and Washington 

during 1951 and 1952: U. S. Geol. Survey, TEM-444A, U. S. Atomic Energy 

Comm., Tech. Inf. Service, Oak Ridge, Tenn.

Dunning, C. H., 1950, Radioactive phenomena at the Hillside mine: Science, v. 

Ill, p. 475.

Ellsworth, H. V., 1928, Thucolite, a remarkable primary carbon mineral from 

the vicinity of Parry Sound, Ontario: Am. Mineralogist, v. 13, p. 419-441.

Ellsworth, H; V., 1932, Rare-element minerals of Canada: Geol. Survey Canada, 

Econ. Geol. Ser. no. 11.

Emory, K. O., and Dietz, R. S., 1950, Submarine phosphorite deposits off California and Mexico : Calif. Jour. Mines Geol., v. 46, p. 7-15.

*Erickson, R. L., Myers, A. T., and Horr, C. A., 1953, The association of uranium 

and other metals with crude oils, asphalts, and petroliferous rocks: Geol. 

Soc. America Bull., v. 64, p. 1505 (abs.) ; Am. Assoc. Petroleum Geologists 

Bull., v. 38, p. 2200-2218, 1954.

*Evans, R. D., and Goodman, Clark, 1941, Radioactivity of rocks: Geol. Soc.

America Bull., v. 52, p. 459-490. 

Everhart, D. L., 1954a, Uranium: Eng. and Min. Jour., v. 155, no. 2, p. 84-86.
50 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Everhart, D. L., 1954b, Origin of uranium deposits, a progress report: Min. Engineering, p. 904-908, 1954.

Everhart, D. L., and Mathez, M., 1951, Geology of uranium deposits condensed 

version: U. S. Atomic Energy Conini., RMO-732, Oak Ridge; Tenn.

*Everhart, D. L., and Wright, R. J., 1953, The geologic character of typical

pitchblende veins : Econ. Geol., v. 48, p. 77-96. 

Paul, H., Gott, G. B., Manger, G. E., Mytton, J. W., and Sakakura, A. Y. 1952,

Radon and helium in natural gas: 19th Int. Geol. Gong., Res. des communications, p. 59, Algiers. 

Faul, H., and Tittle, C. W., 1951, Logging of drill holes by the neutron, gamma

method, and gamma ray scattering: Geophysics, v. 16, p. 260-276. 

Finch, W. L, 1953, Geologic aspects of the resource appraisal of uranium

deposits in pre-Morrison formations of the Colorado Plateau: U. S. Geol.

Survey TEI-328A, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak

Ridge, Tenn.

* 1955, Preliminary geologic map showing the distribution of uranium 

deposits and principal ore-bearing formations of the Colorado Plateau 

region: U. S. Geol. Survey Min. Inv. Field Studies Map 16.

*Fischer, R. P., 1937, Sedimentary deposits of copper, vanadium-uranium, and 

silver in southwestern United States: Econ. Geology, v. 32, p. 906-951.

* 1950, Uranium-bearing sandstone deposits of the Colorado Plateau: 

Econ. Geology, v. 45, p. 1-11.

Fischer, R. P., and Hilpert, L. S., 1952, The Uravan mineral belt: U. S. Geol. 

Survey Bull. 988A, p. 1-13.

Fredrickson, A. F., 1948, Some mechanisms for the fixation of uranium in certain sediments: Science, v. 108, p. 184.

Frondel, J. W., and Fleischer, M., 1952, A glossary of uranium- and thoriumbearing minerals: U. S. Geol. Survey Circ. 194; U. S. Geol. Silrvey Bull. 

1009-F, 1955.

Foote, R. S., 1954, How geophysics helps find uranium: Eng. and Min. Jour., 

v. 155, no. 9, p. 96-97.

George, D'Arcy, 1949, Mineralogy of uranium- and thorium-bearing minerals: 

U. S. Atomic Energy Comm. RMO-563, Tech. Inf. Service, Oak Ridge, Tenn.

Gilkey, A. K., 1953, Fracture pattern of the Zuni uplift: U. S. Atomic Energy 

Comm. RME-3050, Tech. Inf. Service, Oak Ridge, Tenn.

Gill, J. R., and Moore, G. W., 1955, Carnotite-bearing sandstones in Cedar 

Canyon, -Slim Buttes, Harding County, So. Dak.: U. S. Geol. Survey Bull., 

1009-1 (in press).

Gillerman, E., 1952a, Uranium deposits in the Blackhawk district, Grant County, 

N. Mex., (abs.) : Geol. Soc. America Bull., v. 63, p. 1254; U. S. Geol. Survey 

Bull. 1009- (in press, 1955).

* 1952b, Uranium deposits of the White Signal district, New Mexico (abs.) : 

Geol. Soc. America Bull., v. 63, p. 1329.

Glebov, S. M., 1941, Radioaktivnost diktionemovykh slantzer: Leningradski 

gornyi Institut, Leningrad, Zapaski, v. 14, p. 1-12.

Gott, G. B., and Erickson, R. L., 1952, Reconnaissance of uranium and copper 

deposits in parts of New Mexico, Colorado, Utah, Idaho, and Wyoming: 

U. S. Geol. Survey Circ. 219.

Gott, G. B., and Hill, J. W., 1953, Radioactivity in some oil fields of southeastern Kansas: U. S. Geol. Survey Bull. 988-E.

Gott, G. B., Wyant, D. G., and Beroni, E. P., 1952, Uranium in black shales, 

lignites, and limestones in the United States: U. S. Geol. Survey Circ. 220.
SEARCH FOR URANIUM IN THE UNITED STATES 51

Granger, H. C., 1951a, Preliminary summary of reconnaissance for uranium In 

Arizona: U. S. Geol. Survey unpub. Trace Elements Memo. Kept. 304.

 1951b, Kitten No. 1, Yavapai County, Arizona: U. S. Geol. Survey unpub.

Prelim. Reconnaissance Rept., D-33. 

Granger, H. C., and Bauer, H. L., Jr., 1952, Uranium occurrences on Merry

Widow claim, White Signal district, Grant County, New Mexico: U. S.

Geol. Survey Circ. 189.

 Graton, L. C., 1930, Hydrothermal origin of the Rand gold deposits: Econ.

Geology, v. 25, no. 3, suppl. 

Gray, J. R., and Tennissen, A. C., May 1953, Uranium investigations near Aladdin,

Crook County, Wyoming: U. S. Atomic Energy Cornm. RME-4016, Tech. Inf.

Service, Oak Ridge, Tenn. 

Griggs, R. L., 1954, A reconnaissance for uranium in New Mexico, 1953: U. S.

Geol. Survey Circ. 354. 

Grimaldi, F. S., May, Irving, Pletcher, M. H., and Titcomb, Jane, 1954, Collected

papers on methods of analysis for uranium and thorium developed by the

U. S. Geological Survey: U. S. Geol. Survey Bull. 1006. 

Grip, E., and Odman, O. H., 1944, On thucholite and natural gas from Boliden:

Arsbok Sveriges Geol. Undersok, v. 38, no. 6, Stockholm. 

Gross, W. H., 1952, Radioactivity as a guide to ore: Econ. Geology, v. 47, p.

722-742. 

Gruner, J. W., 1951, Origin of the uranium deposits in the Shinarump formation,

a preliminary study: U. S. Atomic Energy Cornm. RMO-837, Tech. Inf.

Service, Oak Ridge, Tenn.

 1954, The origin of the uranium deposits of the Colorado Plateau and 

adjacent regions: Mines Mag., v. 44, no. 3, p. 53-56.

 Fetzer, W. G., and Rapaport, I., 1951, The uranium deposits near Marysvale, Piute County, Utah: Eeon. Geol., v. 46, p. 243-251.

Rosenzweig, A., and Smith, D. K., Jr., .1954, The mineralogy of the 'Mi

Vida' uranium ore deposits of the Utex Exploration Company in the Indian 

Wash area, Utah : U. S. Atomic Energy Cornm. RME-3094, Tech. Inf. Service, 

Oak Ridge, Tenn.

Guntz, A. A., 1952, Sur la presence d'uranium dans les phosphates nordafricains: 

Acad. des Sci. Paris, Comptes Rendus, p. 868-870.

Guntz, A. A., and Arene, M., 1953, Sur la presence de 1'uranium dans les phosphates africains: 19th nt. Geol. Cong., Comptes Rendus, v. 11, p. 11 Algiers.

Harrison, J. E., and Leonard, B. F., 1952, Preliminary report on the Jo Reynolds 

area, Lawson-Durnont district, Clear Creek County, Colorado: U. S. Geol. 

Survey Circ. 213.

Harvey, H. W., 1945, Recent advances in the chemistry and biolpgy of sea water: 

Cambridge Univ. Press. %

Hebert, Claude, 1947, Contribution & P6tude de la chimie des phosphates de 

calcium: Annales des Mines, Memoirs, v. 136, no. 4, p. 5-93, Paris.

Hentschelt E., and Wattenburg, H., 1930, Plankton und Phgsphat in der Oberflac-henschicht des Sudatlantischen Ozeans: Ann. Hydrogr. Mar. Meteor., 

Band 58, p. 273-277.

Hewett, D. F., 1923, Carnotite in southern Nevada: Eng. and Min. Jour.-Press, 

v. 115, no. 5, p. 232-235.

 1925, Carnotite discovered near Aguila, Arizona: Eng. and Min. Jour.- 

Press, v. 120, no. 1, p. 19.

Hill, J. W., 1954, Uraniferous asphaltic materials of southwestern Oklahoma: 

Geol. Soc. America Bull., v. 65, p. 1377.
52 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Hinckley, D. N., 1952, Investigation of subsurface isorad methods, Temple Mountain, San Rafael Swell district, Utah: U. S. Atomic Energy Comm. RME4019, Tech. Inf. Service, Oak Ridge, Term., 34 p. 

Holland, H. D., and Kulp, J. L., 1954, The transport and deposition of uranium,

ionium, and radium in rivers, oceans, and ocean sediments: Geochimica et

Cosmochimica Acta, v. 5, p. 197-213. 

Hurley, P. M., 1950, Distribution of radioactivity in granites and possible relation

to helium age measurement: Geol. Soc. America Bull., v. 61, p. 1-8. 

Jaffee, E. B., and Sherwood, A. M., 1951, Physical and chemical comparison of

modern and fossil tooth and bone material: U. S. Geol. Survey TEM-149,

U. S. Atomic Energy Cornm., Tech. Inf. Service, Oak Ridge, Tenn. 

James, W. F., Lang, A. H., Murphy, R., and Kesten, S. N., 1950, Canadian deposits

of uranium and thorium: Trans. Am. Inst. Min. Metal. Eng., v. 187; Min. Engineering, p. 244-247. 

Johnson, J. C., 1954,. The outlook for uranium mining: U. S. Atomic Energy

Comm. release of address before Am. Min. Cong., San Francisco, Calif.,

Sept. 23. 

Kaiser, E. P., 1951, Uraniferous quartzite, Red Bluff prospect, Gila County,

Arizona: U. S. Geol. Survey Circ. 137. 

Kaiser, E. P., and Page, L. R., 1952, Distribution of uranium deposits in the

United States: U. S. Geol. Survey Circ. 220.

Kerr, P. F., Brophy, G., Dahl, H. M., Green, J., and Woolard, L. E., 1952, A geologic guide to the Marysvale area: U. S. Atomic Energy Comm. RMO-924,

Tech. Inf. Service, Oak Ridge, Tenn. 

Kerr, P. F., and Lapham, D. M., 1954, Report on a nodule from Temple Mountain,

Utah: U. S. Atomic Energy Cornm. RME-3096 (pt 1), Tech. Inf. Service,

Oak Ridge, Tenn. 

Kidd, D. F., and Haycock, M. H., 1935, Mineragraphy of the ores of Great Bear

Lake: Geol. Soc. America Bull., v. 46, p. 879-960. 

King, R. U., 1952, Vein deposits of uranium at the Caribou mine: U. S. Geol.

Survey TEM-13, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge,

Tenn.: Nuclear Sci. Abs., v. 6, no. 1, p. 28. 

King, R. U., Leonard, B. F., Moore, F. B., and Pierson, C. T., 1953, Uranium in

the metal-mining districts of Colorado: U. S. Geol. Survey Circ. 215. 

King, R. U., Moore, F. B., and Hinrichs, E. N., 1952, Pitchblende deposits in the

United States: U. S. Geol. Survey Circ. 220. 

Klemic, H., and Baker, R. C., 1954, Occurrences of Uranium in Carbon County,

Pa.: U. S. Geol. Survey Circ. 350. 

Klepper, M. R., 1950, Forty-niner, King Solomon Ridge, and West End claims

near Clancy, Jefferson County, Mont: U. S. Geol. Survey TEM-31, U. S.

Atomic Energy Comm., Tech. Inf. Service Oak Ridge, Tenn. 

Koeberlin, F, F., 1938, Discussion of "Sedimentary copper, vanadium-uranium

and silver in Southwestern United States", by R. P. Fischer: Econ. Geology,

v. 33, p. 458-^61. 

Krauskopf, K. B., 1952, Control of trace-element concentrations in sea water:

Geol. Soc. America Bull., v. 63, p. 1336. 

*Lang, A. H., 1952, Canadian deposits of uranium and thorium (interim account) :

Canada Geol. Survey, Econ. Geol. Ser. No. 16.

Larsen, E. S., Jr., Keevil, N. B., and Harrison, H. C., 1952, Method for determining the age of igneous rocks using the accessory minerals: Geol. Soc. America

Bull., v. 63, p. 1045-1052.
SEARCH FOR URANIUM IN THE UNITED STATES 53

Laughlin, G. F., 1919, Mineral resources of the United States, part II, nonmetals S

U. S. Geol. Survey, p. 20-21. 

Lenoble, A., Salvan, H., and Ziegler, V., 1952, Decouverte de 1'uranium dans les

niveaux phosphates du Maroc: Acad. des Sci. Paris, Comptes Rendus,

p. 976-977. 

Leonard, B. F., 1952, Relation of pitchblende deposits to hypogene zoning in the

Front Range mineral belt, Colorado (abs.) : Econ. Geology, v. 47, no. 7, p. 773. 

Lindgren, W., 1913, Mineral Deposits: McGraw Hill. 

Love, J. D., 1952, Preliminary report on uranium deposits in the Pumpkin Buttes

area, Powder River basin, Wyoming: U. S. Geol. Survey Circ. 176.

 1953, Preliminary report on the uranium deposits in the Miller Hill area, 

Carbon County, Wyoming: U. S. Geol. Survey Circ. 278.

 1954a, Preliminary report on uranium in the Gas Hills area, Fremont and 

Natrona Counties, Wyoming: U. S. Geol. Survey Circ. 352.

 1954b, Uranium in the Mayoworth area, Johnson County, Wyoming:

U. S. Geol. Survey Circ. 358.

MacGregor, A. M., 1953, Discussion of "The gold-uranium ores of the Witwatersrand" by C. F. Davidson: Min. Mag., v. 88, p. 281-282.

Mackay, R. A., and Beer, K. E., 1952, The albite-riebeckite-granites of Nigeria: 

Geol. Survey of Great Britain, Report GSM/AED, 95, publ. H. M. S. O.

Mackin, J. H., and Schmidt, D. L., 1953, Reconnaissance geology of placer deposits 

containing radioactive minerals in the Bear Valley district, Valley County, 

Idaho: U. S. Geol. Survey open file report Trace Elements Memo. Rept. 602; 

Geol. Soc. America Bull., v. 64, p. 1549 (abs.).

Masters, J. A., 1953, Geology of the uranium deposits of the Lukachukai Mountains area, Northeastern Arizona: U. S. Atomic Energy Comm. RME-27, 

Tech. Inf. Service, Oak Ridge, Tenn.

Mawdsley, J. B., 1952, Uraninite-bearing deposits, Charlebois Lake area, Northeastern Saskatchewan: Canadian Min. Met. Bull., v. 482, p. 366-375; Geol. 

Soc. America Bull., v. 64, p. 1550,1953 (abs.).

McKelvey, V. E., and Nelson, John M., 1950, The characteristics of marine 

uranium-bearing sedimentary rocks: Econ. Geology, v. 45, p. 35-53.

McKelvey, V. E., Swanson, R. W., and Sheldon, R. P., 1953, The Permian phosphorite deposits of western United States: 19th Int. Geol. Gong., Comptes 

rendus, v. 11, p. 45-64.

McLean, C. S., 1954, South African uranium deposits: Address before the Chem., 

Met., and Min. Soc. of South Africa, described in Min. Mag., v. 90, p. 259.

Mead, W. E., and Wells, R. L., 1953, Preliminary reconnaissance of the Dripping 

Spring quartzite formation in Gila and Final Counties, Ariz.: U. S. Atomic 

Energy Comm. RME-4037, Tech. Inf. Service, Oak Ridge, Tenn.

Merritt, P. L., 1949, Pitchblende the primary source of uranium: Conference on 

radioactive ores, Michigan College of Mining and Technology, Houghton, 

Michigan, p. 10-11.

 1954, Review of recent developments in uranium exploration : Mines Mag., 

v. 44, no. 3, p. 83-84.

Mertie, John B., Jr., 1953, Monazite deposits of the southeastern Atlantic states: 

U. S. Geol. Survey Circ. 237.

Meyers, B., 1953, Uranium jackpot: Eng. and Min. Jour., v. 154, no. 9, p. 73-75.

Miller, L. J., 1953, Uranium ore controls of the Happy Jack deposit, White 

Canyon, San Juan County, Utah: U. S. Atomic Energy Comm. RME-33, 

Tech. Inf. Service, Oak Ridge, Tenn.
54 CONTEIBUTIONS TO THE GEOLOGY OF URANIUM

Mirsky, A., 1953, Preliminary report on uranium mineralization in the Dakota

sandstone, Zuni uplift, New Mexico: U. S. Atomic Energy Comm. RME-47,

Tech. Inf. Service, Oak Kidge, Tenn. 

Moore, F. B., and Butler, C. R., 1952, Pitchblende deposits at the Wood and Calhoun mines, Central City Mining district, Gilpin County, Colorado: U. S.

Geol. Survey Circ. 186. 

Moore, F. B., and Cavender, W. S., 1952, The pitchblende deposit at the Caribou

mine, Boulder, Colorado (abs.) : Geol. Soc. America Bull., v. 63, p. 1281. 

Moore, G. W., 1954, Extraction of uranium f/om cold water solutions by coal

and other materials: Econ. Geology, v. 49, p. 652-658. 

Moore, G. W., and Levish, M., 1955, Uranium-bearing sandstone in the White

River Badlands, Pennington County, S. Dak.: U. S. Geol. Survey Circular

359. 

Moore, G. W., and Stephens, J. G., 1954, Reconnaissance for uranium-bearing

carbonaceous rocks in California and adjacent parts of Oregon and Nevada:

U. S. Geol. Survey Circ. 313. 

Morehouse, G. E., 1951, Investigations of thucholite deposits near Placerville,

Colorado: U. S. Atomic Energy Comm. RMO-910, Tech. Inf. Service, Oak

Ridge, Tenn. 

Moxham, R. M., 1954, Airborne radioactivity surveys for phosphate in Florida:

U, S. Geol. Survey Circ. 230. 

Muilenburg, G. A., 1949, Notes on uranium: Missouri Geol. Survery, Inf. Circ.

No. 5. 

Mullens, T. E., and Freeman, V. L., 1954, Lithofacies of the Salt Wash member

of the Morrison formation: U. S. Geol. Survey Trace Elements Inv. Rept.

341. 

Narten, P. F., Crawford, J. E., and Butler, A. P., Jr., 1951, Summary review of

analytical data pertaining to the uranium content or radioactivity of domestic shales: U. S. Geol. Survey unpub. Trace Elements Memo. Rept. 240. 

Nelson, H. E., and Barrett, D. C., 1953, Silver Lady Mining claim, Kern County,

Calif.: U. S. Atomic Energy Comm., unpub. Prelim. Reconnaissance Rept.

SC^-SL-8. 

Nelson, J. M., 1954, Prospecting for uranium with car mounted equipment: U. S.

Geol. Survey Bull. 988-1, p. 211-220.

Nelson, J. M., and Stratton, E. V., 1949, Trace elements reconnaissance in Indiana, Illinois, Missouri, Arkansas, and Kentucky, preliminary report: U. S.

Geol. Survey unpub. Trace Elements Inv. Rept. 34. 

Neuman, W. F., Neuman, M. W., Main, E. R., and Mulryan, B. J., 1949a, The

deposition of uranium in bone, IV. Adsorption studies in vitro: Jour. Biol.

Chemistry, v. 179, p. 325-333.

 1949b, The deposition of uranium in bone, V. Ion exchange studies: Jour. 

Biol. Chemistry, v. 179, p. 335-340.

 1949c, The deposition of uranium in bone, VI. Ion competition studies:

Jour. Biol. Chemistry, v. 179, p. 341-348.

*Nininger, R. D., 1954, Minerals for atomic energy: New York, D. Van Nostrand

Company, Inc. 

Pabst, A., 1954, Brannerite from California: Am. Mineralogist, v. 39, p. 109-117.

*Page, L. R., 1950, Uranium in pegmatites: Econ. Geology, v. 45, p. 12-34. 

Page, L. R., and Redden, J. A., 1952, The carnotite prospects of the Craven Canyon

area, Fall River County, S. Dak.: U. S. Geol. Survey Circ. 175. 

Phair, G., 1952, Radioactive Tertiary porphyries in the Central City district,

Colorado and their bearing upon pitchblende deposition: U. S. Geol. Survey
SEARCH FOR URANIUM IN THE UNITED STATES 55

TEI-247, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.; 

Nuclear Sci. Abs., v. 6, p. 776.

Phair, G., and Levine, H., 1953, Notes on the differential leaching of uranium, 

radium, and lead from pitchblende in H2SO4 solutions: Econ. Geology, v. 48, 

p. 358-369.

Phair, G., and Shirnamoto, K. O., 1952, Hydrothermal uranothorite in fluorite 

breccias from the Blue Jay mine, Jamestown, Boulder County, Colo.: Am. 

Mineralogist, v. 37, p. 659-666.

Pierson, C. T., Burbank, W. S., and Singewald, Q. D., 1952, Some uranium occurrences in the central and southwestern parts of the Colorado mineral belt: 

Geol. Soc. America Bull., v. 63, p. 1368 (abs.).

Pierson, C. T., and Singewald, Q. D., 1954, Occurrences of uranium-bearing minerals in the St. Kevin district, Lake County, Colo.: U. S. Geol. Survey Circ. 

321.

*Proctor, P. D., 1953, Geology of the Silver Reef (Harrisburg) mining district,

Washington County, Utah: Utah Geol. Min. Soc. Bull. 44. 

Rasor, C. A., 1952, Uraninite from the Grey Dawn mine, San Juan County, Utah:

Science, v. 116, p. 89-90. 

Reinecke, L., 1930, The location of payable ore-bodies in the gold-bearing reefs

of the Witwatersrand: Geol. Soc. South Africa Trans., v. 30, p. 89-119.

 1940, Gold in the Witwatersrand system, in mineral resources of South

Africa: South Africa Geol. Survey, p. 110-163. 

Reinhardt, E. V., 1952, The distribution of uranium-vanadium deposits in the

Colorado Plateau relative to Tertiary intrusive masses: U. S. Atomic Energy

Comm. RMO-816, Tech. Inf. Service, Oak Ridge, Tenn. 

Reyner, M. L., 1950, Preliminary report on some uranium deposits along the west

side of the San Rafael Swell, Emery County, Utah: U. S. Atomic Energy

Comm. RMO-673, Tech. Inf. Service, Oak Ridge, Tenn. 

Ridland, G. C., 1950, Radioactivity at the Caribou silver mine, Boulder County,

Colo.: Min. Engineering, v. 187, p. 98-101. 

Riley, L. B., and Shoemaker, E. M., 1952, Distribution of ore deposits and spectrographic analyses of some rocks and ores on the Colorado Plateau: U. S. Geol.

Survey unpub. Trace Elements Inv. Rept. 278.

Robeck, R. C., and Conant, L. C., 1951, Reconnaissance search in parts of Kentucky, Tennessee, Indiana, Virginia, and Ohio for areas where uraniferous

black shale may be mined by stripping: U. S. Geol. Survey unpub. Trace

Elements Inv. Rept. 64. 

Roberts, W. A., and Gude, A. J., 3d., 1953, Uranium deposits west of Clancy,

Jefferson County, Mont.: U. S. Geol. Survey Bull. 988-F. 

Roberts, W. A., and Gude, A. J., 3d, 1954, Geology of the area adjacent to the

Free Enterprise uranium-silver mine, Boulder district, Jefferson County,

Mont.: U. S. Geol. Survey Bull. 988-G. 

Robinson, S. C., 1950, Mineralogy of the Goldfields district, Saskatchewan: Geol.

Survey Can. Paper 50-16, Ottawa, Ontario. 

Rodden, C. J., and Tregoning, J., 1950, U. S. Atomic Energy Commission, New

Brunswick Laboratory, Manual of analytical methods for the determination

of uranium and thorium in their ores: U. S. Govt. Printing Office, 55 p. 

Rosenzweig, A., Gruner, J. W., and Gardner, L., 1952, Widespread occurrence

and character of pitchblende in the Triassic and Jurassic sediments of the

Colorado Plateau: Econ. Geology, v. 47, no. 7, p. 776-777 (abs.); v. 49, p. 351-

361,1954.
56 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Ruch, J. W., 1954, Status of uranium recovery from low grade sources: Mines

Mag., v. 44, no. 3, p. 105. 

Runnels, R. T., Schleicher, J. A., and Van Nortwiek, H. S., 1953, Composition of

some uranium-bearing phosphate nodules from Kansas shales: Kansas Geol.

Survey Bull. 102, p. 93-104

 Russell, W. L., 1945, Relation of radioactivity, organic content and sedimentation : Am. Assoc. Petroleum Geologists Bull. v. 29, p. 1480.

Schlottmann, J. D., and Smith, L. E., 1954, Preliminary report on uranium 

mineralization in the Troublesome formation, Middle Park, Grand County, 

Colo.: U. S. Atomic Energy Comm. RME-1042, Tech. Inf. Service, Oak 

Ridge, Tenn.

Schopf, J. M., and Gray, R. J., 1954, Microscopic studies of uraniferous coal 

deposits: U. S. Geol. Survey Circ. 343.

Senftle, F. E., and McMahon, C., 1949, Determination of uranium in ores by field 

analysis: Canadian Min. Met. Bull. 42, p. 618-621.

Sharp, B. J., and Hetland, D. L., 1954, Preliminary report on uranium occurrence 

in the Austin area, Lander County, Nevada: U. S. Atomic Energy Comm. 

RME-2010, Tech. Inf. Service, Oak Ridge, Tenn.

Sheridan, D. M., Collier, J. T., and Maxwell, C. H., 1954, Geology of the Lost 

Creek schroeckingerite deposits, Sweetwater County, Wyoming: U. S. Geol. 

Survey Trace Elements Inv. Rept. 302, in preparation.

Shoemaker, E. M., and Luedke, R. G., 1953, Map of the uranium region of the 

Colorado Plateau: U. S. Geol. Survey Trace Elements Memo. Rept. 279, 

open file report. '

Sims, P. K., and Phair, G., 1953, Geology of the Copper King mine area, Prairie 

Divide, Larimer County, Colorado: U. S. Geol. Survey TEI-311, U. S. Atomic 

Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

Sims, P. K., Osterwald, F. W., and Tooker, E. W., 1955, Uranium deposits in the 

Eureka Gulch area, Central City district, Gilpin County, Colorado: U. S. 

Geol. Survey Bull, 1032-A (in press).

Singewald, Q. D., and Pierson, C. T., 1953, Results of reconnaissance for radioactive minerals in parts of the Alma district, Park County, Colorado: U. S. 

Geol. Survey Circ. 294.

Slaughter, A. L., 1945, Radioactivity of Pennsylvanian black shales and coals in 

Kansas and Oklahoma, preliminary report: U. S. Geol. Survey unpub. Trace 

Elements Inv. Rept. 18.

Slaughter, A. L., and Clabaugh, S. E., 1945, Preliminary report on trace elements 

reconnaissance in central and southwestern states: U. S. Geol. Survey 

unpub. Trace Elements Inv. Rept. 9.

Smyth, H. D., 1954, Industrial application of Atomic Energy: U. S. Atomic 

Energy Comm. release of address before third Annual Conference of Business Economists, Chicago, 111., April 23.

Staatz, M. H., 1945, Trace elements reconnaissance in Florida, preliminary report: 

U. S. Geol. Survey, unpub. Trace Elements Inv. Rept. 17.

Staatz, M. H., and Bauer, H. L., Jr., 1951a, A preliminary report on radioactive 

fluorite deposits, Thomas Range, Juab County, Utah: U. S. Geol. Survey 

TEM-167, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

 1951b, Virgin Valley Opal district, Humboldt County, Nevada: U. S. Geol. 

Survey Circ. 142.

 1952, Uraniferous fluorspar pipes and veins in the Thomas Range of Juab

County, Utah (abs.): Geol. Soc. America Bull., v. 63, p. 1371.
SEARCH FOR URANIUM IN THE UNITED STATES 57

Staatz, M. H., and Bauer, H. L., Jr., 1953, Uranium in the East Walker River area,

Lyon County, Nevada: U. S. Geol. Survey Bull. 988-C. 

Staley, W. W., 1948, Distribution of alluvial minerals in Idaho: Idaho Bureau

of Mines and Geology, Min. Res. Rept. no. 5. 

Steacy, H. RM 1953, An occurrence of uraninite in a black sand: Am.

Mineralogist, v. 38, p. 549-550. 

Stead, F. W., 1950, Airborne radioactivity surveying speeds uranium prospecting:

Eng. and Min. Jour., v. 151, no. 9, p. 74-76. 

Stead, P. W., and Davis, F. J., 1952, Development and application of airborne

radioactivity surveying (abs.) : Econ. Geology, v, 47, p. 126. 

Stevenson, J. S., 1951, Uranium mineralization in British Columbia: Econ.

Geology, v. 46, p. 353-366. 

Stewart, R. H., 1951, Radiometric reconnaissance examination in southeastern

Pennsylvania and western New Jersey: U. S. Geol. Survey TEM-255, U. S.

Atomic Energy Comm., Oak Ridge, Tenn. 

Stieff, L. R., Stern, T. W., and Milkey, R. G., 1953, A preliminary determination

of the age of some uranium ores of the Colorado Plateaus by the leaduranium method: U. S. Geol. Survey Circ. 271. 

Stokes, W. L., 1952, Uranium-vanadium deposits of the Thompsons Area, Grand

County, Utah, with emphasis on the origin of carnotite ores: Utah Geol.,

Min. Soc. Bull. 46. 

 1953, Relation of sedimentary features of the Salt Wash sandstone to

tectonic elements and uranium mineralization: U. S. Atomic Energy Comm.

RME-3058, Tech. Inf. Service, Oak Ridge, Tenn. 

 1954, Relation of sedimentary trends, tectonic features, and ore deposits

in the Blanding district, 'San Juan County, Utah: U. S. Atomic Energy

Comm. RME-3093 (pt. 1), Tech. Inf. Service, Oak Ridge, Tenn. 

Str0m, K. M., 1948, A concentration of uranium in black muds: Nature, v. 162,

p. 922. 

Stugard, F., Jr., 1952, Two uranium deposits in sandstone, Washington and Kane

Counties, Utah, (abs.) : Geol. Soc. America Bull., v. 63, p. 1373. 

Stugard, F., Jr., Wyant, D. G., and Gude, A. J., 3d., 1952, Secondary uranium

deposits in the United States: U. S. Geol. Survey Circ. 220. 

Sullivan, C. J., and Matheson, R. S., 1952, Uranium-copper deposits, Rum Jungle,

Australia: Econ. Geology, v. 47, no. 7, p. 751-758, 3 figs. 

Swanson, R. W., McKelvey, V. E., and Sheldon, R. P., 1953, Progress report on

investigations of western phosphate deposits: U. S. Geol. Survey Circ. 297. 

Swanson, V. E., 1953, Uranium in the Chattanooga shale (abs.): Geol. SoCo

America Bull., v. 64, p. 1481. 

Tavelli, J. A., 1951, Review of airborne radioactivity survey techniques in the

Colorado Plateau: U. S. Atomic Energy Comm. RMO-697, Tech. Inf.

Service, Oak Ridge, Tenn. 

Teichman, R. A., Jr., 1952, Method of outlining an ore body by maximum gamma

log deflection values on Polar Mesa, Grand County, Utah: U. S. Atomic

Energy Comm. RME-15, Tech. Inf. Service, Oak Ridge, Tenn. 

Thomas, H. D., 1954, Uranium in Wyoming: Mines Mag., v. 44, p. 81. 

Thompson, M. E., 1952, Further studies of the distribution of uranium in rich

phosphate beds of the Phosphoria formation: U. S. Geol. Survey TEI-275,

U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn. 

 1953, Distribution of uranium in rich phosphate beds of the Phosphoria

formation: U. S. Geol. Survey Bull. 988-D.
58 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Thoreau, J., and Trien de Terdouck, R., 1933, Le gite d'uranium de ShinkolobweKasolo (Katanga) : Inst. Roy. Colonial Beige, Section des Sciences Naturelles et Medicales, Brussels, Memoires, Tome 2, Fasc. 1; Abstract, Geol.

Soc. America Bull., v. 46, p. 941-942, 1935. 

Thurlow, E. E., and Wright, R. J., 1950, Uraninite in the Coeur d'Alene district,

Idaho: Econ. Geology, v. 45, p. 395-404. 

Thurston, R. H., and Trites, A, F., Jr., 1952, Intrusion breccias of Majuba Hill,

Nevada (abs.) : Geol. Soc. America Bull., v. 63, p. 1305. 

Tolmachev, U. M., 1943, Adsorption of uranyl salts by solid adsorbants: U. S.

S. R. Acad. Sci. Bull., no. 1, p. 28-34. 

Towle, 0. C., and Rapaport, I., 1952, Uranium deposits of the Grants district,

New Mexico: Min. Engineering, v. 4, no. 11, p. 1037-1040. 

Trites, A. F., Jr., and Tooker, E. W., 1953, Uranium and thorium deposits in

east-central Idaho and southwestern Montana: U. S. Geol. Survey Bull.

988-H. 

Troyer, M. L., McKay, E. J., Bolster, P. E., and Wallace, S. R., 1954, Summary

of investigations of uranium deposits in the Pumpkin Buttes area, Johnson

and Campbell Counties, Wyoming: U. S. Geol. Survey Circ. 338. 

United States Atomic Energy Commission, 1951, Tenth semiannual report:

U. S. Govt. Printing Office.

 1954, Fifteenth semiannual report: U. S. Govt. Printing Office.

 and the United States Geological Survey, 1951, Prospecting for uranium: 

U. S. Govt. Printing Office.

United States Geological Survey, 1953a, Search for and geology of radioactive 

deposits, Semiannual Progress Report Bee. 1, 1952-May 31, 1953: TEI-330, 

U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

 1953b, Search for and geology of radioatcive deposits, Semmiannual 

Progress Report June 1-Nov. 30,1953 : TEI-390, U. S. Atomic Energy Comm., 

Tech. Inf. Service, Oak Ridge, Tenn.

 1954a, Geologic investigations of radioactive deposits, Semiannual Progress Report, December 1, 1953 to May 31, 1954: TEI-440, U. S. Atomic 

Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

 1954b, Geologic investigations of radioactive deposits, Semiannual Proggress Report, June 1 to November 30, 1954: TEI-490, U. S. Atomic Energy

Comm., Tech. Inf., Service, Oak Ridge, Tenn. 

Vergie, P. C. de, 1953, Preliminary drilling at the Nash Car area, White Canyon

district, San Juan County, Utah: U. S. Atomic Energy Comm., RME-4032,

Tech. Inf. Service, Oak Ridge, Tenn. 

Vickers, R. C., 1953, Preliminary report on the monazite-bearing Goodrich

quartzite, Palmer area, Marquette County, Michigan: U. S. Geol. Survey

unpub. Trace Elements Memo. Rept. 558. 

Vine, J. D., and Moore, G. W., 1952, Uranium-bearing coal and carbonaceous rocks

in the Fall Creek area, Bonneville County, Idaho: U. S. Geol. Survey

Circ. 212. 

Vine, J. D., and Prichard, G. E., 1954, Uranium in the Poison Basin area, Carbon

County, Wyoming: U. S. Geol. Survey Circ. 344. 

Walker, G. W., 1953, Rosamond uranium prospect, Kern County, Calif.: Calif.

Div. of Mines, Special Rept. 37. 

Walker, G. W., and Levering, T. G., 1954, Radioactive deposits in California:

Calif. Div. of Mines Bull, (in press). 

Wallace, J. H., and Smith, H. B., 1955, Bibliography of U. S. Geol. Survey trace

elements and related reports to June 1,1954: U. S. Geol. Survey Bull. 1019-B.
SEARCH FOR URANIUM IN THE UNITED STATES 59

Wantland, DM and Casey, R. D., 1952, Field tests for the U. S. A. BJL O. on the 

use of the seismic geophysical method for tracing "buried channels" in the 

Monument Valley area, Arizona: U. S. Bureau of Reclamation Geol. Rept. 

G-123, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

Waters, A. O., and Granger, H. C., 1953, Volcanic debris in uraniferous sandstones, and its possible bearing on the origin and precipitation of uranium: 

U. S. Geol. Survey Circ. 224.

Weeks, A. D., Cisney, E. A., and Sherwood, A. M., 1953, Montroseite, a new 

vanadium oxide from the Colorado Plateaus: Am. Mineralogist, v. 38, 

p. 1235-1242.

Weeks, A. D., and Thompson, M. E., 1954, Identification and occurrence of 

uranium and vanadium minerals on the Colorado Plateau: U. S. Geol. 

Survey Bull. 1009^-B.

Weir, D. B., 1952, Geologic guides to prospecting for carnotite deposits on Colorado Plateau: U. S. Geol. Survey Bull., 988-B.

Westergard, A. H., 1944a, Borrningar genom Skanes alunskiffer 1941-1942: 

Sveriges geol. undersokning, ser. C, no. 459.

 1944b, Borrningar genom alunskifferlagret pa oland och i Ostergotland

1943: Sveriges geol. undersokning, ser. C, no. 463.

Whitehead, W. L., 1952, Studies of the effect of radioactivity in the transformation of marine organic materials into petroleum hydrocarbons: in Am.

Petroleum Inst, Fundamental research on occurrence and recovery of

petroleum, 1950-1951, p. 192-201. 

Whitehead, W. I/., Goodman, C., and Breger, I. A., 1951, The decomposition of

fatty acids by alpha particles: Jour. Chimie Physique, v. 48, p. 184-189. 

Williams, F. J., and Barrett, D. C., 1953, Preliminary report of reconnaissance

in the Cameron area, Arizona: U. S. Atomic Energy Comm. RME-4002, Tech.

Inf. Service, Oak Ridge, Tenn. 

Williams, F. J., and Davis, H. O., 1953, Moonlight group, Humboldt County,

Nevada: U. S. Atomic Energy Comm. unpub. Prelim. Reconnaissance Rept.

N-SL-6. 

Wilmarth, V. R., 1953, Yellow Canary uranium deposits, Daggett County, Utah:

U. S. Geol. Survey Circ. 312. 

Wilmarth, V. R., and Johnson, D. H., 1954, Uranophane at Silver Cliff mine,

Lusk, Wyoming: U. S. Geol. Survey Bull. 1009-A. 

Wilmarth, V. R., Bauer, H. L., Jr., Staatz, M. H., and Wyant, D. G., 1952, Uranium

in fluorite deposits: U. S. Geol. Survey Circ. 220, p. 13-18. 

Wilson, E. E., Rhoden, V. C., Vaughn, W. W., and Faul, H., 1954, Portable

scintillation counters for geologic use: U. S. Geol. Survey Circ. 353. 

Wimpfen, S. P., 1951, Uranium from phosphate rock: A paper presented at the

National Fertilizer Assoc., Atlanta, Ga., Nov. 14; summarized in Chem. Eng.

News, v. 29, p. 5112.

 1954, The present and future of domestic uranium production: Mines

Mag., v. 44, no. 3, p. 79. 

Wright, R. J., 1950, Reconnaissance of certain uranium deposits in Arizona:

U. S. Atomic Energy Comm. RMO-679, Tech. Inf. Service, Oak Ridge, Tenn.

 1953, What the uranium prospector should know about radiation: Eng. 

and Min. Jour., v. 154, no. 1, p. 92-95.

 1954a, Prospecting with a counter: U. S. Atomic Energy Comm., Washington, D. C.

 1954b, Where to look for uranium: Eng. and Min. Jour., v. 155, no. 9, 

p. 91-95.
60 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Wyant, D. C., Beroni, E. P., and Granger, H. C., 1952, Some uranium deposits in 

sandstone: U. S. Geol. Survey Circ. 220.

Young, R. B., 1917, The banket: London, Gurney and Jackson.

Zeller, H. D., and Baltz, E. H., Jr., 1954, Uranium-bearing copper deposits in the 

Coyote District, Mora County, New Mexico: U. S. Geol. Survey Circ. 334.

Zuckert, R., 1926, Die Paragenesen von Gediegen Silber und Wismut mit KobaltNickel-Kiesen und der Uranpechblende zu St. Joachimstal: Preussische 

Geol. Landes., Mitterlungen Abt. fur Gesteins-, Erz-, Kohle-, und SalzUntersuchungen, 1926, p. 69-132; Geol. Soc. America Bull., v. 46, p, 942-943 

(abs.). 1935.
INDEX

Acknowledgments 2 

Airborne reconnaissance__________... 20,33 

Alum shale, Sweden_____ . 14 

Aluminum phosphate.._ .... .... 14,37

Apatite-..-------..--.----.-_..._........ 14

Arikaree formation, uranium percolated down

from...____------ 8

Arizona, Cameron____ .. 32 

Dripping Springs quartzite 33 

Katherine and Michael district....... 25

Lukachukai district._____.... . 32

Monument Valley_____ . 32 

Arsenic______...___ 9 

Asphaltite and related substances. __ 12-13,33-36 

Australia, Bum Jungle district, replacement

deposit at. 7 

Autunite__.__.. .... 3,6

B

Bear River formation, Wyoming_______ 36 

Belgian Congo, Shinkolobwe, nickel-cobaltsilver veins at..__________ 6 

Betafite.._____________________ 5 

Bibliography.............___________ 46-60

Birch Island, British Columbia, replacement

deposit at.__... 6-7 

Black Hills.......... ...................... 10

Blackhawk district, New Mexico_______ 25 

Bone, adsorption of uranium by 18 

Bone Valley formation.---.-._.._... 14,16,17,37 

Bostonite_____________________ 28 

Botanical prospecting methods_____... 21-22 

Boulder, Mont., vein deposits at... 25 

Brannerite..-________________.. 3,17 

British Columbia, Birch Island, replacement

deposit at-.____________ 6-7 

Browns Park formation__________. .. 13,33

California, Buckeye district-. . 25

Randsburg district________.__... 28

Rosamond district_______________ 28

Silver Lady district-____._______ 25

Cameron, Ariz...._______________ 32

Canada, Great Bear Lake, veins at_____ 9

Halliburton-Bancroft area.________ 7

Saskatchewan, Goldfields. ________. 6 

Carbonaceous materials, association of uranium

with . _- 19

Carbonate-fluorapatite-____________ 3

Caribou-Grand Island area, Colorado _ 25 

Carnotite____.__..______ 3,7,8,13,28,29

Carrizzo Mountains_____.... 10

Central City area, Colorado________.. 25

Page

Chalcedonic limestone..._.__.__ 13 

Chattanooga shale...___________ 14,16,37,40 

Cherokee shale. 15 

Chinle formation___________...__. 9,32 

Chlorite ____________ 10

Chloritoid......._... - . 10

Coal, adsorption of uranium by..... 18

Coal and carbonaceous shale 7-8,36 

Cobalt--...... . 9,10,25

Colorado, Caribou-Grand Island area 25 

Central City area..___________. 25 

Front Range, vein deposits at. 25 

Hermosa formation_ 36 

Jamestown district.____________ 25 

Lawson-Dumont area.. 25 

Leyden mine___ 8 

Plateau-.... _......... 8,21,29

Poison Basin_...... 33

Ralston Buttes area__.. . 25

St. Kevin district-._______ ... 25

St. Peters Dome district__________ 25

Conclusions________.. , 44-45

Conglomerate.._.. 8-12

Copper....__...._________.__. 9,10, 22, 25

Copper King mine. 25 

Coyote district, New Mexico . 40 

Crandallite .__-___.__ 14 

Czechoslovakia, Joachimsthal..____ ... 6

Dakota sandstone... 

Davidite... ........ ._____ 3

Deposits, uranium, types of_..... 3-19

aluminum phosphate__ . 14,37 

asphaltite and related substances_ 12-13,33-36 

coal and associated carbonaceous shale 7-8,36 

distribution (see also Distribution of

uranium)__.-.--.,--._....... 24-44

hydrothermal vein................ 5-6,19, 24-28

origin of ores... 11-12 

limestone______.... . 13, 29

pegmatites__________.__ 5,18,19 

phosphorite__...._________... 16-17,37

placers_.........__.______ 17-18,21,40

regional distribution of 10 

replacement_.______.... 6-7,24-28

stream-channel deposits___ 9,11,21,28 

sandstone, continental, and conglomerate. 8-12,

29-33 

shale, black.................__.. 14-16,37-40

summary of geology of.__-...- . 18-20 

tuff and tuffaceous sediments___. 7,22,28-29 

Discoveries, outlook for future.. 40-44 

Distribution of Uranium deposits in United

States..... 24-44

asphaltite... .....__...__ 12-13,33-36

61
62 INDEX

Page 

Distribution of Uranium, etc. Continued

coal and continental carbonaceous shale. 7-8,36 

limestones__________________ 13,29 

marine black shales_________ 14-16,37-40 

outlook for future discoveries..... ___.. 40-44

phosphorites..____....__.._... 16-17,37

placers..__.........._............ 17-18,40

sandstones_______________ 8-12,29-33

tuffaceous rocks____________ 7,22,28-29

vein and replacement-_________ 5-6,24-28

Dripping Springs quartzite, Arizona.___.. 33

E

Electric logging__________________ 21 

Entrada formation.__ ..._ 9 

Euxenite.__ ___ ____ __. 3,5,17

Fall Eiver sandstone_____________ 32 

Fergusonite __ . 3,17 

Florida, Bone Valley formation_... 14,16,17,37 

Hawthorne formation-.. __ ..__ 17 

Fluorapatite . 3 

Fluoride, sodium, fusion with uranium

minerals______________ 2 

Fluorite... .......... ..... ..... ... 13,25

Fort Union formation..__ _ .. 36 

Fracture fillings, uranium bearing_...___ 24 

Franklin limestone, Warren County, N. J.,

replacement deposit at_ ..... 7 

Free Enterprise mine___..________ 28

Gas, natural... ............

Oeiger counter..___ __..._.....

Geochemical prospecting methods......

Geologic prospecting methods..........

Geologists employed in uranium search .

13 

20 

22 

20 

1

Geology of Uranium deposits, summary.. 18-20 

Geophysical prospecting methods____. . 20-21 

Gold....-.. . ..-. .... ...- 10,25 

Goldfields, Saskatchewan, pyrite galenapitchblende veins at__ __ 6 

Goodsprings district....__ _____ 25 

Grants area, New Mexico.._______.... 32 

Great Bear Lake, Canada, nickel-cobalt-silver

veins at.._____________ 6 

Green River district....__.______.... 32

H

Halliburton-Bancroft area, Ontario, replacement deposits at_________ 7 

Happy Jack mine, Utah____________ 32 

Hartvllle dome__________________ 40 

Hartville formation_______________ 15,37 

Hawthorne formation.._____._____ 17 

Henry Mountains, Utah.. __...... _ 32

Hermosa formation..._____________ 36 

Hydromica. . . 8

Idaho, Salt Lake formation. . ... 36 

Indicator plants___._.._.__._.._ 22

IntroductionsIron_____.

Page

1

25

Jamestown district, Colorado_____.".__ 25 

Joachimsthal, Czechoslovakia, nickel-cobaltsilver veins at.._________ 6 

Juniper, indicator plant..__________ 22

Kaoline.. _______.. 

Katherine and Michael district. 

Kolm__.___.______..

Lakota sandstone______..._______ 32 

La Sal Mountains___.__ 10 

Lawson-Dumont area, Colorado_______ 25 

Lead...... .. .:. *- 9,10,25

Leyden mine, Colorado_____________ 8 

Lignite, uranium bearing_______... 8,24,36,41 

Limestone..__......._____._..____ 13, 29

Lithium fluoride, fusion with uranium minerals________ . 2 

Logging, electric______ 21 

Lukachukai district, Arizona. 32

M

Majuba Hill district... ...... ........... 25

Marysvale, Utah, vein deposit at______ 25

Mi Vida mine, Utah.............__......... 32

Miller Hill, Wyo................ ... . .. 29

Milton dolomite .......... . 13

Minerals, common uranium (see also names of

minerals)______________ 2-3

Moenkopi formation____._-____... 9

Molybdenum__________.____... 9 

Monazite.. . 3,17,40

Montana, Boulder, vein deposits at_____ 25

Free Enterprise mine____.._ .. 28

Woodrow Wilson mine__________ 28

Monument Valley, Ariz__________._ 32

Morrison formation_____ 9,32

N

Nevada, Goodsprings district 25 

Majuba Hill district...................... 25

New Jersey, Franklin limestone, replacement

deposit at_____________ 7

New Mexico, Blackhawk district_______ 25 

Coyote district. ... ... ... .. 40 

Grants area________________ 32 

Todilto limestone. _______ 7,10,13,29,32 

White Signal district .................. 25

Nickel...................................... 9,10,25

Nigeria_______..______ ._ 14

O

Oklahoma, Cherokee shale__________ 15 

Origin of ores, Witwatersrand and Colorado

Plateau 11-12
INDEX 63

Page

Peat, adsorption of uranium by_______ 18 

Pegmatites__________________ 5,18,19 

Phosphate, aluminum, deposits_______ 14,37 

Phosphoria formation_____________ 16,37 

Phosphorite ............................ 16-17,37

Physical prospecting methods ________ 23 

Pitchblende __................ 3,6,7,8,25,33

Placers................... ........... 17-18,21,40

Placerville thucholite deposits________ 25 

Plankton, extraction of uranium by _____. 15 

Poison Basin Wyoming and Colorado. ___ 33 

Portugal, Urgeirica, pyrite-galena-pitchblende

veins at______________ 6

Prospecting methods. _____.______ 20-24

botanical._______.......___ 21-22

geochemical________ ______ 22 

geologic_________ ..._____. 20 

geophysical_____ ...... 20-21

physical__________ ____ 23

Selection of areas for prospecting_..._ 23-24

Pumpkin Buttes deposits, Wyoming 33

Pyrite .. . ._ 10, 14

Pyrochlore___________________ 3

Q

Quartz-sulflde deposits____ ____ 25

R

Radium____________________ 21 

Radon_____________________ 21 

Ralston Buttes area. ___ _______ 25 

Randsburg district, California_________ 28 

Red Desert, Wyo...__... ...___.___ 36 

Refraction seismic surveys__________ 21 

Replacement deposits..__.. ____ 6-7,24-28 

Resistivity surveys_------------___._. 21

Rosamond district, California... ___ ___ 28 

Rum Jungle district, Australia, replacement

deposit at_____________ 7 

Russia, Tyuya Muyun__ ______ 13

St. Kevin district ._____________ 25 

St. Peters Dome district....----....-____ 25

Salt Lake formation, Idaho__________ 36 

Saltbrush, indicator plant-.-________ 22 

Samarskite__________________ 3,5,17 

San Rafael Swell district___________ 32 

Sandstone, continental-.._......_... 8-12,29-33

Saskatchewan, Qoldnelds..._________ 6 

Schroeckingerite________________ 3,6 

Scintillation counter______________ 20 

Seismic surveys, refration___________ 21 

Selenium___._____________.'._ 9,22 

Senegal_____________________ 14 

Sericite_____________________ 10 

Shale, black......-..- ............... 14-16,37-40

carbonaceous, and coal._________ 7-8 

Shinarump formation..__________... 9,32 

Shinkolobwe, Belgian Congo, nickel-cobaltsilver veins at.. ____... 6 

Silver........................................ 9,25

Silver Lady district-______________ 25

Page

Sodium fluoride, fusion with uranium minerals__..__... _________ 2 

South Africa, Witwatersrand________ 8,10,11 

South Dakota, Arikaree formation, uranium

percolated down from.______ 8 

Black Hills....-.......... . ........ 10

Fall River sandstone_______._... 32 

Spergen limestone...____._____ . 13,15 

Stream channel deposits ..... 9,11,21,28

Summerville formation____________. 9

Temple Mountain.. 32 

Tennessee, Chattanooga shale.____. 14,16,37,40 

Thomas Range fluorspar pipes.._______ 24-25 

Thorianite..___..______________ 6 

Thucholite.___...___...._______ 10,25

Todilto limestone, Grants, N. Mex_ 7,10,13,29,32 

Torbernite...__... 3,6 

Trachyte..____..._............. 6

Tuff and tufiaceous sediments._____ 7,22,28-29 

Tyuya Muyun, Russia . 13 

Tyuymunite_____... _____ 3,32

u

Uinta formation_..__..__________ 13 

Uraninite.____.___ ____.. 3,5,10,25

Uranium minerals, common_________ 2-3

Uranophane___.__ ___.... 3, 28

Uranothorite.______ _____ .. 17

Uravan mineral belt_ ...... 10

Urgeirica, Portugal, pyrite-galena-pitchblende

veins at....__ ____. . 6

Utah, Happy Jack mine _ 32

Henry Mountains_ __ 32

Marysvale....__ ... 25

Mi Vida mine-. . . ___.___ 32

San Rafael Swell district_________ 32

Yellow Canary district______ 25

Vanadium........._____..___ 9,22

Veins, hydrothermal__________ 5-6,19,24-28 

Vermont, Milton dolomite. __ 13

w

Wasatch formation.______________ 33,36 

Water, natural, uranium content of___... 22 

WaveUite................ . 14

Weathering of deposits.. __ 6,18 

Wind River Basin, Wyoming.__.. 33 

Wind River formation____.____.. 33 

White River formation, uranium-bearing lignite below 8 

White Signal district..__._.... 25

Wichita Mountains__________.__.. 36 

Witwatersrand, South Africa________ 8,10,11 

Woodrow Wilson mine.. . 28 

Wyoming, Bear River formation.... . 36

Browns Park formation...__ 13,33 

Green River district_ __ 32 

Hartville dome____________ 40 

Hartville formation. . 15,37 

Miller Hill._..__.____.____... 29
64 INDEX

Wyoming, Bear Eiver formation Continued Page 

Poison Basin.___.___.______ 33 

Pumpkin Buttes deposits.________ 33 

Red Desert__________________ 36 

Wind Eiver Basin.. ..... 33

Yellow Canary district. 25

Zinc-...

Zippeite. 

Zircon...

Page

9,10,25

3

.. 3,17

o
Stratigraphy of Parts 

of De Soto and 

Hardee Counties 

Florida

By M. H. BERGENDAHL

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM 

GEOLOGICAL SURVEY BULLETIN IOSO-B

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U, S. Government Printing Office 

Washington 25, D. C.
CONTENTS

	Page

Abstract_______________________________________ 65

Introduction.. _______________________________ _ ______ ___ 65

Purpose and scope__________________________ _______ --_ 65

Methods of investigation____________________ ____ __ _ 67

Culture. _._____________________________ 67

Topography. ____________________________ ____ 68

Drainage. ________________________ . __ - 68

Acknowledgments. _________________________________________ 68

Stratigraphy. ___________________________ __ __ 69

Miocene series._________________________________________ ___ 69

Hawthorn formation_______________________________________ 69

Sand of late Miocene age_____________--____-_---_-------___ 73

Miocene to Pliocene series_________________-___-____-___________ 79

Undifferentiated phosphatic sand and clay____________ _ . 79

Pliocene series._____________________________ _____ ___ 84

Caloosahatchee marl________________________ _____________ 84

Pleistocene series.__________________________________________ 86

Deposits of Pleistocene age_______________________________ 87

Sediments of Recent age______________________________________ 90

Mechanical analysis______________________________________________ 91

Geologic history_____________________________________________ 92

Miocene....___________________________________________________ 92

Pliocene__.._____________________________________ 93

Pleistocene-_____________________________________ 93

Recent. _ _ ______________________________________ 94

Economic considerations________________________________________ 94

Literature cited._______________________________________ 95

Index._____.._________________________________ 97

ILLUSTRATIONS

[All plates in pocket]

PLATE 1. Geologic map showing location of outcrops and drill holes in 

parts of Hardee and De Soto Counties, Fla.

2. Geologic sections through parts of Hardee and De Soto Counties.

3. Cumulative frequency curves of samples from 12 auger holes.

4. Classification of the upper Tertiary rocks in Florida, showing 

stratigraphic terms used by various authors.

m
IV CONTENTS

Page 

FIGURE 6. Index map of land-pebble phosphate district, Hardee and

De Soto Counties_____________________________ _ 66

7. Summary of exposed formations in Hardee and De Soto

Counties. _______________________________ 70

8. Diagram showing general stratigraphic relations of the

formations in Hardee and De Soto Counties.____________ 71

9. Sketch map and cross sections of borrow pit, 1.6 miles east of

Nocatee, De Soto County____________________________ 74

10. Sketch of section exposed along west bank of Peace River,

near Gardner, Hardee County________ __ 78

11. Plan and profile sketch of exposure along Horse Creek, at

bridge on Florida Route 72, De Soto County., ___ _ 91
CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

STRATIGRAPHY OF PARTS OF DE SOTO AND HARDEE 

COUNTIES, FLORIDA

By M. H. BERGENDAHL

ABSTRACT

The late Cenozoic stratigraphy of part of central Florida immediately south of 

the land-pebble phosphate district was studied in detail to determine the southern 

limit of the economically important Bone Valley formation and its relations with 

marine rocks of late Miocene and Pliocene age in south-centra1! Florida. In addition, a reconnaissance-type appraisal of the phosphate and uranium resources of 

this area was desired. The upper Tertiary and Quaternary rocks were mapped, 

and the economic geology'was studied in a general manner.

The Hawthorn formation, of early and middle Miocene age, is the oldest rock 

exposed. Undifferentiated phosphatic sand and clay of late Miocene to Pliocene 

age may be composed of: (1) the Bone Valley formation, (2) a combination of Bone 

Valley formation and residuum of weathered Hawthorn formation, or (3) residuum 

of the Hawthorn alone. The Bone Valley formation and residuum of the Hawthorn formation appear to be almost identical in cuttings from auger drilling in 

this area. It was neither feasible nor practical to map these two units separately. 

The undifferentiated phosphatic sand and clay interfingers with a marine sand of 

late Miocene age. The Caloosahatchee marl, of Pliocene age, is present in the 

southeast corner of the area investigated. It is apparent that the undifferentiated phosphatic sand and clay was undergoing subaerial erosion and reworking 

during deposition of the Caloosahatchee marl. Stratified sand and clayey sand 

containing scattered thin lenses of fresh-water limestone and marl of Pleistocene 

age are believed by the writer to be either flood-plain deposits or subaerial top-set 

beds of a delta made by the Pleistocene Peace River. Stream deposits of Recent 

age are present locally along the Peace River and its tributaries.

Bars and shoals in the Peace River south of Brownville, De Soto County, contain appreciable tonnages of low-grade "river-pebble" phosphate. The phosphate 

and uranium content of the undifferentiated phosphatic sand and clay in Hardee 

County is too low to be of economic significance.

INTRODUCTION

PURPOSE AND SCOPE

The results of one part of the investigations of the regional geology 

of central Florida by the U. S. Geological Survey are presented in 

this paper. Work was done on behalf of the Division of Kaw Materials of the U. S. Atomic Energy Commission.

The area covered by this report is immediately south of the Florida 

land-pebble phosphate minina; district (fig. 6).

65
66 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

26

84° " """"" 82° 

FIGURE 6. Index map of land-pebble phosphate district, Hardee and De Soto Counties.

Although the geology of Hardee and De Soto Counties is described 

in a number of reports (Matson and Clapp, 1909; Matson and 

Sanford, 1913; Cooke and Mossom, 1929; Cooke, 1945), several 

important problems remained unsolved. The southern extent of the 

Bone Valley formation, which .contains the economic phosphate 

deposits, was never accurately mapped. The northern limit of the
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 67

Caloosahatchee marl, a fossiliferous shallow-water marine rock of 

Pliocene age that is present throughout southern Florida, was not 

precisely determined.

This investigation was conducted for two reasons: (1) to clarify 

the late Cenozoic stratigraphy south of the land-pebble phosphate 

district, particularly the relations of the Bone Valley formation with 

the Caloosahatchee marl; (2) to appraise the potential economic 

value of the area for phosphate and uranium.

METHODS OF INVESTIGATION

The area mapped in Hardee and De Soto Counties is a strip 42 

miles long and 15 to 17 miles wide, roughly parallel to the Peace 

River (pi. 1). It includes about 700 square miles within the approximate boundaries of 27°2' to 27°39' north latitude and 81°40' to 82°3' 

west longitude. Gardner, which is near the center of the area, is 

about 58 miles (airline) southeast of Tampa and about 50 miles 

(airline) south of Lakeland.

The region is of such low relief that exposures are limited to the 

banks xrf streams and to shallow borrow pits. In addition, a mantle 

of surficial alluvium and wind-blown sand effectively conceals the 

older sediments. Less than 40 outcrops were found; the maximum 

section was 16 feet thick. A power auger, mounted on the rear of a 

4-wheel-drive truck, was used to obtain more detailed subsurface 

information at 92 localities. In general, holes were drilled at intervals 

of 1 to 2 miles along the rights-of-way of state and county roads. 

In addition, well logs and limestone cores from the U. S. Atomic 

Energy Commission contract drilling in this area were studied.

Topographic maps for this region were not available when field 

work was in progress. Planimetric county road maps, published on 

a scale of 1:125,000 by the Florida State Road Department, were 

used as a base for geologic mapping.

Altitudes of outcrops and drill holes were obtained by aneroid 

barometer traverses. It was possible during traverses to visit U. S. 

Geological Survey and U. S. Coast and Geodetic Survey bench marts 

within time intervals of less than 10 minutes. These elevations 

should be accurate to within 5 feet.

The period May through part of September 1953 was spent in the

field.

CULTURE

The major towns in the area are Wauchula (population 2,872), the 

county seat of Hardee County, and Arcadia (population 4,764), the 

county seat of De Soto County. U. S. Highway 17, which passes 

through Wauchula and Arcadia, is the principal north-south highway 

(pi. 1). State Highways 70 and 72 link Arcadia with Sarasota, on
68 ''" CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

the west coast, and with Sebring to the east. In De Soto County 

and southern Hardee County, cattle raising is the chief vocation. 

In northern Hardee County, the well-drained sandy soil is adaptable 

to orange groves and truck farming.

TOPOGRAPHY

The area includes two natural topographic subdivisions the Central Highlands, and the Coastal Lowlands (Cooke, 1939, p. 14). The 

northern part of Hardee County is within the Central Highlands. 

The topography is gently rolling, and altitudes generally range between 90 and 150 feet.

Immediately south of Zolfo Springs and Ona, the Central Highlands 

give way to the prairie country of the Coastal Lowlands. This area is 

a conspicuously flat plain, sloping slightly to the south. Altitudes 

range from 35 to 70 feet. In southern De Soto County the banks of 

the Peace River are less than 20 feet above sea level. The water table 

is close to the surface in this region, and many temporary shallow ponds 

appear during the rainy season.

DRAINAGE

The area is drained principally by the Peace River, which flows 

southward from its source in central Polk County for about 70 miles 

to Charlotte Harbor, near Punta Gorda, in Charlotte County.. Major 

tributaries in Hardee and De Soto Counties are Payne's Creek, Charlie 

Apopka Creek, Joshua Creek, Horse Creek, and Prairie Creek. 

Intense rainfall during the summer and fall often causes the stream 

levels to rise 15 to 20 feet. During such periods, pastures adjacent to 

the streams are flooded for weeks at a time, and occasionally bridges 

are swept away. Outcrops are submerged by swollen streams, dirt 

roads are impassable, and drilling is difficult because of the flooded 

roadside conditions. .

Streams are degrading at present. At many points along the Peace 

River and Charlie Apopka Creek, the banks are vertical. PrePleistocene phosphatic formations are being eroded, and the phosphate 

is being redeposited in shoals and bars along the lower reaches of the 

streams.

ACKNOWLEDGMENTS

Jean Hough identified the vertebrate fossils, and F. S. MacNeil 

examined and identified collections of invertebrate fossils. Radiometric analyses for percent equivalent uranium were made by B. A. 

McCall, Anthony Cerkel assisted the writer in the field.
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 69

STRATIGRAPHY

MIOCENE SERIES 

HAWTHORN FORMATION

The term "Hawthorn formation" has a complex history in Florida 

geology. It is essential that at least a brief review be given here.

Originally, the name "Hawthorne" was given by Dall (1892, p. 107) 

to the phosphatic limestone believed to be of "older" Miocene age 

(pi. 4) near the town of Hawthorne in Alachua County. Younger 

than the Hawthorne "beds", but still of "older" Miocene age, were the 

Tampa, Chipola, and Alum Bluff "beds", which were assigned by Dall 

(1892, p. 112) to the Tampa group (pi. 4). Later, due to a readjustment of the Oligocene-Miocene boundary, the Tampa group was 

regarded as Oligocene by Dall and others.

Matson and Clapp (1909, p. 67-69) combined rocks of the upper 

Oligocene into the Apalachicola group, which consisted of the following 

four formations: Tampa, Chattahoochee, Hawthorne, and Alum Bluff

(pJ. 4).

Matson and Sanford (1913, p. 87-88) shortened the name "Hawthorne" to "Hawthorn." They (Matson and'Sanford, 1913, p. 145) 

believed that the land-pebble phosphate deposits lie upon an eroded 

surface of the Alum Bluff formation.

According to Sellards (1915, p. 34-35), the Alum Bluff formation 

was the parent rock from which the land-pebble phosphates were 

derived. Sellards (1916, p. 91-92) later introduced evidence of a 

Miocene vertebrate fauna in the Alum Bluff formation. The opinion 

that the Alum Bluff formation should be considered Miocene was 

generally accepted by later workers (pi. 4).

Gardner (1926, p. 1-2) recognized three distinct marine faunas of 

Miocene age, and, on the basis of these faunas, she raised the Alum 

Bluff to the rank of a group divided into three formations, each of 

which was characterized by a separate fauna. In descending order 

these were: Shoal River formation, Oak Grove sand, and Chipola 

formation (pi. 4).

Cooke and Mossom (1929, p. 98) retained Gardner's Alum Bluff 

group but reinstated the Hawthorn formation as a lateral equivalent 

in peninsular Florida of the Alum Bluff group in western Florida. 

Within the Hawthorn formation, Cooke and Mossom (1929, p. 115) 

included the earlier Alum Bluff formation of Matson and Clapp (1909, 

p. 91) and the original Hawthorne "beds", the Manatee River marl, 

the Sopchoppy limestone, and the Jacksonville limestone of Dall. In 

general, Cooke (1945, p. 144) retained this classification, but he

378283 5C
70 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

tentatively transferred to the Duplin marl some beds of late Miocene 

age that Cooke and Mossom (1929, p. 115) assigned to the Hawthorn 

formation.

The Alum Bluff-Hawthorn equivalence has survived to the present; 

however, current views do not all agree on the age of the Alum Bluff 

group. According to F. S. MacNeil (written communication, Sept. 

1955), "The Chipola, the basal formation of the Alum Bluff group, is 

regarded by some as late early Miocene, by others as early middle 

Miocene."

The term "Hawthorn formation" as used in this report includes all 

marine rocks in central and southern peninsular Florida that are 

younger than the Tampa limestone, of early Miocene age, but older 

than the lowermost sediments of late Miocene age (fig. 7).

Stream terraces and bars

Mostly gray to white quartz sand, containing varying percentages of phosphate nodules. Thickness 0-28 ft. Economic 

value: Source of river-pebble phosphate

Pleistocene deposits 

Brown quartz sand and clayey sand, with scattered thin lenses

of blue-gray day. Sand is locally crossbedded. Lentils 

*of fresh-water limestone are included. Thickness 0-20 ft. 

Economic value: Limestone is'usedfor road fill

Caloosahatchee marl 

Gray to blue-gray quartz sand, slightly 

clayey in places. Abundant marine 

fauna forms a shell bed locally. Thickness 0-20 ft. Economic value: Use as 

road fill, when shells are abundant

Sand of late Miocene age 

Dark-green to light-gray quartz sand, 

with few phosphate nodules. Contains a characteristic marine fauna. 

Thickness 0-40ft. Economic value: 

Use as road fitt, when shells are abundant

Bone Valley formation 

Mostly variegated shades of red, gray, 

brown, and blue. Phosphate nodules 

and pellets usually dominant constituent. Quartz sand, clay-size material 

may be abundant in places. Vertebrate remains are locally conspicuous. 

Thickness 0-35 ft. Economic value: 

Possible source of land-pebble phos- 

' uranium

Hawthorn formation 

Light-gray to buff phosphatic, silty, 

sandy limestone. Casts of marine invertebrates in upper few feet. Thickness unknown in this area. Economic 

value: None in this area

Weathered residuum of

Hawthorn formation 

Phosphate nodules, sand, clay; similar 

to Bone Valley formation. Thickness 

unknown. Economic value: Possible 

source of land-pebble phosphate and 

uranium

FIGURE 7. Summary of exposed formations in Hardee and De Soto Counties.

Lithology. As seen at outcrops along streams in this area and in the 

phosphate mines to the north, the Hawthorn formation is a gray to 

cream, locally buff-colored limestone. Stratification is indistinct and, 

in places, is marked by concentrations of phosphate grains in beds or 

lenses. Commonly, the Hawthorn formation is consolidated; locally, 

it is indurated.

Fine-grained quartz sand, quartz silt, clay-size particles, phosphate 

nodules, and calcium carbonate are the chief constituents. Magnesium carbonate is usually a minor constituent, but it may be present 

locally in sufficient quantity to make the formation dolomitic. Indi-
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 71

victual sand grains are sub-angular to rounded. Phosphate nodules 

range from fine sand to cobbles. The phosphate in the Hawthorn 

formation is predominantly brown; individual grains are glossy 

surfaced.

Irregular chert nodules of cobble to boulder size are locally common 

in the upper part of the Hawthorn formation. Some nodules are 

lenticular, others are in a variety of shapes. The nodules are distributed randomly, and the long axes have no apparent relation to the 

bedding in the limestone. These characteristics suggest an authigenic origin for the chert.

Internal and external molds of pelecypods and gastropods are 

abundant in the upper part of the Hawthorn formation.

Distribution. The Hawthorn formation underlies the undifferentiated phosphatic sand and clay throughout most of Hardee County 

(pi. 2, and fig. 8). A slight southward dip is indicated by elevations

20 25 30 35 40 Miles

FIGURE 8. Diagram showing the general stratigraphic relations of the formations in Hardee and De

Soto Counties.

of exposures and drill holes, but this is virtually impossible to measure 

because of the eroded relief on the present upper surface of the Hawthorn formation. Well records show that the Hawthorn formation 

varies in thickness. A well drilled at Quincy, in Gadsden County, 

revealed 210 feet of Hawthorn formation (Cooke, 1945, p. 145). Near 

Hilliard, in Nassau County, nearly 400 feet of Hawthorn formation 

was identified from well cuttings (Cooke, 1945, p. 145). Greater 

thicknesses may have been deposited at points farther from the Ocala 

uplift (Cooke, 1945, p. 5-7), particularly in southern Florida, but 

much of the present range in thickness in central and northern Florida 

reflects post-Hawthorn erosion. In southern Hardee and De Soto 

Counties, the formation has been reached in drill holes; however, the 

thickness in this region is unknown.

Details and fauna. Nearly all of the fossils listed in this section 

are described by Gardner (1926) in her detailed work on the middle 

Miocene molluscan fauna of Florida.

Because natural exposures of the Hawthorn formation are limited 

to the upper few feet, details on lithology, sedimentary structures, and
72 CONTRIBUTiaNS TO THE GEOLOGY OF tJRANTUM

fauna are difficult to obtain. Many outcrops are either barren of 

fossils or they are so close to water level of streams that extensive 

investigation is impossible.

The thickest section of Hawthorn formation in this region was found 

along the north bank of the Peace River, at the bridge on U. S. Highway 17 (loc. 22-53, pi. 1), 0.5 mile north of Zolfo Springs (NE^SE)^ 

sec. 22, T. 34 S., R. 25 E., Hardee County). Here, 6 feet of gray 

indurated limestone is exposed above water level in the river. Chert 

cobbles and boulders are incorporated within the upper 2 feet of the 

limestone. The following fossils, identified by F. S. MacNeil, were 

Collected:

Pelecypoda:

Chlamys sp.

Venericardia sp. 

Bryozoa

Although these invertebrates are not diagnostic of the middle 

Miocene, the lithology of the limestone is typical of the Hawthorn 

formation in this area; furthermore, less than 1 mile south of this 

locality along the Paace River (loc. 16-53, pi. 1) at the northwest 

corner of the bridge over the Peace River on State Highway 64, 1.3 

miles west of Zolfo Springs similar limestone containing a probable 

Hawthorn fauna is exposed at water level. The following external 

molds of pelecypods, identified by F. S. MacNeil, were collected here:

Venericardia sp. aff. V. hadra and V. himerta Dall. Fragment of external mold. 

Cardium (Trachycardium) sp. Sculpture resembles that of C. malacum Dall. 

Fragments of external mold.

Additional evidence for the middle Miocene age of the limestone in 

this region was furnished from fossiliferous limestone cores of the 

U. S. Atomic Energy Commission. In drill hole 10-8, in SW%SW% 

sec. 15, T. 34 S., R. 25 E., Hardee County (pi. 1), the following 

pelecypods were identified (by F. S. MacNeil) in a soft, phosphatic 

limestone at 36.4 feet below the surface:

Anadara sp.

Chione sp. aff. C. sellardsi Gardner

From drill hole 11-1, in NW%NW% sec. 1, T. 34 S., R. 25 E., 

Hardee County (pi. 1), a tan, sparsely phosphatic, clayey limestone 

yielded these invertebrates, which were identified by F. S. MacNeil, 

at depths ranging from 13.6 feet to 17.0 feet below the surface:

Gastropoda:

Cancellaria sp. cf. C. macneili Mansfield (description from Area zone of the 

Choctawhatchee formation of Cooke and Mossom, 1929)

Semicassist 

Pelecypoda:

Glycymeris sp. aff. G. subovata (Say)
STRATIGRAPHY, DE SOTO AND HARDEE - COUNTIES, FLORIDA 73

Anadara sp. cf. A. gunteri Gardner 

Plicatula sp. cf. P. densata Conrad

Phac&ides sp. cf. P. contractus (Say)

Venericardia sp.

Cardium sp.

Dosinia sp.

Venus sp.

This assemblage is probably late middle Miocene and would therefore be from the upper part of the Hawthorn formation.

In drill hole 11-5 in NEtfSEft sec. 31, T. 33 S., K. 26 E., Hardee 

County, and drill hole 11-6 in NE#SE# sec. 31, T. 33 S., R. 27 E., 

Hardee County (pi. 1), the Hawthorn formation was penetrated at 

depths of 49 feet and 72 feet respectively. The following pelecypods 

were identified by F. S. MacNeil from the core in drill hole 11-5}

Glycymeris sp.

Phacoides sp. cf. P. contractus (Say)

The limestone in drill hole 11-6 contained these pelecypods:

Chlamys sp. aff. C. nicolsi Gardner. Fragments of external mold. 

Venericardia sp. Internal mold. 

Chione sp. aff. C. chipolana Dall 

Venus sp. Internal mold.

In the southern part of the area, an undetermined thickness of 

strata of late Miocene age overlies the Hawthorn formation. The 

Hawthorn formation is not exposed in De Soto County. The 

upper Miocene sediments, some of which are limestones, thicken 

southward, down dip, and diagnostic fossils are necessary for differentiating the Hawthorn formation from the lower strata of the 

upper Miocene rocks.

Origin. The lithology of the Hawthorn formation indicates deposition in a shallow sea. North of the land-pebble phosphate 

district, in Pasco and Hernando Counties, the Hawthorn formation is predominantly sand, which is suggestive of deposition in a near-shore environment. Most writers (Eldridge, 

1893, p. 196-231; Matson and Clapp, 1909, p. 139, 167; Matson and 

Sanford, 1913, p. 145-206; Matson, 1915, p. 65; Sellards, 1915, p. 58); 

believed the subjacent Hawthorne formation to be the source rock; 

for the phosphate in the economic land-pebble phosphate deposits.

SAND OF LATE MIOCENE AGE

A gray to green, slightly phosphatic, marine sand underlies all of 

De Soto County and the southern part of Hardee County and ,con-: 

tains an invertebrate fauna, including many large oysters and bar-, 

nacles. The characteristic lithology and associated fauna are easily 

identified, even in auger cuttings. The sand is the youngest of the 

upper Miocene strata in this area (fig. 7). It is well exposed in a
74 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

borrow pit (NWKSEK sec. 24, T. 38 S., R. 24 E.) along Florida Koute 

760, 1.6 miles east of the junction of U. S. Route 17 and Florida 

Route 760 at Nocatee (fig. 9). Fossiliferous sand is exposed at or 

below water level in the pit. Piles of dredged material around the 

sides of the pit yielded marine fossils, which establish the latest 

Miocene age of the sand. A drill hole near the east end of the pit 

revealed a thickness of 16 feet of the Miocene sand at this locality. 

In the borrow pit this late Miocene sand is overlain by 6 feet of a 

surficial sand and calcareous clayey sand containing fresh-water and

c

s'-

EXPLANATION

' Pleistocene 

c-x-Xv:£vX£v*»:*"v:v"v" r deposits

WATER LEVEL \ Sand of late 

< Miocene age

100 300 Feet

Contour interval 6 feet 

Datum is wafer /eve/ in pit

Fossiliferous (non-marine) 

phosphatic quartz sand

Stratified phosphatic sand

FIGURE 9. Sketch map and cross sections of borrow pit, 1.6 miles east of Nocatee, De Soto County.
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 75

land gastropods of probable Pleistocene age. The upper contact of 

the late Miocene sand with this surficial material is sharp and, at 

several places in the pit, is marked by a 3- to 6-inch bed of phosphate 

pebbles and cobbles comprising the basal unit of the Pleistocene section (fig. 9, sec. A A', B B', C C'}, The lower contact of the 

sand with the Hawthorn formation is not exposed at this locality. 

Indurated limestone (Hawthorn? formation) was encountered in the 

auger hole (fig. 9) at a depth of 27 feet below the surface. No limestone sample was recovered. A bed of nonfossiliferous phosphate 

gravel, 2 feet thick, immediately overlies the limestone at this locality.

No vertebrate fossils were found in the sand of late Miocene age in 

the area investigated; however, MacNeil (written communication, 

July 1954) reported that he found remains of the mastodon Serridentinus floridanus (a "good lower Pliocene" species) in the lower part 

of.,,.or immediately below, similar sand in Charlotte County. This 

apparent coincidence of vertebrate lower Pliocene and invertebrate 

uppermost Miocene fossils points out the current uncertainty as to 

the exact stratigraphic position of the Miocene-Pliocene boundary.

On the basis of MacNeil's invertebrate fossil identifications this 

sand of late Miocene age is either younger than, or equivalent to, the 

uppermost part of the Tamiami formation, because this formation is 

now used to include marine rocks of late Miocene age in southern 

Florida (Parker, 1951, p. 823).

Lithology. The sand of late Miocene age is a fine-grained, darkgreen to light-gray quartz sand, slightly to extremely clayey in places. 

Phosphate, in sand measuring to gravel size, is a conspicuous, though 

minor, constituent. The phosphate nodules are hard, dark colored, 

and smooth surfaced. None of the crumbly white-weathered phosphate, common in the undifferentiated phosphatic sand and clay, is 

present.

In general, the lower part of the unit contains appreciably more 

clayey material than is present in the upper part. Beds of green calcareous clay and scattered lenses of soft sandy limestone are encountered beneath the typical gray to green sand facies during drilling. , The lithology changes somewhat in southern Hardee County. The 

unit is thinner, more clayey, and contains moderate amounts of 

phosphate. Fossils are absent in this area.

Fauna. W. C. Mansfield (1932, p. 43-56) listed and described the 

marine invertebrates collected from the limestone that is exposed in 

ditches along the Tamiami Trail in Collier and Monroe Counties. At 

that tune, he regarded the fauna as Pliocene in age, and he considered 

the limestone to be a facies of the Caloosahatchee marl. Later 

(W. C. Mansfield, 1939, p. 8), he gave this limestone the name 

"Tamiami" and assigned it to the lower part of the Pliocene^ thus
76 CONTRIBUTIONS TO THE GEOLOGY OF TJRANIUM

considering it to be older than the Caloosahatchee marl. Mansfield's 

collection lacked the diagnostic fossils that indicate a Miocene age 

for the Tamiami formation.

During 1947 and 1948, while working with the U. S. Geological 

Survey Florida Phosphate Project, F. S. MacNeil made large new 

collections from the upper Miocene and Pliocene formations in 

southern Florida. As a result, he was able to revise (unpublished) 

the age of the faunas involved. The sequence established by Mansfield (1939) for the Buckingham, Tamiami, and Caloosahatchee 

faunas was supported, but his Buckingham and Tamiami limestones 

were reassigned to the late Miocene.

Many of the species collected from the sand of late Miocene age in 

De So to and Hardee Counties are also found in the Tamiami formation. 

The following fauna, identified by F. S. MacNeil, was collected from 

dredged material piled along the sides of the large borrow pit located 

1.6 miles east of Nocatee (fig. 9):

Gastropoda:

Rapanal or Ecphora n. sp. 

Pelecypoda:

Chlamys (Plagioctenium) n. sp.? aff. C. eboreus watsonensis Mansfield and 

C. caloosensis Mansfield, both upper Miocene

Ostrea tamiamiensis monroensis Mansfield ( OmeridionaMs Heilprin?) 

disparilis Conrad subsp.?

Pododesmus n. sp.?

Laevicardium sp. 

Cirripedia:

Balanus sp.? A large barnacle, seemingly characteristic of this zone.

Distribution. Auger holes revealed that the sand of late Miocene 

age underlies all of De Soto County and extends northward into 

Hardee County, where it interfingers with the undifferentiated phosphatic sand and clay (pi. 2, fig. 8). Apparently, it occurs over an 

area much larger than Hardee and De Soto Counties. Gardner 

(1945, p. 37-41) described fossils from an oyster "reef" of late Miocene 

age, which was discovered during dredging operations off the southeastern end of Snell Island in Tampa Bay within the city limits of 

St. Petersburg. The matrix between the closely packed oysters 

consists of clear quartz sand and light-gray limy clay. To date, 

this is the most northwesterly occurrence of the sand of late Miocene 

age.

In De Soto County the sand attains thicknesses of 40 feet or more, 

but it gradually becomes thinner northward. In southern Hardee 

County the unit is usually less than 20 feet thick.

Details. Dall (1892, p. 131-133) reported a light-colored phosphatized calcareous sand at a locality 6 miles north of Arcadia, on Mare 

Branch, which is a tributary of the Peace River. He named this
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 77

rock the "Arcadia marl" and considered it early Pliocene in age. 

Dall (1892, p. 131-133) also described an outcrop along the Peace 

River at Shell Point, about 3 miles north of Arcadia. He called this 

rock an "oyster marl" and reported that it contained oysters, barnacles, 

and pectens that are similar to those occurring in the Caloosahatchee 

marl. According to Dall, a similar "oyster marl" was found along 

Joshua Creek near Nocatee and another exposure was found in the 

banks of a small stream just north of Zolfo Springs. The shell bed 

at Zolfo Springs is overlain by 20 to 25 feet of partly indurated 

yellow sand. Matson and Clapp (1909, p. 123) regarded Ball's 

"Arcadia marl" as a phase of the Caloosahatchee marl.

The "Arcadia marl" and "oyster marl" of Ball are both included in 

the unnamed sand of late Miocene age, described herein. At the southwest corner of the bridge over the Peace River, 1.2 miles west of 

Brownville, Be Soto County (NE^SEK sec. 31, T. 36 S., R. 25 E., 

loc. 18-53, pi. 1), a soft, buff-colored, phosphatic, sandy limestone 

exposed at water level is probably the "Arcadia marl" described by 

BaU. Core from drill hole 10-15, in SE^NEK sec. 32, T. 36 S., R. 

25 E., Be Soto County (pi. 1), about 1 mile east of the above exposure, 

contained Balanus sp., bryozoa, and echinoid spines in a sandy shell 

bed at a depth of 50 feet. This assemblage compares favorably 

with the upper Miocene fauna collected from the borrow pit east of 

Nocatee. The 50-foot depth, at which this shell bed was penetrated, 

is at almost the same elevation as both the limestone along the Peace 

River near Brownville and the shell bed at the pit near Nocatee. 

Results of auger drilling in the immediate area further substantiated 

the fact that the exposure at the Brownville bridge is a lens of clayey 

limestone within the sand, which is present in the Arcadia-NocateeBrownville area; the Caloosahatchee marl occurs south of Nocatee. 

Ball's "Arcadia marl" is the lower and more clayey part of the sand 

in which his "oyster marl" is the typical material. The occurrence of 

"Arcadia marl" near Zolfo Springs is considered Hawthorn formation. 

The northern limit of upper Miocene and Pliocene marine rocks in 

this region is about 5 miles south of Zolfo Springs.

The contact between the Hawthorn formation and sand of late 

Miocene age is exposed along the west bank of the Peace River (fig. 

10), at the site of a former bridge (NW%SE% sec. 17, T. 36 S., R. 25 E., 

Hardee County, loc. 20-53, pi. 1) located 1% miles west of Gardner. 

A section extending 16 feet above water level is exposed. A thickbedded, phosphatic, slightly clayey calcareous sand disconformably 

overlies a thin-bedded, sparsely phosphatic, silty, soft limestone. 

A phosphate conglomerate occurs at the base of the upper calcareous 

sand. On the basis of similar lithology, the lower thin-bedded unit 

is tentatively called Hawthorn formation. Results of drilling in the

378283 56 3 '
78 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

EXPLANATION

Fossiliferous (marine) phosphatic

Pleistocene 

deposits

Sand of late 

Miocene(?)age

: DISCONFORMITY

Hawthorn(?) 

, formation

i 

i

Phosphatic limestone

FIOUEE 10. Sketch of section exposed along the west bank of the Peace River, near Gardner, Hardee

County.

vicinity favor a late Miocene age for at least the upper thick-bedded, 

calcareous material. From drill hole 10-14 (N%SEK sec. 21, T. 36 

S., R. 25 E., De Soto County), located slightly more than 1 mile 

southeast of the exposure just described, limestone was encountered 

from 27 to 37 feet below the surface. Drilling was discontinued at 

37 feet. Limestone core from 33 to 35.5 feet contained the following 

pelecypods, which were identified by F. S. MacNeil:

Ostrea sp. aff. 0. puelchana d'Orbigny

Chlamys sp.

Cardita sp.

Cardium sp.

Venus?

Spisulal

The oyster is unlike any found in the Hawthorn formation, and this 

assemblage is tentatively identified as upper Miocene.

The limestone in drill hole 10-14 could be equivalent to the thinbedded limestone at the exposure near Gardner (fig. 10). Conversely, 

the phosphatic sand at the Gardner bridge could be a more sandy, 

and more phosphatic phase of the limestone hi the drill hole.

Origin. The sand of late Miocene age was deposited in a shallow 

marine environment. In southern Florida, the Tamiami formation 

and the Buckingham marl of Mansfield (1939) are deeper water sediments of the same sea. In southern Hardee County, the character 

of the sand changes, and the following features suggest an estuarine 

environment hi this immediate area:
STRATIGRAPHY, DE SOTO AND HARDER COUNTIES, FLORIDA 79

1. Preponderance of fine-grained sand atid clayey sand within the 

formation.

2. Absence of fossils. Changes in pH of the estuarine waters 

caused by fluctuations in the discharge volumes of rivers might create 

unfavorable conditions for organisms.

3. Lack of well-defined beach deposits oil bars.

MIOCENE TO PLIOCENE SERIES 

UNDIFFERENTIATED PHOSPHA.TTC SAND AND CI^AY

The phosphorite, which underlies the northern two-thirds of Hardee 

County (pi. 1), is composed of either the Bone Valley formation or 

weathered residuum of Hawthorn formation, or both. These two 

units appear almost identical and are composed of phosphate nodules, 

sand, and clay. In Polk and eastern Hillsborough Counties, the phosphatic beds are well exposed on mine faces. Separate mapping of the 

Bone Valley formation and the residuum of Hawthorn formation may 

be possible where outcrops are relatively abundant and where observations of sedimentary structures and textures of the rocks in place 

reveal discrete strata. Where subsurface information depends 

primarily on interpretation of auger cuttings, no practical basis exists 

for discriminating between two stratigraphic units of such similar 

lithology. For this reason, the phosphorite in Hardee County is 

mapped as undifferentiated.

Two of the earliest workers in the land-pebble phosphate district of 

central Florida were Dall (1892, p. 14l4l42), and Eldridge (1893, 

p. 196-231).

Matson and Clapp (1909, p. 138-141) named these phosphate 

deposits "Bone Valley gravel" from a locality west of Bartow, Polk 

County. As defined by them, the Bone Valley gravel consists of 

poorly sorted phosphate pebbles, clay, and sand of Pliocene age. 

Matson and Clapp (1909, p. 140-141) divided the Bone Valley gravel 

into lower beds rich in phosphate nodules £,nd an upper non-economic 

unit containing very little phosphate. Recording to these writers, 

an unconformity separated the Bone Valley gravel from the overlying 

surficial sand of Pleistocene age. Relations between the Bone Valley 

gravel and the older formations were not known at that time.

Sellards (1915, p. 58) agreed with most bf the earlier writers on the 

Pliocene age of the Bone Valley gravel.

Later, from vertebrate fossil evidence, Matson (1915, p. 21) suggested a late Miocene age for the Bone Valley gravel. Horse teeth 

(species of Merychippus or Neohippariofy), a mastodon upper jaw 

(Tetrabelodon), and a second upper molar that differed only slightly 

from the corresponding tooth of Teleoceras fossiger, all of which were 

found in the Bone Valley gravel, are indicative of an upper Miocene
80 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

fauna. Matson (1915, p. 22) located the southern boundary of the 

Bone Valley gravel in the vicinity of Zolfo Springs, Hardee County.

Cooke and Mossom (1929, p. 134) stated that the Bone Valley 

gravel lies unconformably on the Hawthorn formation in the phosphate mines in Polk County. They also reported an unconformity 

at the top of the Bone Valley gravel.

Cooke, (1945, p. 203) suggested that the name "Bone Valley formation" was more appropriate than "Bone Valley gravel/' because gravel 

makes up only a small fraction of the rock. Cooke (1945, p. 206) 

proposed that some of the Bone Valley formation "* * * may be the 

residual products of the decomposition in place of the Hawthorn 

formation."

Altschuler and Boudreau (unpublished material, 1949) studied in 

detail the mineralogy and petrography of the Bone Valley formation. 

Cathcart (unpublished material, 1949, 1950) discussed the importance 

of the leached upper portion of the Bone Valley formation as a source 

of uranium.

Lithology. The undifferentiated phosphatic sand and clay is an 

unconsolidated rock of a prevailing brownish to buff color. Individual 

lithologic units may be blue green, brown, white, or gray.

The Bone Valley formation may display distinct bedding locally. 

Seams of blue to green clay are disseminated throughout the formation. Residuum of Hawthorn formation is similar in color and 

lithology to the Bone Valley formation, but bedding is rarely preserved. Phosphate in clay to granule size is usually the most abundant component of both the Hawthorn residuum and Bone Valley 

formation. Fine-grained quartz sand, silt-sized quartz, and clay 

minerals comprise the nonphosphatic fraction. The phosphate 

grains are polished and are brown, black, gray, and white.

The upper few feet of the Bone Valley formation is generally 

severely leached and weathered. Where the Bone Valley formation 

is thin, or absent, this intense weathering is superimposed on the upper 

part of the Hawthorn residuum. In this leached zone (sometimes 

called the aluminum phosphate zone), the phosphate, which originally 

was present as nodules of carbonate fluorapatite, is altered to crandallite (pseudowavellite), which is the hydrous phosphate of aluminum 

and calcium, and to wavellite, which is the hydrous phosphate of 

aluminum (Altschuler and Boudreau, unpublished material, 1949, 

p. 36-38). The former presence of phosphate nodules is marked by 

molds in vesicular clayey sand loosely cemented by wavellite and 

crandallite.
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 81

Fauna. No fossils were found in the undifferentiated phosphatic 

sand and clay during this investigation.

Occurrences of marine invertebrates in the Bone Valley formation 

are rare; however, MacNeil (written communication, July 1954) reported that marine razor clams were found in exposures in southern 

Polk County.

Vertebrate fossils are abundant. Remains of manatees, whales, 

crocodiles, mastodons, and horses have been recovered from the Bone 

Valley formation during phosphate mining operations. Sharks' 

teeth, which are plentiful, possibly were derived from the subjacent 

Hawthorn formation.

Generally, the Bone Valley formation is considered to be Pliocene 

in age, but until the Miocene-Pliocene boundary is re-established the 

age of this formation cannot be categorically stated.

The vertebrate fauna is considered Pliocene (Simpson, 1929, p. 257; 

1930, p. 180), but this dating is flexible. Most of the vertebrate remains could be late Miocene as well as Pliocene in age. Simpson 

(1929, p. 257) admits that "* * * The possibility of derivation of 

fossils from older beds and of accidental mixture with younger fossils 

on collecting or in the compilation of 'faunal lists' based on general 

localities is obviously great." Simpson (1930, p. 179-180) again 

discussed possibilities of false association of the Tertiary land mammals 

in the Bone Valley formation. Most of the fossils of land mammals 

were found by people with no geologic training during hydraulic mining of the phosphate beds.

Distribution. Auger holes were necessary to determine the extent 

of the undifferentiated phosphatic sand and clay. In Hardee County, 

north of about 27°25' latitude (pi. 1), the Hawthorn formation is overlain by noncalcareous phosphatic sand and clay. The sand of late 

Miocene age interfingers with the undifferentiated phosphatic sand 

and clay in southern Hardee County (pi. 2). The thickness of the 

phosphorite in this area ranges from less than 10 feet to more than 30 

feet (pi. 2).

Details. Exposures of the upper part of the undifferentiated phosphatic sand and clayey sand were found at only three localities in 

Hardee County, as follows:

The Bone Valley (?) formation is exposed in the bottom of a ditch 

along the east side of a dirt road in the NW^NWK sec. 18, T. 33 S., 

R. 26 E., Hardee County (loc. 11-53, pi. 1). Only the upper 2 feet of 

stratified clayey sand and sand, which contains abundant phosphate 

nodules, can be seen.
82 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

At the bridge over the Peace Kiver (loc. 27-53, pi. 1), 1 mile southeast of Wauchula, Hardee County (NWK sec, 11, T. 34 S., R. 25 E.), 

along the east bank of the river, the following section is exposed:

Formation

Depth from 

surface 

(in feet)

Description

Pleistocene deposits. _ _ 0-2&

Disconformity.

Undifferentiated phosphatic sand and 

clay.

6-11%

Sand, fine-grained, quartz, tan.

Clayey sand, dark-brown, iron-stained; contains scattered soft, white (weathered) 

phosphate nodules.

Slightly clayey sand; contains scattered 

fresh phosphate nodules. Lower 1 foot 

is coarse-grained sand; bottom 4 inches 

is a bed of gravel- to pebble-sized phosphate, fish teeth, worn bone fragments. 

No diagnostic fossils.

Bottom of conglomerate stratum in Pleistocene deposits.

Clayey sand; contains very abundant sandsized phosphate. Interval is slightly 

iron-stained in upper 7 inches, buff to 

olive color below. Entire interval is 

noncalcareous; bedding indistinct.

At this exposure, it was not possible to determine whether the 

phosphorite is Bone Valley formation, Hawthorn residuum, or a 

combination of both. The obscure stratification could be relict 

from the parent Hawthorn formation, or it could be a primary structure of Bone Valley sedimentation. The lower contact of the phosphatic sand and clay with calcareous Hawthorn formation is below 

water level in the river.

In a borrow pit (loc. 10-53, pi. 1), 0.3 mile west of the Peace Eiver 

bridge (NE% sec. 28, T. 34 S., R. 25 E., Hardee County) on Florida 

State Highway 64, 1.3 miles west of Zolfo Springs, the upper part of 

the Bone Valley formation is exposed beneath sand of Pleistocene 

age. The stratification is distinct below a zone of iron accumulation. 

Individual layers are 2 to 6 inches thick and are differentiated by 

variations in the amounts of clay and phosphate. Phosphate is 

present as partly leached nodules and possibly also as clay-sized 

wavellite and crandallite. Partly indurated sand cobbles, which 

comprise single beds, still retain small voids previously occupied by 

phosphate grams. Several tiny phosphatized shell fragments, which 

could not be identified, were in the indurated sandy cobbles. Phosphate was very abundant at one point. Individual strata, 2 to 3 

inches thick, composed of leached phosphate nodules and quartz
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 83

sand are conspicuous. The bedded phosphatic material in this pit 

is interpreted as a reworked deposit of the aluminum phosphate 

zone of the undifferentiated phosphatic sand and clay. The preservation of bedding, the stratification of the sandy cobbles, and the 

variation of phosphate content along the face of the pit indicate a 

redeposition of previously weathered material, rather than an accumulation in place of the residual products of a parent rock such as 

the Hawthorn formation.

Origin. While forming hypotheses of the origin of the Bone Valley 

formation, many of the earlier workers presupposed a phosphatic 

residuum of Hawthorn formation that was modified by a variety of 

agents during Pliocene time.

Eldridge (1893, p. 196-231) considered the phosphate deposits as 

a residuum that was later reworked by marine action.

Matson and Clapp (1909, p. 138-139) interpreted the poor sorting 

and the absence of distinct local stratification as evidence of a fluviatile origin. They admitted that some deposition may have occurred 

in the margins of estuaries. Fragments of bone and sharks' teeth were 

assumed to have been derived from older formations.

Matson and Sanford (1913, p. 145-206) described this formation as 

a deposit hi a shallow sea. Submergence during Pliocene time resulted 

in the reasserting and redeposition of residual weathered material by 

wave action.

Sellards (1915, p. 58) postulated an advancing sea that redeposited 

material derived from the underlying phosphatic marl.

Cooke and Mossom (1929, p. 164) believed that the phosphate deposits were accumulations within the lower reaches of a river and 

adjacent to its low-lying banks. Cooke (1945, p. 206) reasoned that 

these phosphatic sediments were deposited in the delta of a southwardflowing river. Estuarine deposition occurred seaward from the delta. 

Cooke also stated that some of the Bone Valley formation may be the 

residual product of weathered Hawthorn formation.

MacNeil (written communication, July 1954) considers the Bone 

Valley formation to be of marine origin, equivalent stratigraphically 

to the unnamed sand of late Miocene age of this report.

The undifferentiated phosphatic sand and clay and the sand of late 

Miocene age interfinger in southern Hardee County (pi. 2). If the 

Bone Valley formation is a marine sediment, it is probable that the late 

Miocene sea inundated all of Hardee County, thus completely reworking the phosphatic Hawthorn residuum and redepositing it as Bone 

Valley formation.

If the Bone Valley formation is of fluvial origin, the incomplete 

reworking of weathered Hawthorn formation would preserve patches 

of residuum, especially on higher areas. Under this hypothesis, the
84 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

late Miocene shoreline may have been approximately parallel to the 

present northern limit of the sand of late Miocene age. The age of this 

phosphorite, if undifferentiated, would range from middle Miocene 

through Pliocene, because Pliocene marine deposits have never been 

reported as overlying the phosphorite.

Therefore, as long as any possibility exists that the Bone Valley 

formation is a fluvial deposit, it is necessary to refer to the phosphorite 

in this area as undifferentiated phosphatic sand and clay.

PLIOCENE SERIES

CALOOSAHATCHEE MARL

During his explorations in southern Florida, Angelo Heilprin (1887) 

first identified fossiliferous beds exposed along the Caloosahatchee 

River as Pliocene hi age.

Ball (1892, p. 140-149) named these beds "Caloosahatchie" and 

extended the marine Pliocene as far northward as Zolfo Springs in 

Hardee County. At that time, his "Arcadia marl" and "oyster marl" 

were considered to be equivalent to the "Caloosahatchie beds."

Cooke (1945, p. 216-217) believed the Caloosahatchee marl to be 

present in the southern part of De Soto County. He thought that the 

Bone Valley formation and Caloosahatchee marl merged somewhere to 

the north.

The fauna of the Caloosahatchee marl is well known, and the 

Pliocene age of this formation has never been seriously questioned. 

Outcrops along the Caloosahatchee River near La Belle, Hendry 

County, are collecting grounds for the large and well-preserved fauna. 

The precise boundaries and the stratigraphic relations of the Caloosahatchee marl with formations to the north were largely speculative 

because of the limited number of outcrops along the streams. Many 

writers, following Ball's pioneer work, extended the Caloosahatchee 

marl much farther north into De Soto and Hardee Counties; actually, 

it does not extend thi& far to the north.

- Lithology. The Caloosahatchee marl in this area is a gray finegrained sand, slightly clayey to clayey in places. It is predominantly 

a sand rather than a marl. The marine invertebrate fauna is large, 

and it contains many fossils of present-day species. In some places 

the Caloosahatchee marl is composed primarily of shells for example, 

along Prairie Creek in De Soto County, where it is mined for road fill. 

Exposures along Prairie Creek are surficially cemented by iron oxide. 

Unweathered material is gray to blue-gray. Delicate shells are 

unusually well preserved, which is an indication of deposition with 

little wave action.

Distribution. Auger holes disclosed that the Caloosahatchee marl 

is. restricted to the southeastern part of De Soto County (pi. 1). In
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 85

the vicinity of Pine Level, 9 miles northwest of Arcadia (sec. 10, 

T. 37 S., R. 23 E., De Soto County), and along Horse Creek (sec. 1, 

T. 38 S., R. 23 E., De Soto County) discontinuous, thin patches of nonfossiliferous calcareous clayey sand are present beneath the Pleistocene 

sediments. This material may be Caloosahatchee marl, but it probably is sand of late Miocene age, because fossiliferous sand of late 

Miocene age is close to the surface here (pi. 2).

Shell fragments in the interval from 5 to 14 feet from an auger hole 

in the SE^SWM sec. 22, T. 38 S., R, 25 E., De Soto County floe. 42-53, 

pi. 1) mark the northernmost known occurrence of the Caloosahatchee 

marl in the area. Locally, the abundance of land and fresh-water 

snails in the Caloosahatchee fauna suggests that the known distribution of this formation is very close to the Pliocene shoreline. Drill 

records show that the Caloosahatchee marl does not exceed a thickness 

of 20 feet in De Soto County (pi. 2).

Details and fauna. The fauna of the Caloosahatchee marl is described by Heilprin (1887) and by Dall (1903). More than 600 species 

were identified by Dall. Mollusks are predominant among the 

excellently preserved shells.

At a borrow pit in the SW% sec. 26, T. 39 S., R. 25 E. (k>c. 1-53, 

pi. 1), about 1,500 feet west of Florida State Highway 31 along 

Prairie Creek, the upper 2 feet of a shell bed is exposed above water 

level in the pit. Such Pliocene species as Area wagneriana Dall, 

Strombus leidyi Heilprin, and Turritella perattenuata Heilprin are 

common among a large molluscan fauna. This Caloosahatchee shell 

bed extends westward at least as far as the NW% sec. 33, T. 39 S., 

R. 25 E., De Soto County (k>c. g-53, pi. 1). At this location, the 

following species, identified by F. S. MacNeil, were collected from 

the top of the shell bed exposed at water level along Prairie Creek:

Gastropoda:

Turritella apicalis Heilprin 

Pelecypoda:

Echinochama arcinella Linnaeus

Chione cancellata Linnaeus

Two limestone pebbles, apparently derived from Mansfield's 

Buckingham marl, of late Miocene age, were incorporated in the 

Caloosahatchee marl at this locality. These pebbles contained the 

following shells, which, according to MacNeil, who identified them 

(written communication, January 1954), are common in Mansfield's 

Buckingham marl:

Pelecypoda:

Chlamys (Plagiocteniwri) eboreus buckinghamensis Mansfield

Chione athleta Conrad 

Cirripedia:

Balanus sp., which is a medium-sized barnacle that apparently occurs 

abundantly at Buckingham, Lee County.
86 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The upper 6 inches of Caloosahatchee marl is exposed above water 

level near the bottom of a drainage ditch in southern De Soto County 

(SWMSW}£ sec. 28, T. 38 S., R. 25 E., map loc. 25-33, pi. 1). A 

4-inch layer of iron-stained phosphate gravel overlies the Pliocene 

shell bed. This gravel is the basal unit of the surficial sand and 

clayey sand of Pleistocene age, which is 3% feet thick here. The 

species listed below, identified by F. S. MacNeil, were collected 

from the spoil banks along the ditch. The assemblage is clearly a 

Caloosahatchee fauna.

Gastropoda:

Conus sp. (juvenile)

Oliva frag, cf. 0. sayana Ravenel

Turritella subannulata Heilprin

apicalis Heilprin

perattenuata Heilprin 

Pelecypoda:

Anadara lienosa (Say) 

Chlamys harrisi Dall 

Anomia simplex d'Orbigny 

Ostrea sculpturata Conrad

virginica Linnaeus 

Cardita arata Conrad 

Phacoides caloosaensis (Dall) (mold) 

Echinochama arcinella (Linnaeus) 

Chione cancettata Linnaeus

Origin. The Caloosahatchee marl was deposited hi a shallow sea. 

The preservation of fragile shells indicates that wave action was 

negligible. It is possible that offshore bars or groups of islands 

acted as barriers against storms. Phosphate nodules were not 

deposited during this submergence.

PLEISTOCENE SERIES

Differentiation of the Pleistocene sediments into formations is difficult in Florida because of the intensely weathered condition and the 

lithologic similarity of the surficial material especially in the ulterior 

of the peninsula. Much of the study of rocks of Pleistocene age has 

been limited to the fossiliferous limestones and marls that are exposed 

in the southern part of the State. The alternating fresh-water and 

marine limestones and clayey sands of Pleistocene age, comprising 

the Fort Thompson formation, have been described by Cooke and 

Mossom (1929), Parker and Cooke (1944), and Cooke (1945).

A number of marine terraces are recognized by geomorphological 

evidence. These terraces are remnants of higher shorelines that were 

developed during pauses in the oscillations of the Pleistocene sea. 

The surficial sediments associated with each terrace have been given 

formation names by some writers.
STRATIGRAPHY, DE SOTO AND,HARDEE COUNTIES, FLOEIDA 87

Matson and Sanford (1913, p. 32-35) recognized three terrace deposits of Pleistocene age. The highest of these, called the Newberry, 

included surficial sand and clay at elevations ranging from 70 to 100 

feet above sea level. The surficial sediments at elevations ranging from 

40 to 60 feet above sea level represented a later Tsala Apopka terrace. 

The lowest terrace, which they called the Pensacola, covered a broad 

plain that was less than 40 feet above sea level; it was composed of 

limestone in the southern part of the State.

Richards (1938, p. 1284-1285) found no evidence of marine deposits 

of Pleistocene age above 25 feet altitude along either coast of Florida. 

Above, 25 feet, sediments of Pleistocene age contained no fossils; he 

believe4 .that this land stood relatively high during most of the 

Pleistocene.

Cooke (1945, p. 247-248) identified seven, and possibly eight, shorelines that represent stands of sea level during Pleistocene time.

Altitude 

Terrace (feet)

Brandywine_______________________________________________ 270

Coharie__________________________________________ 215

Sunderland.-__._________________________________ 170

Wicomico_________________________________________ 100

Penholoway_______________________________________________ 70

Talbot--__ __.____-_.__________________________ 42

Pamlico____________________________________________________ 25

With these seven shorelines, he assigned corresponding formations 

comprising.the surficial sand within each topographic interval. The 

possible eighth shoreline of Cooke, the Silver Bluff, is 5 feet above 

present sea level. Cooke (1945, p. 289) postulated that most of De 

Soto County is covered by the Penholoway formation.

MacNeil (1950, p. 99) reported that the terraces below 150 feet 

are entirely of marine origin. He recognized the following Pleistocene 

shorelines, which he believed to represent peaks of marine transgression.

Terrace Altitude Age 

(feet)

Okefesaofeee______________ 150 Yarmouth interglacial stage

Wicomico______________ 100 Sangamon interglacial stage

Pamlico________________ 25-35 Middle Wisconsin glacial recession

Silver Bluff-_________ 8-10 Post-Wisconsin

No evidence of marine deposition during Pleistocene time was found 

in the area investigated in this report.

DEPOSITS OF PLEISTOCENE AGE

Lithology. The Pleistocene deposits in the area are made up of 

lenticular strata of varying percentages of quartz sand, silt, and claysized material. These beds are generally brown to tan. Crossbedding 

is conspicuous, especially in the lower part of the formation. A con-
88 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM. .....

glomerate, or gravel, composed primarily of phosphate granules and 

pebbles is nearly always present within the lower 1 foot. Along 

Payne's Creek the deposits are cross-stratified, and a phosphatic 

gravel rests directly on the Hawthorn formation.

The lenticularity of the lithologic units is exhibited at the borrow 

pit near Nocatee (fig. 9), where a waxy blue clay grades laterally to a 

coarse sand within a distance of less than 100 feet. Similarly, the 

section along Horse Creek reveals a layer of brownish clay pinching out 

within a crossbedded sand stratum 2 feet thick.

At every outcrop the depth anddnteusity of the weatheriug'prbfile 

developed on the Pleistocene deposits are similar. An iron-cemented 

zone is always present from 3 to 6 feet below the surface. This zone 

is usually less than 2 feet thick, and locally it may be an indurated 

crust or layer of ferruginous cobbles and boulders. Several feet below 

this zone of iron accumulation the color gradually changes to tan and 

the rock is relatively fresh.

Scattered thin deposits of sandy fresh-water limestone are included 

within the unit (pi. 1). These limestones contain fresh-water fossils. 

Root structures, which have been replaced by calcium carbonate, are 

common. The limestone is friable, and it normally grades laterally 

into a blue-gray marl or calcareous clayey sand.

Fine-grained quartz sand is the most abundant constituent. Lenses 

of blue-gray clayey sand and clay, 1 to 3 feet thick, are scattered 

throughout the sand. Phosphate nodules may be abundant locally.

The grain size of the quartz sand is generally greatest near the 

bottom of the formation. Phosphate nodules, if present, are more 

abundant near the lower contact, regardless of the lithology of the 

underlying rock.

Fauna. At an exposure along Prairie Creek (NW% sec. 33, T. 39 S., 

R. 25 E., De Soto County; loc. 8-53, pi. 1), the Caloosahatchee marl 

is overlain by 6 feet of Pleistocene deposits. A 6-inch stratum of 

coarse sand, bone fragments, and minor phosphate gravel is the-basal 

unit. Within this basal gravel was found a lower incisor of a rhinoceros, probably Aphelops, which was identified by Jean Hough. The 

age of Aphelops is early to middle Pliocene.

At a borrow pit near Nocatee, part of an upper molar of Neohipparion, identified by Jean Hough, was found in the stratified surficial 

sand. Neohipparion is a horse of early to middle Pliocene age. At 

the borrow pit east of Nocatee (fig. 9), and at a borrow pit northwest 

of Nocatee (SE%SW% sec. 11, T. 38 S., R. 23 E., De Soto County), 

molars of a horse, probably Neohipparion, identified by Jean Hough, 

were collected from the surficial sediments.

Although the vertebrate teeth suggest that the deposits are Pliocene, other evidence points more conclusively to a Pleistocene age.
STRATIGRAPHY, DE SOTO ANI> HARDEE COUNTIES, FLORIDA 89

The invertebrate fauna, which consists predominantly of a freshwater and land assemblage of gastropods, is different from the freshwater mollusks in the Caloosahatch.ee marl. Many of the species are 

also common in the brackish and fresh-water sediments of Pleistocene 

age tfeceagh.out southern Florida. In addition, the unit unconformably 

overties the Caloosahatchee marl, which is definitely Pliocene, possibly late Pliocene, in age. The vertebrate teeth, which are resistant 

to erosion and weathering, were probably derived from the Bone 

Valley formation. Erosion of these earlier sediments supplied the 

components of the Pleistocene deposits.

Most of the invertebrate species listed in this section also appear 

in Pleistocene faunal lists by Sellards (1916, p. 144), and by W. C. 

Mansfield (1939, p. 33^5). The fauna listed by Sellards was associated with human remains at an exposure near Vero Beach. The 

fossils described by W. C. Mansfield were collected from numerous 

localities throughout southern Florida.

At the borrow pit east of Nocatee (fig. 9) the following invertebrates, identified by F. S. MacNeil, were collected from the phosphatic sand directly overlying sand of late Miocene age:

Gastropoda:

Fresh water:

Viviparus georgianus Lea 

Campeloma sp. 

Goniobasis sp. strong axials 

Helisoma (Seminolina) duryi (Wetherby) var.? 

Land:

Euglandina sp. cf. E. rosea (Ferussac) 

Polygyra seplemvolva volvoxis Pfeiffer 

Pelecypoda: 

Rangia sp.

In a shallow ditch along Florida Route 661, 3.5 miles north of 

Limestone, Hardee County (SW^SWX sec. 24, T. 35 S., R. 24 E.), 

the gastropods listed below, identified by F. S. MacNeil, were collected from a 2%-foot section of surficial sandy limestone exposed 

above water level.

Land snails:

Polygyra sp. cf. P. cereolus (Muhlfeld) var. floridana Hemphill? 

Succinea sp. (very inflated) aff. S. campestris Say?

Under the heading "Fort Thompson beds," Sellards (1919, p. 

71-73) included alternating fresh-water and marine marl and limestone of Pleistocene age in the vicinity of La Belle and Fort Thompson 

in Hendry County. Cooke and Mossom (1929, p. 211) later changed 

the name to Fort Thompson formation. On the basis of invertebrate 

fossils and stratigraphic position, the unnamed Pleistocene strata 

of this report are correlated with the Fort Thompson formation.
90 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Distribution. The Pleistocene strata are flat-lying surficltt^posits. 

Auger holes disclosed that they cover the entire area, "except where 

stream erosion has bared the older rocks or where Recent sediments 

are present. Vertical exposures are found along Payne's Creek, Peace 

River (fig. 10), Charlie Apopka Creek, Horse Creek, and Joshua Creek, 

In each drill hole, similar lithology and degree of weathering were 

noted in the surficial sediments. Pebbles of phosphate from the basal 

conglomerate were observed in the cuttings from several holes. The 

thickness of the Pleistocene strata is variable, but it generally does not 

exceed 20 feet.

Origin. The general character of the Pleistocene strata suggests 

deposition in the lower reaches of a river flood plain. Aggrading 

streams, threading channels across a flat plain close to sea level, 

spread a thin veneer of silt and fine sand on the interfluvial areas 

during floods. Channel sediments are characterized by lenticular 

bodies of sand and clay and by crosslamination. Scattered occurrences 

of fresh-water limestone were deposited in flood-plain lakes.

It is possible that part of these beds was deposited in a subaerial 

deltaic environment. In an area of such low relief and poor exposures 

it is difficult to determine where the flood plain ends and where the 

delta begins. Regardless of the precise environment, the evidence is 

clear that the unit was deposited by subaerial agents not far from a 

Pleistocene strand.

Although no evidence exists of any Pleistocene marine invasions in 

this area, there is abundant evidence of invasions at other places in 

the Atlantic Coastal Plain. Flint (1940, p. 757-787) critically examined the literature dealing with Atlantic Coastal Plain sediments of 

Pleistocene age. South of the James River in Virginia he found that 

morphologic evidence favored widespread marine deposition; north of 

the James the sediments are regarded largely as alluvial.

SEDIMENTS OF RECENT AGE

At many places along the banks of the Peace River and its tributaries, exposed stream terraces are clearly younger than the Pleistocene deposits (figs. 7 and 8). Included with these deposits are the 

"river-pebble" phosphate gravels that were mined prior to 1908.

These stream sediments are not extensive. They are confined 

chiefly to the present banks of streams (pis. 1 and 2). The dominant 

lithology is fine quartz sand, with a negligible amount of clay. Phosphate occurs in sand to cobble size. At many places along the Peace 

River near Nocatee, Arcadia, and Brownville, the sediments of Recent 

age consist of natural levees of fine white quartz sand which line 

both banks. Phosphate, concentrated in bars and shoals in the 

Peace River, is abundant from Brownville southward.
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 91

These river sediments are not conspicuously weathered. The 

stratigraphic position, fresh appearance, and limitation of these sediments to present stream courses indicate that they are of Recent 

age. An outcrop on Horse Creek along the east bank of the stream, 

about 8 miles west of Arcadia, on Florida State Highway 72 (loc. 

32-53, pi. 1 and fig. 11), shows the contact of a Recent stream deposit 

with Pleistocene strata.

%S&ti^l*&&&S$!tf£^^ ^K^^f^^'^i^i^^a^^fy^^^mi^^M^^

OF HtiaSE OMTEK

Quartz sand Quartz sand and Clayey sand 

phosphate nodules

FIGURE 11. Plan and profile sketch of exposure along Horse Creek, at bridge on Florida Route 72, De

Soto County.

MECHANICAL ANALYSIS

Mechanical analyses of the Pleistocene deposits, the sand of late 

Miocene age, and the undifferentiated phosphatic sand and clay were 

made to determine tte existence of significant differences in grain 

size and to see whether such differences were characteristic of the 

formation or whether they were merely local variations. Striking and 

consistent interformational differences in median diameter of quartz 

sand, for example, would be useful for correlation purposes in instances 

where fossils were lacking or where lithology and sedimentary features 

were altered and obscured by the effects of weathering.

Sampling was done on a lithologic basis. Each sample represents 

a lithologic unit, regardless of thickness. Samples from 12 auger 

holes were submerged in muriatic acid for 24 hours, weighed, and 

screened for 7 minutes in a mechanical shaker. Samples, before
92 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

sieving, weighed approximately 60 grams. The samples were run 

through the following screen sizes:

Mesh size

(in milliTyler screen no. meters)

20 .__-_-_-_ 0. 833 

28____-_-_-.__-_____-_-_._ . 589

35__________________ . 417 

48 _____________________ . 295

Mesh size

(in milliTyler screen no. meters)

65 0. 208 

100 . 147

150_________________ . 104

200_____-_____________ . 074

All material below 0.074 mm (200 mesh) was discarded. All soluble 

components had been dissolved in the acid, therefore only quartz 

sand and a minor amount of accessory heavy minerals were screened. 

For each sample, a cumulative curve was plotted from which the 

median-grain diameter was determined (pi. 3).

The results of the work described in this section are not considered 

absolute values for these sediments. Certain inaccuracies were introduced because of the possible contamination of the auger cuttings. 

Even though the method of sampling was not precise, any consistent 

differences in grain-size distribution among the various sediments 

would still be valid.

The average of the median-grain diameters from all samples was 

computed for each formation. The table below summarizes the 

results:

Median-grain size (in millimeters) _ _ __

Pleistocene 

deposits

0. 174

Sand of late 

Miocene age

0.210

Undifferentiated 

phosph'atic sand 

and clay

0.244

All of the above averages are within the fine-sand range (0.125- 

0.250 mm) of the Wentworth grade scale. Slight differences such as 

these are not considered significant in themselves; however, an inspection of the cumulative curves for drill holes 62, 75, 86, 90, 99, and 124 

(pi. 3) shows a slight but very noticeable increase in grain size of the 

sediments underlying the surficial material. The finer grain size of 

the Pleistocene deposits seems to be consistent throughout this area. 

In each drill hole, except 117 and 85, the median-grain diameter of 

the sand of the Pleistocene deposits is less than that of the sand of late 

Miocene age or of the undifferentiated phosphatic sand and clay.

GEOLOGIC HISTORY

MIOCENE

Submergence during the middle Miocene was extensive, and much of 

peninsular Florida was inundated. The Hawthorn formation was 

deposited in this shallow marine environment. The recession of the
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 93

middle Miocene sea, probably accomplished in part by crustal upwarping associated with the closing stages of the Ocala uplift (Cooke, 

1945, p. 5-7), exposed the Hawthorn formation to weathering and 

erosion as far south as Hardee County and perhaps as far as De Soto 

County. A drainage system, similar in pattern to present drainage, 

was developed on this land surface, and a weathered%esiduum of the 

less soluble components of the limestone slowly accumulated. This 

mantle consisted of phosphate nodules, clay, and quartz sand. Periodic fluvial reworking of the residual weathered products occurred 

during this time.

During late Miocene time, the sea again advanced, and all of the 

southern part of the Florida peninsula, including De Soto County and 

possibly all of Hardee County, was submerged. The Tamiami formation and the Buckingham marl of Mansfield record this inundation in 

southern Florida. Slightly later, as the sea transgressed farther 

inland, the sand of late Miocene age was deposited in the more shallow 

water to the north. If the Bone Valley formation is of marine origin, 

it was deposited in this sea.

PLIOCENE

Marine deposition in Florida during the Pliocene epoch is marked by 

the Caloosahatchee marl. There is no knowledge of an important 

erosion interval after the late Miocene. Shallow Pliocene seas covered 

all of southern Florida and extended at least as far north in this area as 

southern De Soto County (pi. 1). There is no evidence of an extensive 

submergence during Pliocene time. The Caloosahatchee marl has not 

been found at altitudes of more than 40 to 45 feet.

PLEISTOCENE

After withdrawal of the Caloosahatchee sea, much of peninsular 

Florida was exposed. The post-Pliocene exposure was of brief duration, as evidenced by the fact that much of the thin Caloosahatchee 

marl is still preserved; furthermore, the upper part of the Caloosahatchee is relatively fresh and unweathered.

The retraction and release of tremendous volumes of water during 

glacial and interglacial stages caused extraordinary fluctuations in sea 

level during Pleistocene time. Elsewhere in Florida, and northward 

into Georgia, the Carolinas, Virginia, and Maryland, terraced Coastal 

Plain sediments present more graphic evidence of oscillations of sea 

level during the Pleistocene than is exhibited in Hardee and De Soto 

Counties. The Pleistocene strata in this area were deposited by the 

aggrading Peace River while the sea was at a higher level than at 

present. No precise record of earlier and higher stands of the sea 

during the Pleistocene is present here, although Cooke (1945, p. 245-
94 CONTRIBUTIONS TO THE GEOLOGY OF TJRANTDM

312) and MacNeil (1950, p. 95-107) mapped shorelines elsewhere in 

Florida at elevations of more than 100 feet. These shorelines represent pauses during the latest general retreat of the sea.

RECENT

The stream deposits of Recent age indicate very little change from 

the present environment. Terraces are not more than 15 feet above 

water levels in the streams. The Peace River and its tributaries are 

incised and are establishing a new base level adjusted to the present 

strand.

The Recent history of this area has been essentially a minor readjustment of the drainage to present sea level. Accelerated erosion of 

the Bone Valley formation, the Hawthorn formation, and the Hawthorn residuum in the region to the north is reflected ift the accumulations of "river-pebble" phosphate in the streams south of Brownville, 

De Soto County.

ECONOMIC CONSIDERATIONS

Field studies and radiometric analyses of samples indicate that the 

phosphate and uranium resources of the area covered in this report are 

unimportant under present economic conditions.

Examination of samples of the undifferentiated phosphatic sand and 

clay showed a substantially lower percentage of phosphate nodules 

than is characteristic of the phosphorite in the mining district to the 

north. Phosphate is a minor constituent in the sand of late Miocene 

age, Caloosahatchee marl, and the Pleistocene deposits.

Prospecting data in this region are nonexistent. Mansfield (1942, p. 

35) noted that there was no prospecting information available in regard to the area south of T. 34 S., Hardee County. Exploration since 

1942 has been concentrated in the land-pebble phosphate district, and 

the writer could find no record of recent prospecting in Hardee County.

The aluminum phosphate zone of the phosphorite is thin and discontinuous in this area. It cannot be considered a significant source of 

uranium. The low phosphate content in the sediments is a further 

deterrent to consideration of this area for uranium possibilities.

A total of 135 unsieved samples were analyzed radiometrically for 

percent equivalent uranium. The results ranged from less than 0.001 

percent to 0.009 percent. The summarized values are shown below:

Percent 

equivalent 

Number of samples uranium

16_.__ _ _ __ 0. 004

23__ _-_______________ .003

36___________________ .002

13___ __-_--------_____ . 001

27______-_____---_-------_--<. 001

Percent

equivalent

Number of samples uranium

!__._______________.___.___. 0. 009

3_____-.._______________ . 008

4_______________________ . 007

6_._._______________________ . 006

6_ __ ___________ _ ____ . 005
STRATIGRAPHY, DE SOTO AND HARDEE COUNTIES, FLORIDA 95

The average of the percent equivalent uranium for each stratigraphic 

unit was determined from the 135 samples. The results appear as 

follows:

Percent

equivalent

Formation uranium

Pleislaeesedeposits._______________________ _____ 0. 001

Caloosabatcheemarl_______________________________ _ . 003

Undifferentiated phosphaticsand and clay________________ _ . 003

Upper Miocene deposits.______________________________ _ . 002

Hawthorn formation..._______________________________ . 003

G. R. Mansfield (1942, p. 24-27) reported that "river-pebble" 

phosphate was mined in the Peace River from 1888 to 1908. Competition from the land-pebble and hard-rock districts, rather than 

depletion of reserves, was responsible for the death of this industry. 

Large, but unmapped, reserves of low-grade "river-pebble" phosphate 

are still present in De Soto County in the lower reaches of the Peace 

River and Joshua, Horse, and Prairie Creeks.

LITERATURE CITED

Cooke, C. W., 1939, Scenery of Florida, interpreted by a geologist: Fla. Geol. 

Survey Bull. 17, p. 14.

 1945, Geology of Florida: Florida Geol. Survey Bull. 29.

Cooke, C. W., and Mossom, Stuart, 1929, Geology of Florida: Fla. Geol. Survey

20th Ann. Kept. 

Dall, W. H., 1892, The Neocene of North America: U. S. Geol. Survey Bull. 84.

 1903, Contributions to the Tertiary fauna of Florida, with especial reference 

to the Miocene silex beds of Tampa and the Pliocene beds of the Caloosahatchie River: Wagner Free Inst. Sci. Trans., v. 3, pt. 6.

Eldridge, G. H., 1893, A preliminary sketch of the phosphates of Florida: Am. 

Inst. Min. Eng. Trans., v. 21, p. 196-231.

Flint, R. F., 1940, Pleistocene features of the Atlantic Coastal Plain: Am. Jour. 

Sci., v. 238, no. 11, p. 757-787.

Gardner, Julia A., 1926, The molluscan fauna of the Alum Bluff group of Florida: 

U. S. Geol. Survey Prof. Paper 142-A, p. 1-3.

 1945, Three new species from an upper Miocene oyster reef in Tampa Bay:

Nautilus, v. 69, no. 2, p. 37-41. 

Heilprin, Angelo, 1887, Explorations on the west coast of Florida and in the

Okeecliobee wilderness: Wagner Free Inst. Sci. Trans., v. 1, 134 p. 

MacNeil, F. S., 1950, Pleistocene shorelines in Florida and Georgia: U. S. Geol.

Survey Prof. Paper 221-F, p. 95-107. 

Mansfield, G. R., 1942, Phosphate resources of Florida: U. S. Geol. Survey Bull.

934. 

Mansfield, W. C., 1932, Pliocene fossils from limestone in southern Florida: U. S.

Geol. Survey Prof. Paper 170, p. 43-56.

 1939, Notes on the upper Tertiary and Pleistocene mollusks of peninsular

Florida: Florida Geol. Survey Bull. 18. 

Matson, G. C., 1915, The phosphate deposits of Floriad: U. S. Geol. Survey Bull.

604. 

Matson, G. C., and Clapp, F. G., 1909, A preliminary report on the geology of

Florida, with special reference to the stratigraphy: Fla. Geol. Survey 2d Ann.

Rept., p. 25-173.
96 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM :

Matson, G. C., and Sanford, Samuel, 1913, Geology and ground waters-of Fla.:

U. S. Geol. Survey Water-Supply Paper 319. 

Parker, G. G., 1951, Geologic and hydrologic factors in the perennial yield of the

Biscayne aquifer: Am. Water Works Assoc. Jour., v. 43, no. 10, p. 817-833. 

Parker, G. G., and Cooke, C. W., 1944, Late Cenozoic geology of southern Florida,

with a discussion of the ground water: Florida Geol. Survey Bull. 27, p. 56-64. 

Richards, H. G., 1938, Marine Pleistocene of Florida: Geol. Soc. America Bull.,

v. 49, p. 1267-1296. 

Schroeder, M. C., and Bishop, E. W., 1953, Foraminifera of late Cenozoic in

southern Florida: Am. Assoc. Petroleum Geologists Bull., v. 37, no. 9, p.

2182-2186. 

Sellards, E. H., 1915, The pebble phosphates of Florida: Fla. Geol. Survey

7th Ann. Rept. 

 1916, Fossil vertebrates from Florida; a new Miocene fauna; new Pliocene

species; the Pleistocene fauna: Florida Geol. Survey 8th Ann. Rept., p.

91-95, 144.

1919, Geologic sections across the Everglades of Florida: "Tla. Geol.

Survey 12th Ann. Rept., p. 67-76. 

Simpson, G. G., 1929, The extinct land mammals of Florida: Fla. Geol. Survey

20th Ann. Rept., p. 229-279. 

 1930, Tertiary land mammals of Florida: Am. Mus. Nat. History Bull.,

v. 59, art. 3, p. 149-211.
INDEX

Alum Blufl beds. -..___--------_-..__._..-___ 69,70

Anadaragunteri. 

lienosa 

sp... _ .

Anomia simplex.

Aphelops.. ......

aplcalis,

arata, Cardita.

73

... __ . 72

.. ... . ..... ... . ... .... . 86

... .... . _______ . 88

....................... 85,86

. ...... . ......... .... .. 86

.. .. ... ...... ......... 85

Area zone. _____ _ _ ____ . ___ . _ 72

arcinella, Echinochama ................ . ....... 85

athleta, Chime. ... ...................... ... ... 85

Ealanussp... _ .. __ ..._-.----_.._._.._ 76,77,85 

buckinghamenis, Chlamys (Plagioctenium)

eboreus.... ... ..... ... ..... ..... .. 85

caloosaensis, Phacoides........................

 CalooSahatchee marl, fauna__..__...

lithologic character.__.___...........

origin_.______..___.............

stratigraphic relations- __. __. _.. 84, 

Campekoma sp_-___^__...._..... .

Cancellaria macneili...........................

sp..... .................................

tancellata, Chione..... .......................

Cardita arata............. ____............

sp... ....................................

Cardium malacum................ ............

sp........................................

Cardium (Trachycardium) sp..................

 cereolus floridana, Polygyra..... ________

 Chattahoochee formation........_..........

Chione athleta.................................

84

72

72

85,86

86

78

72

73,78

72

chipolana. 

settardsi...

sp... ..........

 Chipola beds 

chipolana, Chione .

eboreus watsonensis... ...... .. .... ... .....

harrtsi ....... .. .... ..... .... ......... .....

nictAsL.. .......... .......................

sp.. ....... ... ..................... ... 72,

Chlamys (Piagioctenfam) eboreus buckinghamensis _______ .. ....

(Plagioetenium) sp ____________ . 

tontractus, Phacoides .... ... . ..... .......... ...

Conussp.. ... ........... .............. .... ...

85

85,86

73

72

72,73

69,70

73

76

76

86

73

73,78

85

76

73

denaata, Plicatula,..... ........._.___.... 73

dlsparilis, Ostrea.............................. 76

Dosinia sp.......________________ 73

duryl, Hetisoma (SeminvKna).--.............. 89

Page

eboreus buckinghamensis, Chlamys

) . ... ... ... ........ ... 85

Echinochama arcinella ... ........ .............. 85,86

Fconomic importance of mineral resources.. .. 94-95

Eephora n. sp ___ ... . 76

floridana, Polygyra cereolus.

georgianvs, Vtoiparus......................... 89

Gtycymeris subovata........................... 72

sp. ._-_ .. .. - . 72,73

Qoniobasis sp................................. 89

gunteri, Anadara.............................. 73

hadra, Venericardia.........._ 72

harrisi, Chlamys---- 86

Hawthorn formation, fauna.... 71-73

history of name.___..__ 69-70

lithologic character_____ __ 70-71

origin_____._ 73"

stratigraphic reiations.. ___ 69-70,71,72,73

Helisoma (Seminolina) duryi 89

himerta, Venericardia......................... 72

Jacksonville limestone.

Laevicardium sp_. 76 

leidyi, Strombus...................... . .. 85

lienosa, Anadara.. 86 

Location of the area. ___._ 65,66,67

macneili) Cancellaria............. . 72

malacum, Cardium............................ 72

Manatee Elver marl 69 

Mechanical analyses of sediments.._ 91-92 

Merychippussp.............~ 79

Mioceneepoch, geologic history 92-93 

monroensis, Ostreatamiamiensis............... 76

Neohipparion sp 79,88 

nicolsi, Chlamys........... .. 73

Oak Grove sandi.

............................... 86

Ostrea-dispariUs.... ........................ 76

meridionalis . - - 76

 puelchana..... 78

scutpturata.-.-........ .... . .-.-.- 86

tamiamiensismonroengis.................. 76

virginica.. 86

sp. ...... 78

perattenuata, Turritetta. 

Phacoides caloosaensis...

contractus.-.........

sp . .
98 INDEX

Page

Phosphate resources, economic importance__ 94.95

Phosphaticsand and clay, fauna__-..-_ _. 81

lithologic character.---.-._.______ 80

origin-... . .-.- . . .,-___ 83-84

stratigraphic relations.-.._____ 79-80,81-83

(Plagioctenium) eboreus buckinghamensis,

Chlamys......................... 85

Pleistocene deposits, fauna. _________ 88-89 

lithologic character.____________ 87-88 

marine terraces____________-_ 86-87 

origin.-..- .. ____ ___........_ 90

Pleistocene epoch, geologic history,._____ 93-94 

Plicatula densata.............................. 73

sp.------_------_.....___......... 73

Pliocene epoch, geologic history..

Pododesmus n. sp __ _ _

Polygyra cereolus floridana.................

puelchana, Os'rea.........-..

Purpose of the investigation.

Rangia sp-__ _________________ 89 

Rapana.^.................................... 76

Recent epoch, geologic history________ 94 

Recent sediments..______________ 90-91

Sand of late Miocene age, fauna______ 75-76, 78 

lithologic character..___________ 75 

origin -..-..... ................... 78-79

stratietraphic relations.._____. 73-75,76-78 

sayana, Oliva................................. 86

sciilpturata Ostrea............................ 86

tellardsi. Chione. ............................. 72

Semicassis ................................... 72

(Seminolina) duryi, Helisoma................. 89

Page

septemsolvavdaexis, Pdygra................... 89

Serrident inus floridanus....................... 75

Shoal River formation______________ 69

simplex, Anemia................. 86

Sopchoppy limestone._____ ____ 69

Spisula.......................... . 78

Stratigraphic section, on Horse Creek, near

Arcadia.-_____________ 91

on Peace River, near Wauchula.-.__-. 82

Stratigraphy, summary.....__ .. 70

Strombus leidyi............................... 85

subannulata, Turritella ....................... 86

subovata, Olycymeris.......................... 72

Sucdnea campestris........................... 89

tamiamiensis monroensis, Ostrea............... 76

Tampa beds._ ... . 69,70 

Teleoceras fossiger................ 79

Tetrabelodm.................................. 79

(Trachycardium )sp., Cardium.......... _ ..... 72

Turritella apicalis............................. 85,86

perattenuata.............................. 85,86

subannulata.............................. 86

Uranium resources, economic resources.-----. 94-95

Venericardia hadra . 

himerta

sp.

........ 72

, 72 

--.. .. 72,73 

Venus sp.----- -..-. __ 73,78 

vlrginica, Ostrea... ............ . ............... 86

Viriparus georgianus.. .... . ... .. .............. 89

volvoxis, Polygyra septemsolva.. ..* ' 89

wagneriana, Area.

0. 3. GOVERNMENT PRINTING OFFICE] lift


Uranium Deposits at 

Base of the Shinarump 

Conglomerate 

Monument Valley 

Arizona

By I. J. WITKIND

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-C

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Docuhnents, U. S. Government Printing Office 

Washington 25, D. C. - Price 65 cents (paper cover)
CONTENTS

 Page

Abstract__ _________________________________________________ 99

Introduction and acknowledgments^________________________________ 99

General geology.__________________________.______________ _________ 100

Shinarump conglomerate ___________________________________________ 102

Channels,________________________________________________________ 103

Appearance__ ____________________ ______________________ 103

Classification_____ ___________________________ ___________________ 104

Trends________._____________ _________________________________ 106

Widths_______________________________________________________ 113

Floora________________________________________________________ 113

Sediments ___________________________________________ ________ 113

Swales associated with channels. _________________ ______________ 115

Origin. ____________________________________________________ 116

Localization of uranium ore in channels. _ ____________________________ 117

Rods____________________________________________________ ____ 119

Summary____ ____________________________ _____________________ 129

Literature cited ___________________________________________________ 130

ILLUSTKATIONS

[Plates 5, 6 in pocket] 

PLATE 5. Geologic maps and cross sections of the Monument No. 2 area,

Apache County, Ariz. 

6. Geologic map showing swale in the Monument No. 2 area,

Apache County, Ariz.

FIGURE 12. Index map of part of the Monument Valley area in the Navajo Page 

Indian Reservation, Apache and Navajo Counties, Ariz___ 100

13. Schematic block diagrams showing modes of outcrop of

channels in the Monument Valley area, Arizona-_________ 105

14. Geologic map and cross section of Monument No. 1 channel,

Navajo County-_--_--_________________-___-_--__-_-_ 106

15. View of Mitchell Mesa channel 1, Navajo County._________ 107

16. View of Alfred Miles channel 1, Navajo County____________ 108

17. View of Monument No. 2 channel, Apache County.________ 109

IS. Geologic and resistivity interpretations of channels in the

Koley Black area, Navajo County._____________________ 110

19. Map showing distribution of channels in the Monument

Valley area, Anzona __________________________________ 111

20. Diagrams showing channel trends in the Monument Valley

area, Arizona and Utah__ _____________________________ 112

21. Illustrations of simple and complex rods in Monument No. 2

mine, Apache County_________________________________ 120

22. View of large complex rod in Monument Xo. 2 mine, Apache

County.____________________________________________ 121

23. Oblique view of complex rod in [Monument No. 2 mine,

Apache County__________________________---_--__---_ 122

24. Longitudinal view of complex rod in Monument No. 2 mine,

Apache County-_____________________________________ 123

25. Photomicrographs showing orientation of fractures______.___ 124

26. Photomicrograph showing irregular fractures of channel sediments-.-____________________________________________ 125

27. Diagrams comparing orientation of fractures, rods, and 

silicified wood fragments in Monument No. 2 mine, Apache 

County,____________________________________________ 127

in

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIUM DEPOSITS AT BASE OF THE SHINARUMP 

CONGLOMERATE, MONUMENT VALLEY, ARIZONA

By I. J. WITKIND

ABSTRACT

Exposed sedimentary rocks on the Navajo Indian Reservation in Apache and 

Navajo Counties, northeastern Arizona, range from the Halgaito tongue of the 

Cutler formation (Permian) to the Salt Wash member of the Morrison formation (Jurassic). The dominant structural element of the area is the Monument 

upwarp, a large asymmetrical anticline whose northern end is near the junction 

of the Green and Colorado Rivers in Utah and whose southern end disappears 

near Kayenta, Ariz. Asymmetrical anticlines with steeply dipping east flanks 

and gently dipping west flanks are superimposed on the upwarp. These subsidiary structures trend northward.

The uranium-ore bodies are localized in conglomeratic sandstone of the 

Upper Triassic Shinarump conglomerate that fills stream channels scoured in 

the underlying Lower and Middle Triassic Moeiikopi formation. These channels 

range from narrow and shallow, 15 feet wide and 10 feet deep, to broad and 

deep, 2,300 feet wide and 70 feet deep. Two types of channels can be distinguished a short type, less than 2 miles long, and a long type, traceable for 

distances greater than 2 miles. Plant matter in the form of trees, branches, 

and twigs was deposited with Shinarump sediments in the channels. It is 

probable that when the Shinarump conglomerate was invaded by mineralizing 

solutions the uranium ore was deposited primarily in localities formerly occupied 

by the plant material. Also, it is thought that the short channels are more 

likely to hare ore accumulations than long channels.

INTRODUCTION AND ACKNOWLEDGMENTS

During the summers of 1951 and 1952 the U. S. Geological Survey, 

on behalf of the Division of Haw Materials of the U. S. Atomic 

Energy Commission, mapped the geology and uranium deposits in 

three 15-minute quadrangles on the Navajo Indian Reservation in 

Apache and Navajo Counties, northeastern Arizona (fig. 12). The 

area mapped includes the southern half of Monument Valley. The 

work was undertaken to establish guides to uranium deposits and to 

appraise the relative favorableness of different formations for the 

occurrence of uranium deposits. Special emphasis was placed on 

the study of the Shinarump conglomerate (Late Triassic) because all

1)0
100 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

+ | 

Anticline showing trace of axial 

plane and plunge of axis, approximately located

___ | ___

Syncline showing trace of axial 

plane, approximately located

oTUCSON

MEXICO ^____I

- /

I

Ul\ **, 

HOSKINNINI^^ZA c

i'"iGU«E 1H. Index map of part of the Monument Valley area in the Navajo Incl'an 

Reservation, Apache and Navajo Counties, Ariz.

uranium-ore deposits so far known in the Monument Valley area are 

in Sliinarump sedimentary rocks which fill ancient channels at its 

base. In the Sliinarump conglomerate a close relationship exists between uranium-ore deposits and channel sediments.

D. W. Viles, vice president in charge of mining, Vanadium Corporation of America, kindly permitted access to the Monument No. 2 

mine by members of the Geological Survey. Our work in the mine 

was greatly assisted by Robert Anderson, mine superintendent, and 

Carl Bell, mine foreman.

GENERAL GEOLOGY

In Monument Valley, Ariz., exposed consolidated sedimentary 

rocks are of Permian, Triassic, and Jurassic age. (See geologic section below.) Most of the strata are continental in origin, eolian and 

water-laid rocks alternate in a nearly regular sequence. Volcanic 

necks and lamprophyric dikes, thought to be Tertiary in age, cut the 

sedimentary rocks. The dikes generally follow a joint set that trends
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 101

Sedimentary rocks exposed in the Monument Valley Area, Arizona

Age

Jurassic

Jurassic (?)

Triassic

Permian

Stratigraphic unit

Group

San 

Rafael 

group

Glen 

Canyon 

group

Formation

Morrison formation

Bluff 

sandstone

Summerville 

formation

Entrada sandstone

Carmel formation

Navajo sandstone

Kayenta formation

Wingate 

sandstone

Chinle formation

Shinarump 

conglomerate

Moenkepi formation

Cutler formation

Member

Salt Wash 

member

Hoskinnini 

tongue

De Chelly 

sandstone 

member

Organ Rock 

tongue

Cedar Mesa 

sandstone 

member

Halgaito 

tongue

Thickness 

(feet)

?

45

35

110

118

665

150-200

350

1,000

50-100

30-250

10-60

350-450

650-750

500

380

Lithologic and topographic 

characteristics

Gray to chocolate-brown mudstone 

alternating with white to gray finegrained sandstone lenses.

Chocolate-brown fissile siltstone alternating with reddish-brown finegrained sandstone. Few discontinuous white siltstone lenses.

Brown to reddish-brown even-bedded 

siltstone; cliff former; white finegrained sandstone 1 foot thick at 

base.

Lower part reddish-orange massive 

fine-grained sandstone that weathers 

as smooth, rounded slopes. Upper 

part chocolate-brown to reddishbrown even-bedded shaly siltstone 

and sandstone weathering to .rounded 

structures resembling hoodoos. Base 

of upper part locally, marked by 

white fine-grained sandstone 1 foot 

thick.

Predominantly red fissile siltstone 

with local lenses of red platy sandstone; few beds of discontinuous thin 

ledge-forming white crossbedded 

medium-grained sandstone.

Pink and buff massive eolian crossbedded sandstone with interbedded 

thin lenses of siliceous limestone.

Light-violet to reddish-brown irregularly bedded quartz sandstone with 

local lenses of conglomerate.

Reddish-brown massive eolian crossbedded sandstone weathering to 

steep rounded slopes or vertical cliffs.

Lower part, variegated mudstone and 

siltstone with dark sandstone lenses 

near base and thin beds of gray 

cherty limestone near top; upper 

part, reddish-brown even-bedded 

siltstone and sandstone weathering 

to rubble-covered slopes.

Light-gray fluviatile crossbedded conglomeratic quartz sandstone with 

rounded pebbles as much as 2 inches 

in diameter; much silicified wood 

present.

Reddish-brown even-bedded ripplemarked shaly siltstone weathering 

to gentle slopes.

Reddish-brown parallel-bedded siltstone with some interbedded lenses 

of sandstone.

Buff massive eolian crossbedded quartz 

sandstone weathering to steep 

rounded slopes or vertical cliffs.

Reddish-brown siltstone locally interbedded with red to gray sandstone; 

weathers to massive ledges about 5 

feet thick.

Reddish-orange crossbedded sandstone 

with thin beds of gray limestone.

Red siltstone and silty shale with thin 

beds of nodular-weathering gray 

limestone.
102 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

from due north to about IS". 45 ° W. Xenoliths in the volcanic necks 

are only moderately metamorphosed and include pre-Cambrian (?), 

Pennsylvania!!, Permian, Triassic, and Cretaceous rocks. In many 

places all strata are masked by a thin veneer of alluvium or dune 

sand, but exposures on the mesa faces are excellent.

The major structural feature in the region is the Monument upwarp, 

a broad asymmetrical anticline. It extends from near the junction of 

the Green and Colorado Rivers in Utah southward into the Monument 

Valley area of Arizona (Baker, 1935, p. 1482) where it plunges southward and disappears. The upwarp is about 125 miles long and has 

a maximum width of about 75 miles. In the Monument Valley area, 

Arizona, (fig. 12) the eastern flank of the Monument upwarp dips 

steeply and is well defined by Comb Ridge; the western flank, however, dips gently, and its limits are poorly defined.

The gently dipping west flank of the upwarp is interrupted by 

northward-trending subsidiary folds. Like the major upwarp, these 

subsidiary folds are also asymmetrical, with steep eastern flanks and 

gently dipping western flanks. Extensive dissection along these 

structural features has produced the cuestas, mesas, and buttes that 

characterize the spectacular landscape of Monument Valley.

SHINARUMP CONGLOMERATE

In Monument Valley, Ariz., the only known uranium-ore bodies are 

in channel sediments at the base of the Shinarump conglomerate.

On weathered exposures the Shinarump is gray or light buff, and 

only locally does the color deepen to a more somber brown or gray. 

Fresh surfaces are much lighter, approaching a very light gray. 

Although called a conglomerate, the Shinarnmp in Monument Valley 

is more correctly a conglomeratic sandstone. Commonly a coarse conglomerate is at the base, grading upward into sandstone that ranges 

from medium to coarse grained. Both the conglomerate and the 

sandstone beds are crossbedded and lenticular, and they intertonguo 

with one another. Most of the foreset beds dip northwestward, but 

they may dip in any direction. Within any one lens the textures 

show rapid gradation; for example, a lens of coarse-grained sandstone 

more than 5 feet thick can become a conglomeratic standstoiie within 

a lateral distance of 10 feet.

The Shinarump conglomerate consists principally of only the most 

durable materials. Quartz, qnartzite, and chert predominate both in 

the pebbles and the matrix. Pebbles composing the conglomeratic 

facies are commonly well rounded, with smooth, unbroken surfaces and 

ellipsoidal shapes. They are white, red, black, green, and yellow, or 

have many color combinations. Small quantities of limestone, clay, 

and sandstone pebbles are found in a few localities. Silicified wood
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 103

is scattered throughout the Sliinarump as fragments 1 or 2 inches in 

length and as logs as much as 50 feet long and 4 to 5 feet in diameter. 

Although much of the wood within the Sliinarump has been silicified, 

some has not, and localized areas of small pockets of black carbonaceous material are found throughout the formation.

Lenses of claystone as much as 100 feet across and a few inches to 8 

feet thick are common in the uppermost parts of the conglomerate. 

In some places the clay is concentrated within the formation in the 

form of angular blocks that range from 4 feet long and 2 feet high 

to small clay pebbles 1 or 2 inches in diameter. In these localities 

more interstitial clay is present than in areas where clay pebbles are 

rare.

The formation is cemented by a number of materials either individually or in combination; authigenic quartz, iron oxide, calcite, and clay 

are predominant.

Despite the relative thinness of the Sliinarump conglomerate in the 

Monument Valley area, it is remarkably uniform in thickness over its 

widespread area of outcrop. The formation is generally about 75 

feet thick, although locally, as the result of channeling, it thickens to 

150 feet or more; elsewhere, it thins laterally and disappears.

The contact of the Sliinarump with the overlying Chiiile formation 

is graclational, and, locally, the two formations intertongue. The 

contact between the Sliinarump and the underlying Moenkopi formation, however, is a widespread disconformity marked by deep channels. Except for the channels the relief along the disconformity 

ranges from 2 to 4 feet and is marked by a notable textural and compositional change.

In Monument Valley the Sliinarump forms a resistant sandstone 

ledge that caps most of the mesas. On outcrop it tends to form steep 

cliffs as much as GO feet high, that are almost unscalable for considerable distances along the exposure. The formation is jointed 

throughout, and large talus blocks mantle the slopes and commonly 

conceal the lower contact of the formation. Some talus slides extend 

from the base of the Sliinarump cap to the bottom of the mesa, which 

is as much as 800 feet below. Where the Sliinarump conglomerate 

forms a widespread surface, it is extremely irregular, pitted with 

basinlike depressions as much as 20 feet in diameter and 4 feet deep, 

and ridged with hummocks that rise as much as 30 feet above the general surface. In some localities the Sliinarump forms a bench around 

the flanks of mesas capped by younger rocks.

CHANNELS 

APPEARANCE

111 Monument Valley the symmetric and asymmetric troughs that 

are cut into the Moenkopi and filled with Shinarump conglomerate

379273 56 2
104 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

are referred to as channels. These channels accentuate the disconf ormity between the two formations. Deposits of uranium and copper 

minerals are localized within these channel sediments, and as a result 

the channels are of special interest to geologists and prospectors in this 

part of the Colorado Plateau.

The channels are exposed in three different ways in the Monument 

Valley area. Principally, they are exposed along mesa rims and in 

valley walls as U-shaped depressions. In this mode of outcrop the 

channels are buried beneath overlying beds of Shinarump conglomerate (fig. 13J.). Where erosion has been more extensive and the overlying beds of Shinarump have been removed, the channel sediments 

appear as narrow elongate exposures of gray conglomeratic sandstone 

bounded by the red shaly siltstone of the Moenkopi formation (fig. 

135). Where erosion has proceeded still farther, the softer shaly 

siltstone of the Moenkopi has been removed, leaving the more resistant 

channel fills as ridges (fig. loC and fig. 14).

The details of the origin of the channels are still in doubt, but it 

seems likely that the channels are the result of stream erosion. Typical 

cross sections of channels at the base of the Shinarump conglomerate 

are shown in figures 15,16, and 17.

CLASSIFICATION

The channels are difficult to trace commonly, because they are not 

well exposed or because they differ greatly in length. A channel may 

be so short that it is exposed only on one side of a mesa. This is well 

shown by K. A. Black and W. H. Jackson of the U. S. Geological Survey in their interpretations of the resistivity of the channels in the 

Koley Black area where channel 45 ends within 350 feet of the outcrop 

and cannot be traced farther to the northwest (fig. 18). The Koley 

Black group of channels (nos. 37-45 of fig. 18) has confirmed the short 

linear character of some channels. Other channels may persist across 

the mesa and be exposed on both sides. One channel was traced for 4 

miles; others disappear within a mile. I have called the shorter channels "short channels," and the longer ones "long channels," and have 

arbitrarily established the distance of 2 miles as a dividing line between the basinlike short channels and the more continuous long ones.

How the short channels terminate is uncertain, although the results 

of drilling by the U. S. Atomic Energy Commission suggest that 

some of the short channels have ends that are gently concave (pi. 5(7). 

Because of insufficient drilling it is not known how the long channels 

terminate.

These short channels may represent deep scours along the course 

of a former stream, but as yet I have not found these channels alined 

in such a manner as to confirm this. If these short channels do repre-
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 105

300

Approximate scale

E 13. Schematic block diagrams showing modes of on ten 

channels in the Monument Valley area, Avis; ma,
106 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

EXPLANATION

Dune sand 

Shinarump conglomerate

Moenkopi formatic

Hoskmmni tongue

DeChelly sandstone member

Contact, dashed where 

approximately located

Trend of known channel 

dotted where projected

Abandoned mine

FIGURE 14. Geologic map and cross section of Monument No. 1 channel, Navajo County,

Ariz.

sent sporadic scouring, it may be possible to project the trends and 

locate other short channels now concealed beneath overlying beds of 

Shinarump.

TRENDS

111 this area the dominant orientation of the channels is northwestward (fig. 19). In an area as small as Monument Valley, Ariz., 

this northwest orientation is merely suggested by a diagram of the 

channel trends (fig. 2CL.1). This orientation is more apparent in the 

diagram of channel trends in the adjacent part of Monument Valley 

in Utah (fig. 205). Thus, a diagram (fig. 20C) of all the channel 

trends noted in a much larger area (the Utah and Arizona parts of 

Monument Valley) clearly indicates the dominant northwest 

orientation.
URANIUM DEPOSITS. MONUMENT VALLEY, ARIZONA 107
o

00

FIGURE 16. Northeasterly view across the West Fork of Copper Canyon showing the broad deep Alfred Miles channel 1, 

Navajo County, Ariz., and the Shinarump conglomerate ("Eg), Moenkopi formation ("Em), Hoskiiinini tongue of the Cutler 

formation (Pch), De Chelly sandstone member of the Cutler formation (Pcd), and Organ rock member of the Cutler formation 

(Pco).
FIGURE 17. -Southeasterly view of South Ridge showing shape o; Monument No. 2 channel, Apache County, Ariz., and the Shinarump conglomerate (Ts), Moenkopi formation ("Km), Hoskinnini tongue of the Cutler formation (Pch), and De Chelly 

sandstone member of the Cutler formation (Peel). , ' >

O 

CO
110 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Monitor Butte member, 

Chinle formation

Shinarump conglomerate

im^l

°

li4 DeChelly sandstone member

Resistivity data determined and interpreted by R. A. Black

and W. H. Jackson, U. S. Geological Survey 

EXPLANATION

Trend of known channel identified by 

number. Dashed where concealed, 

dotted where eroded

Outline of channel as interpreted from 

resistivity data: deeper scour within 

channel shown solid

Contact, dashed where approximately located

_L3 

Strike and dip of beds

m so 

Strike of vertical joint

X 

Prospect

FIGURE 18. Geologic and resistivity interpretations of channels in the Koley Black area,

Navajo County, Ariz.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 111

»AI'.3

- o <u ^ntrh "liJ

DJS .1. S

^<4UIV ^'"l^ LJ

C^"ix r1 I

^fl,:, $t) 

W

3n<§

^b5?~

379273-
112 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Number of observed channels 

with trend oriented in 10" 

segment

MONUMENT VALLEY, ARIZONA

Number of observed channels 

N. with trend oriented in 10° 

segment

MONUMENT VALLEY, UTAH

Number of observed channels 

with trend oriented in 10" 

segment

MONUMENT VALLEY-ARIZONA AND UTAH

FIGURE 20. Diagrams showing channel trends in the Monument Valley area,

Arizona and Utah.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 113

Although several channels curve (fig. 19), most are nearly straight. 

This observation is substantiated by recent geophysical work in this 

area.

Single channels are most common, but several do bifurcate, and of 

these at least one, in the Koley Black area, appears to give way to 

a series of parallel smaller channels (fig. 18).

WIDTHS

For purposes of discussion the channels are classified roughly into 

three categories based upon width. The first category (narrow) includes channels as much as 50 feet wide, the second category (intermediate) comprises channels ranging from 50 to 350 feet in width, 

the third category (broad) includes channels ranging from 350 to 

2,300 feet in width (fig. 19). Of the 62 channels noted during the 

course of field work, 17 were narrow, 32 were intermediate, and 13 were 

broad. (See table on following page.)

Channel sediments, sorting, and bedding appear identical in all

three categories of channels.

FLOORS

Little is known about the configuration of channel floors. Judging 

from workings in the Monument No. 2 and Skyline mines (fig. 12), the 

floor is known to be undulatory and locally extremely irregular. 

Geophysical work in the Koley Black area (fig. 18) and along the 

Alfred Miles channel 1 (fig. 19) has also indicated that broad shallow 

scours are in channel floors. It has been suggested by geologists of 

the U. S. Atomic Energy Commission (J. W. Chester, 1952, personal 

communication) that these scours may be important centers of 

uranium-ore accumulation.

SEDIMENTS

Sediments filling the channels range from medium- and coarsegrained sandstone to conglomerate. Some of the channels are filled 

completely with massive uniform-textured medium-grained sandstone that is totally devoid of pebbles or conglomerate. Other channels contain conglomerate with minor amounts of coarse sand filling 

the interstices. In general, however, the sediments filling the channels 

appear identical with sediments found elsewhere in the Shinarump 

conglomerate. The prominent difference between channel sediments 

and nonchannel sediments is the amount of fossil wood; channel sediments contain abundant fossil wood, whereas nonchannel sediments 

contain less wood. For example, in certain channels, especially the 

Monument No. 2 channel, the quantities of mineralized wood seem unusually high. Some of this wood is replaced by silica, some by
114 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Characteristics of channels

Location 

number 

(fig. 19)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

53

54

55

57

59

60

61

62

Name of channel

Alfred Miles 1 ........

Cutfinger Canyon.. 

Double 1 - -

Alfred Miles 2i ..._... (')

(i)

(i).._ ._ .

Checker i.. _ _ _

Road i .... ....... ..

Fish 1 . 

Koley Black 2 _ ...

 .do. ..... ..

 .do . . -

 . .do . ...

 .do __ _ 

 ..do _ _ .

.....do- - 

 .do - .

--.. do" . _

 .do... ... ...

 do 

Mltchell Mesa 2. ........

Mike Brodie .... ....

Width 

(feet)

2,150

2,300

1, 500

150

1,800

500

250

600

20

50

(?) 300

400

400

600

30

100

45

250

300

250

150

50

175

10

25

15

200

250

250

80-100

80

50

50

35

110

270

35

110

150

(?) 350

350

150

Kfl

300

300

150

300

300

Depth cut 

into 

Moenkopi 

formation 

(feet)

70

50

50

75

30

0

30

10

6

10-15

40

40

10

20

30

10

30

75

50

Ofl

15

50

30

50

25

5-10

30

30

20

30

30

50

75

70

15

20

20

20

50

20

25

40

20

Length

. do .

 do . ....

... . do ......

Long..

 do . .___

 _do ......

 do ... ....

 do ..... .

 do ......

 do

Short (?) .

... ..do ......

.....do . .....

.... .do ..... .

___._do____ ....

 do ...

 do .

.....do ... ....

Long (?)__-__

. do.-.. __

Short.--......

 do __..

Short-... .

 do ......

Long (?)_ ._

Short.... ...

 _do_ .--

 _do _

 do .. 

 do ..... .

.. do ... ...

 do . ....

 do ..

 do ... _.

 .do .....

 do .

 do 

... ..do... .... ..

 _do .... .

Short ..

... do.-. ..

- do ....

... .do .....

 do ........

Short-- 

Strike

N. 50°E_-_ .

N. 35°E__ . .

(?) 

(?)

N. 40° E. (?)...

East.... ....

N. 80° W ...

N. 80° E.. ...

(?) 

N. 12° E. .......

N. 72° E.. __.._

N. 55° E _

East... -...-.

NE (?) .....

N. 20° E-.. .

N. 25° W___ ...

N. 10° W ...

N. 40° E. ...... .

N. 50° E __-_.

East-.. ... .... .

N. 18° E ......

N. 35°E._ ._

N. 25° E...... .

N. 30° W .....

N. 15° E. to N.

10° W.

N. 65° W ...

N. 45° W-- ...

N. 10° W._ ...

North 

North ..........

N. 65° E. .__-...

N. 27°E._ ...

N. 80° E.. 

N. 35° W ...

N. 10° W 

N. 35° WN. 45° W 

N. 44° WN. 44° W .....

N. 44°W .....

N. 20° W . ... .

N. 45°W . .

N. 45°W .... .

N. 52°W___.___.

N. 20°W. 

N. 45° W 

North- ...

N. 50° W ... -

N. 70° W ... -

N. 55° W 

N 85° W

N. 75° E (?).....

N. 85° E.. ......

N.82°E.. ..

East -- 

N. 18° W. . ...

N. 25°W... .... .

N. 55° W .... .

N. 67°E.._ .

N. 50° W .....

Mineralization

Cu, U.

Cu.

Do.

Cu.

Cu,:u.

Cu.

Do.

Cu.'.U.

Cu.

Cu.

Do.

Cu, U.

Cu, V.

Cu.

Do.

Cu, U.

Do.

Cu, U, V.

i One channel (?).

s Koley Black refers to a group of unnamed channels in the Koley Black area.

3 Main channel of the Koley Black group.

tyiiyamuiiite and limoiiite, some by uraninite, and same lias been 

altered to a carbonaceous material. Furthermore, many of the rich 

ore bodies at the Monument No. 2 mine may represent deposition of 

uranium minerals in localities once occupied by buried logs. In several other channels, notably the Alfred Miles channels 1 and 2, and
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 115

the Double channel (fig. 19), fragments of wood partly replaced by 

copper minerals (azurite and malachite) are found in basal channel 

sediments. Lenticular pods of black coaly material (vitrain?) have 

been found associated with several ore deposits and are believed to 

represent buried logs.

It appears that two types of clay fragments are included in the 

Shinarump conglomerate. Most profusely distributed are those fragments derived from the Moenkopi formation. Other clay fragments, 

less common, may be- the result of alteration of volcanic ash deposited 

during original accumulation of the Shinarump (Waters and Granger, 1953, p. 6).

In the Skyline mine (fig. 12) angular boulders of clay, derived from 

the Moenkopi formation, as much as 4 feet on a side, and clay fragments of smaller sizes are profusely distributed throughout the channel sediments. Similar clay fragments are found in other channels. 

Preliminary X-ray work by D. H. Johnson of the Geological Survey 

has indicated that most of these clay pebbles are composed of quartz, 

hydromica, and possibly a little montmorillonite. (See table below.)

Whether either type of clay fragment is instrumental in the localization of uranium ore is unknown. Conflicting evidence has been 

noted at several mineralized locations. Geologic niapping in the 

Monument No. 2 mine has suggested that clay has no significance in 

such locaKzation, but at both the Monument No. 1 and the Skyline 

mines clay pebbles appear to have acted as focal points for the accumulation of uranium minerals.

Composition of some flay pelibles from the Monument TaUey area, Arizona and

Utah, as determined by means of the X-ray spectrometer 

[Analyzed and compiled by D. H. Johnson, Denver Trace Elements Laboratory]

Sample 

no.

W-175A-. 

W-175BW-176A._ 

W-176B__

W-180- 

W-182___. 

W-186 -

W-187 

W-188 _

Location

Monument No. 1 mine, Navajo 

County, Ariz. 

- do-' 

Base of channel, Monument No. 1 

mine, Navajo County, Ariz. 

.. do- __ 

Monument No. 1 mine, Navajo 

County, Ariz.

Monument No. 1 Annex, Navajo 

County, Ariz.

Utah. 

 -do 

---.do 

Composition

Quartz, hydromica, and a little kaolinite.

apatite (?). 

Quartz, hydromica, and a little carbonate apatite (?) .

bonate apatite (?) and kaolinite or 

chlorite. 

Quartz, hydromica, a little kaolinite, 

and possibly a little montmorillonite. 

Quartz, hydromica, and probably a 

little montmorillonite.

- do 

little montmorillonite.

Benzidine test

Very slightly 

positive (?). 

Do.

Very slightly 

positive.

Negative.

Very slightly 

positive.

Do. 

Do.

Do.

Do.

SWALES ASSOCIATED WITH CHANNELS

The Monument No. 2 channel is in the center of, and collinear with, 

a broad very shallow, elongate swale in the top of the Moenkopi formation (pi. 6). However, this cannot be perceived from the ground
116 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

because of the dissection of the area, as well as the great width and 

relative shallowness of the feature. An isopachous map, prepared 

from measured sections of the combined Hoskinnini and Moenkopi 

strata indicates its width and extent clearly (pi. 6). The swale is 

about 3 miles wide and can be traced southeastward for S1/^ to 4 miles 

before it disappears below the alluvium of Cane Valley. At the edges 

of the swale the combined thicknesses of Hoskinnini and Moenkopi 

strata amount to about 80 feet. Along the flanks of the Monument 

No. 2 channel in the center of the swale, this thickness decreases to 30 

feet. Erosion during the formation of the channel has removed these 

30 feet of strata adjacent to the channel, and consequently channel 

sediments of the Shinarump conglomerate rest with pronounced disconformity on the De Chelly sandstone member of the Cutler 

formation.

Although this swale-channel relationship is best displayed in the 

Monument No. 2 area, analogous features have been noted on Hoskinnini Mesa. There, however, the swales are not as well formed nor as 

broad.

ORIGIN

One hypothesis regarding the origin of channels suggests that they 

were formed during a period following deposition of the Moenkopi 

formation but prior to deposition of the Shinarump conglomerate. 

This viewpoint is presented by Gregory and Moore (1931, p. 52) who 

wrote 

After Moenkopi time there was widespread erosion which partly beveled the 

soft Moenkopi strata and in places carved distinct erosion channels in them. 

The subsequently deposited Shinarump conglomerate constitutes a very widespread thin veneer which covers this erosion surface and fills its depressions.

Stokes (1950, p. 94) interprets this as meaning that the unconformity and the channels were formed probably during Middle Triassic, with the Shinarump deposited much later in a second independent episode in Late Triassic time.

Another hypothesis suggests that the channels were formed by 

the streams that deposited the Shinarump, and thus are contemporaneous in age with basal Shinarump sedimentary rocks. This viewpoint is expressed by Stokes (1950, p. 97) who regards the unconformity as a Middle Triassic pediment surface formed during the 

deposition of the Shinarump conglomerate, which in turn represents a 

pediment deposit.

Essentially there appears to be general agreement that the Shinarump was deposited on a widespread surface of low relief. Stokes 

considers the surface to have formed synchronously with the deposition of the Shinarump; McKee (1951, p. 91), however, considers it 

to have been a flood plain upon which the Shinarump was deposited.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 117

Apparently streams transported sands and gravels from a raised 

area to the south and gradually spread them northward as a thin 

blanket. When one considers the coarse-grained and resistant materials that compose the Shinarump conglomerate it seems unlikely 

that the formation could have been deposited without some scouring 

in the softer siltstones and shales of the underlying Moenkopi formation. It is suggested, therefore, that the major channel scour occurred 

during deposition of the Shinarump conglomerate and not in any 

period of erosion prior to this deposition.

Why one channel is continuous and another not, is unknown; the 

short channels may represent sporadic scour depressions. Bryan, 

(1920, p. 191) in discussing present streams, suggests that scour 

depressions are most likely to form near the outside bend of a stream 

where the erosive force of the stream is at a maximum. If this 

concept is applied to the Shinarump, it may be that a former meandering stream, carrying Shinarump sediments cut these deeper scours 

wherever it swung about. Thus, Monument No. 1 (fig. 14), a gently 

curving short channel, might have formed in this manner.

Another possibility is that local differences in the hardness of the 

Moenkopi formation that once formed the banks of the former streams 

may have caused the formation of "narrows1 '. These narrows may 

have been instrumental in ponding the water and thus forming sizable 

lakes upstream. The attendant increase in gradient across the 

more resistant rocks would have augmented the velocity. Downward 

erosion would have increased at the expense of lateral planation, and 

the final result would have been the formation of short channels. 

Matthews (1917, p. 337-342), referring to elongate scour depressions 

as much as 2,000 to 7,200 feet long, 200 to 300 feet wide, and 40 to 60 

feet deep in the floor of the Susquehanna River, suggests that these 

"deeps," as he calls them, are the result of such constrictions.

LOCALIZATION OF URANIUM ORE IN CHANNELS

This paper is concerned with the localization of uranium minerals, 

which are more correctly identified as uranium-vanadium minerals 

inasmuch as the chief ones are tyuyamunite [Ca (UO2 ) 2 (VO4 ) 2 'nH2O] 

and camotite [K2 (UO2 ) 2 (VO4') 2 3H2O].

Although uranium ore is in channel sediments, the ore is not continuous along the channel's length nor does it appear to be restricted 

to any specific sector of the channel sediments. At the Vanadium 

Corporation of America's Monument No. 2 mine, where extensive 

workings permit examination of channel sediments, ore has been found 

in the basal, middle, and uppermost beds as well as along the channel 

flanks.
118 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

One fact, however, is clearly evident in the Monument Valley area: 

no ore has been found outside of channels. This is not to be construed to mean that uranium minerals are not found away from channels ; they are, but to date they have been found in such small amounts 

as to make them of academic rather than economic interest. This 

relationship between uranium ore and channels is well known, and 

most prospectors seek and stake claims on such channels.

The relationship between uranium minerals and channels is repeated 

many times in the Monument Valley area of Utah and Arizona. Generally, these exposures are small and of slight extent, but more than 

one-third of the channel outcrops examined contain some uranium or 

copper minerals in their basal sediments.

The spatial relationship between uranium-ore deposits (economic 

concentrations of uranium minerals) and channels, is based on only 

two examples. Essentially, in the Monument Valley area, Arizona, 

uranium-ore deposits have been found in one of the intermediate-type 

channels, and in one of the broad channels. Despite this unimpressive accounting, it should be noted that many of the channels are as 

yet untested and may contain deposits of uranium ore. Most important, however, is the realization that of the thousands of miles of 

Shinarump outcrop examined, deposits of uranium minerals seem to 

be largely restricted to channel sediments. The apparent relationship 

between channels and uranium-ore deposits also seems to be suggested 

elsewhere on the Colorado Plateau.

As a result of the spatial association between channel sediments and 

uranium ore, a continuing search is underway for the factor or factors 

which were instrumental in localizing the ore in the channel sediments. 

The search has been unsuccessful in that conclusive evidence favoring 

any factor (or combination of factors) is yet to be produced. Strong 

'"suggestions" have been noted by field geologists working in the Monument Valley area. For example, at the Skyline mine, ore is in channel 

sediments that contain much clay and pods of carbonized wood. A 

similar situation exists at Monument No. 1 mine. Despite this apparent relationship in these two localities between clay and carbonized 

wood and uranium ore, it is difficult to state conclusively what role 

these factors played in the localization of uranium ore. Clay as well as 

pods of carbonized wood are found away from channels, and ore is not 

present in these localities. In Monument No. 2 mine clay and carbonized wood are in considerable amounts within the channel sediments, 

but in no instance was a sizeable quantity of uranium ore associated 

with either. In fact, areas were found in the mine where concentrations of clay, boulders, and carbonized wood were distant from ore 

localities.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 119 

RODS

Throughout the Monument No. 2 mine many of the major bodies of 

uranium ore appear as flattened, cylindrical bodies. The miners 

refer to them as trees or logs. Because these two terms bear a genetic 

connotation, a new term, suggested by L. B. Kiley of the U. S. Geological Survey, is proposed herewith. It is suggested that these crudely 

ovate, flattened, elongate, cylindrical bodies be known as rods.

All the rods are in channel sediments of the Shinarump conglomerate ; none are in any of the underlying strata. Ore bodies similar to 

these have been noted in the Morrison formation and called cylindrical 

masses (Coffin, 1921, p. 163). The origin of these rods in the Shinarump is obscure. Some may result from chemical changes induced in 

the mineralizing solutions by carbonaceous matter; others may result 

from unusual conditions of permeability and porosity in the host rock.

The rods in the Shinarump can be classified roughly into two categories : simple and complex. The simple type of rod is illustrated in 

figure 21. Essentially it consists of an outer rim of sandstone impregnated with limonite, within which is a rim of tyuyamunite-impregnated sandstone, which in turn surrounds a core of extremely friable 

light-gray sandstone.

The complex type of rod is bounded similarly by an outer rim of 

limonite-impregnated sandstone within which is a rim of tyuyamuniteimpregnated sandstone. These rims, however, are much more irregular than in the simple type. A further subdivision of the complex 

rod is possible. One type contains irregular masses of mixed limonite 

and tyuyamunite randomly distributed throughout the gray sandstone 

center (fig. 2L.4. and fig. 22) ; a second type may have these irregular 

masses of limonite and tyuyamunite in the sandstone center, but in 

addition has a central core of silicified wood (figs. 21Z>, 23, and 24).

Near many of the rods the confining strata are interrupted at the 

rims; elsewhere, they arch over the rods. Grain size changes abruptly 

at the edges of some rods. Most rods are remarkably straight and, 

where mining operations have followed them, many have been found 

to taper and bifurcate. Many complex rods are associated with silicified wood; and, invariably, where longitudinal exposures are available, 

the silicified wood is seen to be collinear with the rods (block diagram 

in fig. 21; and fig. 24). In several rods, exposures are large enough 

to afford longitudinal examination of the gray sandstone core filling 

their centers. In these, the direction of crossbedding is totally different from the direction of crossbedding of those sediments outside 

the rods.

Small fractures cutting the sand grains are restricted to the limonite-impregnated sandstone zone and the tyuyamunite-impregnated 

sandstone zone, both of which form the rims of the rods. These
120 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

fractures are not apparent in those grains that fill the cores of the 

rods, nor in the grains distant from the boundaries of the rods. Moreover, the fracturing halts along very definite boundaries which in 

some cases are so distinct they can be delineated in thin section. For 

example, in thin sections of edges of rods, the grains on part of the 

are intensely fractured, whereas the grains on the remainder of

Circular pattern of fractures 

Limonite

Tyuyam unite

Simple rod

Complex rod B

Silicified wood core

"Gray friable sandstone

Complex rod A

Tyuyamunite, limonite, and 

gray sandstone core

3 Feet

Gray friable sandstone

Gray friable sandstone 

Silicified wo

FIGURE 21. Illustrations of simple and complex rods in Monument No. 2 mine, Apache

County, Ariz.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 121
122 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 123
124 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 25. Photomicrographs of thin sections of specimens collected in the Monument 

No. 2 mine; specimens contain secondary uranium and vanadium minerals in interstices 

and fractures. A, Rim of rod showing distinct boundary between fractured and unfractured grains. B, Rim of rod showing quartz grains broken by parallel set of 

fractures.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 125

JVJGUKE 26. Photomicrograph of thin section of specimen collected in the Monument No. 

2 mine, showing irregular fractures of channel sediments about 1 foot away from rim 

of rod. Specimen contains secondary uranium and vanadium minerals in interstices 

and fractures.

the slide are whole (fig. 25). The separation between fractured and 

unf ractured grains is a zone not more than 1 millimeter wide.

Two systems of fractures were noted: one consists of a set of parallel 

fractures (fig. 26) with a subsidiary set trending more or less at right 

angles; the other is a plexus of fractures that lacks orientation. Each 

fracture of the parallel set is as much as 1 millimeter away from 

adjacent fractures, and each fracture can be traced for as much as 

10 to 15 millimeters in a relatively straight line as it continues uninterrupted through sand grains. In places this parallel set is cut 

by a subsidiary set that is at right angles to the main set. The subsidiary set offsets the main fractures slightly; but those fractures with 

no determinable pattern are less common. The fractures are jagged 

and end at the grain boundaries. The gross appearance of this 

fracture system is that of an interlacing network, devoid of orientation or system.

Filling the fractures, interstices, and other voids are secondary 

uranium and vanadium minerals, calcite, and authigenic quartz. The 

depositional sequence appears to be as follows: First, authigenic 

quartz; second, secondary uranium and vanadium minerals; and third, 

emplacement of calcite.

The circular pattern formed by the fractures as they outline the 

rods is distinctive and has been found only in the Monument No. 2 mine.
126 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

How these circular fracture patterns form and the reason why some 

grains are fractured whereas others only a few millimeters away are 

not fractured is unknown. One answer may involve factors of selective cementation. Perhaps those grains in the fractured zones were 

once tightly cemented. When stress was applied, possibly as a result 

of load, the cemented grains may have fractured, but the unceniented 

grains may have merely rolled and readjusted themselves to the forces 

applied.

Many of the rods \vere interpreted by me to represent replacement 

of coalified logs by silt, pyrite, and uraninite. Subsequent oxidation 

altered the pyrite to limonite. and the uraninite to becquerelite and 

carnotite. It was thought that the woody texture of these coalified 

logs is now reflected in the rims of the rods by these materials. To 

test this concept, six samples were sent to James M. Schopf of the 

Geological Survey. Five of the samples were collected from the rims 

of the rods, and the sixth was collected from silicifiecl wood in the core 

of a rod. It was requested that he determine whether any of the 

samples represented replaced plant matter. In selecting the samples 

an effort was made to include a range from those that seemed to show 

woody texture to others that appeared to contain only rudimentary 

traces of former plant matter.

Of the six samples submitted, Schopf identified only one as replaced fossil wood, and that was the one collected from the core of 

the rod: the others contained no trace of organic matter. It appears, 

therefore, that although parts of some rods may represent replacement of some form of former plant matter, the mineralized rims of 

the rods do not show this phenomenon. The similar pattern between 

trends of rods and of silicified wood fragments (fig. 27), however, 

as well as the collinearity apparent between many of the rods and 

silicified remnants of logs, suggests that some relationship does exist 

between these former buried logs and the rods.

Possibly the shape, size, and distribution of the rods were determined by the buried logs. During or very shortly after burial the 

original organic matter of the buried logs may have been removed 

and other, more stable materials, such as sand, silt, and clay may have 

been deposited in the voids so formed. The removal of the organic 

matter and its subsequent replacement was probably a gradual process 

and affected only part of any log at any one time. It may have been 

during this episode that porosity and permeability conditions were 

changed; possibly this was sufficient to localize the ore solutions when 

they invaded the Shinarump conglomerate. Thus, those rods over 

which the bedding arches, as well as those that show abrupt changes 

in grain size between the confining strata and the rod boundaries, 

may merely represent the former presence of buried logs, which have 

since been replaced by sand, silt, and clay.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 127

Number of observed fractures 

oriented in 10° segment

FRACTURES

Number of observed rods 

N. oriented in 10" segment

RODS

Number of observed silicified-wood 

frogments oriented in 10° segment

SILICIFIED-WOOD FRAGMENTS

FIGURE 27. Diagrams comparing orientation of fractures, rods, and silicined wood 

fragments in Monument No. 2 mine, Apaclie County.
128 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Other rods may have formed from mineralizing solutions in response to halos of decomposition products, such as humic colloids and 

organic resins, spreading outward from buried coalified logs. Possible examples of this type are those rods that contain silicified wood at 

their centers.

Still another possibility is that the rods may be completely independent of plant matter and may merely reflect fracture patterns 

formed during processes of compaction and authigenic crystal growth.

Probably no single concept will explain how rods formed. Perhaps 

combinations of the processes mentioned above are involved. For instance, the shape, size, and distribution of the rods may have been 

determined by the presence of buried logs. During or shortly after 

the logs were buried, their rims may have been partly replaced by 

more stable materials. If at this time compaction and authigenic 

crystal growth began, fracturing may have occurred along the zones 

represented by the former edges of the logs. In the voids formed by 

this fracturing, the ore solutions may have deposited their minerals.

Although the rods constitute the richer concentrations of ore, considerable quantities of secondary yellow uranium minerals are found 

elsewhere and in different forms in channel sediments. Thus, in much 

of the conglomeratic sandstone exposed between rods, yellow uranium 

minerals fill interstices and coat pebbles and fractures. Although 

rods are not present in the De Chelly sandstone member, yellow uranium minerals coat cross-lamination planes, fill fractures, and also impregnate the sandstone. The concentration of uranium minerals in 

sediment between rods and in the De Chelly is low. These weakly 

mineralized localities are believed to represent secondary migration 

by percolating ground water. Most of the uranium minerals are 

thought to have been leached from the richer ore bodies represented by 

the rods, and then moved short distances both laterally and vertically 

before being deposited once again in the matrix of the sandstone.

Fischer (1947, p. 455), in discussing the vanadium deposits of the 

Colorado Plateau, implies that a close affinity may exist between 

vanadium deposits, channel sediments, and organic matter in the 

Morrison formation of Jurassic age. In a later report, still referring 

to the Morrison formation, Fischer and Hilpert (1952, p. 12) indicate 

that although fossil plants are erratically distributed most of the 

carnotite deposits are in parts of the sandstone that contain fairly 

abundant plant remains. From my observations in the Monument 

Valley area on the habits of uranium ore in the Shinarump conglomerate, I concur with Fischer and Hilpert and believe that a close spatial 

relationship exists between pockets of uranium ore, channel sediments, 

and former plant matter.
URANIUM DEPOSITS, MONUMENT VALLEY, ARIZONA 129

The channels, apparently, were places where plant matter was concentrated. Trees growing along the flanks of these channels may 

have fallen into them and then have been buried by the channel sediments. Other trees and organic material may have been rafted into 

the channels and buried. Subsequently, when mineralizing solutions 

moved through the Shinarump, favorable conditions of permeability 

and porosity resulting primarily from the former presence of buried 

logs may have been responsible for the formation of the rods.

Not all channels contain known uranium deposits even though they 

may contain organic matter. One possible explanation for the lack 

of ore in some channels is that ore may have been deposited but was 

later leached by ground water. The great length of long channels, 

for example, may have permitted accelerated movement of ground 

water solutions resulting in more effective leaching of ore. Conversely, leaching would have been less effective in the short channels. 

A final result would be ore accumulations in short channels and 

essentially barren strata in continuous channels.

SUMMARY

Six stages are proposed in the localization of uranium ore to achieve 

present conditions in Monument Valley, Ariz.: (1) Cutting of 

short and long channels prior to or during deposition of Shinarump 

sediments; (2) burial of plant matter (trees, branches, and twigs) 

in channels synchronously with deposition of Shinarump sediments; 

(3) some form of alteration of the plant matter resulting in unusual 

conditions favoring the precipitation of uranium minerals; (4) invasion of Shinarump sediments by mineralizing solutions; (5) precipitation and localization of uranium ore from these solutions 

primarily in localities formerly occupied by plant matter; and (6) 

leaching and movement of uranium minerals by ground water out 

of the continuous long channels, and retention of uranium minerals 

in the short channels.

LITERATURE CITED

Baker, A. A., 1935, Geologic structure of southeastern Utah: Am. Assoc. Petroleum Geologists Bull., v. 19, p. 1472-1507.

Bryan, Kirk, 1920, Origin of rock tanks and charcos: Am. Jour. Sci., 4th ser., 

v. 50, no. 297, p. 188-206.

Coffin, R. C., 1921, Radium, uranium, and vanadium deposits of southwestern 

Colorado : Colo. Geol. Survey Bull. 16.

Fischer, R. P., 1947, Deposits of vanadium-bearing sandstone, in J. W. Vanderwilt, Mineral resources of Colorado: Denver, Colo., Colo. Min. Res. Board, 

p. 451-456.

Fischer, R. P., and Hilpert, L. S., 1952, Geology of the Uravan mineral belt: 

U. S. Geol. Survey Bull. 988-A.
130 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Gregory, H. E., and Moore, R C., 1931, The Kaiparowits region, a geographic 

and geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. 

Survey Prof. Paper 164.

Mathews, E. B., 1917, Submerged ''deeps'' in the Susquehanna River: Geol. 

Soc. America Bull., v. 28, p. 333-346.

McKee, E. D., 1951, Triassic deposits of the Arizona-New Mexico border area: 

N. Mex. Geol. Soc. Guidebook, 2d Field Coiif., p. 85-91.

Stokes, W. L., 1950, Pediment concept applied to Shinariunp and similar conglomerates : Geol. Soc. America Bull., v. 61, no. 2, p. 91-98.

Waters, A. C., and Granger, H. C., 1953, Volcanic debris in uraniferous sandstones, and its possible bearing 011 the origin and precipitation of uranium: 

U. S. Geol. Survey Circ. 224.

O
Accuracy of Ore-Reserve 

Estimates for UraniumVanadium Deposits 

on the Colorado Plateau

By A. L. BUSH and H. K. STAGER

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-D

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 19S6
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 45 cents (paper cover
CONTENTS

	Page 

Abstract___ _..__-._.______-_________________________.____---__-_ 131

Introduction._____________________________________________________ 132

Method of study..______________________-________ 133

Definition of reserves____________________.________-_-_-------- 135

Method of calculation____________________________________ _ 135

Character of data___________________-________________----------- 138

Accuracy of original reserve estimates______-__________----_---__----_ 139

Tonnage___________________________________._-. 139

Grade___.______________________________..__..________ 140

Variation with size of deposit.__________________________________ 141

Variation with density of drilling______-_____________-___--_---_- 143

Causes of inaccuracy_____________________________________________ 145

Original reserve estimates______________________________________ 145

Revised reserve estimates_____________________________________ 146

Conclusions___________________________________________________ 147

Literature cited.________________________________________________ 148

ILLUSTRATIONS

PLATE 7. Sketch maps of reserve blocks, showing location of original page 

and revised reserve blocks and mine workings, Uravan 

mineral belt, C olorado Plateau ____________________ In pocket

FIGURE 28. Map of part of the Colorado Plateau showing location of the

Uravan mineral belt and of mineral claim groups studied. _ 133 

29 Graph showing variation in accuracy of original tonnage

reserve estimates_________-_-__________--___-_-------_ 140

30. Graph showing variation in accuracy of original reserve estimates of grade of UaOg, classed by size of deposit_________ 141

31. Graph showing variation in accuracy of original reserve estimates of grade of VaOs, classed by size of deposit.._______ 142

32. Graph showing variation in accuracy of original tonnage reserve estimates, for deposits classed by density of drilling.. 145

m

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ACCURACY OF ORE-RESERVE ESTIMATES FOR

URANIUM-VANADIUM DEPOSITS ON THE

COLORADO PLATEAU

By A. L. BUSH and H. K. STAGER

ABSTRACT

The U. S. Geological Survey has made estimates of the reserves of uranium 

and vanadium in the carnotite deposits explored by Geological Survey drilling 

on the Colorado Plateau. This report presents an appraisal of the accuracy 

of the reserve estimates for carnotite deposits in the Uravan mineral belt, the 

causes of inaccuracy, and the significance of the estimates in terms of the total 

known reserves of the region.

The appraisal was confined to carnotite deposits that contain ore reserves of 

1,000 short tons or more. These reserves are classed as indicated and inferred 

reserves. Reestimates of the amount of material in the ground at the time of the 

original estimate were made for more than 30 deposits. This was done where 

information on size and grade, additional to that used at the time of the original 

estimate, was available. The reestimated reserves (revised reserves) include 

production since the original reserve estimates, plus the estimate of reserves 

remaining in the ground, and, therefore, can be compared with the original estimates, to furnish a measure of the accuracy of the original estimates.

The reappraisal indicates that for individual deposits the original reserve estimates range from large overestimates to very large underestimates (for both 

tonnage and grade). However, the original reserve estimate for the total reserves 

of all the carnotite deposits studied in the Uravan mineral belt is a very small 

underestimate. For the carnotite deposits studied in the mineral belt, the revised tonnage of ore reserves is about 15 percent greater than originally estimated. 

In terms of grade, the original and revised estimates are the same for Us Os and 

differ by less than 2 pounds per ton for V^Og. Primarily as a function of the 

increased tonnage of reserves, the amount of contained UaOg is about 15 percent 

greater, and the amount of contained V2 0s is about 20 percent greater than 

originally estimated.

All of the individual deposits contained more than half the amount of ore 

originally estimated. A little more than 25 percent of the deposits contain over 

twice as much ore as originally estimated. The errors in estimation for individual 

deposits are mutually compensating; as more deposits are grouped into a single 

estimate, the amount of error decreases both in tonnage and grade.

131
132 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The general source of error in the original estimates is the restricted number 

of points of observation (mostly drill holes) on which the estimates are based. 

This is complicated by the deviation of the ore deposits from an idealized uniformly tapering layer both in plan and in section, and by the erratic distribution 

of metal values within the deposit. No mathematical correction can be applied 

to the reserve estimate to compensate for this sampling error.

As the deposits studied in the mineral belt represent a fair sample of all the 

uranium-vanadium deposits that the Geological Survey is finding in the Morrison 

formation, the realization ratios (the "accuracy of prediction" figures) given 

above can be applied with reasonable confidence to the total of the estimates of 

known reserves for all of the deposits found by the GeologicalSurvey. This 

total estimate is one of the major objectives in the exploration work. As the 

error in the original estimate of total reserves for the deposits studied in the 

mineral belt is small, the methods of exploration and estimation being used are 

adequate to achieve a realistic appraisal of the total uranium-vanadium reserves 

of the region.

INTRODUCTION

Since November 1947, the U. S. Geological Survey on behalf of the 

Division of Raw Materials of the U. S. Atomic Energy Commission 

has been conducting diamond- and wagon-drill exploration for uranium-vanadium deposits on the Colorado Plateau. Much of this 

exploration has been in southwestern Colorado, within the area described by R. P. Fischer and L. S. Hilpert (1952) as the Uravan 

mineral belt (fig. 28). In this belt, most of the deposits are in lenticular 

sandstone beds in the upper part of the Salt Wash sandstone member 

of the Morrison formation of Jurassic age. Uranium and vanadium 

minerals impregnate the sandstone and form roughly tabular bodies 

that generally parallel the bedding of the sandstone. In places the 

deposits cut across the bedding at a sharp angle. The deposits are 

irregular in plan, and they range in thickness from a knife edge to a 

few tens of feet, averaging a few feet thick. They range in content 

from only a few tons to many thousand tons. A more complete description of these deposits is given by Fischer (1942).

An integral part of the Geological Survey's exploration program has 

been the estimation of the reserves of uranium and vanadium in the 

explored deposits. The individual reserve estimates serve as a basis 

for the leasing of deposits on Government-controlled land, and collectively are useful as a measure of expectable production.

The uranium-vanadium deposits of the Colorado Plateau are of the 

type classed by McLaughlin (1939, p. 589-621) as "extramensurate 

those difficult to explore and measure much in advance of mining." 

It must be expected, therefore, that reserve estimates that are based 

mainly on samples from only a few drill holes would not be highly 

accurate for individual deposits. The present study has been undertaken to determine the accuracy of the reserve estimates, to investigate the causes of inaccuracy and the possibility of correction of these
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES 133

. HB:OLORADO 

INDEX MAP

Grand Junction^

Thompson

GRAND MESA

t\\ Gateway

p

MAVERICK

. CALAMITY 

'x^OUTLAW M£SA

\ \ GATEWAY

SAN JUAN

 - -f ~ ~ "" 

I \

D O\ L O R E S

FIOUEE 28. Map of part of the Colorado Plateau showing location of the Uravan mineral belt and of mineral

claim groups studied.

inaccuracies, and to determine the significance of the estimates in 

terms of total known reserves of the region.

METHOD OF STUDY

It is obvious that the accuracy of a reserve estimate can best be 

determined when the reserve block (the ore body) has been completely 

mined out. Only then can direct comparison be made between the 

estimated content and the actual content, as to both tonnage and 

grade. Very few of the deposits on the Colorado Plateau, for which
134 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

the Geological Survey has made reserve estimates, have been entirely, 

or even significantly depleted. In this sense this study is premature. 

However, interest is in the present content of the deposits, as well as 

the accuracy of the original estimate, not in a post-mortem knowledge 

of what the content or accuracy was. The study must take the form, 

therefore, of a reestimate of the total reserves of the deposit that 

existed at the time of the original estimate. This reestimate (the revised reserve estimate) includes the production from the deposit since 

the original reserve estimate plus the estimate of the reserve remaining 

in the ground. By comparing the revised reserve estimate with the 

original reserve estimate, an expression of the accuracy of the original 

estimate is obtained.

Information additional to that available at the time of the original 

reserve estimate is necessary for a meaningful reappraisal of the 

reserves in these deposits. For this reason, only those deposits that 

have yielded, since the original reserve estimate, about 25 percent 

or more of the tonnage of the original reserve estimate were selected 

for study. Additional information resulting from drilling done by 

the mine operator in conjunction with the mining was also available 

for many deposits. Furthermore, because the production potential 

of small deposits is not very important, only deposits estimated to 

contain about 1,000 tons or more of ore were included in this study. 

These factors resulted in the selection of 30 deposits for reappraisal. 

These deposits, however, are thought to be typical and to represent a 

good sample of all deposits for which reserves have been estimated 

by the Geological Survey.

These deposits were mapped, generally at scales of 1 inch to 40 or 

50 feet, to obtain information on extent of mining, habits, thicknesses, 

and grades of the deposits and ore bodies, and their general trends. 

This information, plus the additional drilling information, was compiled on maps showing the original information available (drill holes, 

mine workings, ore-deposit boundaries, and reserve-block locations). 

On the basis of the additional information, the boundaries of the 

deposits and the location and size of the original reserve blocks were 

redefined. Thus the revised reserve blocks include the material in 

the ground at the time of the original reserve estimate.

In general, experience has shown that after 1,000 to 1,500 tons of 

ore has been produced from a deposit, or in the case of small (less 

than 5,000 tons) deposits, after about 25 percent of the ore has been 

mined, the cumulative grade of the production is a fair representation 

of the overall grade of the deposit. For this reason, the grade of ore 

produced was used in many cases as the grade of the reserves in the 

revised reserve estimate. The validity of this approach appears to 

borne out by an extremely close correspondence of the average U8O8
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES 135

and V2O6 grades of the original reserve estimate for all the deposits 

studied with the average grade for the production from those deposits. 

The mines were mapped in their extent as of December 31, 1952. 

To correlate with this extent of the mining, figures of production to 

the same date were used.

DEFINITION OF RESERVES

In 1949, the Geological Survey staff on the Colorado Plateau 

prepared a statement to define the general philosophy and the 

rules for the calculation of reserves for the uranium-vanadium 

("carnotite") deposits of the Colorado Plateau, in order to obtain a 

reasonable consistency of reserve calculations made by different 

geologists and to assist those who would use these figures in interpreting their significance.

The terms "indicated" and "inferred" reserves are applied to the 

uranium- and vanadium-bearing materials in the deposits that are 

known from exposures in natural outcrops, mine workings, or drill 

holes. These reserves are subdivided by thickness and grade cutoffs 

and the method used in calculating them is explained on pages 136-137.

Known reserves are classed as indicated and inferred. Reserves 

that might be classed as measured are included with indicated reserves, 

because the amount of measured reserves that could be calculated 

within a small limit of error is so small as to be nearly negligible. 

This is due to the general lack of abundant sample data for individual 

reserve blocks and the erratic deviations, within short distances, in 

the thickness and grade of the carnotite ore.

Indicated reserves are those for which the grade is computed from 

drill-hole samples, exposures in mine workings and natural outcrops, 

gamma-ray logs, and production data, and for which the tonnage is 

computed by projection for a reasonable distance on geologic evidence 

from points of exposure (drill holes, mine workings, and natural outcrops). Inferred reserves are those for which quantitative estimates 

are based largely on broad knowledge of the geologic character of the 

deposits, and for which there are few, if any, samples or measurements.

METHOD OF CALCULATION

Reserves are not classified according to their availability for mining, 

although consideration is given to current mining and milling practices 

in selecting the higher grade and thickness cutoffs. This is done to 

obtain figures for a category of reserves that will express as nearly as 

possible the tonnage and grade of the material that actually might be 

mined from these deposits under present conditions.

379289 56 2
136 CONTRIBUTIONS TO THE GEOLOGlf OF URANIUM

Both chemical data from assay of drill cores and gamma-ray data 

from probing of drill holes are used in classification of the ore-bearing 

rock as to thickness and grade.

Thickness cutoff. Mining practices differ from place to place in the 

region as well as with individual operators, but under present conditions most ore bodies of average grade are being mined to where 

they pinch to a layer about 1 foot thick. Reserves, therefore, are 

calculated with a thickness cutoff of 1 foot. Layers of material less 

than 1 foot thick are mined in places if the grade is high. The tonnage 

of minable material less than 1 foot thick is small with respect to the 

total reserves, and for that reason reserves less than 1 foot thick are 

calculated in a separate category.

Grade cutoffs: The deposits contain two metals of economic value, 

uranium and vanadium. Within the deposits, the two metals are so 

erratically distributed that a single sample, such as obtained from a 

drill hole, is not necessarily representative of the grade or metal ratio 

of the material near the point sampled. Knowing this by experience, 

the miner will drive to a drill hole that shows a good value in vanadium 

even though the uranium content of the sample might be negligible. 

Thus, the material in the vicinity of this sample must be classed as a 

reserve, even though the sample shows a value for only one metal. 

Under 1953-54 price schedules, the vanadium content of the ore 

represents an appreciable part of the ore's market value. Both metals, 

therefore, must be considered in reserve appraisals and in selecting 

grade cutoffs.

Reserves 1 foot or more thick are classified by two grade cutoffs. 

The higher cutoff used 0.10 percent U3O8 or 1.0 percent VzO5 

corresponds to the AEC purchase cutoff for uranium and the approximate cutoff used at the government-owned mill at Monticello, Utah, 

in selecting ore for treatment to extract vanadium. Reserves also are 

figured on a lower cutoff 0.05 percent U3O8 or 0.50 percent V2O6 on 

the possibility that conditions in the future might demand or permit 

the mills to accept low-grade ore.

Calculation of tonnage. The method used for calculating the volume, 

and hence the tonnage, of a reserve unit 1 foot or more thick differs 

with the geologic interpretation of the form of the deposit. Some 

deposits are roughly tabular or lenticular, so that projections can 

reasonably be made between drill holes, and the average thickness of the 

drill-hole samples that can be combined within a specified grade class 

can be assumed to be the average thickness of the reserve unit. Other 

deposits consist of small bodies of ore of minable thickness, connected 

by layers of mineralized sandstone that are too thin to mine. Reserves 

are estimated by assuming that each drill hole in ore indicates a single 

minable body that is comparable in tonnage to the average size of the
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES ,137

ore bodies that have been mined nearby, or that the deposit contains 

a comparable tonnage per unit area to that of a deposit that has been 

mined nearby.

The tonnage of indicated reserves is computed by projection for a 

reasonable distance on geologic evidence. The distance that indicated 

reserves are projected, both between and beyond drill-holes and other

sample points differs with the geologic habits of 

limits of projection used are specified. Reserves are

rather than indicated if they are projected farther than the limits

chosen for the indicated class. Inferred reserves ar 

assumed limits of the deposit, as assumed by geol 

interpretation; no arbitrary limit is placed on the dist 

Although a single drill hole in ore obviously perm 

of some tonnage of indicated reserves, there is no

is projected to the 

gic evidence and 

,nce of projection. 

 -s the designation 

reasonable basis

for projecting an indicated reserve block more tha 

a single hole. Rather than calculate such a separat 

block, or assign a small arbitrarily selected amoun 

serves to a single hole, the reserve block is project 

limits and the ore calculated and classed as inferrec 

A constant of 14,cubic feet per ton is used to cal 

Calculation of grade. The grade of indicated re 

block is calculated by weighting the assay grades 

samples. If the deposit has been mined in part, th

i a few feet from

indicated reserve 

- of indicated red to its assumed

ulate tonnage, 

erves in a single 

by lengths of the 

grade of the ore

produced is also considered in establishing the grad 

reserve block. In reserve blocks containing only 

holes, however, if the core assays are appreciablj 

average grade of the ore mined nearby, it may be

drill penetrated abnormally high-grade parts of tie body, and an

estimated grade may be assigned. The grade of 

inferred block is considered, but is used in conjunct 

of production from nearby mines, or from the area

Strict grade cutoffs are used in calculating reserv 

thick. Except as noted in the following paragr 

belonging to a class with a lower grade cutoff is inclu 

of a higher cutoff class, even though the weighted 

the whole is above the cutoff grade of the higher ch

In mining, layers of waste, or of low-grade min 

less than 1 foot thick, would probably be blasted ^ 

layers of ore. Some of this material might be pic 

but most of it would go to the mill with the ore. 

thickness of this interbedded ore and waste is 1 foot 

included in calculating reserves, thereby increasing

ore, but decreasing the grade proportionately. 

according to the grade of the weighted average. If

;he deposits; the 

;lassed as inferred

3 of the adjoining

one or two drill

higher than the

assumed that the

tie samples in an 

on with the grade 

as a whole. 

is 1 foot or more 

,ph, no material 

ded with material 

average grade of 

ss.

sralized material, 

1th the enclosing 

:ed out by hand,

If the aggregate 

or less thick, it is

the thickness of

T lis ore is classed

the waste is more
138 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

than 1 foot thick, it probably would be blasted separately from the 

ore layers in mining, and thus ore layers more than 1 foot apart, with 

waste or low-grade material between, are calculated as separate ore

bodies.

CHARACTER OF DATA

The original reserve estimates were based largely on drill-hole data, 

supplemented in some cases by exposures in mine workings and natural 

outcrops. In general, the amount of information available for the 

reserve estimate is a function of the drill-hole spacing. A major objective of the Geological Survey's exploration work is the discovery of 

ore deposits, and the estimation of their size, in terms of reserves that 

are not more precise than the indicated class. At this level of precision, 

the spacing of drill holes is designed to outline the limits and to indicate 

the order of magnitude of the deposits with a minimum of drilling. 

The drill holes were spaced mostly at 50- to 100-foot intervals; in a 

few places holes were as much as 200 feet apart.

Chemical assays for U3O8 and V2O6 are available for all the mineralized rock cored in the drilling. Although core recovery differs from 

hole to hole, as well as from one lithologic unit to another within a 

single hole, the average core recovery for mineralized rock is probably 

about 80 percent. The core recovery for barren sandstone is usually 

better and in many units is 95 to 100 percent. The position and thickness of the mineralized rock, therefore, can often be determined with 

considerable accuracy, despite core loss within the unit. The grade 

can be seriously distorted by core loss, however, as the richer material 

is commonly fine and friable. A partial correction for the loss of the 

richer material may be made through the use of gamma-ray data obtained by probing the drill holes.

The revised reserve estimates are invariably based on additional 

information. The habits of the deposits can be studied in new or expanded mine workings, the boundaries of the deposit are exposed in 

places, additional drilling in many cases is available so that the extent 

and average thickness of the deposit are better known, and the production records give a strong basis for the assignment of grades to the 

unmined ore.

Generally, the data available from additional drilling done by the 

mine operator is less reliable than that from Geological Survey drilling. 

Drill-hole locations may be less accurately recoverable, chemical assays 

on the core are usually lacking, and data on the position and thickness 

of the mineralized material, both in core and noncore drilling, may be 

somewhat less reliable. Many of these disadvantages, however, are at 

least partially compensated by the greater density of drilling. In 

some cases a major weakness exists in the production record. Frequently the ore from several deposits on a claim, or a group of claims,
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES 139

is grouped and attributed to a general area, rather 

deposit. It thus becomes impossible to assign the 

rately to the individual deposit, and the reliability 

serve estimate is weakened thereby.

than to a specific 

production accuof the revised reACCtJRACY OF ORIGINAL ORE RESERVE

The basic tool in the assessment of the accuracy of the original 

estimate is the realization ratio, the ratio of the revised estimate to the

ESTIMATES

original estimate. Realization ratios have been cal 

deposit (or each case studied) in terms of tonnage r 

of both UaOs and V2Ofl , and content ratio of both

ulated for each 

tio, grade ratio 

UsOg and V2 O5 .

Ratios have also been calculated for each large grouj 

each district, and for all 30 deposits studied in the 

Errors in the original reserve estimates decrease 

number of deposits included in the estimate is increas 

pensation of individual errors. Estimates on ind: 

range widely in accuracy, from large overestimate 

underestimates. Estimates for the mineral belt, he 

within the limits of accuracy expected, constituting

of deposits, for 

lineral belt.

snerally, as the

)d, due to comvidual deposits 

to very large 

wever, are well

a small underestimate for tonnage, contained U8O8 , and contained V206. The

progression is orderly, the error is greatest on individ

on large groups of deposits, still less by districts, least for the entire 

mineral belt.

For the entire mineral belt, this study indicates that the tonnage

of the revised estimate is about 15 percent more

estimated. There is also about 15 percent more Ua( >g and about 20 

percent more V2O5 in the revised reserves than in the reserves originally

estimated. Expressed in terms of grade, in the revi 

average U3O8 grade is the same as the original es

average V2O6 grade is slightly higher than the original estimate, 

differing by less than 2 pounds per ton.

The Geological Survey's reports to the Atomic Ene 

on carnotite reserves have included the following stat

Because of the variations in thickness and grade of ore and the 

data, the indicated reserves in any single reserve block migh

to as much as twice or as little as one-half the calculated tonnage. The limit

of error of the total tonnage for several blocks, however, is apt

lower, perhaps not more than 25 percent of the calculated tonnage. The limit of

error in the tonnage figures for inferred reserves, of course, i 

than for the indicated reserves. The possible limit of error ii 

estimated grade for both indicated and inferred reserves prol 

smaller than the possible limit of error in the tonnage figures.

TONNAGE

The data presented in figure 29 show that the qi 

above is substantially correct. The comparison shows 

deposits studied actually contained (according to

al deposits, less

than originally

ed reserves the 

imate and the

fgy Commission 

iment 

scarcity of sample 

actually amount

to be considerably

apt to be higher 

the calculated or 

ably is somewhat

oted statement 

that all of the 

the revise^ esti*
140 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM,

/ 2

&

OR Kit AND ISTRIC

i*

EXPLANATION

lndr«di»l deposits

Claim group

District 

Uravan miners! bett

S i 888 8 S

REVISED ESTIMATE, IN THOUSANDS OF SHORT TONS

S 1 §

FIOUEE 29. Graph showing variation in accuracy of original tonnage reserve estimates.

mate) more than one-half the originally calculated tonnage of both 

indicated and inferred reserves. The only deviation from the statement is that a little over one-quarter of the deposits appear to contain 

more than twice the amount of indicated and inferred reserves.

The limits of error are smaller for groups of deposits than they are 

for single deposits. In four of the eight large groups, the realization 

ratios for tonnage of indicated and inferred reserves fall between 0.8 

and 1.3. The other four all contain from 1% to a little less than 3 times 

the originally calculated tonnage of indicated and inferred reserves.

Considered by districts, the tonnage realization ratios for two of the 

three districts are 0.8 and 0.9, the third contains over twice as much 

reserves as originally calculated. For all the deposits studied in the 

mineral belt the tonnage realization ratio is about 1.15.

GRADE

In general, the range of error and the limit of error in U3O8 and V2O5 

grades (figs. 30 and 31) are considerably smaller than those for the
ACCURACY OF TJRANIUM-VANDIUM RESERVE ESTIMATES 141

tonnage of ore (fig. 29). On an individual basis, almost 

of the deposits have U3O8 grade realization ratios between 

and seven-tenths of the deposits have V2O5 grade re 

between 0.75 and 1.25. By groups, the U3O8 realization 

of the eight groups are between 0.5 and 1.5 (a seventh 

1.6) and five of the eight groups are between 0.75 and 

realization ratios of all eight groups are between 0.85 

six of the eight groups are between 0.95 and 1.05. By 

the U3O8 and V2O5 realization ratios are between 0.85 

all the deposits studied in the mineral belt, the U3O8 

tion ratios are 1.0 and 1*05 respectively.

three-quarters 

0.5 and 1.5, 

alization ratios 

ratios of six 

has a ratio of 

1.25. TheV2O5 

and 1.1, and for 

districts, both 

and 1.1. For 

atid V2O5 realizaVARIATION WITH SIZE OF DEPOSIT

A study was made of the accuracy of the original 

grouped by size of the ore deposits. (See table below

reserve estimates 

and figs. 30 and

X 2X 3X 4X 

U308 GRADE (ARBITRARY UNITS), REVISED ESTIMATE

EXPLANATION

Less than 5000 tons

D 

10,000-50,000 tons

A X 

5000-10,000 tons More than 50,000 tons

FIOUBB 30. Graph showing variation in accuracy of original reserve estimates of grade of UiOs, classed by

size of deposit.

5X
142 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

uj4X 

I

lax 

o

2X

$/

f

X 2X 3X 4X 

V2O5 GRADE (ARBITRARY UNITS), REVISED ESTIMATE

EXPLANATION

5X

Less than 5000 tons 10,000-50,000 tons

5000-10,000 tons More than 50,000 tons

Graph showing variation in accuracy of original reserve estimates of grade of VjOs, classed by 

size of deposit.

31.) The deposits were classed into four categories less than 5,000 

tons, 5,000-10,000 tons, 10,000-50,000 tons, and more than 50,000 tons. 

The distribution of deposits in these classes is such that there are 

probably sufficient cases in the first three categories to warrant some 

generalizations. With only two cases in the fourth category, it is not 

possible to make significant generalizations.

On the basis of the size of the reserve block as originally estimated, 

deposits thought to be in the less than 5,000 ton class are underestimated in tonnage in about nine-tenths of the cases, and underestimated in both U3O8 and V2O6 grade in about two-thirds to threequarters of the cases. In the 5,000-10,000 ton class, tonnage is underestimated in four-fifths, and both U3O8, and V2O6 grades are underestimated in three-fifths of the cases. In the 10,000-50,000 ton class
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES 143

tonnage is underestimated in two-fifths, U3O8 grade 

and V2O5 grade in two-fifths of the cases. The relative 

error represented by the average realization ratios 

decreases from the less than 5,000 ton class to the 10, 

class.

n three-fifths, 

amount of 

for each class 

000-50,000 ton

Variation in accuracy of original estimates of reserves, grouped ly size of deposit.

Deposit class

5,000-10,000 tons... ............ ...

10,000-50,000 tons ...............

Number 

of

cases

18 

5 

5 

2

Original 

reserve 

estimate, 

in short 

tons i

50,740 

42,160 

91,610 

169, 875

Revised 

reserve 

estimate, 

in short 

tons '

103,900 

80,300 

76,200 

154, 100

Bealizat

Tonnage

2.05 

1.90 

.85 

.90

Conten

UsO«

2.45 

2.05 

.90

.75

V

on ratios *

jOs

2.25 

1.85 

.80 

.85

Grade

U»Os

1.20 

1.05 

1.10 

.80

Vj05

1.10 

.95 

.95 

.95

1 Includes indicated and inferred reserves.

2 Ratio of revised estimate to original estimate.

VARIATION WITH DENSITY OF DBILLIM Q

igifral

feet

An analysis was made of the accuracy of the ori 

mates grouped by the density of drilling. (See table bel< 

As is to be expected, denser drilling permitted more 

estimates. The density of drilling by the Geological 

described briefly on page 138. Most of the deposits 

Geological Survey in the mineral belt were explored 

plan consisting of four drill holes at a spacing of 50 

discovery hole, followed by other drill holes at a spac: 

(pi. 7A). Other deposits were explored by six drill hoi 

of 50 feet around the discovery hole, followed by other 

the same spacing, with additional drilling at a spacing 

some deposits (pi. IB}.

Of the 30 cases studied, 25 fall into these two classes 

drilling; there are 18 cases of Type B drilling to only 7 

drilling. The Geological Survey has used three other 

one of which is illustrated in plate 7(7, but with only 

these 3 classes, generalizations are not significant. In 

where Type A drilling information was used, the revised 

mate for tonnage is more than twice the original, and 

to 8 times the original. Where Type B information was 

revised reserve estimate was more than twice the orij 

the 18 cases, and the range was up to only 3 times, 

show a general increase in accuracy for both U3O8 and 

the cases for which more information is available.

reserve estiow and fig. 32.) 

accurate reserve 

Survey has been 

drilled by the 

under a drilling 

around the 

ng of 100 feet 

}s at a spacing 

drill holes at 

of 100 feet on

cases

of density of 

of Type A 

drilling plans, 

5 deposits in 

of the 7 cases 

reserve estinhe range is up 

available, the 

in only 2 of 

The data also 

2O5 grades in

iginal
144 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Variation in accuracy of original estimates of reserves, grouped by density of drilling

and size of deposit

[See also figure 32]

Drilling plan and deposit class

TypeAri 

Less than 5,000 tons.. .........

5,000-10,000 tons ____ . _ ....

Totals and weighted

Type B: * 

Less than 5,000 tons ...........

5,000-10,000 tons...............

10,000-50,000 tons.-. . ...

Totals and weighted

Type C:» 

Less than 5,000 tons __ . __

10,000-50,000 tons.. ... ......

Totals and weighted

TypeD:* 

Less than 5,000 tons. __ ......

More than 50,000 tons.. . ......

Totals and weighted 

averages _ . ...............

Type E:' 

More than 50,000 tons. ........

Totals and weighted

Number 

of 

cases

5 

2

7

11 

3 

4

18

1 

1

2

1 

1

2

1

1

Original 

reserve 

estimate, 

in short 

tons

11,400 

18,080

29,480

34, 110 

24,080 

71,610

129, 800

830 

20,000

20,830

4,400 

71,500

75,900

98,375

98,375

Revised 

reserve 

estimate, 

in short 

tons

31,100 

55,400

86,500

55,300 

24,900 

63,200

143,400

5,900 

13,000

18,900

11,600 

72,200

83,800

81,900

81,900

Realization ratios

Tonnage

2.75 

3.05

2.95

1.60 

1.05 

.90

1.10

7.10 

.65

.90

2.65 

1.00

1.10

.85

.85

Content

U»08

4.05 

2.35

2.70

2.00 

1.75 

1.00

1.35

10.20 

.65

.75

2.80

.70

.80

.75

.75

VsOs

2.55 

2.75

2.70

1.95 

1.15 

.85

1.20

9.00 

.60

.85

3.10 

.80

.90

.95

.95

Grade

UsOs

1.45 

.75

.90

1.20 

1.70 

1.10

1.20

1.45 

.95

.85

1.05 

.70

.75

.90

.90

VjO«

0.95 

.90

.90

1.20 

1.10 

.95

1.10

1.25 

.90

.95

1.15 

.80

.90

1.10

1.10

> One cycle of four drill holes around discovery hole, at 50-foot distance; additional holes at 100- 

foot intervals.

s One or more cycles of six drill holes around discovery hole, at 50-foot distance: additional holes at 100-foot 

intervals.

3 One or more cycles of drill holes around discovery hole at 100-foot distance; additional holes at 100-foot 

intervals.

* One or more cycles of drill holes around discovery hole at 100-foot distance; additional holes at 150- to 

200-foot intervals.

* Drill holes 50 to 100 feet apart, along lines 200 feet apart
ACCURACY OF URANIUM-VANDIUM RESERVE ESTIMATES 145

"6 7 "6 9 10 20 30 40 

REVISED ESTIMATE, IN THOUSANDS OF SHORT TONS

50 .60 70 80 90100

FIGURE 32. Graph showing variation in accuracy of original tonnage reserve estimates, for deposits classed 

by density of drilling. (See table on page 144 for explanation of letters.)

CAUSES OF INACCURACY

Both the original and the revised reserve estimates are subject to 

error. In general, the causes of error differ for the type of estimate, 

but one major cause of error is common to both; the restricted number 

of point of observation (sample points) on which the estimates are 

based.

ORIGINAL RESERVE ESTIMATES

The density of sampling is the basic source of error in the original 

reserve estimates. In general, the drilling is sufficient to indicate the 

approximate outline and extent of the ore deposit, but in specific cases, 

the ore bodies may extend between barren or weakly mineralized drill 

holes for a significant distance (pi. 7A and D). The drill holes may 

not adequately sample, however, or may not even intercept the parts 

of the deposit that constitute the ore bodies (pi. 7A).
146 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The drill-core samples, in addition, may not be representative of 

the average thickness of the ore body or of its average grade. Core 

loss hi drilling may result in significant misinterpretations of the thickness of the mineralized rock. In addition, the more richly mineralized 

rock is generally softer and more friable and hence is more subject to 

grinding and disintegration. Core loss, therefore, is frequently concentrated in the more richly mineralized rock, so that the apparent 

grade of the sample is less than the true grade.

In most cases, the concept of the deposits (and ore bodies) as uniformly tapering tabular layers, essentially parallel to the bedding of 

the host sandstone, is used in calculating the reserves (pi. 7B). Other 

limiting conditions are also assumed; for example the edge of the 

deposit is assumed to be midway between a sample point in barren 

rock and a sample point in mineralized rock. Deviations in form, 

shape, and habit from these idealized conditions introduce errors in 

the reserve estimate (pi. 7A and C).

REVISED RESERVE ESTIMATES *"

The revised reserve estimates also have their basic source of error 

in the restricted number of points of observation. The influence of 

this distribution is less pronounced than in the case of the original 

estimate, as the prerequisite to the revised estimate is additional information. Additional drilling by the operator frequently outlines 

both the deposit and the ore bodies far better (pi. 7D). The mine 

workings permit a more accurate assessment of the habits of the deposit, and the concentration and size of the ore bodies (pi. 7B and O). 

In many cases, however, the thickness and grade data available from 

the operator's drilling is less reliable than data from the Geological 

Survey's drilling, because of difference in objectives, technique, and a 

common lack of chemical assay data.

Major use is made of the production data in revising the estimate 

of tonnage and grade given in the original reserve estimate. Several 

opportunities for error in the revised estimate may result from the 

character of the production data. In many cases the production 

record cannot be broken down with sufficient reliability to permit the 

accurate assignment of production to individual deposits. In such 

cases, the production must be estimated for each deposit, or the 

deposits must be grouped and a combined depletion estimate for the 

group must be made. It is obvious that additional uncertainties 

are introduced in either case, both for tonnage and for grade. Such 

uncertainties, however, are thought to be small generally, and certainly 

do not invalidate the overall picture presented here.

Nearly all the mine operators attempt to hold to a shipping grade 

above 0.20 percent I^Og, because the AEC pays bonuses for ore
ACCURACY OF URANIUM-VANDItTM RESERVE ESTIMATES 147

above this grade. Although the grade cutoff used by the Geological 

Survey in its estimates is 0.10 percent U3O8 (the lowest grade that is 

being purchased by the AEC), the average grade of the ore at this 

cutoff is generally above 0.20 percent U3O8. Thus the material 

mined and that for which reserves are estimated are comparable. 

One other factor affects the use of the production data the dilution 

of ore by waste. The effect of this source of error is relatively minor, 

as the methods of reserve estimation used by the Geological Survey 

make allowance for a certain amount of dilution.

CONCLUSIONS

The accuracy of the Geological Survey's estimates of total indicated 

and inferred reserves, for the 30 cases studied in the Uravan mineral 

belt, fall well within the defined limits of error for indicated reserves 

alone, and indeed fall almost entirely within the defined limits of 

error (20 percent) for measured reserves. The limits of error, and 

the range in error, are greatest for reserves on individual deposits, 

less for reserves on groups of deposits, and still less for reserves of 

districts. The inaccuracies involved are largely compensating, to 

the point of very little error if a sufficient number of deposits are 

considered.

The 30 cases considered in this study represent a fair sample of all 

deposits on which the Geological Survey has made reserve estimates. 

They include deposits ranging from less than 1,000 tons of reserves 

to more than 50,000 tons; deposits where all the information came 

from drill-hole samples and deposits where a larger part of the information came from extensive mine workings; and deposits where the drillhole samples came from close-spaced, medium-spaced, and relatively 

wide-spaced holes, or any combination of these. As such, the realization ratios determined for the total group of cases studied can 

be applied with reasonable confidence as correction factors to the 

total of the indicated and inferred reserves estimated for all the 

deposits discovered or explored by the Geological Survey. These 

realization ratios are about 1.15 for the tonnage of ore, 1.15 for the 

amount of contained UgOg, and 1.20 for the amount of contained 

V2O5. The original grade estimate for U3O8 is the same as the revised 

estimate, and the original grade estimate for V2O5 differs from the 

revised estimate by less than 2 pounds per ton.

Correction factors cannot be applied to the individual reserve estimates. On a numerical basis, in about two out of every three cases 

the tonnage of reserves was underestimated; the range of the realization 

ratios is from about 1.0 to 8.0. However, in two-thirds of the cases 

where the tonnage of reserves was underestimated, the range of the 

realization ratios is from 1.0 to only 2.0. The range of the realization
148 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ratios for overestimated reserves is from 0.6 to nearly 1.0. Thus any 

single correction factor designed to reduce the error of underestimate 

will increase the error of overestimate in one of every three cases. The 

range and distribution of error for the estimates of grade and amount 

of U3O8 and V^O5 are similar to those for total tonnage of ore, and 

these errors, as well, cannot be remedied by applying single correction 

factors to the individual deposits.

The realization ratios for each group of deposits studied can be applied with a measure of certainty to the total indicated and inferred 

reserves of all the deposits in that group. The reliability of the ratios 

increases with the number of cases used in determining the ratios. 

Still more reliance can be placed on the realization ratio for the reserves 

compiled by districts.

One of the Geological Survey's major objectives in the exploration 

work is the appraisal of the uranium-vanadium resources of the Morrison formation on the Colorado Plateau. The study indicates that 

the accuracy of the appraisal of the total known reserves is good. As 

such, the methods of exploration and estimation being used (are adequate to achieve the desired objectives.

Within the framework of the exploration done by the Geological 

Survey, increased accuracy in the estimates can only be obtained by 

increased knowledge of the geologic habits of the deposits, and this is 

largely dependent on the increase in the amount of information available at the individual deposit level supplied by additional and more 

closely spaced drilling. So long as the major interest is in the overaU 

appraisal, the present methods are adequate. Increased accuracy on 

individual deposits will increase the accuracy for each succeeding 

grouping of deposits, but the significance of this increased accuracy 

decreases for each succeeding grouping as the amount of error involved 

under the present methods also decreases markedly.

LITERATURE CITED

Fischer, R. P., 1942, Vanadium deposits of Colorado and Utah, a preliminary

report: U. S. Geol. Survey Bull. 936-P. 

Fischer, R. P., and Hilpert, L. S., 1952, Geology of the Uravan mineral belt:

U. S. Geol. Survey Bull. 988-A. 

McLaughlin, D. H., 1939, Geological factors in the valuation of mines: Econ.

Geology, v. 34, no. 6.

o


Study of Radioactivity in 

Modern Stream Gravels as 

a Method of Prospecting

By RANDALL T. CHEW, III

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

"i

GEOLOGICAL SURVEY BULLETIN 1030-E

The detection of radioactivity anomalies 

by means of portable instruments of sealer 

type, and application of the method in 

locating deposits of radio.active ores in the 

Colorado Plateau

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of the 

Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 25 cents (paper cover)
CONTENTS

	Page 

Abstract________-__-____-_-_________________--__-______-____---- 149

Introduction._____________________________________________________ 149

Previous investigations-____________________________________________ 149

General considerations.____________________________________________ 150

Field methods_________________________________________ 158

Anomalies. _______________________________________________________ 160

Areas studied-____________________________________________________ 162

Results, and evaluation of the method--_____________________________ 166

^Suggestions for future work_________________________________________ 167

Literature cited.__________________________________________________ 1$9

ILLUSTRATIONS

PLATE 8. Graph showing radioactivity in stream gravels, Temple Mountain area, San Rafael district, Emery County, Utah_ _ _ In pocket

Page 

FIGURE 33. Index map of part of Colorado Plateau showing areas where

radioactivity of modern stream gravels was studied-______ 153

34. Radioactivity in modern stream gravels range and average 

of four 2-minute readings at each probe setting, Corral 

Canyon, Seven Mile area, Grand County, Utah._________ 154

35. Radioactivity in modern stream gravels range of two 4- 

minute readings at each probe setting, Corral Canyon, Seven 

Mile area, Grand County, Utah_______________________ 155

36. Radioactivity in modern stream gravels range of two 

6-minute readings at each probe setting, Corral Canyon, 

Seven Mile area, Grand County, Utah_ ________________ 156

37. Radioactivity in modern stream gravels one 8-minute 

reading at each probe setting, Corral Canyon, Seven Mile 

area, Grand County, Utah______________________ 157

38. Radioactivity of Colorado River gravels near Climax Uranium Company mill, Grand Junction, Colo-__--_-_------ 161

39. Diagrammatic sketch of the Temple Mountain area, San

Raf ael district, Emery County, Utah, for use with plate 8_ 163

40. Graph showing radioactivity in stream gravels and a comparison of radioactivity to grain size of sediments, Corral 

Creek, Seven Mile area, Grand County, Utah___________ 165

41. Radioactivity of gravel in washes draining Happy Jack mine 

and first canyon west, White Canyon area, San Juan 

County, Utah____________________________ 168

ill

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

STUDY OF RADIOACTIVITY IN MODERN STREAM 

GRAVELS AS A METHOD OF PROSPECTING

BY KANDALL T. CHEW, III

ABSTRACT

Traverses along some streams of the Colorado Plateau in areas known to 

contain minable uranium deposits show that anomalous radiation in the stream 

gravels can be detected with a suitable counter downstream from the deposits.

Intensity of radiation is influenced by the size of the uraninum deposit, the 

size of the drainage area of the stream, the grain size of the sediments, and 

the lithology of the rocks over which the stream flows.

The spacing of the stations where readings are taken is controlled by the size 

of the stream, and special readings are also taken just downstream from important tributaries. An anomaly is empirically defined as a 10 percent rise over 

background.

Radioactive material from large uranium deposits has been detected as much 

as 1 mile downstream. Radioactive material from smaller deposits is detectable 

over shorter distances. The method is slow but appears to be a useful prospecting 

tool under certain conditions.

INTRODUCTION

This report describes investigations of the radioactivity of gravels 

in modern stream channels undertaken by the U. S. Geological Survey 

on behalf of the Division of Kaw Materials of the U. S. Atomic Energy 

Commission. The purpose of this study has been to determine 

whether this radioactivity can be used as a guide in locating uranium 

and thorium ore deposits or mineralized areas. Some of the ideas 

presented here are based on assumptions or working hypotheses; 

further work may change these assumptions. However, the author 

feels that the assumptions are basically correct, and that radioactivity of stream gravels can be a useful prospecting tool under some 

conditions.

PREVIOUS INVESTIGATIONS

As early as 1945, the Geological Survey had made investigations of 

the radioactivity of stream gravels in Alaska. K. S. Cannon, Jr. 

(unpublished report, 1953) reported that the results of four radiation

149
150 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

measurements made in alluvium near uranium deposits in South 

Dakota indicated a detectable radioactivity anomaly downstream from 

the uranium deposits.

As a follow-up to Cannon's work, W. E. Bales (personal communication) completed a traverse of about a dozen stations through an 

intensely mineralized area in South Dakota. Bales found that an 

anomaly did exist in the stream gravels downstream from the deposits. 

This anomaly was of about the same magnitude as those described in 

this report.

Shawe x describes a study of stream gravels on the eastern slope 

of the Sierra Nevada where he measured radioactivity of the gravels 

with a Geiger counter equipped with a neon light for the counting 

device and also made a detailed study of the heavy minerals. The 

sources of the stream gravels described by Shawe are granitic and 

metamorphic rocks, and the radioactivity in the gravels appears to 

have monazite as its chief source in some drainages and ilmenite in 

other drainages. The source rock of the various radioactive minerals 

is discussed in some detail. Most of the radioactivity detected comes 

from thorium minerals; 110 miiiable uranium deposits have been found 

in the Sierra Nevada area. Some of the concepts and results described 

by Shawe may find application as a possible prospecting tool in future 

study of radioactivity in modern stream gravels.

GENERAL CONSIDERATIONS

The primary purpose of this study was to determine whether uranium ore deposits contribute a measurable amount of radioactive material to the streams that drain them. This material is detected by its 

radioactivity. Other factors which affect the amount of radioactivity 

measured must also be considered. These include fluctuations in 

radiation caused by the diurnal variation in background and differences in the natural radioactivity of various lithologic units. Secondary considerations which influence the validity of the anomalies are: 

selection of the most suitable radiation instrument for the work, 

statistical considerations affecting the adequacy of a reading or series 

of readings, effect of variation in a stream size and drainage area, and 

effect of variation in grain size of the alluvium.

A sealer type instrument must be used in measuring the radioactivity in modern stream gravels because the scaling circuit records 

each gamma ray counted by the Geiger-Muller tube. This feature 

makes small variations in radiation detectable when recorded on a 

counts-per-minute basis over an adequate period of time. A counter

1 Shawe, D. R., Heavy detrital minerals in stream sands of the eastern Sierra Nevada 

between Lewining and Independence, Calif.: Calif. State Div. Mines Special Kept in 

preparation.
RADIOACTIVITY IN MODERN STREAM GRAVELS 151

equipped with a ratemeter showing only radiation detected over a 

relatively short time interval will not show these small variations with 

a sufficient degree of certainty because of the high random variation 

of gamma rays (both as to intensity and direction) at the low counting rate. A portable sealer equipped with a Geiger-Muller tube with 

an effective cathode area of 3 square inches was used in this study. 

At all levels of radioctivity encountered, this tube had sufficiently low 

sensitivity so that all counts recorded by the tube were shown on the 

scaling circuit. The Geiger-Muller tube used is similar to those 

found in most portable counters.

The author made several readings in areas of anomalous and nonanomalous radiation using both a Geiger counter and a scintillation 

counter equipped with ratemeters. Neither of these instruments 

showed any anomalies in areas which are considered anomalous on the 

basis of the sealer readings.

The sealer should make more than 400 counts during the reading 

period in order that the probable error of the reading be safely within 

the limits which constitute an anomaly. The formula for percentage 

probable error mentioned by Faul (1954, p. 22) can be used in computing the number of counts necessary during a single reading period. 

Faul gives the formula 2?=0.6745 \/7V where p equals the probable 

error of a given reading and N equals the number of counts recorded. 

He then states that the "percentage probable error is the ratio of the 

absolute probable error to the value of the quantity measured expressed

0 6745 in percent." Stated algebraically, this reduces to E ' _ XlOO

where E equals the percentage probable error and N equals the number of counts recorded as before. Faul shows a graph of this percentage probable error. The probable error of 400 counts is ±3.35 

percent. Experience has shown that if 8-minute readings are made 

using an instrument equipped with the Geiger-Muller tube just described, the relative probable error will be ±3.3 percent or less. This 

relative error is low in comparison with the increase of approximately 

10 percent over the normal radioactivity that is considered anomalous; 

and, if 8-minute readings are made, the statistical error will always 

be low enough that anomalous readings can be considered valid.

At stations which are obviously giving high readings (more than 

100 counts per minute) the reading can be stopped after 500 or 600 

counts have been recorded and the average can be computed. If 625 

counts are recorded, the probable error is ±2.68 percent. If the 

reading is obviously anomalous, as shown by a high counting rate, the 

probable error becomes unimportant.
152 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Variations in radioactivity over a limited geographical area are 

unimportant. The table below shows the results of two traverses

Average reading (counts per minute) and range of three readings taken in closely 

spaced holes at each station, Seven Mile area, Grand County, Utah

Station No. Average Range 

Seven Mile Canyon traverse

I..- -- - 59

2......................-....... ... 57

3 53

4 .--.---- _ . 53

5............... ............ .-..... 54

58-61

52-63

51-56

49-58

53-55

Corral Canyon traverse

3...- -...-.-- -_- - . 107 92-116

4............................... 84 80-87

5. 99 97-101

made to show variation in readings obtained by moving the probe 

slightly between readings. Three readings were taken at each station, 

but the probe was moved slightly between readings. At six stations 

the readings were taken on a triangular grid with the corners about 

4 feet apart. At two stations the readings were spaced about 4 feet 

apart in a line parallel to the stream flow. The readings show a maximum range of 24 counts per minute (about 50 percent) caused by moving the probe slightly between readings. In general, the range is 

least where the radiation is at the lowest level and greatest where 

radiation is at the highest level. The range is great enough that 

probably no single reading less than 20 percent above average should 

be considered anomalous. Three or more stations with readings of 

more than 10 percent above average can be considered anomalous. 

Apparently a longer low peak is more likely to occur downstream 

from a uranium deposit than a single high one.

In Corral Canyon, Seven Mile area; Utah, (fig. 33), the range in 

a series of reading shown in figures 34-37 illustrates the error made 

possible by readings of insufficient duration. The probe setting numbers at the top of each graph denote the same setting of the probe on 

each graph. Stations 3, 4, and 5 consist of three readings in different 

holes within about 4 feet of each other. An 8-minute reading was 

taken in each hole. While the measurements were being taken, the 

sealer was read at 2-minute intervals to obtain data for the shorter 

readings. Figure 34 shows the average and range of four 2-minute 

readings. The others show the ranges of two readings except figure 

36 which shows only one reading.
RADIOACTIVITY IN MODERN STREAM GRAVELS

109°

153

Cortez / cjburango 

COLORADO)

109°

FIGURE 33. Index map of part of Colorado Plateau showing areas where radioactivity 

of modern stream gravels was studied.

The dashed line connects the same readings on each graph. The 

readings connected by the dashed line have been arbitrarily selected 

but might h&ve been obtained in a traverse where only one reading of 

the duration shown on each graph was taken at each station. The 

dashed line shows two reverses in pitch as the result of the theoretically 

improved "sampling." The first change is between stations 1 and 2 

and the other is between stations 3b and 4b.

To some extent, an anomally is influenced by the size of the deposits 

and the size of the stream draining the area. A deposit in the drainage 

area of a small stream will give a larger anomaly than the same size 

deposit in the drainage area of a large stream because the greater 

amount of barren sediments in the large stream tend to mask any 

j|aoinalqus radioactivity. On the basis of reserve estimates and pro879803 56 2
150

50

STATION NUMBER AND PROBE SET

3b 3c 4o 4b 

Line connecting the 

same points as on 

. figures 35,36,and37

84. Radioactivity in modern stream gravels range and average of four 2-mi

Seven Mile area, Grand County, Utah
ISO

140

130

uj 120

3

| MO 

(E

£ 100

3a

STATION NUMBER AND PROBE SET

3b _____3c_____ 40 4b 

Direction of 

§ 90

o

o

80

70

60

50 

FIGURE

Line connecting the 

some points as on 

figures 34,36,and 37

35. Radioactivity in modern stream gravels range of two 4-minute reading

area, Grand County, Utah.
150

140

130

120

IU

tD

1 110

2

UJ 100

CO

Z 90

g

° 80

70

60

50 

FIGUEB

3o

STATION NUMBER AND PROBE SET

3b 3c 4o 4b 

Line connecting-the 

some points as on 

figures 34, 35,and 37

Direction of f

36. Radioactivity In modern stream gravels range of two 6-minute readings a

Grand County, Utah.
RADIOACTIVITY IN MODERN STREAM GRAVELS 157
158 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

duction records, deposits have been considered for this report to be 

either "small" deposits containing less than 1,000 tons of ore, or "large" 

deposits containing more than 1,000 tons. Streams were classed as 

"small," having a width of less than 10 feet where its width is not controlled by the local topography; "intermediate," with a width of from 

10 to 35 feet; and "large," with a width greater than 35 feet. This 

width reflects, to some extent, the size of the drainage area of the 

stream and the amount of sediment carried by it.

The grain size of the rock probably has some effect upon the radiation through the "mass effect." Sediments of a small median grain 

size show higher radioactivity than sediments of similar composition 

and larger median grain size. Apparently this is caused by close 

packing of the small material around the probe.

It was believed, early in the work, that diurnal variations in the 

cosmic-ray background radiation might affect the readings; therefore, a reading of the background was taken at every station. Readings of the background radiation were also taken in several areas at 

about 1-hour intervals over several days. This was done to obtain 

some record of the diurnal variations in background radiation and also 

to determine the effects of background readings on the radiation recorded from stream gravels. These background readings were about 

the same as or slightly lower than readings in barren gravels and 

seem to have no adverse effect 011 the readings taken in the gravels. 

Readings taken with the probe buried 6 inches in the gravels probably 

record gamma radiation derived from both cosmic rays and radioactive 

material in the sediments. The radiation recorded is the sum from 

these two sources and thus the cosmic-ray background radiation has 

no practical effect on the readings in the gravels.

FIELD METHODS

In this study the intensity of gamma radiation was measured at 

stations along streams that cross known deposits and also along 

streams that cross no known deposits. Spacing of the stations was 

determined by the size of the stream, but in many places this spacing was reduced where the amount of radioactivity detected in the 

gravels began to approach the anomalous level.

On small streams, the stations can be spaced at 0.2 mile intervals 

with spacing narrowed to 0.1 mile where an anomaly is suspected. 

Intermediate streams can have the stations spaced at intervals of 

half a mile. These can be narrowed to 0.2 mile intervals where an 

anomaly is suspected. Readings from stations spaced 0.1 mile apart 

on streams of intermediate size will probably not give any additional 

useful information.
RADIOACTIVITY IN MODERN STREAM GRAVELS 159

A somewhat different technique is necessary on large streams, especially perennial ones, because the amount of radiation seems to vary 

significantly on opposite banks of a large stream. In wide streams 

it appears possible to determine from which side of the stream the 

radioactive material is introduced by taking closely spaced readings 

on each side. For ordinary reconnaissance work on large streams, 

stations on one side of the stream are sufficient; stations can be spaced 

1.0 mile apart and narrowed to 0.5 mile where an anomaly is suspected. 

If readings are made on each side of the stream, it appears practical 

to narrow the spacing to 0.2 mile. This may give additional information as to the source of an anomaly. In an entirely unexplored 

region, stations spaced at wider intervals might give some useful 

information as to the location of large areas for more intense exploration. Stations spaced at intervals of 2 to 3 miles might conceivably 

have some significance in an entirely untried area, but more closely 

spaced stations should generally be used. A traverse along the Colorado River from Rifle, Colo., to Moab, Utah, using stations spaced at 

intervals of 5.0 miles, gave readings which have been interpreted as 

too unsystematic to be useful.

The probe was buried 6 inches below the surface in the stream 

gravels and covered as well as possible. Complete burial of the 

probe is important. If it is not well covered, the readings will be 

lower than the true radioactivity of the station. Where the ground is 

frozen or boulders make burial difficult, a small mound of loose material should be piled over the probe to simulate burial.

Because apparently they do not affect the radioactivity of the 

alluvium, moisture content and abundance of organic matter need not 

be noted in prospecting. Topographic features such as constrictions 

in the streams and the location of the station in relation to major 

bends which might affect deposition of gravels should be noted.

A sketch map of the stream is useful in interpreting the results of 

the traverse. The map can be made by using a compass and some 

means of measuring distance either the odometer of a car or pacing 

and stratigraphy, structure, and topography can be plotted in relation 

to the location of the stations while the readings are made. To make 

anomalous areas more easily recognizable the readings are plotted on 

graph paper. The distances between stations and the various geographic check points are plotted on the abcissa and the readings, in 

average counts per minute, are plotted on the ordinate. Readings 

both in gravels and in country rocks, the average size of the smallest 

grains, and points where the contact between distinctive stratigraphic 

units are crossed can be plotted on the graphs.
160 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ANOMALIES

The number of counts per minute defined in this section as constituting an anomaly is empirical and is based on the field work. These 

figures have proven sufficiently consistent within the limits given here. 

Traverses have been conducted only over barren rock, mill tailings 

piles, and uraninite-type deposits. No traverses have been made over 

vanadium-bearing carnotite-type deposits or oxidized deposits that 

do not contain vanadium. A significant variation from the figures 

cited here may occur in the amount of radioactive material in sediments downstream from these other types of deposits, especially if 

the source of the radiation in the gravels is detrital uranium minerals. 

These minerals have differing solubilities and this may produce various 

amounts of radiation.

Barren gravel shows radioactivity ranging from 55 to 65 counts per 

minute regardless of grain size. However, single readings as high as 

72 counts per minute should not be considered anomalous. A continuous series of readings at several stations averaging less than 55 

counts per minute should be questioned as the sealer may not be 

functioning properly.

Single readings of more than 80 counts per minute, or three or more 

consecutive stations giving readings of more than 72 counts per minute 

can be considered anomalous. An area which gives unequal readings 

of 65 to 75 counts per minute at several stations may be anomalous 

and should be investigated further. This irregularity has been noticed near smaller deposits that do not show definite high counts, and 

is most common in small streams.

In summary, a rise of 10 percent in the average number of counts 

per minute above the average background can be considered anomalous. This figure of 10 percent is a convenient one derived from 

the statements in the preceding paragraphs, that is, multiple readings of 72 counts per minute is considered anomalous over an average 

of 65 counts, a rise of 7 counts or about 10 percent.

The amount of radiation recorded from the gravels tends to rise 

slowly as the deposit is approached from the downstream side, reaches 

a peak where sediments from the deposit are added, and falls off very 

sharply upstream. The best example of this tendency obtained in 

the present study is shown in figure 38, which shows readings taken 

near the Grand Junction, Colo., mill of the Climax Uranium Company. Wet tailings from the mill are emptied into a marsh near 

the river bank. The curve of the actual readings taken is shown on 

the graph, and the projected curve is shown also. The maximum 

number of counts per minute at the mill as shown on the projected
KADI6ACTIVITY IN MODERN STREAM GRAVELS

West

Direction 'of llo* ^

50 -

EXPLANATION

Projected curve showing 

theoreticol rodiooctivity

Curve showing ocluol 

meosurements

2 3

DISTANCE,IN MILES

FIGURE 38. Radioactivity of Colorado River gravels near Climax Uranium Company mill,

Grand Junction, Colo.

curve are, of course, conjectural. Most curves are much more irregular, but they follow this general pattern.

Geomorphic control of radioactivity does not seem important. 

Anomalous radioactivity is apparently not affected by the rate of flow 

or the location of bends in the channel.

The most important outside influences on the variation of the 

amount of radioactivity in stream gravels are the introduction of 

material by side streams and the lithologic variations of the country
162 CONTRIBUTIONS TO THE QEOLOGY OF URANIUM

rock. Special stations should be placed immediately below large side 

streams because a high reading below an important side stream would 

indicate that it should be investigated. Any radioactivity of sediments from a side stream is, within a short distance, masked by the 

greater amount of nonradioactive sediments in the main stream; 

therefore, the reading should be taken within a hundred yards below 

the confluence. On a large stream, the reading should be taken on 

the side on which the side stream enters.

The gravels in streams over some stratigraphic or lithologic units 

may show abnormally high radioactivity over wide areas which do 

not contain any minable deposits. The stream gravels on the Mancos 

shale of Late Cretaceous age exhibit this property wherever they have 

been checked during this investigation. At least 30 percent of the 

readings in stream gravels over the Mancos shale have exceeded 70 

counts per minute; the highest reading was 84.

The tributary streams that flow into the Colorado River from the 

north between Palisade, Colo., and Dewey, Utah, cross the Mancos 

shale. These tributaries give high readings and might give the impression of being anomalous if this special characteristic of the country 

rock were not taken into account. However, there is no noticeable 

increase in the radioactivity of the Colorado River alluvium in this 

area. Apparently the amount of alluvium from the Mancos contributed to the river gravels is too small in relation to the amount 

of less radioactive gravels already present to affect noticeably the 

radioactivity of the river gravels.

Where the country rock is thought to be abnormally radioactive, a 

few readings should be taken on fresh outcrops. If they are abnormally radioactive, the number of counts per minute considered necessary to constitute an anomaly should be revised upward. A 10-percent 

rise in the number of counts per minute over the higher background 

can then be considered anomalous. Thus, where 85 is the average 

number of counts per minute in the gravels, 93 or more counts could 

be called anomalous.

AREAS STUDIED

The results of two traverses are explained here in detail because 

they demonstrate all the controlling factors discussed in preceding 

sections of this paper.

Traverses in the Temple Mountain region, Utah, revealed three 

areas that show anomalous radioactivity (fig. 33, pi. 8). One is the 

main Temple Mountain uranium deposit, which is drained by the 

stream here referred to as the north wash (fig. 39). This wash is of intermediate to large size and drains a large area of nonmineralized rock
RADIOACTIVITY IN MODERN STREAM GRAVELS 163

Moenkopi formation 

ond older rocks

Shinarump conglomerate 

ond younger rocks

16 17 

Station numbers

Cliff face along which 

Shinarump conglomerate is exposed

Adit

1 Mile

J

Approximate scale

PIGUEE 39. Diagrammatic sketch of tbe Temple Mountaia area, San RafaeV district, Emery 

County, Utah, for use with plate 8.

in addition to the main workings. The readings are irregular (pi. 8) 

without being definitely anomalous. The gravels of the side streams 

gave anomalous or nearly anomalous readings. A side stream that 

drains only areas of unaltered Moenkopi gave readings (pi. 8, sta. 37, 

38) well below the average for the north wash a's a whole. The irregularity of the graph showing the amount of radioactivity in the
164 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

gravels in the main stream and the general high count of the gravels 

in the side streams is indicative of anomalous radioactivity and, if 

the area were new, would suggest need for further exploration.

South wash (fig. 39, pi. 8) drains an area of mineralized Shinarump 

conglomerate that has been thoroughly prospected, but contains only 

the one minable deposit shown in figure 39 near the confluence of the 

three washes. The amount of Shinarump in the drainage area is 

fairly large, and the radioactivity anomaly is more pronounced than 

that on the north wash. If the area were new, this type of anomaly 

would warrant further exploration.

West wash (pi. 8) has a drainage area of less than 1 square mile and 

is underlain by the Moenkopi formation. About one-half of this area 

is composed of interbedded sandstones and siltstone of the Moenkopi 

showing some alteration under the sandstone beds. This entire unit 

is slightly radioactive. The large amount of slightly radioactive material caused a very sharp anomalous reading. However, the countryrock reading, not shown on the graph, was exactly the same as that in 

the stream, and it was obvious that the anomaly was more apparent 

than real. Upstream from this slightly radioactive area the readings 

are below the anomaly level. If the region were unexplored, further 

investigation would be justified. Careful observation and note-taking 

while traversing the west wash showed the anomaly in the Moenkopi 

to be of small extent and low grade.

The smoothness of the curve (pi. 8) below station 9, which represents the confluence of the three washes, is noteworthy. Temple Wash 

is outside the mineralized area, and any sediments contributed to it 

below station 9 are not significantly radioactive.

The graph also shows, below station 9, that the radioactivity tends 

to decrease to a constant with increasing distance downstream from 

an ore deposit. The constant here averages about 63 counts per minute.

Figure 40 shows the graph of the traverse along Corral Creek in 

the Seven Mile area, Grand County, Utah. The Shinarump No. 3 

mine is located on the east side of Corral Creek Canyon. The stream 

is of intermediate size. This was the first traverse made and 2-minute 

readings were taken at each station. The possible relative error 

ranged from ±7.6 to ±9.2 percent. These figures show that the 

observation time was too short; statistically the chances are about even 

that the average number of counts would show either an anomaly 

where none existed or would miss an anomaly where one did exist. 

Apparently, however, the average number of counts obtained at each 

station was somewhat nearer the number that would have been obtained with a longer counting period than the probable relative error 

formula shows; thus, the graph has some value. This occurred purely
Boulders 

Pebbles 

Sand

2000 2250 

DISTANCE, IN FEET

FIGURE 40. Graph showing radioactivity in stream, gravels and a comparison of radi

Seven Mile area, Grand County, Utah. Grain-size designations are based on w

sand" includes all sizes smaller than fine sand, "sand" includes all sizes from 

includes granules, and "boulders" includes all sizes larger than pebbles in the W

the smallest class forming an important (> 10 percent) component of the alluvium
166 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

by chance. The curve showing radioactivity is probably much more 

irregular than it would have been had longer readings been taken.

This graph includes a line showing grain size of the stream gravels 

plotted above the line showing the radioactivity. The relation between grain size and the amount of radioactivity is well shown, especially from stations 10 to IT. Especially high readings were obtained 

from stations 15 to IT where the alluvium consists of fine sand. A low 

reading was obtained from station 14 where the alluvium consists of 

boulders.

The double peak in the graph just below the mine may be significant. 

The Shinarump outcrop is almost 500 feet wide where the stream 

crosses it. Since the traverse was made, miners have stripped the 

gravel from this outcrop and mined some of the underlying Shinarump 

bedrock as ore. This concentration of ore-grade rock immediately 

under the gravels may account for the double peak and the elongate 

shape of the anomaly.

The Moab fault and the rocks of the Morrison formation of Jurassic 

age apparently have no effect on the radioactivity of the gravels.

RESULTS, AND EVALUATION OF THE METHOD

The investigation has shown that a recognizable radioactive anomaly occurs in alluvium downstream from both large and small uranium 

ore deposits. A large deposit in the drainage area of a small stream 

will cause anomalous readings as much as a mile downstream. A large 

deposit in the drainage area of an intermediate stream will cause 

anomalous readings not more than 0.1 to 0.2 mile downstream. A 

small deposit in the drainage area of a small stream will cause anomalies 0.1 to 0.2 mile downstream, but a small deposit in the drainage 

area of a large stream would probably not give an anomalous reading 

unless a station were set by chance exactly upon the point where the 

deposit contributed to the stream gravels.

Measuring the radioactivity of modern stream gravels as a prospecting method is slow compared to other reconnaissance methods such 

as the use of airborne and carborne scintillation counters. Measuring 

the radioactivity of the stream gravels only, it is possible to cover about 

five stations per hour. At 0.1 mile intervals this is somewhat less than 

a half a mile per hour or about 3% miles per day. Using a 1-mile 

spacing on larger streams, probably only four stations per hour could 

be read because of the time consumed in moving from station to station. About 30 miles per day could be covered under ideals conditions.

The greatest usefulness of the method probably would be in areas of 

poor outcrop and moderate relief that had been explored by airborne 

scintillometer. Here the sealer could be used in checking anomalous
RADIOACTIVITY IN MODERN STREAM GRAVELS 167

radioactivity detected by the scintillation counter. The method wpuld 

be used to limit the area of search for the deposit and might show the 

presence of a deposit that is covered by soil.

Another somewhat specialized use would be applicable along aj dissected cliff face such as is common on the Colorado Plateau. The 

small restricted drainages flowing out onto the fan at the foot of the 

cliff could be checked with one or two stations in each wash. A 

traverse along such a cliff front could be made at the rate of seyeral 

miles per day and might show the presence of a relatively small deposit 

which otherwise would not be found except by the examination of 

many miles of outcrop. This method was tried at the large deposit 

of the Happy Jack mine in the White Canyon area of Utah (fig. 33), 

and the results are shown in figure 41. Two small streams [were 

studied. The anomaly shown in the gravel 0.5 mile below the mine is 

very large, over 100 counts per minute. A smaller ore body occurring 

in a similar area would also be noticed though the magnitude ojf the 

anomaly would naturally be smaller. The drop in radioactivity 

below the point where the two small streams coalesce is very sharp. 

In using this method of prospecting, the prospector must be careful 

to check each individual stream above the point where it coalesces 

with another.

There are probably other uses for this prospecting method that 

have not come to light. Under ideal conditions anomalies have been 

noted in stream gravels as far as 1 mile from the nearest known outcrop of radioactive material in large deposits. Small deposits will 

cause detectable irregularities in radioactivity that can be traced over 

several hundred feet of stream gravels. Even though the method is 

slow, deposits can apparently be detected farther away than bV the 

other means of reconnaissance prospecting; thus the measurement of 

the radioactivity of modern stream gravels would seem to be useful 

in certain instances.

SUGGESTIONS FOR FUTURE WORK

The work reported in this paper shows only that study of the radioactivity in modern stream gravels appears to be a useful tool in prospecting for uranium deposits. Additional work must be done bsfore 

the applicability of the method under all conditions will be completely 

proved.

The traverses described in this paper and from which the conclusions 

stated herein have been drawn were all made over1 uraninitej-type 

deposits that predominantly contain primary uranium minerals. No 

traverses have been made over carnotite-type deposits that predominantly contain oxidized minerals. Additional traverses over bther
168 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

North

100

90

80 -

70

60 -

South

Direction of flow

EXPLANATION.

Stream draining Happy 

Jack mine area

Stream draining first canyon 

west of Happy Jack mine

O.I 0.2 0.3 

DISTANCE, IN MILES

0.4 0.5

Happy Jack mine O.5 mile

I 2

FIGURE 41. Radioactivity of gravel in washes draining Happy Jack mine and first canyon 

west, White Canyon area, San Juan County, Utah.

types of deposits in igneous and metamorphic rocks as well as in sedimentary rocks are necessary before the adequacy of the method under 

all field conditions has been proved.

The source of the radioactivity in the stream gravels is not known. 

It may be detrital uranium or thorium minerals in the gravels, or 

uranium or radium salts coating the sand grains and filling pore 

spaces. The radioactivity may come from both sources or from others.
RADIOACTIVITY IN MODERN STREAM GRAVELS 169

If the source varies with the different types of deposits, gravel downstream from oxidized deposits might produce different amounts of 

radioactivity from those described here.

One method of determining the source of the radioactivity is 

through the use of the nuclear-track plates as described by Stieff and 

Stern (1952). The radioactive particles can be located on the plates, 

but it will probably be necessary to use X-ray photographs and chemical tests to identify the minerals (T. W. Stern, written communication, 1954).

LITERATURE CITED

Faul, Henry (editor), 1954, Nuclear geology. John Wiley and Sons, Inc., NewYork.

Stieflf, L. B., and Stern, T. W., 1952, Preparation of nuclear-track plates and stripping films for the study of radioactive minerals: Am. Mineralogist, v. 37, 

p. 184-196.

Wentworth, C. K., 1922, A scale of grade and class terms for clastic sediments: 

Jour. Geology, v. 30, p. 377-392.

U. S. GOVERNMENT PRINTING OFFICE: I9M



Geology and Monazite 

Content of the Goodrich 

Quartzite, Palmer Area 

Marquette County 

Michigan

By R. C. VICKERS

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-F

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seatont Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 50 cents (paper cover)
CONTENTS

	Page 

Abstract__________________________________ 171

Introduction-_________________________________________________ 171

Location, accessibility, and history_____________________________ 172

Acknowledgments. ____________________________________________ 172

Geology_______________________________________ 173

General features___________________________________________ 173

Rock units________________________________________________ 175

Palmer gneiss.______________________________________ 175

Ajibik quartzite.__________________________-_______________ 175

Siamo slate_-_____-_________________-_____-______-___-____ 176

Negaunee iron-formation-__________________________________ 176

Goodrich quartzite_______________________________________ 176

Dike rocks______________________________ 177

Structure____________________________________ 177

Occurrences of monazite__________________________________________ 179

Mineralogy.__________________________________________________ 179

Determination of the monazite content of samples of Goodrich

quartzite-__________________________________________________ 181

Distribution __________________________________ 182

Results of sampling of outcrops____________________________ 182

Results of gamma-ray logging of drill holes___________________ 183

Results of analyses of core-__________________________---____ 184

Occurrences of monazite in the Goodrich quartzite outside the Palmer

area_____________________________________________________ 184

Conclusions.--____-_.!__ ___________________________________________ 185

Literature cited.__________________________________________________ 185

ILLUSTRATIONS

PLATE 9. Geologic map of the Palmer area, Marquette County, Mich__ In pocket 

10. Geologic cross section through part of sec. 29, T. 47 N., R. 26 

W., Marquette County, showing gamma-ray logs of drill 

holes in Goodrich quartzite._______________________ In pocket

Page 

FIGURE 42. Index map showing the location of the Palmer area.________ 173

43. Sketch of a photomicrograph (X 28) of Goodrich quartzite-_ 179

44. Graph showing relationship between equivalent uranium and 

monazite content of samples of Goodrich quartzite from 

the Palmer area_____________________-_-__-____---_-_- 181

TABLES

Page

TABLE 1. Chemical and spectrographic analyses of monazite concentrates from the Goodrich quartzite, Palmer area__________ 180

2. X-ray powder diffraction data of monazite from the Goodrich

quartzite, Palmer area_______________________________ 180

m

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGY AND MONAZITE CONTENT OF THE GOODRICH 

QUARTZITE, PALMER AREA, MARQTJETTE COUNTY,

MICHIGAN

By R. C. VICKERS

ABSTRACT

The Palmer area, which is on the south limb of the Marquette synclinorium, 

consists of a downfaulted block of Precambrian sedimentary rocks about 4 miles 

long and three-quarters of a mile wide. The block is composed mainly of middle 

Huronian Ajibik quartzite and Negaunee iron-formation and upper Huronian 

Goodrich quartzite. Monazite occurs in the Goodrich quartzite as rounded 

detrital grains concentrated mainly in the matrix of quartz pebble conglomerate 

which is interbedded with coarse-grained quartzite.

Correlation of gamma-ray logs of drill holes which penetrate an apparent thickness of 1,100 feet of Goodrich quartzite and enter the underlying Negaunee ironformation shows that most of the monazite occurs more than 300 feet above the 

base of the Goodrich quartzite. Drill-core specimens contain as much as 54 

pounds of monazite per ton of rock. Outcrops of Goodrich quartzite, which are 

practically restricted to the lower 200 feet of the formation, contain an average 

of 2.9 pounds of monazite per ton. Samples from locally derived erratics contain 

as much as 110 pounds of monazite per ton.

Laboratory work indicates that more than 85 percent of the monazite is recoverable by gravity methods after grinding and sizing.

INTRODUCTION

Abnormal radioactivity in specimens of Goodrich quartzite on rock 

dumps at the Old Volunteer and Old Maitland mines near Palmer, 

Marquette County, Mich., was detected in 1951 by Robert Reed, 

geologist working for L. P. Barrett, U. S. Atomic Energy Commission 

contractor. Analyses of the rock indicated that most of the radioactivity was caused by thorium. The locality was brought to the 

attention of the writer during an examination of radioactive materials 

in northern Michigan in August 1952, and subsequent chemical and 

spectrographic analyses of the samples indicated that the Goodrich 

quartzite contains locally as much as 0.37 percent thoria and O.X 

percent each of Ce, La, Nd, Y, and Zr. Additional information 

concerning the radioactive material was obtained during 2 days 

of fieldwork in the Palmer area in November 1952 and in subsequent 

laboratory study.

171
172 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Preliminary laboratory work indicated that most of the radioactivity is caused by detrital grains of thorium-bearing monazite in 

the matrix of pebble conglomerate of the Goodrich quartzite and 

that about 85 percent of the monazite is recoverable by gravity concentration after grinding and sizing.

To obtain further information concerning the geology of the Goodrich quartzite and the tonnage and grade of monazite-bearing rock 

that might be present in the Palmer area, 1 month was spent during 

the 1953 field season in mapping the Goodrich quartzite, sampling 

outcrops of the Goodrich, and gamma-ray logging three drill holes 

that penetrated the Goodrich. An examination was also made of 

many outcrops of Goodrich quartzite outside the Palmer area.

This report presents the results of the fieldwork together with the 

results of laboratory study. The work was done by the U. S. Geological 

Survey on behalf of the Division of Raw Materials of the U. S. Atomic 

Energy Commission.

LOCATION, ACCESSIBILITY, AND HISTORY

The Palmer area, whose location is shown in figure 42, is about 3 

miles south of Negaunee on Michigan Route M-35, Marquette 

County, Mich.; it includes parts of sees. 27, 28, 29, 30, 31, 32, 33, and 

34, T. 47 N., R. 26 W. The area is served by a branch of the Chicago 

and North Western Railway.

The Palmer area, part of the Marquette iron district, has been a 

source of iron ore since the 1870's. About 17 million tons has been 

shipped from the area, of which about 25 percent has been produced 

from underground mines. The workings of several of the mines 

penetrated part of the Goodrich quartzite but are inaccessible at 

present.

ACKNOWLEDGMENTS

The writer wishes to acknowledge the cooperation and interest of 

personnel of the Cleveland-Cliffs Iron Co., who made available the 

results of recent diamond drilling in the Palmer area and reopened a 

diamond-drill hole so that it could be gamma-ray logged. E. R. 

Randolph, geologist of the Cleveland-Cliffs Iron Co., assisted in the 

gamma-ray logging.

J. H. Eric assisted the writer in the fieldwork during August 1953, 

and L. P. Barrett, of the U. S. Atomic Energy Commission, supplied 

special information on the Marquette and Gwinn districts.

Equipment of the Department of Geology and of the Department 

of Mining and Metallurgy of the University of Wisconsin was used 

for the preparation and study of samples.
MONAZITE IN GOODRICH QTJARTZITE, PALMER AREA, MICHIGAN 173

Jjte??6 synclinorium ^Marquette

-f^-^wgftrsi^ ^^L^smmmmL

MARQUETTE

10 20 Miles

FIOUKE 42. Index map showing the location of the Palmer area, Marquette County, Micb.

GEOLOGY

GENERAL FEATURES

The Palmer area is on the south limb of the Marquette trough, a 

westward-plunging synclinorium about 40 miles long and from 1 to 6 

miles wide, that is composed of Huronian rocks locally intruded by 

dikes and sills of diorite and minor amounts of granite. The position
174 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Cambrian

Precambrian

Upper Cambrian sandstone

Killarney granite A ... . 

Stratigraphic position doubtful Acldic intrusiv« 8

Keweenawan Basic intrusives

o> 

&

a rH

1

Archean type

Huronian

Upper

Middle

Lower

Laurentian granite

Keewatin

Upper slates

 . , . , ^ Bijiki iron-for- Michigamme slate mation member

Lower slates

Clarksburg volcanic s 

Greenwood iron-formation 

Goodrich quartzite

Negaunee iron-formation 

Siamo slate 

Ajibik quartzite

We we slate 

Kona dolomite 

Mesnard quartzite

Granite, syenite, peridotite 

Palmer gneiss

Kitchi schist and Mona schist

of the Palmer area in relation to the Marquette trough is shown in. 

figure 42. The stratigraphy of the Marquette trough as given by 

Leith, Lund, and Leith (1935, opposite p. 10) is shown above.

The Palmer area consists of a downfaulted block of Huronian sedimentary rocks, about 4 miles long and three-quarters of a mile wide, 

which is separated from the main part of the Marquette synclinorium. 

by an eastward-trending fault. All known outcrops of Goodrich, 

quartzite are shown on the geologic map of the Palmer area (pi. 9), 

whereas outcrops of other formations are shown only to indicate the 

position of the Goodrich contacts and the general geology of the? 

adjacent area.
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 175

BOCK UNITS

According to Van Hise and Leith (1911) the sequence of Precambrian rocks in the Palmer area is as follows:

Approximate 

Series Formation thickness (feet)

Upper Huronian__ Goodrich quartzite _________ 850

Middle Huronian___ Negaunee iron-formation.._____ 1,000

Ajibik quartzite._____________ 150

Archean. __________ Palmer gneiss. _______________ _____

Other interpretations of the geology in the Palmer area have been 

proposed more recently. The Palmer gneiss is believed by Lamey 

(1935, p. 1137-1161) to consist mainly of metamorphosed lower and 

middle Huronian rocks. Furthermore, according to Tyler and Twenhofel (1952, p. 118-128), the Negaunee iron-formation and Goodrich 

quartzite of Van Hise and Leith in the Palmer area are correlated with 

the Goose Lake iron-formation member of the Siamo slate and the 

Siamo slate, respectively.

The correlation of the quartzite that overlies the iron-formation in 

the Palmer area with the Goodrich quartzite of the Marquette range 

proper, as proposed by Van Hise and Leith, is accepted by the writer 

because of the lithologic similarity of the quartzite mapped as Goodrich in the Palmer area to known Goodrich quartzite in outcrops about 

5 miles to the northwest near the center of the Marquette trough; 

the presence of monazite both in the quartzite in the Palmer area and 

in outcrops of known Goodrich quartzite; and the absence of abnormal 

radioactivity in the Siamo slate (see table 1) in the Marquette trough.

PALMER GNEISS

The highly metamorphosed rocks along the southern boundary of 

Huronian rocks in the mapped area were assigned to the preHuronian Palmer gneiss by Van Hise and Leith (1911, p. 255-256). 

This interpretation is followed in the present report, but some of these 

rocks may represent metamorphosed lower or middle Huronian sedimentary rocks in accordance with the interpretation of Lamey (1935).

These rocks are granite, granite gneiss,, diorite, amphibolite, chlorite 

schist, sericite schist, dolomite, and quartzite.

AJTBEE: QUARTZITE

The recognition of the Ajibik quartzite is difficult, because it grades 

from a massive, dense, white or reddish quartzite with scattered beds 

of conglomerate to a highly sericitized and granitized quartzose rock. 

Some of the rocks mapped as Ajibik quartzite may consist in part of 

lower Huronian Mesnard quartzite which has a similar lithologic 

character. The Ajibik quartzite is probably about 300 feet thick in

333411 56 2
176 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

the eastern part of the mapped area and thins to about 50 feet in the 

western part.

SIAMO SLATE

The Siamo slate was not recognized in the Palmer area by Van 

Hise and Leith (1911). However, several outcrops of interbedded 

coarse-grained quartzite and sericitic slate occur in the SW% sec. 28 

and NW% sec. 30 (pi. 9), and these have been designated on the map 

as Siamo slate. These beds dip about 60° to the northeast, overlie 

the Ajibik quartzite, and underlie the Negaunee iron-formation.

NEGAUNEE IKON-FORMATION

The Negaunee iron-formation overlies the Ajibik quartzite in most 

of the Palmer area and consists of alternating laminae of red jasper 

and specular hematite or of interbedded gray chert and fine-grained 

hematite, possibly specular. Interbedded with the chert and hematite 

are many beds of coarse quartzite. At the Moore mine (S% sec. 28) 

many lenses and beds of coarse quartzite and conglomerate, some of 

which contain cobbles as large as several inches in diameter, are 

associated with the iron-formation. Some of the lenses have been 

interpreted by Tyler and Twenhofel (1952, p. 123) as filled channels 

that were cut in the iron-formation, but H. L. James (1954, written 

communication) believes that they are in infolded masses.

The true thickness of the Negaunee iron-formation in the Palmer 

area is probably about 800 feet. However, the thickness is not 

uniform and in places much, if not all, of the Negaunee iron-formation 

may be absent because of faulting. Thinning of the iron-formation on the flanks of the major folds has also probably occurred. 

Other geologists have interpreted the thinning and local absence of 

the iron-formation in the Palmer area as caused by pre-Goodrich 

erosion.

GOODKICH QTTARTZITE

In the Palmer area the Goodrich quartzite is composed of a locally 

developed basal cobble or boulder conglomerate which grades upward 

into interbedded coarse-grained quartzite and pebble conglomerate.

Locally the lithologic character of the basal conglomerate varies and 

is dependent upon the character of the subjacent formation. At the 

Isabella mine (SW% sec. 29) the lower part of the Goodrich is composed almost entirely of cobbles and boulders of granite and schist 

derived from the early Precambrian to the south and also abundant 

jaspilite derived from the underlying Negaunee iron-formation. 

Locally, as at the Old Volunteer mine (on section line between sees. 30 

and 31), the basal part of the Goodrich contained enough specular 

hematite fragments to constitute ore. The local abundance of ironformation fragments in the lower part of the Goodrich indicates that
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 177

erosion of the underlying iron-formation was taking place during 

Goodrich time. Because of the difference in competence between the 

two formations, as evidenced by the complex folding in the iron-formation as contrasted with the gentle folding in the quartzite, the contact 

is commonly faulted, and the Goodrich seems to rest with angular 

unconformity on the underlying Negaunee iron-formation.

Except for the local development of boulder and cobble conglomerate near the base of the formation, the Goodrich quartzite consists 

almost entirely of alternating beds of coarse quartzite and pebble 

conglomerate. The thickness of the observed pebble conglomerate 

beds ranges from about 2 inches to 2 feet. The pebble conglomerate 

beds are separated by beds of coarse sand, which range from 1 foot to 

10 feet or more in thickness. These lithologic relationships are based 

on outcrops of only the lower 200 feet of the Goodrich. The lower 

part of the Goodrich is fairly well exposed in the Palmer area, but only 

one exposure is known which is definitely more than 200 feet from the 

base. Because monazite is most abundant in beds of pebble conglomerate and because gamma-ray logs show an increase in monazite content in the middle acd upper parts of the formation, the percentage 

of pebble beds probably increases similarly in those parts of the 

formation.

The maximum thickness of Goodrich quartzite penetrated by diamond drilling in the Palmer area is about 1,100 feet. The true 

stratigraphic thickness of the formation is not known because no 

sediments younger than the Goodrich quartzite were penetrated in 

the diamond drilling, and no information is available on the amount 

of folding that might be present.

DIKE ROCKS

An eastward-trending metadiabase (H. L. James, 1954, written 

communication) dike occurs in the N% sec. 31 and the S% sec. 29. 

The total thickness of the dike is not shown in any of the several outcrops but the writer believes it ranges from 50 to 100 feet. An outcrop of sheared metadiabase( ?) in the SW% sec. 28 is along the strike 

of the metadiabase dike and is probably a sheared and altered portion 

of the dike. Others (Tyler and Twenhofel, 1952, p. 123-124) have 

:interpreted this outcrop as being pyroclastic material in the ironformation.

Hotchkiss * has reported a northward-trending dike about 30 feet 

wide in the underground workings of the Old Volunteer mine.

STRUCTURE

The interpretation of the structure of the Palmer area is complicated 

by the lack of good exposures. The main structural features are the

1 Hotchkiss, W. O., 1903, Some changes in the geology of the area about Palmer, Mich.: Unpublished Bachelor of Science thesis la flies of Univ. Wis. Library, Madison, Wis.
178 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

major eastward-trending Palmer fault, which separates the Palmer 

area from the main part of the Marquette synclinorium, and several 

other faults of smaller displacement. The general dip of the rocks 

in the Palmer area is northward, but locally in the Negaunee ironformation the rocks are tightly folded ar»d highly contorted.

The Palmer fault, originally described by Hotchkiss, 2 has a vertical 

displacement of probably 1,000 to 3,000 feet, and its position on the 

surface has been inferred chiefly on the basis of topography (pi. 9). 

A fault-line scarp is formed by steep south-facing hills composed of 

lower(?) and middle Huronian quartzites, in contrast to the relatively flat valley to the south which is underlain by the more easily 

eroded upper Huronian Goodrich quartzite.

According to Hotchkiss, 3 the Volunteer fault is known mainly from 

diamond drilling at the Old Volunteer mine; it probably extends eastward as evidenced by the brecciation in quartzite along the north 

side of the hill of Ajibik quartzite in the N%t>W% sec. 28.

The fault in the SK sec. 28 and trending southeast through the N% 

sec. 34 is inferred to explain the northwestward-trending hill composed of Ajibik quartzite in the SWK sec. 28. This quartzite has been 

designated as Goodrich quartzite by other writers (Van Hise and 

Leith, 1911, pi. 17), but it is believed by the writer to be Ajibik, as it 

exhibits no abnormal radioactivity and is a hard dense white to reddish fine-grained pure quartzite and lithologically is very similar to 

known Ajibik quartzite in outcrops north of the Palmer fault.

The structural relationships at the Old Maitland mine (W% sec. 30) 

are not known. Abundant pieces of Goodrich quartzite occur on the 

dump near the shaft, but the nearest outcrop of Goodrich is about 

2,000 feet east of the shaft. Geologic information in the area of the 

Old Maitland mine is scanty, but there probably is a downfolded or 

downfaulted segment of Goodrich quartzite in the vicinity of the 

shaft.

The absence of the iron-formation between the Ajibik quartzite and 

the Goodrich quartzite in the SE% sec. 30 is probably due to faulting. 

Slickensided surfaces in Ajibik quartzite near the center of sec. 30, 

where the road crosses the railroad, strike N. 55° W. and dip vertically. The thinning of the iron-formation in the N% sec. 31 may be 

due to flowage of material from the more steeply dipping flanks of 

the major folds.

The occurrence of Goodrich quartzite near the east side of the New 

Richmond pit (sec. 27) is probably due to a small downfolded or downfaulted block of quartzite into the iron-formation.

2 Hotchkiss, W. O., 1903, op. cit., p. 35-42. 

* Idem, p. 28-35.
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 179

OCCURRENCES OF MONAZITE 

MINERALOGY

The monazite occurs as rounded to subrounded detrital grains in 

the matrix of quartz pebble conglomerate. The brownish-red to 

honey-colored monazite grains are generally 0.10 to 0.20 mm in diameter. The identification of the monazite was confirmed by the writer 

by X-ray powder diffraction photographs. Locally the monazite 

jjrains make up more than 50 percent of the matrix in the conglomerate, and several lenses of monazite grains as much as 2 mm 

thick were noted in thin sections. A sketch of a photomicrograph of 

a concentration of monazite in the quartzite is shown in figure 43.

IIGURE43. Sketch of a photomicrograph (X 2!) of Goodrich quartzite showing quartz (g), interstitial 

monazite (TO), and altered feldspar (/). Stippled areas (a) are mainly serieite, chlorite, hematite, rutile, and 

magnetite.

Results of chemical and spectrographic analyses of a relatively pure 

sample of monazite are shown in table 1. X-ray powder diffraction 

data are shown in table 2.

The sample of monazite (about 92 percent pure) was extracted from 

a composite chip sample of several glacial boulders and selected mine 

dump samples. The sample is probably representative of the monazite in the Palmer area. The monazite was concentrated by gravity 

separation on a Wilfley table after grinding and sizing, and then 

further purified with a Frantz isodynamic separator and separated
180 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

magnetically into two fractions to find out if the difference in magnetic 

susceptibility was related to a difference in chemical composition.

Heavy minerals other than monazite in the Goodrich are mainly 

hematite, magnetite, ilmenite, and rutile.

TABLE 1. Chemical and spectrographic analyses of monazite concentrates from the 

Goodrich quartzite, Palmer area, Marquette County, Mich.

MMMc> MMMd

Chemical analyses ' 

P2 06 __ _ 

Rare-earth oxides (total) _ _ _ _ 

Th02 - ____________

SiO2 ___ - __________ -

Fe2 03 8 - ------------

A12O3 8 - ____ -_-_-_._

Ti02 3 -_--_ _ _-___

U 

PbO »...._. _________ _______

Total _______________

19.4

47.9 

7.6

6.9 5-10

5-10

1-5

0.18 1-5

94-112

19.3

46.0

7.4

5.7 5-10

5-10

1-5

0.17 1-5

91-109

Spectrographic analyses 4

Percent range:

5-10_____ _________

1-5 __. ______________

.5-1 ___________________

.1-.5- _________________

.05-.! _ __

.01-.05-. ______________

.005-.01. ______________

.001-005 __________

.0005-.001- ____________

.0001-0005.- __________

Ce

P, Si, La, Th

Fe, Al, Nd, Pr, Pb

Dy, Mg, Gd, Er, Y

Sm, Zr, Sr, Ca, Ni, Tm

Yb, Ho, Co, Y

B, Mn, Sc, Eu, Cu, Lu

Ba

Cr

Ag, Be

Ce

P, Si, La, Th

Pb, Fe, Al, Nd, Pr

Ti

Dy, Gd, Y, Er, Mg

Sm, Zr, Sr, Ca, Ni, Tm

Yb, Ho, Co, V

B, Mn, Sc, Eu, Cu

Lu, Ba

Cr

Ag, Be

i Sample MMMc slightly more magnetic than sample MMMd. Specific gravity 4.63 (Berman balance 

determination of several grains). 

' By Harry Levine, U. S. Geological Survey. 

« Spectrographic analyses. 

* By Katherine E. Valentine, U. S. Geological Survey.

TABLE 2. X-ray powder diffraction data of monazite from the Goodrich quartzite, 

Palmer area, Marquette County, Mich.

[X-ray data by R. O. Vickers. Spacing obtained with a diffractometer calibrated with a silicon standard. 

Copper radiation, nickel filter, speed J4° per min]

d(A)

4.79 ______ __ __

4 17

3 53

3 51

3 285

3 086

2.975.__ _______

Intensity 

estimated

1

2

 ___ _ 2

__ _ _ _____ 6

_____ ______ 2

_ -_ _4

8

______________ 10

______ __ ____ 1

Intensity 

d (A) estimated

2 Cfi7 f*

2 135 6

1 963 3

1.892. __ __ _____ _ ___________ 2

1.866 __ _____ __ _____________ 4

NOTE. The above d-values agree very closely with those calculated by Pabst (1951, p. I 

(dimensions determined by Parrish (1939, p. 651-652) for a thorium-free monazite.

from unit cell
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 181

DETERMINATION OF THE MONAZITE CONTENT OF SAMPLES OF 

GOODRICH QUARTZITE

The monazite content of all samples of Goodrich quartzite listed in 

this report was determined by comparing the beta-gamma activity 

oi the sample with prepared standards. The standards were prepared 

by separating relatively pure monazite obtained from a composite 

sample of several glacial boulders and mine dump samples of Goodrich 

quartzite and then re-mixing various proportions of the monazite 

with the crushed rock from which the monazite had been separated. 

A graph was then plotted to show the relation of the monazite content 

of the standards to their equivalent uranium content (fig. 44).

The ordinate intercept at 0.002 percent eU represents the background radiation of the quartzite and may be due in part to small 

amounts of monazite that could not be recovered in the separation.

This method of monazite determination was used because a study 

of alpha-sensitive stripping film on thin sections of the quartzite 

indicated that almost all radioactivity of the quartzite was due to

EQUIVALENT URANIUM, PERCENT INope o o 

b c:_

tn -c»ao K> oj ~.

/

/

/

/

Standard 

known

/

X

sample con 

amount of me

/

7

aining 

nazite

10 20 30 40 50 6

MONAZITE CONTENT, IN POUNDS PER TON

FinuEE 44. Graph showing relationship between equivalent uranium and monazite content of samples 

of Goodrich quartzite from the Palmer area, Marquette County, Mich.
182 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

monazite. The accuracy of the method was checked by determining 

the monazite content of a sample by three methods. The methods 

and results are tabulated below.

Monazite 

pounds 

Method per ton

Grain count of heavy liquid fraction (plus 2.96 specific gravity)_________ 36. 6

Gravity (Wilfley table) and magnetic concentrate (Frantz isodynamic

separator)______________________________________________________ 34. 9

Equivalent uranium content (from graph)____________________________ 34. 0

In using the radioactivity of the samples to determine their monazite content, it is assumed that the radioactivity of the monazite (due 

mainly to its thorium content) in the individual samples tested is 

about the same as the average radioactivity of the monazite in the 

composite sample that was used to prepare the standards, and that 

the ratio of other radioactive minerals to monazite is very low.

DISTRIBUTION

The stratigraphic position and lateral extent of the monazitebearing beds are known from (1) samples of outcrops which are mainly 

restricted to the lower 200 feet of the formation, (2) gamma-ray logs 

of three diamond-drill holes that penetrate an apparent thickness of 

1,100 feet of the Goodrich quartzite, and (3) analyses of several diamond-drill core samples.

RESULTS OF SAMPLING OF OUTCROPS

In most outcrops examined, the monazite was concentrated in 

narrow beds of pebble conglomerate from 2 inches to 2 feet thick and 

separated by beds of coarse-grained quartzite from 1 foot to 10 

feet or more thick. Samples from the coarse sand beds contained as 

much as 6 pounds of monazite per ton, whereas samples from the pebble conglomerate beds contained as much as 23 pounds of monazite 

per ton.

Eighteen chip-channel samples were taken across the beds in most 

of the outcrops which represent only the lower part of the Goodrich 

quartzite. The total of the individual stratigraphic thicknesses 

sampled was about 65 feet. However, some of the samples from 

different outcrops may represent the same stratigraphic position in 

the Goodrich, and therefore the actual stratigraphic thickness sampled 

may be considerably less. Two of the samples taken from the lower 

part of the Goodrich contained 11.5 and 17 pounds of monazite per 

ton in beds 0.5 and 0.2 foot thick, respectively. The remainder of 

the outcrop samples contained less than 6 pounds of monazite per 

ton. The weighted average monazite content of all samples taken 

from the lower 200 feet of the Goodrich was 2.9 pounds per ton.

A sample of pebble conglomerate from the only quartzite outcrop 

that is known to be more than 300 feet from the base of the formation
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 183

contained 23 pounds of monazite per ton. This outcrop is about 500 

feet east of DDH-4, near the center of sec. 29 (pi. 9). The full thickness of the pebble conglomerate bed was not exposed, and, because of 

weathering, the attitude of the beds could not be determined. A 

scintillation-counter survey of the outcrop containing the pebble 

conglomerate indicated an average monazite content of about 6 

pounds per ton.

Because of the relatively high monazite content found in many 

glacial boulders (as much as 110 pounds per ton) and from mine dump 

samples (as much as 50 pounds per ton), it was apparent that the 

higher grade monazite-bearing beds were not observed in outcrops.

RESULTS OF GAMMA-RAY LOGGING OF DRILL HOLES

Three diamond-drill holes that penetrated the Goodrich quartzite 

were logged with a portable gamma-ray logging instrument consisting 

o:: a 1- by 12-inch Geiger-Muller tube in a waterproof probe, 700 

feset of cable, and a portable survey meter. The meter deflection 

was recorded by the operator at 2-foot intervals and at all inflection 

points.

Two of the holes (DDH-3 and DDH-4) were drilled during the 

past 4 years by the Cleveland-Cliffs Iron Co. The third hole (DDH101) was drilled during the early 1900's and was recently reopened 

by the Cleveland-Cliffs Iron Co. The results of the gamma-ray 

logging are shown hi plate 10. DDH-5, also drilled many years 

ago, was logged but showed no anomalous radioactivity. This hole 

is just north of the Palmer fault and is probably in the middle Huronian 

Si amo slate. The water level in all the holes was within a few feet of 

the surface.

Because the logging reel was equipped with only about 700 feet of 

cable, the lower part of the Goodrich quartzite could be logged in 

only one drill hole (DDH-3); the gamma-ray log indicates that most 

of the radioactivity occurs more than 300 feet from the base of the 

formation. The sharp peaks of the gamma-ray logs are interpreted 

ass being caused by relatively thin beds of monazite-bearing pebble 

conglomerate that contain from 20 to 160 pounds of monazite per ton. 

These monazite-rich layers are separated by beds of coarse quartzite 

which range from a few inches to a few feet in thickness.

The fairly close correlation between the gamma-ray logs suggests 

that the zones composed of more closely spaced monazite-bearing 

beds are persistent laterally for several hundred feet in a north-south 

direction. The persistence of the zones east and west of the cross 

section can only be inferred.

Accurate calibration of the gamma-ray logs in terms of actual 

monazite content is not possible because of the many variable factors 

involved and because of the lack of enough analyzed core for standardizlng the instrument. The approximate monazite content can be
184 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

estimated, however, by comparing the results of channel sampling of 

the lower part of the Goodrich with the values obtained on the gammaray log of DDH-3. If the average gamma-ray log value for the lower 

200 feet of the Goodrich quartzite in DDH-3 is about 0.12 thousand 

counts per minute (background 0.05 thousand counts per minute), 

representing 2.9 pounds per ton, then a gamma count of 0.4 thousand 

per minute may indicate a monazite content of as much as 10 pounds 

per ton.

RESULTS OF ANALYSES OF CORE

Specimens of core representing about 3 percent of the total core 

from diamond-drill holes DDH-3 and DDH-4 were scanned with a 

scintillation counter, and several 3-inch lengths of the core were found 

to be abnormally radioactive.

The specimens were analyzed with the following results:

Field no.

MM-113-52.. _______ __ _ _ __

MM-97-53.... _ __ _______

MM-98-53.. __________________

MM-99-53.. _____________ _ __

MM-100-53________ _ ___ _ __

MM-101-53.... __ ____ _

MM-102-53 ______ _ _ _

Hole no.

DDH-4

DDH-4

DDH-4

DDH-4

DDH-4

DDH-3

DDH-3

Footage. 1

36-52

523-532

362-385

567-585

585-611

30-36

59-71

eU2

0 049

014

006

013

021

007

Oil

Monazite 

(pounds per 

ton) s

54

14

4

13

22

6

10

1 Footage is the drilled interval from which a single specimen of core was saved and does not represent 

footage of entire sample. Actual length of core samples was about 3 inches for each sample.

2 Analyses by S. P' Furman, U. S. Qeol. Survey, Denver, Colo.

3 Based on eU/monazite ratios of standard samples. (See p. 181.)

The location and monazite content of the samples are shown on the 

cross section, plate 10.

Because only a small percentage of core was available for study from 

the drill holes, the analyses of the core are of little value for quantitative appraisal. It is noteworthy that, although specimens of core from 

the lower 300 feet of the Goodrich quartzite from DDH-3 and DDH-4 

were scanned with a scintillation counter, no abnormal radioactivity 

was detected.

OCCURRENCES OF MONAZITE IN THE GOODRICH QUARTZITE 

OUTSIDE THE PALMER AREA

A brief examination with a scintillation counter was made of the 

Goodrich quartzite outside the Palmer area to determine the extent 

of the monazite-bearing beds. Outcrops of Goodrich quartzite were 

examined in several places in the Marquette trough including the 

Goodrich mine on the south side of the Marquette trough, the Blueberry mine on the north side, the Humbolt and Michigamme mines 

toward the west end, and in the city of Ishpeming in the east-central 

part of the Marquette trough. Only slight abnormal radioactivity
MONAZITE IN GOODRICH QUARTZITE, PALMER AREA, MICHIGAN 185

was detected in the Goodrich at these localities. The highest radioactivity (0.05 mr/hr, background 0.02 mr/hr) was detected in an outcrop of Goodrich quartzite in the N% sec. 20, T. 47 N., R. 27 W. A few 

grains of monazite were identified in thin sections from this outcrop, 

which is about 5 miles N. 75° W. of Palmer and is the closest occurrence 

of Goodrich quartzite in the Marquette trough to the Goodrich in the 

Palmer area.

In the Gwinn district, which is an outlier of upper Huronian rock 

about 12 miles southeast of Palmer, quartzite probably correlative 

with the Goodrich was found by L. P. Barrett to exhibit local abnormal radioactivity. The author re-examined the area briefly and 

found several local concentrations of monazite in a coarse arkosic 

quartzite that overlies and grades downward into a granite porphyry. 

Samples from this locality (SW% sec. 19, T. 45 N., R. 25 W.) contained 

as much as 9 pounds of monazite per ton. A scintillation-counter 

survey of the outcrops indicated that the monazite concentrations 

were of a very local extent.

CONCLUSIONS

The study of the occurrence of monazite in the Goodrich quartzite 

in the Palmer area, Marquette County, Mich., shows that monazite is 

concentrated in beds of pebble conglomerate from a few inches to a 

few feet thick. Sampling of outcrops, which are mainly restricted 

to the lower 200 feet of the quartzite, indicates an average monazite 

content of only about 2.9 pounds per ton, but correlation of gamma-ray 

logs of diamond-drill holes that penetrate 1,100 feet of the Goodrich 

indicates that most of the radioactivity probably occurs more than 

300 feet above the base of the formation. Individual beds of pebble 

conglomerate in glacial erratics contain as much as 110 pounds of 

monazite per ton.

The large tonnages of monazite-bearing quartzite suggest that 

this area should be considered as a potential low-grade monazite

source.

LITERATURE CITED

Lamey, C. A., 1935, The Palmer gneiss: Geol. Soc. America Bull., v. 46, p. 1137-

1162. 

Leith, C. K., Lund, R. J., and Leith, Andrew, 1935, Pre-Cambrian rocks of the

Lake Superior region: U. S. Geol. Survey Prof. Paper 184. 

Pabst, Adolf, 1951, Huttonite, a new monoclinic thorium silicate: Am. Mineralogist,

v. 36, p. 60-65. 

Parrish, William, 1939, Unit cell and space group of monazite (La, Ce, Y) PCh:

Am. Mineralogist, v. 24, p. 651-652. 

Tyler, S. A., and Twenhofel, W. H., 1952, Sedimentation and stratigraphy of

the Huronian of Upper Michigan: Am. Jour. Sci., v. 250, p. 1-27, 118-151. 

Van Hise, C. R., and Leith, C. K., 1911, The geology of the Lake Superior

region: U. S. Geol. Survey Mon. 52.

o

Wall-Rock Control of 

Certain Pitchblende 

Deposits in Golden Gate 

Canyon, Jefferson County 

Colorado

By JOHN W. ADAMS and FREDERICK STUGARD, JR.

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

»___________________________________

GEOLOGICAL SURVEY BULLETIN 1030-G

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. G. - Price 50 cents (paper coyer)
CONTENTS

	Page 

Abstract______________________________ __--_-______ 187

Introduction______________________________________________________ 187

Geology______________________________________ 190

Petrography of the wall rocks________-_---_______________-____-_ 191

Hornblende gneiss__----_-__--_---_--------_--_-__----_--_. 191

Quartz-biotite gneiss___---__-____---__-_-___--____---_--___ 191

Breccia reefs__-____----_-__-_--_---__-__-_----_---_----__- 194

Ore deposits,_______________-___-_________--_-____---______-_-_-__ 195

Union Pacific deposit____------------__-------___--_---___---_- 195

Mineralogy of the ore--_---_----__--_---------_---------___ 195

Ore minerals__-______----__-___-_--____-__---__---------_- 195

Gangue minerals..------._-______--__-_-__---____-----__-_ 199

Paragenetic history_____________ __ ________________ 200

Wall-rock control at the Union Pacific deposit______________ 202

Buckman adit deposit__--_-_---------_--__-_-------_----------- 205

Discussion of pitchblende deposition.________________________________ 206

Conclusions_____________________________________________________ 207

Literature cited _____.__________.__________________--______-_-_.__ 208

ILLUSTRATIONS

Page 

PLATE 11. Geologic map and section of the Union Pacific deposit,

Jefferson County, Colo__--_----_________-______-_- In pocket

12. A, Photomicrograph of thin section of ore from Union Pacific

deposit; B, Photomicrograph of polished section____ Faces 198

13. Photomicrographs of polished sections_________ ____ Faces 199

FIGURE 45. Index map of central Colorado showing location of Golden

Gate Canyon and Ralston Creek areas._________________ 188

46. Geologic sketch map showing distribution of uranium occurrences in the Golden Gate Canyon area, Jefferson 

County, Colo___________________________ 189

47. Camera lucida drawing of ore showing localization of tennantite by earlier pyrite-________-___.______-______- ___ 198

48. Chemical changes during alteration of gneiss___________-___ 201

49. Paragenesis of the minerals at the Union Pacific deposit.___ 203

50. Geologic map of adit, Buckman deposit ___________________ 205

in
IV CONTENTS

TABLES

Page 

TABLE 1. Rock analyses, Union Pacific deposit, Jefferson County,

Colo__________________________________-______-._______ 192

2. Spectrographic and uranium analyses of rocks and ore,

Golden Gate Canyon area_____________________________ 193
CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

WALL-ROCK CONTROL OF CERTAIN, PITCHBLENDE

DEPOSITS IN GOLDEN GATE CANYON, JEFFERSON

COUNTY, COLORADO

By JOHN W. ADAMS and FREDERICK STUGARD, JR.

ABSTRACT

Carbonate veins cutting metamorphic rocks of Precambrian age in the Golden 

Gate Canyon area, Colorado, contain pitchblende and base-metal minerals. 

The veins occupy extensive faults considered to be of Laramide (earliest Tertiary) 

age, but normally contain pitchblende only where they cut hornblende gneiss. 

At the Union Pacific deposit, which was studied in detail, pitchblende, hematite, 

and some ankerite formed before the sulfide minerals, except possibly for minor 

earlier pyrite. Base-metal minerals and the bulk of the ankerite vein filling 

were deposited after the pitchblende. Chemical analyses show a high ferrous 

iron content in the hornblende gneiss in contrast to low ferrous iron in the adjacent biotite gneiss. It is thought that ferrous iron released by alteration of 

hornblende was partly oxidized to hematite by the ore-bearing solutions and, 

contemporaneously, uranium was reduced and deposited as pitchblende.

In other veins that are not in hornblende gneiss, biotite or iron sulfide may 

have been similarly effective in precipitating pitchblende. Apparently both 

the ferrous ion and the sulfide ion can serve as reducing agents and control pitchblende deposition. Conditions that seem favorable for uranium deposition 

include those where uranium-bearing solutions had access to rocks rich in ferrous 

iron or preexisting sulfide minerals.

INTRODUCTION

Pitchblende and secondary uranium minerals are found in vein 

deposits in northern Jefferson County, Colo. The deposits, which 

were recently discovered, occur in or near Laramide fault zones that 

cut gneiss, schist, and pegmatite of Precambrian age. They have 

been found in two areas about 6 miles apart (fig. 45); the northern 

or Ralston Creek area contains the Schwartzwalder (Ralston Creek) 

mine now being actively worked, the North Star mine, the Nigger 

Shaft, and several other more recently discovered deposits. Eight 

occurrences of uranium minerals are known in the southern or Golden 

Gate Canyon area and include the Union Pacific, Buckman, and 

Ladwig deposits. Pitchblende is the most abundant uranium mineral

187
188 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

oJomestown 

BOULDER

RALSTON CREEK AREA \

CANYON AREA

s 

Golden Idaho

Springs Clear , Creek 

Georgetown I

CLEAR CREEK I

FIGURE 45. Index map of central Colorado showing location of Golden Gate Canyon and Ralston

Creek areas.

in the deposits and is associated with copper minerals in a carbonate 

gangue with quartz and potash feldspar. Lead and zinc minerals 

are present in the ore but are not abundant.

A preliminary investigation of these deposits (Adams, and others, 

1953) was made in 1952-53 as part of the study of uranium deposits 

undertaken by the U. S. Geological Survey on behalf of the U. S. 

Atomic Energy Commission. During this study it was noted that 

most of the occurrences of uranium minerals and of high radioactivity 

anomalies in the Golden Gate Canyon area (fig. 46) were found where 

fault zones crossed a single bed of hornblende gneiss 100-150 feet 

thick. No significant radioactivity has been found along the same 

fault zones where they pass through other rocks.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 189
190 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

As the preliminary data indicated "favorable" and "unfavorable" 

rock types, further investigations were made to establish, if possible, 

the reason for the apparent wall-rock control. Although the field 

and laboratory studies of this problem were concerned primarily 

with the Golden Gate Canyon area, notably the Union Pacific deposit, the results may be found applicable to uranium occurrences in 

other environments. For the present investigation, a map was 

made on a scale of 1 inch to 1,000 feet (fig. 46) to show the distribution of the known uranium occurrences in relation to the hornblende gneiss beds and breccia zones. A geologic map of the 

Ralston Buttes quadrangle (scale, 1:24,000), which includes the 

Golden Gate Canyon and Ralston Creek uranium areas, is now in 

preparation by the U. S. Geological Survey.

GEOLOGY

The rocks in the Golden Gate Canyon area include Precambrian 

hornblende gneiss, quartz-biotite gneiss, granite gneiss, quartzite, 

and pegmatite. Intrusive rocks of Tertiary age, such as are found 

in the Central City district (Phair, 1952), have not been recognized.

Hornblende gneiss and quartz-biotite gneiss are the rock types 

most closely associated with the uranium deposits. Both are similar 

in outcrop appearance and show distinct foliation that strikes about 

N. 80° E. and dips steeply north. These rocks are cut by several 

northwestward-trending faults characterized by carbonate-potash 

feldspar vein filling. The faults presumably are of Laramide age 

and are related to the highly siliceous breccia "reefs" or "dikes" of 

similar trend mapped by Lovering and Goddard (1950). One such 

fault on the west side of Golden Gate Canyon in sees. 24 and 25 

(fig. 46) probably is a southern extension of the Hurricane Hill breccia 

reef, a structure that has been traced for almost 20 miles to the northwest (Lovering and Goddard, 1950, pi. 2). The relationship between 

the breccia reefs and the uranium deposits will be discussed in another 

section of this report.

The geology of. an area including and extending north of Golden 

Gate Canyon has been mapped by Gabelman * on a scale of about 

1 inch to 850 feet. As a result of his work, Gabelman believed the 

granite gneiss to be the marginal facies of a granitic intrusion lying 

south of Golden Gate Canyon and the other metamorphic rocks to 

represent the south limb of a large truncated synclinal fold. The 

other limb of the fold is believed to lie several miles to the north.

i Gabelman, J. W., 1948, The geology of the Golden Gate-Van Bibber Creek area, Jefferson County, 

Colo.: Unpublished thesis in flies of Colo. School of Mines, Golden, Colo.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 191 

PETROGRAPHY OF THE WALL ROCKS

Field studies indicate that most of the uranium deposits in Golden 

Gate Canyon occur in hornblende gneiss in an area of predo:tnmant 

quartz-biotite gneiss; therefore these rocks were studied in detail by 

petrographic, spectrographic, and chemical methods. These two 

types of rocks are described below.

HORNBLENDE GNEISS

In the area studied, hornblende-plagioclase-quartz gneiss occurs 

in two main beds about 100 feet thick and in a few narrow layers in 

the adjoining quartz-biotite gneiss. The rock, which will be called 

hornblende gneiss, is fine grained and well foliated and in outcrop 

appears black or dark gray. Hand specimens show banding or 

layering of dark and light minerals, but these bands generally do not 

exceed a few millimeters in thickness. Biotite may be abundant 

along individual foliation planes, but it is a minor constituent of the 

rock. At the Union Pacific deposit, and presumably elsewhere, the 

rock contains small epidote-bearing lenses and a few narrow quartz 

stringers, neither sufficiently abundant to affect the bulk composition 

of the rock. The hornblende gneiss is uniform in composition as 

determined by examination of several thin sections; three typical 

modes are as follows:

Percent by volume 

Hornblende_______________________ 41 48 50

Plagioclase (andesine)_________.____ 42 35 37

Quartz_________________________ 14 14 10 

Opaque minerals____--____-_____-___-__-__ 222

Others.._______________________ 111

Apatite is the most abundant nonopaque accessory mineral. "Biotite, 

as previously noted, is common along some foliation planes and may 

be of secondary origin. Sphene, zircon, and garnet are less common 

than apatite. The opaque minerals as determined by polished-section 

methods and X-ray powder patterns are chiefly ilmenite and nmgnetite 

containing minor amounts of pyrite and chalcopyrite. Th& magnetite and ilmenite may be partly altered to hematite.

The results of chemical and spectrographic analyses of channel 

samples of the hornblende gneiss are given in tables 1 and 2,

QUARTZ-BIOTITB GNEISS

The term quartz-biotite gneiss is applied in this report to the bulk 

of the layered metamorphic rocks adjoining the hornblende gneiss 

beds in the Golden Gate Canyon area. They are, for, the most 

part, lighter in color than the hornblende gneiss and tend to be more 

massive with fewer foliation planes per unit thickness. Although 

variable in mineral proportions, all are characterized by the presence

384541 56 2
192 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

of biotite and the absence of hornblende. The fabric of the quartzbiotite gneiss layers commonly is granoblastic but may be locally 

gneissic. The following mode is typical of the granoblastic rock in 

the vicinity of the Union Pacific deposit:

Percent by volume

.___________._ 30 

___.______._..._.____.. 50

Quartz. _______ _________

Plagioclase (albite-oligoclase).

Biotite. 

Others.

20

Apatite is the most abundant accessory mineral in the rock represented by this mode, but, including zircon and opaque mineral grains, 

constitutes less than 1 percent of the total composition. Calcite, 

sphene, clinozoisite, and epidote have been noted in the thin sections. 

In the less common gneissic beds, most of the biotite is restricted 

to thin bands separated and commonly crosscut by layers of quartz, 

plagioclase, and microcline. The laminated rock apparently was 

derived from the injection of silicic igneous material into the granoblastic quartz-plagioclase-biotite gneiss. Thin and polished sections 

show that the biotite rocks contain about one-third as much opaque 

material as the hornblende rocks and that most of this is magnetite 

or magnetite-hematite intergrowths. The results of the spectrographic and chemical analyses of a composite sample representing 

100 feet of the biotite gneiss at the Union Pacific deposit are given in 

tables 1 and 2.

TABLE I. Rock , Union Pacific deposit, Jefferson County, Colo. 

[Lucille M. Kehl, analyst]

Field no.

JWA-64-53 

JWA-77-53...

JWA-82-53...

JWA-73-53...

JWA- 3-54...

Field no.

JWA-64-53...

JWA-77-63...

JWA-82-63...

JWA-73-63...

JWA- 3-54...

Description of rock

Hornblende gneiss. Composite sample representing 25.8-foot chip channel. East side of fault zone.

Hornblende gneiss. Chip channel

across 11.4 feet of gneiss 130 feet west

of fault zone.

Altered hornblende gneiss. Chip

channel across 5 feet of altered rock

underlying JWA-77-53. 

Breccia "reef" material. Composite

sample of fresh rock from mine

dump.

NajO

3.87

3.28

3.32

2.46

.21

KiiO

2.52

.79

.67

3.30

7.13

HjO0.10

.30

.27

1.93

.15

H»0+

0.72

1.35

1.33

3.74

.23

TiOj

0.45

1.41

1.58

1.72

.81

SiOj

68.92

54.86

55.78

51.70

32.87

COj

0.09

.05

.04

.17

20.58

AljOa

14.55

14.65

13.82

18.06

9.10

PiO»

0.13

.31

.41

.25

.36

Fe»O8

1.95

4.66

4.85

12.36

.45

8

0.02

.02

.01

.01

MnO

0.08

.22

.24

.28

.29

FeO

2.89

7.99

8.55

.16

10.57

Total

100.04

99.96

100.05

99.70

100.38

MgO

1.50

3.40

2.84

1.15

5.60

Less 

OforS

0.01

.01

.......

CaO

2.25

6.67

6.34

2.41

12.03

Adjusted 

total

100.03

99.95

.........
TABLE 2. Spectrographic and uranium analyses of rocks and ore, Golden Gat

[A single asterisk (*) indicates Spectrographic analysis by G. W. Boyes, Jr. A double asterisk (**) 

Field no. Description of sample eU Al Fe Ti Mn Ca

JWA-64-53..

JWA-82-53..

JWA-73-53. 

JWA- 3-54-

JWA-90-53-. 

JWA-92-53..

JWA-94-53.. 

UP- 4-52..

*Biotite gneiss. Composite of chip 

samples at Moot intervals for 100 

feet.3

*Hornblende gneiss. Channel sample across 11.4 feet.3

*Altered hornblende gneiss.'.._...

*Breccia reef material; 5-pound 

dump sample from Union Pacific 

deposit.3

**Hurricane Hill reef; 12-foot channel 

sample west of Buckman adit.3

**Reef 750 feet WNW of Union Pacific deposit; 3-foot channel sample.'

**Reef 700 feet NW of Union Pacific 

deposit; 40-inch channel sample.3

*Pitchblende-bearing ore from 

Union Pacific deposit.3

20.002

iOOl 

z.OOO

8.009 

«.006

'.004

« 0.004 

8.001

«.001

XX. 0

XX 

XX

x+

XX 

XX

XX

XX. 0

XX

XX 

X

x+

X

X.O

x+ 

x+

X

x+

X

x+

X

O.X

.X 

.X

.X 

.X

0. OX+ X. 0-

.X X+

.X

 OX+X

.X- 

.X-

. OX+ X+

.X x+

Field no. Co Cr Cu Ga La Mo Nb Ni Pb Sb 

JWA--64-53 ....

JWA-82-53 _. 

JWA-73-53......

JWA-3-54 ....

JWA-90-53.......

JWA-92-53 

JWA-94-53-. 

UP- 4-52..-..

O.OOX- 

.OOX- 

.OOX 

.OOX- 

.OOX- 

.OOOX+ 

.OOOX+

o.oox- 

.ooox

.OOOX+

.oox-

.ooox-

.oox

.oox

.00x4-

O.OOX 

.OOX+

.oox 

.ox 

.oox 

.oox 

.ooxX

Tr.

.oox- 

.ooxTr.

.OOOX+ 

.OOOX+ 

.OOOX+ 

0

Tr.

0

0

0

0

.OOX 

.OOX

0 

0

Tr.

.OOX+ 

0 

0 

0

.ox

0

0

0

0

.oox- 

.oox

Tr.

0. OOOX+

Tr.

.OOOX+ 

.OOX- 

.OOX- 

.OOX- 

.OOX-

.ooox

0. OOX0 

Tr.

.OOX

.OOX-

.oox- 

.oox0 

0 

0 

0 

0 

0 

0 

.X

o

.

.

-

-

.

.

.

i The concentrations are reported as elements, not as oxides or compounds. 

The following classification is used for the Spectrographic data, in percent:

XX =>10 

X+=4 64-10 

X =2.15-4.64 

X-=1.0-2.15

.X+=0.46-1.0

. X *=0.215-. 464

.X-=0.10-215

Tr. = Near threshold amount.

* Analysts: J. W. 

' Other elements l

Hg, In, Ir, Li, Nd, O

^ Analyst: J. W. 

6 Analyst: S. P. F

6 Analysts: Jesse 
194 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

BRECCIA REEFS

The composition and character of the breccia reefs are of special 

interest because the uranium deposits are believed to be genetically 

related to them. The major reefs are presumably the southern 

extensions of structures along which faulting and silicification took 

place during the Laramide orogeny (Lovering and Goddard, 1950, 

p. 216-217). There is, however, a marked difference between the 

composition and appearance of the reefs to the north as compared 

with their presumed southern extensions. The northern reefs are 

highly siliceous and ferruginous and form resistant wall-like outcrops 

composed chiefly of iron-stained quartz. The southern reefs are 

not siliceous but consist of carbonate-potash feldspar as a finegrained groundmass enclosing rock fragments that have been replaced in varying degrees by these minerals. Because of its carbonate 

content, the reef material is subject to more rapid chemical weathering than the country rocks, and good outcrops are uncommon. 

Typical exposures are reddish brown, and breccia fragments stand 

out in relief above the groundmass; the color is the result of the 

oxidation of iron from ankerite. Where unweathered, the rock is 

almost white and is compact and tough.

The chemical and spectrographic analyses of reef material (tables 

1 and 2) show that it contains abundant potash. Part of this potash 

can be attributed to the included wall-rock fragments, but much 

presumably has been introduced. The reef material from the shaft 

at the Union Pacific deposit contains many fragments of the enclosing hornblende gneiss. These fragments retain the fabric of the 

gneiss, but of the original mineral components only quartz remains. 

The hornblende has been converted to an extremely fine grained 

material, presumably carbonate, and the plagioclase is replaced by 

potash feldspar, possibly by a base-exchange reaction.

The fine-grained groundmass of the reef material is probably composed of a carbonate having the approximate composition of ankerite, 

and an orthoclase-type feldspar. These two minerals, followed by 

later calcite, apparently are the products of a widespread introduction of hydrothermal solutions into not only the major faults but 

also the many presumably contemporaneous smaller subparallel 

fractures.

It was formerly thought (Adams, and others, 1953, p. 8) that 

the copper and uranium minerals found along the reefs were introduced late in the period of carbonate deposition. The study of the 

Union Pacific deposit now makes it appear more likely that the principal ore minerals were introduced early in the hydrothermal process 

and that the bulk of the fault-filling occurred after ore deposition.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 195

The scope of this investigation did not permit more than a limited 

study of the reefs, but it is apparent that a better understanding of 

these structures would be of material aid in the search for additional 

uranium deposits. If the carbonate-potash feldspar reefs are extensions of the siliceous reefs, a significant temperature-zoning pattern 

might be established to delineate areas favorable for uranium 

deposition.

ORE DEPOSITS

Except for some recently discovered occurrences in the Ralston 

Creek area, the known uranium vein deposits in northern Jefferson 

County have been described by Adams and others (1953). For this 

reason mention will be made of the geology of only those deposits 

reexamined for the purposes of this investigation; namely, the "Union 

Pacific and Buckman adit deposits.

UNION PACIFIC DEPOSIT

At the Union Pacific deposit (pi. 11), pitchblende and base-metal 

minerals occur along the hanging wall of a carbonate-potash feldspar 

reef which cuts hornblende gneiss. The pitchblende-bearing rock 

exposed in the mine workings is less than half a foot thick but may 

contain as much as 5 percent uranium. Only the leached oxidized 

exposure of the vein is now accessible because the shaft is filled, with 

water. So far as is known, the ore is confined to the hornblende 

gneiss, which at the deposit forms a steeply dipping bed about 100 

feet thick. Quartz-biotite gneiss lies above and below the hornblende-gneiss unit.

MINERALOGY OF THE ORE

The ore mineral assemblage at the Union Pacific deposit may be 

representative of the uranium deposits in the two areas. Whether 

the mineralogy of an individual deposit is simple or complex, the 

association of pitchblende with copper sulfide and arsenide minerals 

is persistent. The ore minerals are also characterized by a finegrained texture in which individual mineral grains commonly are 

less than a millimeter in diameter and may require polished-section 

techniques for identification and study.

ORE MINERALS

Pitchblende. Pitchblende is the only uranium mineral that has 

been found at the deposit. In polished section it shows a uniform 

high reflectivity and gray color somewhat lighter than tennantite 

with which it is commonly associated. The pitchblende is seldom 

recognizable to the unaided eye unless it is present in the form- of
196 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

films which may be several millimeters thick and occupy fractures 

in iron-stained altered gneiss. These pitchblende films commonly 

include minute euhedral crystals of carbonate and may coat crystals 

of potash feldspar (pi. 12A) that have grown from the walls of fractures. Ore showing pitchblende films contains only sparse sulfides and 

probably formed in the outer edge of the ore zone. In a more common 

type of ore, the pitchblende, which is not discernible without the 

use of the ore microscope, occurs in colloform masses that 

commonly are less than 0.1 millimeter in diameter and densely coat 

crystals of ankerite of comparable dimensions (pi. 121?). The pitchblende-ankerite veinlets are irregularly distributed through intensely 

altered wall rock and are replaced in varying degrees by later sulfide 

minerals (pi. 13 A). This second type of ore probably formed in 

the fractured wall rock near the central channelway, but this could 

not be confirmed because of the present inaccessibility of the pitchblende-bearing area in the Union Pacific shaft.

Hematite. Finely dispersed hematite gives the hydrothermally 

altered rocks of the deposit a characteristic brick-red color. It 

appears to be most abundant in the altered feldspar and was formed 

from iron progressively released first from the hornblende and later 

from chlorite. Like pitchblende, hematite was deposited on some of 

the vein orthoclase crystals. This hematite formed aggregates 

of transparent bright-red crystals. Platy intergrowths of hematite 

and pyrite replace hornblende or the opaque minerals of the gneiss. 

These intergrowths are the centers for deposition of late copper 

minerals.

Tennantite. Tennantite, probably the most abundant copper 

mineral in the deposit, occurs in discontinuous veinlets that rarely 

exceed 1 millimeter in width. In polished section the tennantite 

is light gray and gives a red powder when scratched. The mineral 

probably is in the tennantite end of the tetrahedrite series because 

of the 4:1 arsenic to antimony ratio in a typical specimen of the ore. 

As no other arsenic-antimony minerals are known in the ore, the ratio 

is assumed to apply to the tennantite. The identification was confirmed by X-ray powder pattern.

Chalcopyrite. Chalcopyrite, which is next to tennantite in abundance, replaces the earlier pitchblende-carbonate veinlets. The 

textural relationship observed in polished sections indicates that 

chalcopyrite was deposited both before and after tennantite. The 

early chalcopyrite is found in fine-grained intergrowth with bornite, 

covellite, galena, sphalerite, and emplectite(?). These intergrowths 

appear as isolated patches engulfed by tennantite. The late chalcopyrite commonly occurs as rims or as isolated grains along the 

margins of tennantite areas. Where the rim structure is formed,
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 197

chalcopyrite has apparently invaded existing interfaces between 

tennantite and pitchblende. Shrinkage of the pitchblende and 

formation of concentric and radial cracks may have afforded channels 

through which the chalcopyrite could migrate and replace the, carbonate gangue of the early pitchblende veinlets. Plate 135 shows 

a relatively large carbonate crystal almost completely replaced by 

chalcopyrite.

Bornite, chalcocite, and covellite. Bornite, chalcocite, and covellite 

are the three most abundant minerals of the early sulfide assemblage. 

Except for the presumably supergene replacement of much of the 

bornite and chalcocite by covellite, the relationship is problematical. 

The bornite commonly contains blades of chalcopyrite in a textural 

pattern that has been ascribed to exsolution (Edwards, 1947, fig;. 79); 

the chalcopyrite of these intergrowths does not extend beyond the 

grain boundaries of the bornite.

Sphalerite. Sphalerite is sparse in the ore, appearing as irregular 

grains that have a brown, mottled, nonmetallic appearance with 

crossed nicols. The largest sphalerite grain seen in polished specimens of the ore was approximately 0. 3 millimeter in maximum dimension. Sphalerite probably was one of the early suite of sulfide 

minerals, more abundant before replacement by tennantite and late 

chalcopyrite.

Galena. Galena is commonly associated with sphalerite but is 

the less abundant of the two minerals. Like sphalerite it is considered one of the early-formed minerals.

Emplectite. Emplectite (CuBiS2) was tentatively identified in 

the ore. The mineral occurs intergrown with chalcopyrite in irregular 

patches in tennantite. The emplectite(?)-chalcopyrite intergrowths 

are extremely fine grained and, without high magnification, appear 

as a single mineral resembling chalcopyrite but of a somewhat paler 

color. Under high magnification, the chalcopyrite is seen to be 

intergrown with a mineral that is pale cream-yellow and shows 

brownish-green and violet interference colors. The mineral has a 

hardness about that of chalcopyrite and stains brown with HNO3.

Material removed from the pale yellow areas gave a microchemical 

reaction for bismuth. The powder tested unavoidably included 

some of the surrounding tennantite, but when tennantite apparently 

free of these minerals is similarly tested it reacts for antimony rather 

than bismuth. Spectrographic analysis of ore from the deposit 

indicates that bismuth is present in the same relative abundance as 

arsenic (table 2). As little emplectite(?) was found in the polished 

sections studied, it is probable that some bismuth may be contained 

in the tennantite.

Pyrite. Pyrite is not abundant in the ore, and where present is 

found in minute grains intergrown with hematite. These intergrowths
198 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

EXPLANATION

Pyrite partly replaced by 

chalcopyrite and tennontite

Altered gneiss

Chalcopyrite Carbonate vein let

FIQUEK 47. Camera lucida drawing of ore showing localization of tennantite by earlier pyrite.

probably are relics of some of the original iron-bearing minerals of 

the hornblende gneiss. The shape of many of these intefgrowths 

suggests that they were originally hornblende, but others may represent 

ilmenite or magnetite grains; these are commonly associated with 

leucoxene. The pyritization was probably an early reaction between the host rock and the first solutions introduced into th« fault 

zone. Where the pyrite-hematite grains are transected by veinlets 

containing copper minerals, replacement of the pyrite is discernible
BULLETIN 1030 PLATE 12

* - W" fr-

'/.. ;> . tfj ^^SF^;*^

^. PHOTOMICROGRAPH OF THIN SECTION OF ORE FROM UNION PACIFIC DEPOSIT 

Shows pitchblende (p) coating orthoclase (o) crystals formed on altered wall rock (ivr). Plain light, X 80.

B. PHOTOMICROGRAPH Of POLISHED SECTION

Shows typical pitchblende (p) ankerite (a) intergrowth, containing tennantite (t) and 

chalcopyrite (cp). X 1190.
GEOLOGICAL SURVEY BULLETIN 1030 PLATE 13

A. Shows pitchblende (p) coating ankerite (a), both replaced by tennantite (t) and chalcopyrite (cp). X 580.

B. Shows replacement of ankerite crystal (a) by chalcopyrite (cp) marginal to tennantite (t). 

Gray areas are pitchblende (p). X 580.

PHOTOMICROGRAPHS OF POLISHED SECTIONS
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 199

(fig. 47), and no additional pyrite appears to have been deposited 

until the end of hydrothermal activity.

Very small grains of pyrite, probably deposited after the bulk of 

the ore minerals, are found throughout the main mass of the ankeritic 

breccia filling. These pyrite grains surround small calcite-filled 

cavities and fractures and probably represent the final stage of metallization. Deposition of pyrite rather than chalcopyrite, and calcite 

rather than ankerite, indicates that the solutions had become impoverished in copper and iron.

GANGTJE MINERALS

Only a few gangue minerals of hydrothermal origin have been 

recognized in the ore. These include the carbonate minerals, ankerite 

and calcite, potash feldspar, chlorite, and minor sericite. Although 

quartz is a common constituent in the ore, and to a lesser degree in 

the carbonate vein filling, the rounded or fragmental grains are 

presumably derived from the wall rocks. Some vein cfliartz, however, 

has been noted in the Ralston Creek deposits.

Carbonate minerals. A carbonate mineral close to ankerite in 

composition is common in the ore and breccia and for the most part 

was introduced after the ore minerals. Together with potash feldspar 

and pitchblende, ankerite makes up the early pitchblende-bearing 

veinlets. Little gangue was deposited with the copper minerals, 

and replacement of earlier carbonate minerals by chalcopyrite and 

tennantite is common. After deposition of the copper minerals, 

ankerite was formed abundantly until the reef filling was nearly 

complete. Then minor amounts of calcite were deposited. The 

ankerite was identified by X-ray powder pattern and is readily distinguished from calcite by staining with potassium ferrocyanide. 

Hydrothermal alteration of the hornblende in the wall rocks has 

produced an extremely fine grained white aggregate believed to be 

largely carbonate minerals.

Potash feldspar. Potash feldspar is a characteristic mineral 

of the breccia and the associated pitchblende deposits. The exact 

nature of the feldspar has not as yet been determined, but it is presumably a variety of orthoclase, possibly adularia. Some grains, 

however, show an optic angle (2 V} estimated to be between 20° 

and 30° so that an unusual type of feldspar may be present. Birefringence of the mineral is very low. The widespread distribution 

of potash feldspar in the altered wall rock and breccia filling is strikingly shown by staining rock slices or uncovered thin sections with 

sodium cobaltinitrite solution (Gabriel and Cox, 1929) and is further 

confirmed by the potash content of these rocks (table 1).
200 CONTRIBUTIONS TO THE GEOLOGY OF I

The orthoclase occurs both as replacements of anhedral plagioclase 

grains in the hornblende gneiss and as small crystals formed on 

fragments of brecciated gneiss. The crystals surrounding the breccia 

fragments are clear and transparent by comparison with the cloudy 

orthoclase (pi. 12A) formed by replacement. No euhedral orthoclase 

crystals have been recognized in the main mass of the carbonate vein 

filling, but the rock contains innumerable fragments of altered gneiss 

in which orthoclase is abundant. The observed relationship of 

orthoclase in the deposit leads to the conclusion that potash was 

introduced during the early stage of hydrothermal activity.

Chlorite. A green mineral presumed to be a member of the chlorite 

group forms very fine grained aggregates in the ore and is relatively 

abundant below the zone of oxidation in the altered gneiss of the 

hanging wall. In a specimen of this gneiss containing pitchblende, 

the chlorite is confined to the pitchblende-coated gneiss fragments 

that have been isolated by carbonate veinlets. The chlorite and 

associated seribite are evidently products of a propylitization-type 

of rock alteration that preceded the introduction of uranium. Gneiss 

fragments in the carbonate breccia underlying the chlorite-bearing 

gneiss contain no chlorite, and it is assumed that the minerals of the 

earlier propylitization were largely destroyed by chemical action of 

concentrated carbonate-bearing solutions.

PARAGENETTC HISTORY

Studies of thin and polished sections of the rocks and ores indicate 

that a complex series of events was effective in the formation of the 

deposits.

Formation of the major faults and many other subsidiary fractures, 

such as that at the Union Pacific deposit, presumably took place 

during early Tertiary time. Open parts of these structures then 

became channelways for the migration of alkalic solutions of unknown 

source but of sufficient volume to deposit carbonate throughout 

fault zones miles long and from 1 to 20 feet wide. The effect of these 

solutions in regard to the ore deposition and wall-rock alteration will 

be considered here.

The first process in the formation of the ore is thought to have been 

propylitization of the hornblende gneiss. This resulted in the partial 

conversion of hornblende to chlorite and some sericitization of plagioclase. The sulfide ion concentration of the solutions was probably 

low as only a very little pyrite was formed from the breakdown of 

the iron-bearing minerals, thus permitting any excess iron to deposit 

as hematite.

The extent of the original propylitization is indicated by the outcropping zone of bleached gneiss, 2-5 feet thick, lying above the
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 201

Iron oxides 

Percent

.12.03

CoO 

Percent

6.34_.

1

2.41

No20 332 

Percent I

2.461 ' .0.21

K2O 

Percent I

3.30

--.7.13

C0 2 

Percent

0.04

2058

FIGURE 48. Chemical changes during alteration of gneiss.

central carbonate breccia filling; the footwall bleached zone is not 

as well exposed but is probably of comparable width.

Following, or perhaps during, propylitization, solutions were introduced that raised the potash content of the gneiss from less than 1 

to more than 3 percent (fig. 48). The added potash is in part contained in small clear crystals of orthoclase that line fractures in the 

rock, but as much or more of the potash may be replacing the soda 

of the original plagioclase. This alteration of the plagioclase is shown
202 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM '

by the distribution of potassium as indicated by staining and also 

by the decreased soda content of the gneiss after alteration (fig. 48). 

The replacement of plagioclase by potash feldspar has been described 

by Fenner (1936) and Steiner (1953) as a process of rock alteration 

resulting from hot-spring activity.

The precipitation of uranium followed potassic alteration and 

coincided with the beginning of a carbonate phase. This is shown 

by the deposition of pitchblende on orthoclase crystals and its intergrowth with ankerite. The reduction of U*6 ions to U+* by the 

Fe+2 ions released by the breakdown of (1) hornblende and (2) chlorite probably caused the precipitation of uranium. Gruner (1952) 

has experimentally produced pitchblende and hematite by reduction 

of TJ+6 by Fe+2 ; hematite formed only when the pitchblende was 

synthesized in an H2S-free environment. In the ore deposit, pitchblende and hematite (later ankerite) were deposited at essentially 

the same time and before the formation of the sulfide minerals with 

the exception of the very minor pyrite formed during propylitization.

After depletion of the available uranium, several simple copper 

sulfide minerals, sphalerite, galena, and emplectite(?) were deposited 

in an intricate network of fractures that only in part follow the 

original pitchblende-bearing veinlets. Deposition of these sulfide 

minerals was followed by tennantite replacement. It is questionable 

whether this replacement was part of a continuous period of sulfide 

deposition or whether a "rest interval" took place. Polished-section 

relationships favor discontinuity with a new wave of solution containing arsenic and antimony in addition to copper and iron migrating 

along the margins of preexisting veinlets. On the depletion of the 

arsenic and antimony, sufficient copper remained so that chalcopyrite again formed locally throughout the tennantite and along grain 

boundaries of tennantite and other minerals. With the deposition 

of chalcopyrite the sulfide mineralization waned, and a vigorous 

carbonate phase began which was to continue until the close of 

hypogene activity. The bulk of the carbonate deposited was extremely fine grained ankerite, succeeded at the last by somewhat 

coarser grained calcite. The calcite, which is sparse, forms veinlets 

and fills cavities in the ankerite. Minute pyrite crystals that formed 

along the edges of the calcite-filled openings indicate that a very 

weak sulfide phase marked the transition between the two carbonate 

minerals. Figure 49 is a graphic representation of the paragenesis of 

the deposit.

WALL-ROCK CONTROL AT THE UNION PACIFIC DEPOSIT

The ore occurrence at the Union Pacific deposit is, so far as is known, 

confined to hornblende gneiss wall rocks. This localization, repeated
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 203

MineralsN\Propylitization/' Vein stage 

\ stage /

Pyrite

Chlorite

Leucoxene

Ankerite

Potash feldspar

Pitchblende

Hematite

Chalcopyrite

Bornite

Chalcacite

Sphalerite

Galena

Emplect!te(?)

Tennantite

Calcite

-

.

-

? »_ »

? ~-~

?___.

 

-

 - p to

_____ § 

^ _ __ ^

?-

-

-

 

Covellite Presumably supergene

Malachite Supergene

Azurite Supergene

FIQUBE 49. Paragenesis of the minerals at the Union Pacific deposit.

at several other uranium occurrences in the area, seems to be a result 

of the composition and texture of the wall rock.

As discussed under "Paragenetic history," the deposition of uranium probably was effected by the oxidation of ferrous to ferric iron. 

Analyses of the two rock types (table 1) show that the hornblende 

gneiss contains almost four times as much ferrous iron as the biotite 

gneiss. Field observations and thin section studies indicate that 

the hornblende gneiss was readily altered by the solutions introduced 

along the fault, and that hornblende, the dominant iron-bearing 

mineral of the rock, was especially subject to attack. The writers 

believe that the release and subsequent reprecipitation of iron from 

hornblende provided an effective mechanism for uranium deposition.

The nature of the iron-bearing mineral probably was of little consequence, providing it was reactive and present in sufficient quantity. 

Thus a rock rich in biotite might be just as effective a precipitant as
204 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

one containing its iron equivalent as hornblende. In the Joachimsthai District, Czechoslovakia, pitchblende has been observed to be 

more abundant where the wall rocks of the veins were rich in biotite 

(Everhart and Wright, 1953).

A direct comparison of the iron content of rocks as a measure of 

their effectiveness in uranium deposition should be qualified by a 

consideration of the availability of the iron-bearing mineral to contact with the vein fluids. This availability will be a function of 

(1) the degree to which the rock is shattered and hence its surface 

area, (2) the relative solubility of the other mineral components, 

and (3) the texture of the rock.

No opportunity was afforded to compare the shattering of the two 

rock units at the deposit as the biotite gneiss is not well exposed in 

the vicinity of the fault zone. Comparison may be made, however, 

between the rocks in regard to their relative solubility and texture.

The persistence of quartz in highly altered hornblende gneiss indicates that quartz was not readily attacked by the hydrothermal 

solutions. Modal analyses show that the biotite gneiss contains 

from two to three times as much quartz as the hornblende gneiss, 

and hence, in spite of a somewhat higher plagioclase content, the 

biotite gneiss should be the more resistant of the two rocks.

While the rocks classed as biotite gneiss in this report contain layers 

that are markedly gneissic, they are for the most part granoblastic. 

In contrast, the hornblende gneiss is uniformly foliated and contains 

closely spaced layers of light and dark minerals. It would seem 

reasonable that where vulnerable minerals are alined in almost continuous planes, as in the hornblende gneiss, they would be more 

accessible to the invading solutions than where randomly distributed 

throughout the rock.

The relative abundance of metallic minerals, chiefly ilmenite, in 

the hornblende gneiss was first considered by the writers as a possible 

factor in the localization of uranium. Ilmenite, and some magnetite 

and hematite, constitutes about 2 percent of the unweathered gneiss 

but is not found in the altered gneiss of the ore zone. Instead, the 

ore contains intergrowths of pyrite and hematite, and white opaque 

grains of leucoxene. Many of these probably were derived from the 

ilmenite, although some of the pyrite-hematite intergrowths may 

represent earlier hornblende. As ilmenite contains ferrous iron, 

its oxidation to hematite would favor uranium deposition, but probably 10 times as much ferrous iron was available from the more abundant hornblende. Although the ilmenite probably was of negligible 

importance in the deposition of uranium, the pyrite-hematite intergrowths were to some extent effective in precipitating copper.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 205

BUG KM AN ADIT DEPOSIT

The occurrence of pitchblende and secondary uranium minerals 

at the Buckman adit deposit (fig. 46) differs from others in the Golden 

Gate Canyon area in that it is not in hornblende gneiss and is not 

known to be closely associated with a carbonate-potash feldspar 

reef. Instead, the uranium minerals occur in narrow shears that cut 

biotite gneiss, pegmatite, and a discontinuous sulfide-bearing quartz 

vein. The pitchblende is most abundant where a fault sheared the 

quartz vein and it is only sparsely present in the adjoining gneiss. 

The locality is about 300 feet east of a wide carbonate-potash feldsparbearing structure that is presumed to be the southern extension of 

the Hurricane Hill reef.

This apparently anomalous occurrence is probably the result of 

the interaction of uranium-bearing solutions with the sulfide-bearing 

quartz vein, the vein supplying both the structural and chemical 

control for ore deposition.

Movement along small faults sheared the gneissic rocks to some 

extent, whereas the vein was shattered into a breccia of angular 

quartz fragments in which sulfide grains were embedded. This 

zone of brecciated quartz, by reason of its greater permeability, 

provided a favored channelway for the uranium-bearing solutions.

The quartz vein is exposed in the adit as two major segments about 

20 feet long (fig. 50) and small intervening stringers or lenses all 

roughly concordant to the enclosing biotite gneiss. Pyrite, chalcopyrite, and molybdenite occur sparsely in the central part of the

Pitchblende in shear

'oter-filled winze, 

about 25 ft deep

dashed where inferred

_____( 90

Vertical contact

where approximately located

Limit of exposure on surface

Strike and dip of foliation

_S3

Strike and dip of joints

Geology by J. W. Adams, August 1952

FIGURE 50. Geologic map of adit, Buckman deposit, Jefferson County, Colo.
206 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

quartz bodies but are relatively abundant along their margins in 

selvage zones containing biotite and magnetite. Some of the sulfide 

minerals adjoin magnetite grains from which they may have been 

derived in part. Hematite and an iron-bearing carbonate replace 

some of the sulfide grains. The pyrite, chalcopyrite, and molybdenite probably represent a period of mineralization unrelated to 

the uranium-bearing veins, and possibly of Precambrian age.

The pitchblende-bearing breccia differs from the ore found at the 

Union Pacific deposit; copper minerals are sparse and carbonate 

minerals have not been noted. Pitchblende and hematite are the 

most abundant metallic minerals hi the ore. Pitchblende, showing 

typical colloform structures, occurs as rims around the brecciated 

quartz fragments, many of which were later sheared and offset. 

Hematite is interstitial to the pitchblende-coated grains, replaces, 

quartz and sulfide, and veins the pitchblende.

Chalcopyrite, pyrite, and covellite occur in small residual grams; 

in the hematite. Minute grams of an unidentified mineral that may 

be tennantite are present in some quartz fragments and in the interstitial material. Whether any of these sulfides are relics of the 

original quartz-vein minerals has not been determined, but, in any 

event, only a little copper was introduced with the uranium.

Radial aggregates of uranophane crystals line cavities in the hematite and fill fractures in quartz grains; the fractures appear to have 

been enlarged by uranophane replacement of the quartz.

By comparison with the Union Pacific deposit, the occurrence at 

the Buckman adit deposit may represent only the first stages of the 

complete sequence of metallization possible from the solutions that 

invaded the faults. Mineral deposition did not progress far beyond 

the pitchblende-hematite stage, as shown by the relative paucity of 

copper minerals and the absence of the ankerite phase after ore deposition. This relatively brief "life cycle" probably resulted from an 

early choking-off of the narrow channelway by pitchblende and 

hematite.

Precipitation of the pitchblende is thought to have been effected 

by the iron-bearing minerals in and adjacent to the quartz vein. 

Pyrite, chalcopyrite, biotite, and magnetite were all available to the 

solutions moving up the pipelike channel afforded by the sheared 

vein and provided a source of ferrous iron which, through oxidation 

to hematite, could precipitate uranium.

DISCUSSION OF PITCHBLENDE DEPOSITION

Wall-rock control similar to that at the Union Pacific deposit was 

probably effective at all the pitchblende occurrences in the hornblende gneiss beds (fig. 46) in Golden Gate Canyon.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANTON 207

The formation of such pitchblende-hematite-carbonate deposits 

apparently requires an environment relatively free of sulfide ions so 

that Fe+2 can be oxidized to Fe+3. In comparing the pitchblende 

deposits of the Theano Point area, Ontario, with that of the Caribou 

mine in Colorado, Wright (written communication, 1950) states:

The predominance of calcite gangue in the uranium-bearing veins of the Theano 

Point area and the virtual absence of sulfides suggest that the oxidizing action of 

carbon dioxide in the mineralizing solutions, and the small amount of sulfur which 

could act as a reducing agent may provide a partial explanation for the abundance of hematite adjacent to the vein. The almost complete absence of hematite 

in the wall rock of the Caribou occurrence, which is rather rich in sulfides and 

where the gangue is predominantly silica rather than calcium carbonate, is in 

agreement with this explanation.

In the Ralston Creek area (fig. 45) two of the known deposits, the 

Nigger Shaft and North Star, are associated with hornblende gneiss. 

The pitchblende deposit at the Schwartzwalder (Ralston Creek) 

mine, currently being worked, was not studied in detail during these 

investigations, but the writers believe that pitchblende localization 

may be related to the distribution of a tourmaline-garnet skarn-type 

rock that accompanies the more abundant quartz-muscovite schist 

or phyllite of the mine area. The skarn rock, severely bleached and 

altered in the ore zone, may have provided ferrous iron either from 

tourmaline or from primary sulfide minerals.

The role of early sulfide minerals in uranium deposition has not 

been established by this investigation, but these minerals are thought 

to have been contributory at the Buckman adit deposit and may have 

been important at the Copper King deposit in northern Colorado 

described by Sims and Phair (1952). At this deposit, pitchblende 

of Tertiary age occurs in a pyrite-sphalerite ore body genetically 

related to Precambrian granite. Gruner (1952) describes the synthesis of pitchblende by the reaction between iron sulfide and a 

solution of uranyl sulfate. In these experiments, performed at temperatures of about 200° C and under acidic conditions, oxidation of 

sulfur but not iron was detected. "Sooty" pitchblende is commonly 

associated with pyritic ore, such as that found at the Copper King 

deposit, and may be the result of a sulfur oxidation reaction. Where 

hematite has been coprecipitated with pitchblende, as at the Buckman adit deposit, iron oxidation and uranium reduction is indicated 

as the more probable process for uranium deposition.

CONCLUSIONS

The detailed study of the Union Pacific deposit indicates that the 

abundance and availability of oxidizable iron-bearing minerals in 

the wall rocks may determine whether uranium deposition will take
208 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

place. Hornblende has been shown to be an effective source of ferrous 

iron, but other minerals, such as biotite, may serve equally well.

Pitchblende, accompanied by hematite and minor early ankerite, 

was deposited in advance of all sulfide minerals except for possible 

minor amounts of pyrite at the Union Pacific deposit. During the 

period of sulfide mineralization, pitchblende was not deposited; 

and locally it was replaced. Evidence indicates that the requirements for uranium deposition were fully met only during the initial 

stage of mineralization where the sulfide ion concentration of the 

incoming solutions was low.

The studies made during this investigation lead to the conclusion 

that pitchblende-bearing veins of the carbonate type may be expected 

where ample ferrous iron is available in the wall rocks. The difference in the available ferrous iron of the hornblende gneiss and biotite 

gneiss beds is thought to have resulted in the localization pattern 

exhibited by the pitchblende occurrences in the Golden Gate Canyon 

area.

This conclusion may be of some value in prospecting for uranium 

in areas of comparable geologic environments; the nature of the ferrous iron-bearing mineral is probably unimportant so that no special 

significance should be placed on the presence of hornblende. Biotite, 

magnetite, tourmaline, and iron sulfide minerals may be equally 

effective where present in sufficient quantity. In a sulfide environment, conditions resulting in the oxidation of either iron or sulfur 

may precipitate pitchblende. This implies that conditions favorable 

for uranium deposition are presented where uranium-bearing solutions 

have access to sulfide-bearing rocks.

LITERATURE CITED

Adams, J. W., Gude, A. J. 3d, and Beroni, E. P., 1953, Uranium occurrences in 

the Golden Gate Canyon and Ralston Creek areas, Jefferson County, Colo.: 

U. S. Geol. Survey Circ. 320.

Edwards, A. B., 1947, Textures of the ore minerals and their significance: Australasian Inst. Min. and Metallurgy, Melbourne, 185 p.

Everhart, D. L., and Wright, R. J., 1953, The geologic character of typical pitchblende veins: Econ. Geology, v. 48, p. 77-96.

Fenner, C. N., 1936, Borehole investigations in Yellowstone Park: Jour. Geology, 

v. 44, no. 2, pt. 2, p. 225-315.

Gabriel, Alton, and Cox, E. P., 1929, A staining method for the quantitative 

determination of certain rock minerals: Am. Mineralogist, v. 14, no. 8, 

p. 290-292.

Gruner, J. W., 1952, New data of synthesis of uranium minerals: U. S. Atomic 

Energy Comm. Tech. Inf. Service, RMO-983, Oak Ridge, Tenn.

Lovering, T. S., and Goddard, E. N., 1950, Geology and ore deposits of the Front 

Range, Colo.: U. S. Geol. Survey Prof. Paper 223, 319 p.
WALL-ROCK CONTROL OF PITCHBLENDE, GOLDEN GATE CANYON 209

Phair, George, 1952, Radioactive Tertiary porphyries in the Central City district,

Colo., and their bearing upon pitchblende deposition: U. S. Atomic Energy

Comm. Tech. Inf. Service, TEI-247, Oak Ridge, Tenn. 

Sims, P. K., and Phair, George, 1952, Geology of the Copper King mine area,

Prairie Divide, Larimer County, Colo.: U. S. Atomic Energy Comm.

Tech. Inf. Service, TEI-311, pt. 1, Oak Ridge, Tenn.

Steiner, A., 1953, Hydrothermal rock alteration at Wairakei, New Zealand: 

t Econ. Geology, v. 48, no. 1, p. 1-13.

U. S. GOVERNMENT PRINTING OFFICE: 1956

Uranium in Black Shale 

Deposits, Northern 

Rocfky Mountains and 

Great Plains

By W. J. MA^EL

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-H

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 55 cents (paper cover)
Abstract-.-.

Introduction 

Purpose 

Acknow 

Field work a 

Summary of 

Descriptions 

Black si 

Black si 

Heath s 

Literature ci 

Index_____-

CONTENTS

and location. _ ____ _____ _________________ ___________

nd use and interpretation of the gamma-ray logs __________

the results of the investigation. ______ ____ ___ ____ ___.

of selected black shale deposits____ _____________________

lale at the base of the Madison limestone and equivalents. _ _ 

lale at the base of the Brazer limestone. __________ ______

hale _______ _____ _ __ ______________________________

ted _____ ___ _________ ___ _ ______________ _____

TT T TTCimT-l A mT/~VTVTCI

Page 

211 

211 

211 

213 

213 

215 

219 

219 

230 

230 

233 

235

PLATE 14. 

15.

FIGURE 51.

52.

53.

54.

[Plates 14 aud 15 iu pocket.]

Index map showing black shale localities examined for uranium, northern Rocky Mountains and Great Plains.

Map and sections showing thickness and radioactivity of the 

Bakken formation (as used by Nordquist, 1953), northern 

Great Plains.

Locations of selected wells for which gamma-ray logs were 

studied. _ __________________________________________

Sections showing uranium content of basal black shale of 

Mississippian age at outcrops in the northern Rocky 

Mountains region___________________________________ 229

Sections showing uranium content of black shale at the base of

the Brazer limestone, Utah and Idaho __________________ 231

Thickness and distribution of the Heath shale in central 

Montana and the Heath shale and Otter formation in 

eastern Montana and adjacent parts of North and South 

Dakota-___________________________________ 232

Page

214

TABLES

Page 

TABLE 1. Selected wells in northern Great Plains for which gamma-ray

logs were studied_____________________________________ 216

2. Radioactivity of formations containing black shale in selected

oil and gas wells, northern Great Plains. __________________ 217

3. Analytical data and outcrops examined-____________________ 220

m

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIUM IN BLACK SHALE DEPOSITS, NORTHERN 

ROCKY MOUNTAINS AND GREAT PLAINS

By W. J. MAPEL

ABSTRACT

Reconnaissance examinations for uranium in 22 formations containing black 

shale were made in parts of Montana, North Dakota, Utah, Idaho, and Oregon in 

1953. Ab^ut 150 samples from 80 outcrop localities and 5 oil and gas wells were 

submitted for uranium determinations. Most of the black shale deposits 

examined contain less than 0.003 percent of uranium; however, thin beds of black 

shale at the base of the Mississippian system contain 0.005 percent of uranium 

at 2 outcrop localities in southwestern Montana and as much as 0.007 percent 

of uraniura in a well hi northeastern Montana. An 8-foot bed of phosphatic 

black shale at the base of the Brazer limestone of middle and late Mississippian 

age in Ric^i County, Utah, contains as much as 0.009 percent of uranium.

Commercial gamma-ray logs of oil and gas wells drilled in Montana and adjacent 

parts of the Dakotas indicate that locally the Heath shale of late Mississippian 

age contains as much as 0.01 percent of equivalent uranium, and black shales of 

Late Cretaceous age contain as much as 0.008 percent of equivalent uranium.

INTRODUCTION

PURPOSE AND LOCATION

TA reconnaissance search for uranium in black shale in the northern 

Rocky Mountains and Great Plains regions was carried out during the 

summer of 1953 by the U. S. Geological Survey on behalf of the 

Division of Raw Materials, U. S. Atomic Energy Commission. The 

work is part of a continuing program to investigate the uranium 

possibility of untested or incompletely tested black shale deposits in 

the Western States. Most of the localities visited are in southwestern 

and central Montana, central and southeastern Idaho, and northwestern Utah. About 150 gamma-ray logs from wells drilled for 

oil and gas in Montana and adjacent parts of North and South

211
212 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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URANIUM IN BLACK SHALE DEPOSITS 213

Dakota were scanned for anomalous radioactivity, and samples of 

drill cores or cuttings from 5 of the wells were submitted for uranium 

determinations. Plate 14, the index map, shows the localities visited, 

and the table above shows the formations examined.

Previous work by Duncan (1953) indicated that the Heath shale of 

late Mississippian age and a thin black shale sequence of early Mississippian age called variously the Bakken formation (as used by 

Nordquist, 1953), the shale of Kinderhook age, or the Exshaw formation (Warren, 1937) at some places contain abnormally large amounts 

of uranium. Particular attention was given to a systematic sampling 

of these formations in an attempt to define areas of maximum or 

minimum radioactivity which might then be related to facies changes, 

source areas, thickness, or other factors that reflect environments of 

deposition.

Black shale of the Phosphoria formation of Permian age is known 

to contain uranium in the northern Rocky Mountains region, but it 

was excluded from the study because it has been sampled extensively 

as part of a separate investigation by the Geological Survey.

AC KNO WLED GMENTS

The present investigation is a continuation of previous reconnaissance studies made at various times since 1951 in the Rocky Mountains region, as reported by Duncan (1953).

D. C. Duncan, R. J. Ross, J. E. Smedley, R. P. Kunkel, P. W. 

Richards, and H. D. Hadley supplied samples of black shale or guided 

the writer to exposures of shale in Utah and Montana. W. J. Hail, 

Jr., compiled information from the gamma-ray logs and assisted in 

interpreting the results of this work. Radiometric and chemical 

analyses listed in this report were made in Geological Survey 

laboratories.

FIELD WORK AND USB AND INTERPRETATION OF THE 

GAMMA-RAY LOGS

Outcrops of black shale described in the geologic literature or in 

unpublished reports available to the writer were examined for radioactivity at about 80 localities. Estimates of radioactivity were made 

in the field using a portable scintillation detector or a Geiger counter. 

At most of the localities, representative samples of the formation 

were collected for uranium determinations regardless of the observed 

radioactivity. At a few localities, however, only those parts of the 

 formation which showed appreciable radioactivity were sampled.
214 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Roads between outcrops were traversed with a car-mounted scintillation counter, and those areas with higher than average background 

were examined on foot with the portable instruments.

The examination of gamma-ray logs of wells drilled for oil or gas 

provides a convenient means of evaluating the uranium possibilities 

of many black shale formations which otherwise might be difficult to 

test because of poor natural exposures or broad outcrop areas. Gott 

and Hill (1953), in a study of commercial gamma-ray logs of uncased 

wells drilled in the Rangely field, northeastern Utah, found that, on 

the average, a 1-inch deflection of the Lane Wells gamma-ray curve 

at a 10-inch sensitivity scale is caused by about 0.0007 percent of equivalent uranium. They pointed out that variations in this value might 

be caused by such factors as the ratio of thickness to grade of the bed 

tested, the fluid content of the well, the shielding effect of casing in 

cased wells, differences in individual logging instruments, and the 

rate of movement of the ionization chamber. The calibration, therefore, is only approximate, but it gives some measure of the order of 

magnitude of radioactivity of the formations penetrated, and it is 

useful in comparing the radioactivity of the rocks from place to place.

Tables 1 and 2 list 15 wells drilled in Montana and the Dakotas 

and indicate the average and maximum deflections on the gamma-ray 

logs of formations containing significant amounts of black shale. The 

locations of these wells are given in figure 51. Gamma-ray logs of

I 

i

c A N A D A _____ 

""" " ! . 5

, RT 

I D A 1 

M O N *6 T A_ N A ^

! NORTH 

1 DA KOTA

! SOUTH

, ~ DAKOTA 

WYOMING

50 0

. Locations of selected wells for which gamma-ray logs were studied (table 1).
URANIUM IN BLACK SHALE DEPOSITS 215

other wells examined but not listed in tables 1 and 2 show comparable 

radioactivity values.

SUMMARY OF THE RESULTS OF THE INVESTIGATION

Uraniferous deposits of black shale thus far found in the northern 

Rocky Mountains and Great Plains regions are either deeply buried 

and inaccessible, or they are too thin or of too low grade to be of 

value at this time as a source for uranium. Only a few of the deposits 

contain more than 0.003 percent of uranium. Of these few, beds of 

black shale at the base of the Madison limestone of early Mississippian 

age contain 0.005 to 0.007 percent of uranium at three localities in 

Montana and one in North Dakota (Iocs. 43, 44, 82, and 85, pi. 14), 

and 4 feet of a bed of black shale 8 feet thick at the base of the Brazer 

limestone of middle and late Mississippian age contains 0.009 percent of 

uranium at one locality in Rich County, Utah (loc. 30). The analyses 

of samples collected at these and other localities are listed in table 3.

The evaluation of gamma-ray logs of oil and gas wells, as shown by 

table 2, suggests that the Heath shale of late Mississippian age locally 

contains 0.009 percent of equivalent uranium or more hi Musselshell 

and McCone Counties, Mont., and that the Colorado and Pierre 

shales of Cretaceous age contain as much as 0.008 percent of equivalent 

uranium hi Blaine County, Mont., and in Perkins County, S. Dak., 

respectively. No drill cores or cuttings from these wells were available for analyses, and so the actual uranium content of the shale is 

unknown.
TABLE 1. Selected wells in northern Great Plains for which 

Well no.

(%. 51)

1

2 

3

4 

5

6

7

8

9

10 

11

12

13 

14

15

Shell-Little Beaver 21-24-... _ ....

Farmers Union Central ExchangeBunge 1.

Farmers Union Central ExchangeThompson 1. 

Shell-Pine Unit 1...................

Cities Service-K. E. Huffine 1......

Marigold Oil, Ltd.-Farnham 1......

Texas-Davis Ranch 1. _______

Deep Rock Oil CorporationPicard 1. 

Gulf-R. L. Cornwell I..... .,....

Continental-Fast 1 _________

General Petroleum-Erickson 

36-12P. 

Shell-H. D. Veal L ..._.....__.__

Amerada-Harry Bakken 1 ..........

Location

Sec., T.f R., county, and State

Central part NEJ£NWM-24-4N-61E,

Fallen. Mont. 

Central part NEJ£NEJ^-31-9N-35E, 

Rosebud, Mont. 

Central part SEJiNEJ£-22-llN-27E,

Musselshell, Mont. 

SW part SWJ£SWM-7-llN-31E, Mu[)_ 

selshell, Mont. 

SW part SWMNE^-30-12N-57E, Wibaux. Mont. 

Central part SWJ£SEJ£-27-17N-15E,

Fergus. Mont. 

Central part NEJ£NEM-18-23N-4E,

Chouteau, Mont. 

Central part SWMSWM-14-25N-48E,

McCone, Mont. 

Central part SEJ£SWK-4-29N 18Ej

Blaine, Mont. 

Central part NWWNEJi-6-29N-58E, 

Roosevelt. Mont. 

Central part SWMNEJ£-14-30N-38E,

Valley. Mont. 

Central part NEMSEJ£-14-30N-46E,

Roosevelt, Mont. 

SW part NEJ£SWM-12-36]Sr-15E, Hill, 

Mont. 

Central part SEJ£SEJ£-7-17N-15E,

PGrkins S Dak 

Central part' SW^NEM-12-157N-95W,

Williams, N. Dak.

Gamma-ray 

log availableProm To 

(feet) (feet)

0 8,873

24 4,353 

3, 550 3, 800

0 5, 035 

0 9, 746

0 6, 014

0 3, 606

5, 000 8, 953

0 4, 921

5, 600 9, 028 

0 7, 037

50 6, 312

0 6, 312

0 8,315

6, 100 13, 715

O

K

..

M

W

..

..
URANIUM IN BLACK SHALE DEPOSITS 217

TABLE 2. Radioactivity of formations containing black shale in selected oil and? 

gas wells, northern Great Plains

Well no. 

(flg. 51) Bock unit

Depth (feet)

From To 

Thickness of 

unit 

(feet)

Gamma-ray

defle<Jtion.

converted to 

sensitivity of 

10 (inches)

Aver- MaxiDepth in 

well of 

TnjHriinriTn

deflection 

(feet)

Estimated

TnnTJTTHTTn

eUi 

(percent)

Cretaceous rocks

1

2

4

5

6

7

9

11

12

13

14

Claggett ... ... ...

Carlile ..............

Muddy and Skull 

Creek, undivided ....

Claggett and youngerEagle _ .... ..

Frontier and Mowry,

Claggett 

Greenhorn and Belle

Bow Island (of Perry, 

1937)- 

Greenhorn. Belle 

Fourche, and Mowry. 

Skull Creek. .

200

2,160

2,788

2,915

3,460

3,710

3,850

1,117

3,032

0

396

807

2,577

1,135

2,368

2,928

3,705 

3,945

200

1,484

0

1,030

0

2,449

0 

955

1,390

1,842

2,617

2,764

1,525

1,950

2,150

3,050

3,250

3,430

3,900

880

1,550

2,020

*> vn

3,105

600

2,560

3,044 

3,60

3,853

2,160

2,788

2,915

3,460

3,680

3,850

4,100

2,952

3,273

396

807

2,472

2,903

2,368

2,928

Of IWO

3,945 

4,365

1,426

1,990

1,030

1,602

2,449

2,724

955 

1,390

1,842

2,585

2,764

3,148

1,950

2,150

3,050

3,250

3,430

3,590

4,094

1,550

2,020

2,503

3,105

3,737

2.560

3,044

3,605 

3,853

4,037

1,960

628

127

545

220

140

250

1,835

241

396

411

1,665

326

1,233

560

240 

420

1,226

506

1,030+

572

a 44QJ_

275

955+ 

435

452

743

147

384

425

200

900

200

180

160

194

670

470

483

602

632

1,960

484

561 

248

184

3.0

3.7

3.6

3.7

3.1

3.4

2.6

4.8

2.3

3.0

4.1

4.9

3.1

2.2

3.0

3.3

3.0 

2 4

5.0

3.2

2.7

2.2

6.0

4.4

2.0 

3.5

4.0

3.3

3.5

3.0

2.7

3.0

3.4

3.7

4.1

3.7

3.4

3.4

4.6

5.1

5.1

4.2

4.8

5.0

6.2 

0.8

4.

4.8

5.7

4.7

5.7

4.9

4.0

3.7

7.3

8.0

5.1

5.7

8.0

5.0

3.4

4.5

.8

4.0 

4.3

8.2

6.0

4.5

4.5

10.9

6.7

3.3 

4.2

6.7

5.9

4.2

5.7

5.1

3.6

5.7

5.8

6.6

5.4

4.4

4.6

6.5

7.7

7.4

6.0

11.0

8.5

10.0 

9.2

6.7

1,899

2,210

2,860

3,335

3,540

3,811

3,908

2,161

3,151

319

805

1,629

2,738

2,255

2,900

O, 4DV

3,935 

3,955

6412

1,890

200

1,331

1,183

2,498

1,319

1,405

2,029

2,6ft

2,88]

1.85J

. 2,015

3,03i

3,246

3,34!

3,525

3.92J

1,38!

2,460

2,760

2,800

3,488

2,212

2,561

3,480 

3,610

3,872,3,89

0.003

.004

.003

.004

.003

.003

.003

.005

.006

.004

.004

.006

.004

.002

.003

.003 

.003

.006

.004

.003

.003

.008

.005

.002 

.003

.004

.004

.003

.004

.004

.003

.004

.004

.005

.004

.003

.003

.005

.005

.005

.004

.008

.006

.007 

.006

.003

»1-inch deflection=0.0007 percent eU on 10-inch sensitivity scale.
218 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 2. Radioactivity of formations containing black shale in selected oil and 

gas wells, northern Great Plains Continued

Well no. 

(fig. 51) Rock unit

Depth (feet)

From To 

Thickness of 

unit 

(feet)

Gamma-ray 

deflection, 

converted to 

sensitivity of 

10 (inches)

Average

Maximum

Depth in 

well of 

maximum 

deflection 

(feet)

Estimated 

maximum eU » 

(percent)

Jurassic rocks

1

2

4

5

6

10

11

12

13

14

 do..................

.....do.................

. .do.......... .......

 do.................

 do...... ..... ..... .

..... do..... ......

 do ..........

- do.. . . .

... ..do .... ... .....

4,100

3,273

2

QAO

1,990

4,365

5,600

3,148

4,315

3,737

4,037

4,180

3,473

3,120

2,245

4,405

4, 655

4,116

80

200

917

4/1

402

14

340

23

70

3.6

3.3

3.1

3.8

1.8

3.4

3.3

3.7

2.7

5.3

6.6

8.5

4.7

6.4

2.4

4.1

3.7

3.9

3.1

6.2

4,118

3,400

2,922

2,239

4,400

5,661

3,155

4,491

3,738

4,088

.005

.006

.003

.004

.002

.003

.003

.003

.002

.004

Mississippian and Pennsylvania!! rocks

Minnelusa______.

Amsden_______.

Big Snowy group__.

Amsden of local usage..

Heath_..............

Amsden of local usageHeath..................

Amsden of local usage..

Heath_...._____.

Minnelusa______.

Amsden...__.......

Big Snowy group__.

Heath______ _

Otter...__....__..

Amsden._______

Heath and Otter formations, undivided..

Amsden...............

Heath and Otter formations, undivided..

Bakken (as used by 

Nordquist, 1953) 

Big Snowy group......

Englewood.............

Heath and Otter formations, undivided..

Bakken (as used by 

Nordquist, 1953) 

5,700

5,870

6,070

4,017

4,233

3,550

3,747

3,604

5^820 

6,230 

6,374 

2,817 

3,050 

5,650

5,755

7,437

4,940; 

5,182 

6,495

6,900

9,613

5,870

6,070

6,372

4,233

4,325

3,747

3,800+

3,976

4,622

6,230

6,374

7,118

3,050

3,395

5,755

5,990

7,437

7,929

4,976 

5,432 I 

6,570

7,340

9,721

170 

200 

302 

216

92 

197

53+ 

372 

646 

410 

144 

744 

233 

345 

105

235

441

492

36

250

75

440

108

3.1

2.7 

2.9 

1.3 

2.7 

2.2 

3.2 

2.4 

3.0 

1.8 

1.8 

2.7 

3.0 

3.0 

2.3

2.5 

2.3

2.9

5.8, 

6.0

4.6:

9.0

7.1 

5.3 

4.0 

4.8 

4.7 

4.3 

5.9 

8.5 

12.7 

3.6 

3.6 

7.5 

6.6 

8.4 

4.7

15+5, 

5.7

9.5

9.0 

8.8

7.8

5,870

5,903

6,118

4,136

9,280

3,558

3,750

3,930

4,045

6,227

6,356

6,550

2,940

3,169

5,745

>,767, 5,775 

7,304

7,529

4,971

5,358

6,504

7,005 

13+9,625, 9,700

Devonian rocks

7

8

13

14

15

Three Forks ...........

.....do.... .......

.....do... ..............

Devonian, undiflerentiated...... __.__.____

Qu'appelle group (of 

Baillie, 1953) 

2,780

7,930

4,976

6,570

9,724

3,130

8,030

5,030

6,822

9,916

350

100

54

252

192

1.5

4.8

5.1

3.7

3.7

6.3

6.2

6.9

8.0

6.0

3,006

7,972

5,008

6,715

9,798

.004

.004

.005

.005

.004

Ordovician rocks

5

13

14

15

Winnipeg (upper part) .

 .do. __ .. ___ ..

..... do ... ... .... .

.... .do ... .... .......

9,520

6,285

9,527

13,395

9,662

6,312

9,666

13, 562

142

25+

139

167

7.8

9.2

6.6

6.3

10.6

10.0

10.4

8.0

9,535

6,309

9,635

13,453, 13,466

.007

.007

.007

.004

' 1-inch deflection=0.0007 percent eU on 10-inch sensitivity scale.
URANIUM IN BLACK SHALE DEPOSITS 219

DESCRIPTIONS OF SELECTED BLACK SHALE DEPOSITS

BLACK SHALE AT THE BASE OF THE MADISON LIMESTONE AND

EQUIVALENTS

A black shale sequence of early Mississippian (Kinderhook) age, 

which ranges in thickness from a few inches to as much as 100 feet, 

occurs locally at the base of the Madison limestone or its equivalents 

in southwestern and central Montana and in the Williston basin *of 

Saskatchewan, Manitoba, Montana, and the Dakotas. The term 

"Bakken formation" has been used to identify this unit in the subsurface 

in the Williston basin, where it is described by Nordquist (1953, p. 72) 

as mainly "two thin highly radioactive black shales separated by a 

grey calcareous sandstone, siltstone, or dolomite." According to 

Nordquist, the upper shale unit may be correlative with a bed of 

black shale, a few inches to 30 feet thick, which occurs at the base of 

the Madison or Lodgepole limestones in various parts of southwestern 

Montana ahd Utah. The lower shale and medial sandstone-dolomite 

units may correlate with the Sappington sandstone as used by Holland 

(1952), a shale and sandstone sequence as much as 60 feet thick, 

which occurs below the Madison limestone in parts of southwestern 

Montana. In southern Canada, equivalents of the basal shale unit 

and medial sandstone-dolomite unit of the Bakken formation, as used 

by Nordquist (1953), are regarded by him to correlate respectively 

with the Exshaw shale (of Warren, 1937) and the basal sandstone of 

the overlying Banff formation (of McConnell, 1887). In most parts 

of the northern Rocky Mountains region, the Bakken formation (as 

used by Nordquist, 1953) and its equivalents unconformably overlie 

the Three Forks or Jefferson formations of Late Devonian age, and 

they are conformably overlain by limestone of the Madison or Lodgepole formations, or McConnell's Banff formation, all of early Mississippian age.
TABLE 3. Analytical data and outcrops exa

[n. d. c., not determined chemically]

Locality no. 

(PL 14)

Location (Sec., T., R.) Bock unit

Laboratory 

sample 

no.

Equivalent 

uranium 

(percent)

Ur

(pe

Precambrian rocks: Idaho

4

5

6

7

8

9

25-46N-2W.

27-48N-2W. 

21-49N-1W..... ...... ........ .......

3 and 4-48N-H3E. 

12-49N-4E..... ____._..__._....,___.

14-49N-5E. ........ ..... ....

.....do..................--... ..

.....do ..... -.. .... 

..... do.......... ........ ......... .

 . .do................ ......

 .do... ..- --. .-

98503

98506

0.001

(«)

(>)

0)

.002

0)

(n

(n

Precambrian rocks: Montana

32

33

48

49

22-14N-4W. 

3&-13N-W .... ..,. ... ..

Broadwater County _______ ..,,

30-7N-4E. 

20-7N-5E.... .. . . . ..........

.do . .. ... .

.... .do i... ...

94788

94150

94161

94162

0.002

.001

.002

.004

(n

(n

(n

Cambrian rocks: Idaho

Ouster County___. 

SWH-16-13N-18E. 

NEH-3-12N-18E..

Bear Lake County...

12-13S-42E. 

Oneida Cdiinty. __

35-14S-56E.

Garden Creek phyllite. 

.. ...do... ............

Spence shale....._... 

. .do..................

97044 0.003 (n

97045 .003 (n

97024 .002 (n

97023 .002 (n

97042 .003 (n

97043 .003 (n
Cambrian rocks: Utah

25 

28

10-14N-2E. 

SWM-4-11N-4E.. .................. , .do..... .......... ....... ...

97039 

97040 

97041 

97038

0.003 

.001 

.002 

.005

(n

(n

(n

Cambrian rocks: Montana

39 

46

NWM-14-3S-5W.

22-5N-1W.

Unidentified--.-.......... .-..

97012 

94790

0.005 

.002(n

Ordovican rocks: Idaho

12 

13

14 

15

NEJ4-28-11N-17E. 

5-11N-17E. ___ ...

SWM-24-10N-17E. 

Unsurveyed 15 miles northeast of 

Ketchum.

Saturday Mountain formation. . . 

 do 

Phi Kappa formation-. ..........

97046

97047 

97052 

97053

0.003 

(')

.003 

.003 

.003

(n

(n

(n

(n

Ordovician rocks: Utah 

26

27

NWJ4-5-14N-4E. 

NEH-18-12N-3E... ... . . .do.................. --.

97026 

97024 

97031

97030

97029 

97028

0.004 

.004 

.003

.003

.003 

.003

(n

(n

(n

Not sampled.
222 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

3

fl

33

0 

O

4<o

.g

g t*

§ i

«0 1

1 i

s i

1 § 5® Q ITS

S 0

e fl "^ J

1 * £ ^

53> . fl.

^

8

7CO

H

S

fl

'§a

fl

"H ifw

£ §3 t>s

Is®>-|§

pa

J

1 ^

JP

 ^*3

B

 a

«§

rt

CO,

fl

tg

1

 §§3

Sgs

a

e

1

s

ii

I

n

1^

o

oT

.g

81

aj . "a a

OoJ1

3J5

a 10. 

S 05

° o

S s a*

" §

Q w>

§8

C5 '

||

O

ss11

^os

1bfi ft

.1

^

S

!

Tx-;

§|

*?5

R0 §

°s

^gj3 

S 03

S

_ II11

J

"pT3 0> 4)^ *

m f-j r-3 © O

°8 Ji3fl.& rt § ^i 1231 r

 as! 5-2 S-NS? aS en fi ft« gJ-Sa

03 O'C! P

& "STS

u> o5 5 « £« ^ Si

WOO

BBS

1-

8§

O5 OcO 

(^ Oi W

O «

s g

Channel samp 

shale: Top 6 ft.Next ft.5ft. Next6Next 6ft.

Bottom f.7 

Channel sample black shale.

ggc 

fcoc

S 3

a a 

 3 18

a a 

S S

§

S> rt 0> 3§-a

^X3 2^3 

,p tn,Q oa

o o

£

Wi'.S 

|!5^ s?l?

|So^

f^IW

gCQ ^15
36

37

38

40

41

42

43

43

44

61

64

65

78

70

80

81 

82

NEM-5-7N-12W ... .......... .

SWM-4-7N-12W....... .............

NEM-34-9S-8W.

NEM-13-3S-5W.

NWM-16-1N-2W. 

Gallatin County _ -... _ __

11-11&-3E. 

SWM-25-2N-2E... . .

.......do.................... ... 

SEM-2-2N-2E..... ...... .....

9-13N-17E.

SWK-8-12N-18E. ..................

32-12N-19E _ ..............

5-25N-24E. 

2-26N-24E.. ................. __ ...

22-26N-25E. _ _ . .

Daniels County, SW1A-12-36N-47E 

(Carter-Danielson well 1).

Roosevelt County, NE14-2-28N-51E,

(Murphy and others-East Poplar 

well 1).

....-do. .... .....-...........

.....do...... ....... ...............

... ..do . .- ...... ....

... ..do..... .. . ....-.. ...

.....do..... ...... ...-..-........._

 ..do... ._-_.-.. .. .........

Holland, 1953). 

.....do..... ...... ..............

.....do...-..... .-..-.,

 ..do.- .. ..

... ..do...... . _... .......

..... do ...

Bakken formation (as used by 

Nordquist, 1953).

..... do .......................

94153 

94154 

' 94151

94152

97015

97016 

97013

94148

94147 

97011

94139 

94140

94141 

94142 

94143 

94144 

94145

94155 

94156 

94157 

94158 

94159 

201460

94176

94764

201457

201458

201459

204065 

204066 

204067 

204068 

204069 

204070

98518 

98519

.002 

.003 

.001

.002

.005

.004 

.004

.002

.003 

.002

.004 

.004

.003 

.002 

.003 

.002 

.006

.006 

.007 

.008 

.006 

.004 

.004

.004

.004

.003

ncid.

.003

.006 

.005 

.010 

.007 

.008 

.003

.006 

.004

(n

£

(n

(n

(n

(n

(n

(n

(n

(

(

(

i Not sampled.
224 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

d

<D

3

3

a

0

1

s

*>

e

i g

* s i* I

3 -a 

s §

2 &

5 0> 8 §

s *>

! J

3 "

J ^

1 ja

*a 

3

S

1

5

a

i

q

<

H

g

53'ga

fl

S«"

.2|

^a

|||

|ll

J&f- §°i a M M

'a 

aM

o

s

rt

EH'

eo

53 

03S

O

1-1

||

*

2

I

i

0)

1

I

*

1

in <B a> a> 

flQQQ

S8J

 s S

£ 8

I "3

 S -d

* -

us 43

3 M

a? a? "5 "5

o o

a S ^ S

o o <3 o

». *-> ""O ^* -2 -° ^

*a ^ to ^

 ^ ^* § ^*

JS § £ §

n3 O C> i^l

s -g 1 1

w A fl fe

i«<? .§ -2

gJ^I'S I

"g_2°«^j §

 g §^ g^ "s

irtS o" t3

X3 0^ 0^ *

 " S '3 3 N v

^ eg 9 ^ ^

""^ S " ^* ^ aT

Ji fit-if

pi*^ 08^ w,T3 c5

|I|-S|||-!

^H -2^3 m .n "^/"i **

O O D O

"o S S 8

3

8 8 1 i

o

00 O> O T-I

a

PC

Rich County... ____ .

32-13N-6E.

s

 S'a

fe

O

fH

ri

1

o

 g

«

S"3

S3

0]

43

0

a

?- sT o

11 ill "8

o>

8

1

1

o>

 a

ple, 1-f 10-f ple, 

ter -3

roadwater C

SEV4-2N roadwa C

E
70

73

14-0N-10E.

SWiyi-3-16N-10E.

NE%-2-16N-10E_____. _ ..........

6-15N-12E... __ . ____ ..........

NE%-H-14N-11E... ...............

NW1/4-19-14N-12E.......... ........

29-12NT-14E __ ...- ___ . ___

21-11N-15E.. ____________ .

5-10N-13E. 

7-10N-13E.. _________ . ____

7-13N-18E. 

NW}£-23-13N-17E __________

. _ .do.. _ _ _._ _

6-12N-20E.. __ .. __________

.....do _ _ __ .

SWJ£-30-16N-19E...._ _ . ____ ..

SWJ£-14-15N-19E...._ _._.

17-14N-21E .-_ - .

SEJi-30-14N-2lE._____ __ .........

NEJ£-8-13N-2lE._. ____ .. _______

S WM-17-14N-21E ..................

8WJi-16-14N-22E__,.. _____________

.....do - -.. 

..... do ..

..... do. 

 do ..._- 

.....do... - . _.. 

... ..do - .. . - -

.. .do . . ..

.....do... . . .... ......

do _

.....do _ . _ _ - .

local usage.

.....do 

 . .do.,......... .... .

 __do 

So-called Amsden formation of

local usage.

94163

94778

94779

94780

94781

94773

94771

94772 

94766

94765

94783

94785

94784

94177

94173

94174 

94175

94755

94756

94757

94758 

94759 

94760

94761 

94762

94786

94169

94178 

94179

94182 

94183 

94184 

94186

94180

94192

.002

.002

.002

.004

.001

.003

.002

.001 

.001

.003

.001

.002

.003

.002

.003

.004 

.004

.001

.001

.001

.002 

.001 

.003

.003 

.006

.001

.004

.003 

.002

.002 

.002 

.003 

.001

.003

.002

(

(

(

(

(

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226 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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Judith Basin County. ................

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.....do...........................

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94777

04776 

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228 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

The black shale sequence at tke base of the Madison limestone was 

sampled at 17 localities in the mountainous parts of southwestern and 

central Montana and northwestern Utah. Sections at 10 of these 

localities are shown in figure 52. The maximum observed uranium 

content of the sequence is 0.005 percent, in the lower half of a 2%-footthick bed of black shale near Three Forks, Mont. (loc. 43), and 0.005 

percent in the basal part of a 10-foot bed of brownish-black shale 

nearby (loc. 44).

The Bakken formation (as used by Nordquist, 1953) was sampled 

in three wells, two of them in northeastern Montana and the third 

in northwestern North Dakota. Drill cuttings representing 30 feet 

of black shale from one of the wells, Amerada Petroleum Corporation-Harry Bakken well 1, Williams County, N. Dak. (well 15, table 

1), contain 0.005 to 0.007 percent of uranium. A sample of drill core 

from a 10-foot-thick bed of black shale in the C. H. Murphy, Jr., and 

others-East Poplar well 1, Roosevelt County, Mont., sec. 2, T. 28 

N., R. 51 E., contains 0.006 percent of uranium. One of six samples of 

drill core from a 10-foot-thick bed of black shale in the Carter Oil 

Company-S. W. Danielson well 1, Daniels County, Mont., sec. 12, 

T. 36 N., R. 47 E., contains 0.004 percent of uranium. The samples 

from this well are anomalous in that they are decidedly out of balance 

in favor of equivalent uranium, as indicated in the following table:

Descriptions of samples: Carter Oil Company-S. W. Danielson well 1, Daniels

County, Mont.

Sample no.

204065 . 

204066 

2040671- 

204068 

204069-.. ...

204070 . -.

Depth

(feet)

6964

6966

6968

6970

6971

6974

Description

do . . - .. --.. - -.

laminae.

eU 

(percent)

0.006

.005

.010

.007

.008

(¥13

U 

(percent)

0.002

.002

.003

.004

.004

.002

1 J. N. Rosholt, Jr., U. S. Geological Survey Trace Elements Laboratory, investigated the source of the 

high radioactivity in sample 204067, with the following result:

Equivalent uranium (percent)_.. ___ - - - . ,._...._ 0.010

Uranium (percent)_________________________________________ .003 

Th«M (radio-chemical) (percent). . . ..._........ .003

Th»° (ionium) (percent equivalent) . _______________-______________ .009 

Radium (percent equivalent) ____.____ _ ______ .006

The analysis above indicates that Th230 and radium, both daughter 

products of uranium, are the principal contributors of excess radioactivity. The relatively high concentrations of these elements in 

comparison to uranium suggest that leaching of uranium or addition 

of Th230 and radium has occurred in this deeply buried shale tin 

comparatively recent time.

The thickness and the areal distribution of radioactivity in the 

Bakken formation (as used by Nordquist, 1953) as determined from
SOUTHWESTERN MONTANA 

NWi<sec34, Sec 11, NE!< sec 34, NE!< sec 13, NW!< sec 16, SWf sec 25, 

T.11N..R.2E., T.11S..R.3 E., T. 9 S., R. 8 W., T. 3 S., R. 5 W., T. 1 N., R. 2 W. T. 2 N., R. 2 E., T

Cache County, Gallatin County, Beaverhead County, Madison County, Jefferson County, Gallatin County, G

Utah Mont. Mont. Mont. Mont. Mont. 

FIGURE 52. Uranium content of basal black shale of Mississippian age at outcrops 
230 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

published sample descriptions and gamma-ray logs, are shown in 

plate 15. These maps suggest that black shale in the Bakken formation (as used by Nordquist, 1953) is thickest in the northwestern 

corner of North Dakota and that the formation is most radioactive 

slightly east of this area, near the northeastern corner of Montana, 

It seems evident that radioactivity in the Bakken formation (as 

used by Nordquist, 1953) varies appreciably from place to place with 

a definite pattern. Recognition of the pattern will help in outlining 

areas in which maximum concentrations of uranium in the formation 

may be expected.

BLACK SHALE AT THE BASE OF THE BRAZER LIMESTONE

In parts of Utah and Idaho the basal part of the Brazer limestone 

of middle and late Mississippian age consists of a black phosphatic 

shale sequence ranging in thickness from a few inches to about 

75 feet. Exposures of this zone were tested at two places in southeastern Idaho (Iocs. 21 and 22), and at one place in northwestern 

Utah (loc. 30). Beds of black shale at the two Idaho localities are 

mostly nonuraniferous, but in Rich County, Utah, a bed of shale 14 

feet thick in the upper part of the sequence contains as much as 

0.006 percent of uranium, and a bed of shale 8 feet thick in the lower 

part contains as much as 0.009 percent of uranium. The measured 

sections and uranium content of the black shale at the three localities 

are shown in figure 53.

Black shale at the base of the Brazer limestone was examined by 

Duncan (1953) in Ogden Canyon, Weber County, Utah, about 45 

miles southwest of the Rich County locality described above. In 

Ogden Canyon, Duncan reported, beds of phosphatic shale about 

1 foot thick contain as much as 0.005 percent of uranium, 0.18 

percent of vanadium oxide, and 17.3 percent of phosphate.

HEATH SHALE

The Heath shale of late Mississippian age crops out along the margins of the Little Belt and Big Snowy Mountains hi central Montana, 

and it has been penetrated hi drill holes throughout a large area in 

eastern Montana and western North Dakota. The formation consists mainly of black shale, with subordinate amounts of gray lime* 

stone and fine- to coarse-grained sandstone. It is as much as 650 

feet thick in the subsurface in the northeastern corner of Musselshell County, Mont., and it is as much as 400 feet thick where it is 

exposed on the flanks of the Little Belt and Big Snowy Mountains to 

the west. (See fig. 54.) The Heath is underlain by the Otter forma-
URANIUM IN BLACK SHALE DEPOSITS 231

tion of late Mississippian age, which consists of green and black shale 

and gray limestone; it is overlain by the Amsden formation of local 

usage of late Mississippian and Pennsylvanian age, which consists 

mostly of red shale and sandstone and gray limestone and dolomite.

Sec 32, T. 13 N., R. 6 E., NE% sec 23, T. 12 S., R.44 E., 

Rich County, Utah Bear Lake County, Idaho

SE% sec 33, T. 7 S., R. 40 E. 

Caribou County, Idaho

A fl A fl Not sampled

- 20 Feet

Locality no. 

(plate 14)

FrotJBB 63. Uranium content of black shale at the base of the Brazer limestone, Utah and Idaho.
232 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM
URANIUM IN BLACK SHALE DEPOSITS 233

Outcrops of the Heath shale were examined for radioactivity at 8 

places by W. J. Hail and J. R. Gill in 1951 (in Duncan, 1953), and outcrops of the Heath shale were examined at 24 places by the writer in 

1953. The most highly uraniferous black shale thus far found in the 

formation was discovered by Hail and Gill 3 miles southeast of Forestgrove, Mont., in the NW% sec. 24, T. 14 N., R. 20 E., Fergus County. 

At this locality, the upper 4 feet of a bed of black shale 6 feet thick 

near the top of the formation contains 0.006 percent of uranium. 

Samples of black shale from the Heath shale elsewhere in central 

Montana contain a maximum of 0.003 percent of uranium.

A sample of water from a seep in the upper part of the Heath shale 

on the north flank of the Big Snowy Mountains (loc. 66) contains 7 

parts per billion of uranium.

The Heath shale is characterized locally by large deflections on 

gamma-ray logs of oil and gas wells. A bed 10 feet thick in the Heath 

shale penetrated by the Marigold Oil, Ltd.-Farnham well 1, McCone 

County, Mont, (well 3, table 1), may contain more than 0.01 percent of 

equivalent uranium; and gamma-ray logs show some parts of the 

formation in Musselshell County, Mont., to be almost as radioactive. Not enough information is available so far to attempt to 

analyze the distribution of radioactivity in relation to the variations 

in thickness and lithology of the Heath.

LITERATURE CITED

Anderson, S. B., 1954, Stratigraphic sections of the Mississippian system in North

Dakota: N. Dak. Geol. Surv. Dept. of Inv. no. 16. 

Baillie, A. D., 1953, Devonian system of the Williston Basin area: Manitoba

Dept. Mines and Nat. Res., Mines Br., Pub. 52-55. 

Barnes, T. R., 1952, The Williston Basin a new province for oil exploration:

Billings Geol. Soc. Guidebook, 3d Ann. Field Conf., Williston Basin-Black Hills,

p. 97-117. 

Duncan, D. C., 1953, Reconnaissance investigations for uranium in black shale

deposits of the Western States during 1951 and 1952: U. S. Geol. Survey

TEI-381, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn. 

Gardner, L. S., Hendricks, T. A., Hadley, H. D., and Rogers, C. P., Jr., 1946,

Stratigraphic sections of Upper Paleozoic and Mesozoic rocks in south-central

Montana: Mont. Bur. Mines and Geology Mem. no. 24. 

Gott, G. B., and Hill, J. W., 1953, Radioactivity in some oil fields of southeastern

Kansas: U. S. Geol. Survey Bull. 988-E, p. 69-122. 

Holland, F. D., Jr., 1952, Stratigraphic details of lower Mississippian rocks of

of northwestern Utah and southwestern Montana: Am. Assoc. Petroleum

Geologists Bull., v. 36, no. 9, p. 1697-1735. 

McConnell, R. G., 1887, Report on the geological features of a portion of the

Rocky Mountains, accompanied by a section measured near the 51st parallel:

Geol. and Nat. History Survey of Canada, Ann. Rept. (new ser.) v. 2,

p. 1D-41D.
234 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Nieschmidt, C. L., 1953, Subsurface stratigraphy of the Heath shale and Amsden 

formation in central Montana: U. S. Geol. Survey Oil and Gas Inv. Chart 

OC50.

Nordquist, J. W., 1953, Mississippian stratigraphy of northern Montana: Billings 

Geol. Soc. Guidebook, 4th Ann. Field Conf., Little Rocky Mts., Mont., 

southwestern Saskatchewan, p. 68-82.

Perry, E. S., 1937, Natural gas in Montana: Mont. Bur. Mines and Geology, 

Mem. no. 3, 96 p.

Sonnenberg, F. P., Rader, M. T., and Clement, J. H., 1952, Electric and lithologic cross-section from Norcanols Ogema [well] to Weller-Bush-Weisman 

[well]: Billings Geol. Soc. Guidebook, 3d Ann. Field Conf., Williston BasinBlack Hills.

Vine, J. D., 1956, Geology of the Stanford-Hobson area, Judith Basin and Fergus 

Counties, Mont.: U. S. Geol. Survey Bull., 1027-J, p. 405-469.

Warren, P. S., 1937, Age of the Exshaw shale in the Canadian Rockies: Am. 

Jour. Sci., 5th ser., v. 33, no. 198, p. 454-457.
INDEX

Page

Bakken formation as used by Nordquist, correlation... 219 

radioactivity, thickness and areal distribution of. - __ 228,230 

uranium content in drill cuttings 228 

Banff formation of McConnell, correlation.... 219 

Big Snowy Mountains.... 230-233 

Brazer limestone, black shale at base of, description, radioactivity... 230

Daniels County, Mont. 228

Exshaw shale of Warren, correlation.. 219

Forestgrove, Mont.. 233

Gamma-ray logs, use in present study.. 214 

value of sensitivity scale.. 214 

Geologic formations, stratigraphic relations of,

table.......... ....-... .. 212

Heath shales-description, radioactivity_ 230,233 

Jefferson formation, correlation. .. . 219

Page 

Little Belt Mountains.. _.___ 230

McCone County, Mont.. ..._ 233 

Madison limestone and equivalents, black 

shale at base of, description, correlation._ _..._._. 219 

uranium content observed___.____ 228 

Musselshell County; Mont. 233

Ogden Canyon, Utah..... 230

Phosphoria formation, excluded from present

study_ 213

Roosevelt County, Mont 228

Sappington sandstone as used by Holland,

correlation_ ..__ 219

Three Forks.formation, correlation... 219 

Three Forks,'Mont... . 228

Williams County, N. Dak.... 228

o

235



Reconnaissance Study 

of Uranium Deposits 

in the Red Desert 

Sweetwater County 

Wyoming

By DONALD G. WYANT, WILLIAM N. SHARP, and DOUGLAS M. SHERIDAN

CONTRIBUTIONS TO (THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-1

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission 

of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. G.
CONTENTS

	Page 

Abstract_____________.___..___I_________________________ 237

Introduction_______-___-_---__--__---_____-_______________________ 238

Purpose of the investigation-_____-________________.____________ 239

Field work and acknowledgments______________________________ 239

Previous work.. ________ .______________- 239

Location and physiography_____________,_______________________ 240

Accessibility _____ __________________________________________ 240

General geology-___ ____________________________________________ 241

Sedimentary roeks.____________________________________________ 241

Igneous rocks.________________________________________________ 242

Structure_____---___-________________________ 242

Geologic history ____ ___________ ____________ 243

Radioactivity-_______________________________________ ______ 244

Uranium deposits___________________ ___________________________ 245

Uraniferous lignite ________________________________________ 246

Distribution. _____._._____________________ 246

Geology__________________________________ 248

Radioactivity _____________________________________________ 250

Origin___ _ _ ________________________ 253

Lost Creek schroeckingerite deposit____________________________ 254

Location and history_______________________________________ 254

Geologic setting. _________ ___________________________ 256

Mineralogy_________________________________________ 260

Schroeckingerite_____________________________________ 260

Other uranium minerals_____________-__________________ 262

Ore bodies__________________________ .___._ 263

Grade___________________________________ 264

Auger-testing program of 1950_______-______-__________- 265

Sampling and logging procedures. _______________________ 266

Geologic results.______________________________________ 267

Distribution of uranium________________________________ 268

Origin_____-_____-___________________________ 272

Aids to prospecting_____-_________-___________-_____-_____- 274

Future outlook..___________________________________________ 275

Literature cited-___________-_-___----____-___---_____-___-_--__--_ 276

Stratigraphic sections._____________________________________________ 277

Analyses...________._________________________. 283

Auger-hole data.__________________________________________________ 288

Index___.___.__---___--____--_____-_-___-_-___-_-_-_-__.__--- 307

m
IV CONTENTS

ILLUSTRATIONS

[All plates In pocket]

PLATE 16. Reconnaissance geology of part of the Red Desert, Wyo.

17. Geology along line of flight.

18. Columnar sections 1-9, Red Desert, Wyo.

19. Geologic map and sections, Lost Creek schroeckingerite 

deposit.

20. Geologic sections in five trenches, Lost Creek schroeckingerite 

deposit.

21. Assays with proposed exploration, Lost Creek schroeckingerite 

deposit.

22. Geologic section C-C" (pi. 21), Lost Creek schroeckingerite 

deposit.

23. Geologic sections with sample assays, Lost Creek schroeckingerite deposit. 

FIGURE 55. Diagrammatic representation of accepted interpretations of

relations of Wasatch, Green River, and Bridger formations Page 

(after Naee)_________________________________________ 241

56. Section of lignite bed 1, Sourdough Butte, Great Divide

Basin (from Slaughter and Nelson)____-___________ 247

57. Records of gamma radiation obtained from carborne and airborne counters (from Stead)_________ ______ 251

TABLE

TABLES

Page

1. Comparison of radioactivity measurements, Red Desert,Wyo_ 245

2. Summary of paleontologic data, Red Desert, Wyo __________ #49

3. Analyses of material other than lignite, carbonaceous shale,

schroeckingerite, or water, Red Desert, Wyo__-_--------- 283

4. Analyses of water samples (ppm), Red Desert, Wyo__--___- 283

5. Spectrographic analyses (in percent), of uraniferous lignite,

Red Desert, Wyo______________________ -___ 284

6. Analyses of radioactive lignite, carbonaceous shale, clinker,

and ash, Red Desert, Wyo___________________ 284

7. Analyses of rock samples, Lost Creek schroeckingerite deposit- 285

8. Analyses of surface- or ground-water samples, Lost Creek

schroeckingerite deposit-______-____-_--_-__----------- 287

9. Analyses of plant and soil samples, Lost Creek schroeckingerite deposit...____________-_______-______---__-----_ 287

10. Lithology of cuttings from shallow auger holes drilled by the 

U. S. Geological Survey, in 1949, Lost Creek schroeckingerite 

deposit___________________.___________ 288

11. Lithology, content of equivalent uranium and uranium of 

cuttings, and radioactivity of cuttings and wall rocks in 

auger holes ES-1 ES-13 (pi. 21), drilled by the U, S. 

Geological Survey in 1950, Lost Creek schroeckingerite 

deposit__________._______...__________ 289

12. Comparison of analyses (in percent) of 6 samples prepared by

2 different methods, Lost Creek schroeckingerite deposit. _ _ 269
CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

RECONNAISSANCE STUDY OF URANIUM DEPOSITS IN 

THE RED DESERT, SWEETWATER COUNTY, WYOMING

By DONALD G. WYANT, WILLIAM N. SHARP, and 

DOUGLAS M. SHERIDAN

ABSTRACT

The largest known deposit of schroeckingerite, a secondary uranium mineral, 

and uraniferous lignite occur in part of the Red Desert, north of Wamsutter, in 

northeastern Sweetwater County, Wyoming. Schroeckingerite was discovered on 

Lost Creek, 38 miles north of Wamsutter in 1936, and lignite between Lost Creek 

and Wamsutter was found to be uraniferous in 1945. It may be possible to produce uranium from the schroeckingerite deposit economically, but the outlook 

for commercial exploitation of the uraniferous lignite is at present uncertain.

An area of 650 square miles in the Red Desert of the Great Divide Basin was 

studied in reconnaissance in 1949 by a combination of photogeologic and field 

methods, and radioactivity was measured on the ground and from the air. Part of 

the area known to be underlain by uraniferous lignite was mapped in detail, and 

columnar sections were measured to determine, approximately, the stratigraphic 

relation of uraniferous lignite in the southern part of the area to the schroeckingerite-bearing beds in the Lost Creek deposit. The deposit was mapped in detail 

and in 1950 was tested by auger drilling.

The surface rocks in the Red Desert are intertoriguing beds of sandstone, claystone, lignite, oil shale, and arkose of the Wasatch, Green River, and Bridger 

formations and the Continental Peak formation of Nace (1939), all of Eocene age, 

and shale, derived from volcanic ash, of the Chadron formation of Oligocene(?) 

age as defined by Nace (1939). Several units of the Green River formation are 

the only Eocene rocks whose formation may be identified readily. The Tertiary 

rocks are covered in part by Pleistocene lake and stream terrace deposits. Most 

of the rocks in the Red Desert are abnormally radioactive.

The topographic feature, Great Divide Basin, is a structural bowl with a few 

subsidiary, broad, gentle folds. In the northern part of the basin the Cyclone 

Rim fault zone trends northwestward and separates nearly horizontal beds to the 

south from folded beds to the north; stratigraphic displacement of beds is 400 to 

700 feet downward on the southwestern side of the fault zone.

Three main uraniferous lignite beds, each about 10 feet thick and separated by 

45-80 feet of sandstone and claystone, crop out in the southern part of the Red 

Desert. A fourth bed, postulated from drill cuttings, probably underlies the 

three main beds. Unweathered lignite is glossy black, and thin bedded. The 

uranium content of the lignite beds ranges from 0.002 to 0.007 percent. The 

average ash content of the lignite is about 38 percent and the ash contains from

237
238 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

0.004 to 0.022 percent uranium. The uranium in all lignite outcrops is not in 

radioactive equilibrium, probably because some of the uranium originally present 

has been leached from the outcrop. The time and mode of introduction of 

uranium in the lignite, as well as the source of uranium, remain problems. Data 

gathered during this investigation suggest that uranium was present in the 

decaying vegetal matter before it was coalified. More recent studies, in other 

areas, suggest that uranum in coal may'be'epigenetic.

The Lost Creek schroeckingerite deposit is within the Cyclone Rim fault zone 

north of the outcrops of uraniferous lignite. A bed of such lignite, however, 

probably underlies the deposit at a depth of a few hundred feet. Within the fault 

zone, the beds strike northwestward and dip about 20° NE. Schroeckingerite 

is a water-soluble, fluorescent, bright yellow-green uranium salt. Minerals, other 

than detrital quartz and feldspar, that are commonly associated with schroeckingerite are clay, gypsum, aragonite, opal, and effl orescent white salts. Schroeckingerite characteristically occurs in the Lost Creek deposit as round pelletal 

aggregates, as disseminated flakes, or as thin layers. The layers commonly coat 

the ground surface and the flakes are commonly in beds of sandstone. The pellets, 

concentrations of which constitute ore bodies, are distributed irregularly but 

appear to be localized most abundantly in five principal beds of finer-grained 

rocks, shale, claystone, or siltstone (of Eocene age); these beds are separated by 

as much as 100 feet of virtually nonuraniferous sandstone and arkose. Ore 

bodies are about 1 foot thick and extend as much as 35 feet down the dip of the 

beds and a maximum of more than 300 feet along the strike. The uranium content 

ranges from 0.013 to 0.28 percent.

Sandstone adjacent to ore-bearing shale beds, and some of the shale, are commonly stained red, maroon, or orange by iron oxides. Such iron-stained zones 

containing weakly radioactive fluorescent opal and other minerals, as well as nonfluorescent uranium minerals (or uraniferous clay aggregates) were found in auger 

cuttings from beneath the water table. Schroeckingerite, however, has been 

found only above the water table and to a maximum depth of 8 feet beneath the 

ground surface. The water underlying the deposit is slightly alkaline (pH of 

about 8) and contains an abnormal amount of uranium (0.01 to 46.0 parts per 

million).

Schroeckingerite crystallizes near the surface from ascending alkaline ground 

water, preferentially in moist claystone, shale, or in siltstone beds; the process 

differs genetically from deposition of caliche only in the quasi-stratigraphic control. The source of the uranium is not certain. It is possible that uranium, 

transported by ascending ground water circulating within the Cyclone Rim fault 

zone, and derived from uraniferous lignite, may have been deposited above the 

low water table prevailing at times in the Pleistocene epoch; later the rise of the 

water table may have caused the uranium mineral to be dissolved, transported, 

and recrystallized as schroeckingerite. Schroeckingerite may now be forming 

from migrating ground water at about the same rate that it is being dissolved and 

removed by surface water.

^Further geologic and exploratory work on the uranium deposits in the Red 

Desert will be done.

INTRODUCTION

PURPOSE OP THE INVESTIGATION

Uranium-bearing sediments at Lost Creek in the Red Desert north 

of Wamsutter, Wyo., were first described by Larsen and Gonyer 

(1937). During subsequent investigations of the deposit, now termed 

the Lost Creek schroeckingerite deposit, A. L. Slaughter and J. M.
URANIUM IN THE RED DESERT, WYOMING 239

Nelson (unpublished report, 1946) found uranium-bearing lignite and 

shale. The U. S. Geological Survey made a reconnaissance study of 

the Red Desert area in 1949 to appraise the uranium resources of the 

area, and to accumulate data concerning the geology of uranium and 

the genesis of schroeckingerite and of uraniferous lignite, and to outline further work. It is hoped that this report will provide a framework for the reports of more detailed studies made in the area, and 

will stimulate additional discussion of the genesis of the deposits.

FIELD WORK AND ACKNOWLEDGMENTS

During about 6 weeks in the summer of 1949, a planetable map of 

the Lost Creek schroeckingerite deposit and several detailed sections 

were prepared; a geologic and ground radioactivity map was made of 

a small area to serve as a control for airborne radioactivity measurements; samples and radioactivity data were gathered from a large 

part of the area; nine key stratigraphic sections were measured; 

fossils were collected; and a general geologic reconnaissance was made. 

Aerial photographs were used in the field. In the office, uncontrolled 

planimetric base maps were made from the aerial photographs, and 

the geology was compiled on the maps from field notes and from 

office study of the photographs. From October to December 1950, 

preliminary auger testing was carried out at the schroeckingerite 

deposit by the Geological Survey, the results of which, although 

preliminary to more thorough testing, are incorporated hi this report.

The work was done on behalf of the Division of Raw Materials of 

the U. S. Atomic Energy Commission. Samples were analyzed by 

the U. S. Geological Survey. The writers are indebted to Walter 

Byron, president of Uranium Inc., the lease holders; the late Mrs. 

Minnie McCormick, who discovered the schroeckingerite deposit; 

Kleber Hadsell, and Gasper Meyer, residents of the area; L. T. Hart, 

Carter Oil Co.; and R. L. Kretz, Bell Petroleum Co., for their courtesy 

and cooperation.

PREVIOUS WORE

No general account of the geology of the area described in this 

report has been published. The geology of some parts of the area, 

and of bordering areas, has been described by many workers, some 

of whose publications are cited in the list of references (Blackwelder, 

1915; Bradley, 1926, 1928, and 1945; Dobbin and others, 1927; Fath 

and Moulton, 1924; Kemp and Knight, 1903; Nace, 1939; Schultz, 

1909; Sears and Bradley, 1923; Smith, 1909; Westgate and Branson, 

1913).

LOCATION AND PHYSIOGRAPHY

The Red Desert, in northeastern Sweetwater County, is in the 

central part of the Great Divide Basin, a topographic basin of interior
240 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

drainage that occupies about 4,000 square miles on the divide between 

the Colorado and Missouri River watersheds. The basin is bounded 

on the north by the Green Mountains, the Granite Mountains, and 

the Antelope Hills; on the east by the Rawlins Uplift; on the south by 

the Laney Rim and the Sierra Madre Range; and on the west by the 

Rock Springs uplift. The basin is on the eastern margin of the 

larger Green River Basin. About 650 square miles in the northcentral part of the Great Divide Basin, a part of the Red Desert, 

was mapped during the investigation by reconnaissance methods. 

The Red Desert is an area of low relief where the altitude ranges 

between 6,000 and 6,600 feet. Its name refers to the red soil that 

mantles its southwestern part (Fenneman, p. 143, 1931). The 

principal topographic features are the low hills between Wamsutter 

and Chain Lakes; the broad depressions occupied by Chain Lakes 

and Lost Creek Dry Lake; the bluffs northwest of Lost Creek Dry 

Lake; and the escarpment of Cyclone Rim (pis. 1 and 2).

The climate is semiarid, and the vegetation accordingly consists 

largely of low-growing greasewood (Sarcobatus sp.), sagebrush (Artemisia tridentata), saltbush (Atriplex sp.), and some prairie grasses and 

herbs. The Red Desert is in the heart of Wyoming's sheep country; 

consequently the natural water supply, consisting of a few springs 

and permanent streams, has been augmented by several wells.

ACCESSIBILITY

Many trails or roads crisscross the Red Desert. The main-traveled 

road heads north from Wamsutter to the Sweetwater River through 

Crook's Gap in the Green Mountains. In places it is graded. From 

the Lost Creek schroeckingerite deposit fair roads lead east to Bairoil 

and northwest to Atlantic City. Ordinary vehicles may be used on 

all the roads, but they should be driven with caution in the sand-dune 

country near Lost Creek Dry Lake, and throughout the area after 

rains. The nearest supply point is Wamsutter, at the southern edge 

of the Red Desert, 40 miles west of Rawlins and 68 miles east of Rock 

Springs on U. S. Highway 30 and the Union Pacific Railroad.

The Red Desert is underlain largely by Tertiary sedimentary rocks 

(pi. 16). Most are Eocene rocks, of the same general type as those 

in the Green River Basin, which are more readily separated and are 

better known. In the Red Desert these rocks are predominantly 

fluviatile conglomerate, sandstone, siltstone, and claystone, with subordinate beds of lignite, all typical of the Wasatch and Bridger formations, and lacustrine shale, typical of the Green River formation.
URANIUM IN THE RED DESERT, WYOMING 241

Cropping out in a smaller area are younger fluviatile conglomerate and 

tuffaceous sandstone and claystone typical of parts of the Continental 

Peak formation of Nace (1939).

The Eocene rock units are all lenticular and interfinger with one 

another (Bradley, 1926, 1945; Nace, 1939). Figure 55 illustrates 

diagrammatically their relationships. Although these formations and 

members can be readily distinguished northwest of the Red Desert, 

they can be traced only with difficulty into this area, because the 

rocks are similar and the exposures are poor. Accordingly, and 

because of lack of time, the units were not mapped. Shale of Green 

River type, however, is so characteristic of the formation that such 

rock was mapped as lenses of the Green River formation. The area 

includes the eastern limits of several lenses of these shale-strata of the 

Green River formation. The gradation between Green River-type 

shale, and green claystone and sandstone characteristic of the Wasatch 

formation may be seen along the bluffs west of Lost Creek, and about 

2 miles northeast of Eagles Nest (center of the mapped area on pi. 16). 

In the excavation for the sump at the site of the California-Wyoming 

Development Co. oil well (4% miles north of Eagles nest, pi. 16), 8 feet 

or more of shale of the Green River formation is well exposed. Farther 

north, at the schroeckingerite deposit, several thin shale beds ranging 

in thickness from 0.2 to 5 feet are exposed in trenches.

Although formations were not delineated and stratigraphic correlations with formations outside of the area mapped in reconnaissance 

have not been attempted in this report, Bradley has traced from the 

west the Tipton tongue of the Green River formation and the overlying Cathedral Bluffs tongue of the Wasatch formation to within 

about 12 miles west of the exposures of the Green River shown on 

plate 16 north and west of Lost Creek Dry Lake (Bradley, W. H., 

written communication). Also, Nace (1939, p. 25) observed exposures 

of his Continental Peak formation within the Cyclone Rim at Lost 

Creek.

Hiawatha member 

Main body of Wosatch formation, cool bearing

FIGUBE 55. Diagrammatic representation of accepted interpretations of relations of Wasatch, Green River,

and Bridger formations (after Nace). 

388177 57 2
242 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Tentative geologic correlations of the Eocene rocks within the 

Red Desert are shown on plate 18 and are described under the heading 

Stratigraphic sections. As shown on plate 18, an attempt was made 

to correlate the beds in the vicinity of the schroeckingerite deposit, 

on the northeast side of the Cyclone Rim fault zone, with the lignite 

beds south of Chain Lakes. A detailed correlation was not possible, 

owing both to the distances between the measured sections and to poor 

exposures, but the approximate relations of the rocks throughout the 

area are shown.

The youngest Tertiary rocks are light-colored shale containing 

volcanic ash, sandstone, conglomerate, and limestone of the Chadron 

formation of Oligocene(?) age of Nace's usage (Nace 1939). These 

rocks crop out in the northwestern part of the area. They have been 

mapped by Nace to the west of the area shown on plate 16.1 The 

Chadron formation unconformably overlies undifferentiated rocks of 

the Continental Peak formation of Nace (1939) and the Bridger, 

Green River, and Wasatch formations, all of Eocene age.

The thickness of the Tertiary section is probably about 2,000 feet. 

The Eocene rocks west and east of the mapped area rest conformably 

on the Paleocene Tongue River member of the Fort Union formation, 

which in turn rests unconformably on folded Cretaceous and Paleozoic 

rocks. North and northwest of the Red Desert the Tertiary rocks 

rest directly upon the Precambrian and Paleozoic "basement complex" of the Granite and Sweetwater Mountains.

Overlying the Tertiary rocks are Pleistocene and Recent fluviatile, 

lacustrine, eolian, colluvial, and alluvial sediments, which portray a 

complex physiographic history. Conspicuous features of the area 

are the broad depressions formerly occupied by Pleistocene lakes and, 

the terrace deposits bordering Recent and Pleistocene streams.

IGNEOUS BOCKS

Igneous rocks are not exposed within the Red Desert but the 

volcanic ash content of some beds of the Bridger, Continental Peak 

of Nace (1939), and Chadron formations indicate considerable volcanic activity during their deposition. The well-known lava flows 

and associated intrusive alkalic igneous rocks of the Leucite Hills 

are about 30 miles northwest of Lost Creek Dry Lake.

STRUCTURE

Structurally, most of the area is a relatively simple basin, the 

approximate center of which is Lost Creek Dry Lake. Broad, shallow

i Subsequent to the present work, more detailed mapping in the area was done, 1951-1954 by Harold 

Masursky and G. N. Pipiringos. Their work indicates that the Chadron formation of Nace's usage (Nace, 

1939) and as shown on plate 16 may include the Brown's Park(?) formation of late Miocene or early Pliocene 

age. If so, the beds labeled Chadron (Toe) on plate 16 may be a part of the Brown's Park, and true Chadron 

may either be missing, or be present in the Cyclone Rim but included in the strata mapped under the symbol 

Teu as undifferentiated formations of Tertiary age.
URANIUM IN THE RED DESERT, WYOMING 243

folds modify this simple structure; some faults displace the beds in 

Monument Dry Lake.

Relatively intense folding is restricted to the area north of the 

Cyclone Rim. The Rim marks a zone of en-echelon faulting, the 

Cyclone Rim fault zone, a major structural feature of the Red Desert, 

that extends at least 10 miles northwestward, and perhaps farther, both 

to the northwest and the southeast. Apparent stratigraphic displacement along the fault zone is about 400 feet downward on the 

southwest side and may be as much as 700 feet. The fault zone may 

be a high-angle thrust with movement upward on the northeast side, 

but more exploratory work at the schroeckingerite deposit will undoubtedly contribute more detailed information about the faulting. 

Some of the anticlines north of the Cyclone Rim were drilled by oil 

companies, but no records show production of oil or gas in the mapped 

area.

GEOLOGIC HISTORY

Throughout the early part of the Eocene epoch, sediments were 

carried into the area by streams from the surrounding lands to form 

the Wasatch formation. During the first stage of deposition of the 

formation, plant material accumulated in some swamps or bogs to 

form thick lignite beds. Later, intermittent fresh-water lakes were 

formed. The eastern margins of some were approximately along a 

line extending northward from Chain Lakes to a point about 2 miles 

east of the Lost Creek schroeckingerite deposit (pi. 16). In the lakes 

fine-grained sediments rich in organic matter accumulated to form 

the oil-rich shale and fresh-water limestone of the Green River formation that are interlayered with the fluviatile sediments of the Wasatch 

formation. In middle Eocene time, streams deposited grit, sand, and 

clay to form the Bridger formation. These fluviatile sediments were 

eroded, then streams deposited a sequence of tuff and tuffaceous 

sands, the Continental Peak formation of Nace (Nace, 1939). The 

strata formed by consolidation of all these sediments were tilted, 

faulted, eroded, and in Oligocene(?) time covered by the conglomerate, 

ash, and fresh-water limestone of the Chadron formation of Nace's 

usage (Nace, 1939). Before deposition of the Chadron, the Cyclone 

Rim fault zone was formed.2 The Miocene and Pliocene epochs, 

although possibly represented by part of the Chadron formation as 

used by Nace (Nace, 1939) were probably largely epochs of erosion 

and nondeposition hi the area of the Red Desert.

In Pleistocene time, a large amount of water flowed south from 

Lost Creek, past the site of Wamsutter and out of the Great Divide 

Basin, through a former stream channel that extends to the southwest

* More recent work of Masursky and Pipiringos suggests that faulting along the Cyclone Rim fault zone 

may have taken place before deposition of sediments of the Brown's Park(?) formation (of Miocene or Pliocene age) that are included with the Chadron formation in this report, and, possibly, after deposition of the 

true Chadron formation of Oligocene age (if missing in the area) in adjacent areas.
244 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

from the vicinity of the schroeckingerite deposit. The main channel 

of this Pleistocene stream is just beyond the west edge of the area 

shown on plate 16 and is easily recognized along U. S. Highway 30 

about 7 miles west of Wamsutter. Either because of a decrease in the 

amount of water in late Pleistocene time, or because of local structural 

warping, or due to both causes, drainage out of the area ceased and 

large lakes were formed in the basins, whose centers are now occupied 

by small lakes or playas. Thepe former lakes are called, in this 

report, Pleistocene Lost Lake, Pleistocene Chain Lakes (lower and 

upper), and Pleistocene Monument Lake. Stream terraces were cut 

along Lost Creek; the highest terrace above the creek probably was 

cut at the time of the largest expansion of Pleistocene Lost Lake. 

The abrupt change in width of the terrace deposit along Lost Creek 

at its junction with the Cyclone Rim fault zone suggests there may 

have been renewed faulting in the area in late Pleistocene time, but the 

widening may be the result of other causes. The Pleistocene lake 

basins gradually are being filled with debris washed in from the 

surrounding highlands and from the Tertiary sediments traversed by 

the streams. This debris is being modified by wind action.

RADIOACTIVITY

Uraniferous sediments are widespread within the Red Desert. 

The average radioactivity of rocks in the area is greater than is 

common for sediments. As an example, sample DW-102 (S:295), 

(mud and silt) from the center of Lost Creek Dry Lake, contains 0.003 

percent equivalent uranium 3 and 0.002 percent uranium. Evans 

and Goodman (1941) give for terrestrial sediments other than limestone, a uranium content of 1.3 gm per ton (0.00013 percent).

Radioactivity data were obtained with (a) hand-carried GeigerMueller counters and (b) an instrument composed of two 40-inch 

gamma-probes coupled to a car-mounted circuit, or from (c) analyses 

in the laboratory of the samples collected at the outcrop.

Radioactivity measured at several outcrops with both the handcarried and the car-mounted Geiger-Mueller counters was compared 

with the equivalent-uranium content, determined in the laboratory, 

of samples taken from the same outcrops. The comparison established an approximate correlation among the different instruments 

used, and allowed the transformation of field radioactivity measurements to estimated percent equivalent uranium. Although the 

figures for estimated percent equivalent uranium plotted on the maps 

are not quantitatively accurate, they do indicate correctly, orders of

* Equivalent uranium is a measure of the total amount of radioactivity emitted by the sample, and is 

expressed as if all the radioactivity were due solely to uranium in equilibrium with the products in its disintegration series. The radioactivity of all radioactive substances, such as thorium, potassium (K40), or 

uranium would, therefore, be included as the percent equivalent uranium, if they were present. The 

equivalent-uranium content of these samples was determined by Geiger-Mueller counters in the laboratory.
URANIUM IN THE RED DESERT, WYOMING 245

magnitude. It was not feasible during reconnaissance work to collect samples at every station. The correlation among methods used 

in measuring radioactivity is summarized in table *1. More than 150 

observations were made in the area either with the car-mounted 

instrument or with the hand-carried meters. Forty-three samples 

were taken for analysis. Tables 3 and 4 include the laboratory 

analyses of materials other than lignite, carbonaceous shale, or 

schroeckingerite ore.

TABLE 1. Comparison of radioactivity measurements, Red Desert, Wyo.

Laboratory 

analysis 

equivalent 

uranium 

(percent)

0.014 

0.013 

0.012 

0.010 

0.009 

0.008 

0.007 

0.006 

0.005

Average readings on carborne 

Geiger-Mueller 

counter 

(meter units)

15.5 

15.0 

14.0 

13.0 

12.0 

11.0 

10.0 

9.0 

9.0

Average readings on handcarried counter 

(meter units)

17 

14 

11 

10 

9 

8 

7 

5 

5

Most of the material sampled in addition to lignite and schroeckingerite-bearing rock is abnormally radioactive but contains little 

uranium (tables 3 and 4). Pebbles of fluorescent chert collected 

from a wide area northwest of the Lost Creek schroeckingerite deposit, contain as much as 0.010 percent equivalent uranium and 0.006 

percent uranium. A. L. Slaughter and J. M. Nelson (unpublished 

report, 1946) also collected from the general area pebbles of fluorescent chert that contain 0.030 percent equivalent uranium. They 

examined the Leucite Hills, 30 miles to the west of the area shown on 

plate 17, and reported that some of the pumice beneath one flow of 

leucite-rich lava contained an estimated 0.007 percent equivalent 

uranium.

Gypsiferous sandstone and sandy claystone collected at Arapahoe 

Creek contained as much as 0.006 percent equivalent uranium, and 

a maximum of 0.003 percent uranium.

A large quantity of the material in the immediate vicinity of the 

shroeckingerite deposit contains as much as 0.010 percent uranium.

On the road about 3 miles northeast of Eagles Nest the carborne 

Geiger-Mueller counter indicated a slight increase in radioactivity 

above the green claystone and red sandstone that grade laterally 

into shale lentils of the Green River formation.

URANIUM DEPOSITS

Most of the beds in the area mapped in the Red Desert are more 

than normally radioactive but contain too little uranium to be of
246 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

economic significance. The beds of radioactive lignite and the 

schroeckingerite-bearing sediments, which contain the most uranium, 

may, however, be 6f economic significance.

UBANIFEROUS LIGNITE

In 1945, during a reconnaissance examination, A. L. Slaughter and 

J. M. Nelson found that some beds of lignite and carbonaceous shale 

in the Eed Desert were abnormally radioactive. They took samples 

for analysis and measured one exposure of lignite (unpublished report, 

1946). They observed that radioactivity was greater in the interbedded carbonaceous shales than in the adjacent lignite, and chemical 

analyses showed that the equivalent-uranium content was greater 

than the uranium content. Samples taken by them of the more 

radioactive lignite and shale beds contained from 0.010 to 0.015 percent equivalent uranium and from 0.002 to 0.004 percent uranium. 

A columnar section made by them on the west end of Sourdough 

Butte (see pis. 16 and 17) is given in figure 56.

DISTRIBUTION

The area examined in reconnaissance in 1949 in which radioactive 

lignites crop out is shown on plate 17. It extends northward from a 

point about 9 miles north of Wamsutter to the ridge of High Point, 

south of Chain Lakes a distance of 11 miles. The maximum width 

of the area mapped containing radioactive lignites is about 7 miles, 

although the beds extend beyond the limits of this area. Thin beds 

of lignite are present between Wamsutter and the area studied, but 

they are not appreciably radioactive. They may be stratigraphically 

higher than the more radioactive beds.

Lignite also is exposed along U. S. Highway 30 between Kawlins 

and Wamsutter. Many of the exposures were examined by Slaughter 

and Nelson who found only one bed of appreciably radioactive clinker; 

their sample of this bed contained 0.012 percent equivalent uranium 

and 0.004 percent uranium. Smith's map (1909, pi. 12) shows about 

200 square miles of the Red Desert underlain by lignite. This 

area extends well beyond that shown on plates 16 and 17.

Radioactive lignite also was observed (1) in the bluffs west of Lost 

Creek Dry Lake, (2) in cuttings from the sludge pit of a water well 

drilled at the site of the California-Wyoming Development Co. oil 

well, and (3) at Coal Bank dam about 7 miles north of the Lost Creek 

schroeckingerite deposit. Although the maximum extent of the radioactive lignite is unknown, such lignite probably underlies most of the 

area shown on plates 16 and 17, and some beds certainly extend 

beyond it to the east and to the west.
URANIUM IN THE RED DESERT, WYOMING 247

Radioactivity and 

uranium content

25 20 15 10 5

i

z

App 

cr 

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i

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//

 

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 //,

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Radioactiv

roximate radio* 

ushed rock, ex 

pvalent urani

2

S **

^O I .

£~

2.5

0.8

J!±_

0.6 

0.2 ^

1.2

1.6

0.2 , 

0.5

0.2 ^ 

0.8

0.2 / 

0.6 

0.2 ,

1.5 

2.8

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BABUS

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 '

Description

Sandstone, yellow to buff, very fine-grained 

Shale, brown to gray, fissile

Shale, gray to dark-gray, hackly to fissile

Coal, fissile; brown shale in part 

Shale, gray, hackly to fissile 

Coal, fissile

Shale, gray, hackly, fissile in part, yellow-brown stains; separated into 

lenticular parts by thin coal seams

Coal, shaly, fissile, abundant yellow stains

Shale, dark-gray to black, fissile; thin coaly layers; gypsum in thin 

layers in bedding

Coal 

Shale, dark-gray to black 

Coal, shaly, fissile 

Shale, gray to black, partly fissile; gypsum

Coal, shaly, fissile 

Shale, dark-gray to light-gray, clayey, hackly 

Coal, shaly, fissile

Shale, gray, hackly, jointed, yellow stains on joints, darker and more 

fissile in part, soft, clayey; gypsum

Coal, fissile and shaly in part; yellow stains and coatings along bedding; 

gypsum, selenite

Shale, black, fissile

Shale, dark-brown, clayey

Base of section not exposed

EXPLANATION

ity determined by outcrop test §§§§§§§ iiiii

ctivity, determine 

pressed in thous 

im; not determi

0

Uranium content, determined 

d by testing (in field) expressed in thousandt 

andths of percent 

led for all samples

4 Feet i i Measured ;

and John

:§ Si i-i

£ * 

Wasatch (Eocene)

)y chemical analysis 

hs of percent

nd sampled by A. L. Slaughter 

M. Nelson, 1946

FIGURE 66. Section of lignite bed 1, Sourdough Butte, Great-Divide Basin, Sweetwater County, Wyo.
248 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGY

Three prominent zones containing alternating layers of lignite and 

carbonaceous shale have been mapped (pi. 17). These zones are 

designated as lignite beds in this report, and are referred to as lignite 

beds 1, 2, and 3, numbered in ascending stratigraphic order. Cuttings of radioactive lignite from shotholes drilled for seismic surveys 

indicate that another bed underlies bed 1 on the east edge of Pleistocene Monument Lake (pi. 17), but outcrops of this lower bed were 

not observed in the map area.

The radioactive lignite beds are probably early Eocene in age and 

may be correlated with part of the Wasatch formation. Plant fossils 

were collected from partly baked claystone underlying lignite bed 1 

at the south side of Sourdough Butte. They were examined by R. 

W. Brown, who determined their age to be early or middle Eocene 

and tentatively correlated the rocks with the Eocene of Yellowstone 

Park. Gastropod and pelecypod fossils were collected at a point 

about IK miles southeast of No Name well (pi. 16) from a bed of 

calcareous sandstone about 55 feet stratigraphically above lignite bed 

3 and shown'as fossilliferous zone F-9 on columnar section 5 of plate 

18 (see also stratigraphic section 5, p. 280). They were examined by 

T. C. Yen, who determined then* age as early Eocene and correlated 

the sandstone with a part of the Wasatch formation. Fossils of 

similar types were collected from other beds of calcareous sandstone 

about 60 feet higher stratigraphically than the bed in which zone F 

9 occurs and at a point 0.8 of a^mile^northeast of No Name well 

(fossiliferous zone F-6 and F-7 on columnar section 4 of plate 18 

and stratigraphic section 4, p..279). Mr. Yen determined their age as 

late early Eocene and tentatively correlated these sandstone beds 

with the upper part of the Wasatch formation. These paleontologic 

data are summarized in table 2.

As shown in columnar sections 1, 2, and 3 of plate 18 and stratigraphic sections 1-3, (p. 277) the stratigraphic interval between lignite 

beds 1 and 2 is about 80 feet, and that between beds 2 and 3 is about 

45 feet. The stratigraphic interval between bed 1 and the bed that 

is assumed to underly it is not definitely known, but is estimated to 

be about 100 feet. The total stratigraphic interval that contains the 

principal beds of known radioactive lignite is, therefore, about 225 feet.

The lignite beds are interbedded with gray, buff, drab, or white, 

micaceous arkosic sandstone, silty sandstone, and calcareous sandstone; 

brown, gray, or green plastic claystone; and platy carbonaceous shale. 

Details of lithology of the rocks are shown in the columnar sections 

(pi. 18 and fig. 56) and detailed descriptions are given under the heading Stratigraphic sections.

The lignite beds themselves are composed of black vitreous lignite 

seams from about one-sixteenth to one-half inch thick, interbedded
URANIUM IN THE RED DESERT, WYOMING 249

with dark-brown or gray fissile carbonaceous shale layers of similar 

thickness. The thickness of lignite beds 1 and 2 ranges from*about 

2.5 to 20 feet; the average in each is about 10 feet. Bed 3 ranges in 

thickness from about 1 to 6 feet andM averages about 2 feet in^thickness.

TABLE 2. Summary of paleontologic data, Red Desert, Wyo. 

[Identification, age, and correlation of mollusks by T.[C.|Yen and of plants by R. W. Brown]]

Fossiliferous 

zone 

(reference 

no. on pis. 

- 16 and 21)

F-6.. ........

F-8- ...

F-8-. _ ..

F-9

F-10.-- 

F-ll.... ..

JBR-1... _

JBR-2. ...

JBR-3.......

JBR-4.......

JBR-5-.. .

JBR-6.......

JBR-7. 

Columnar 

section 

(pl. 18)

4

4

4

5

6

7

«

7

9

9

9

(*)

(«)

Fossils

Vivlparus paludinaeformis

(Hall).

Viviparus paludinaeformis 

(Hall).

Physa cf. P. pleuromatis White- - 

Viviparus cf. V. paludinaeformis 

(Hall).

0. cf. 0. areta (Meek) 1..........

Viviparus cf. V. paludinaeformis 

(Hall).

Qoniobasis cf. Q. nodulifera 

(Meek).

Unio cf. U. wasatchmsis Coekerell.

Qoniobasis cf. 0. carterii (Con- 

. rad).

identifiable.

Asplmium magnum Knowlton.. 

Smilax lamarensis Knowlton ....

leaves.

Pisidium sp. undet. ] 

Viviparus sp. undet. (.(poorly

Menetus sp. undet. J 

Qoniobasis cf. 0. nodulifera 

(Meek).

Lymnaea cf. L. stntilis Meek ....

Goniobasis cf. Q. nodulifera 

(Meek).

Australorbls cf. A. spectabilis 

(Meek).

determinable.)

Hayden).

Probable age

... .do.... ..

Late early Eocene.

Early to mid

die Eocene.

Possibly Eocene. 

Eocene ____

....do ... ...

Middle Eocene.

Probable correlation

formation.

Do.

Do.

Part of the Wasatch formaUpper part of the Wasatch 

or lower part of the Bridger

is possibly equivalent to 

JBR-4 below).

Eocene of Yellowstone NaNone (habitat area was

water).

Upper part of the Wasatch 

or lower part of the Bridger

formation.

or lower part of the Bridger 

formation (the collection is

above).

i Goniobasis arcta (Meek) was originally described from the Bridger formation in southwest Wyoming. 

8 No columnar section measured, Sourdough Butte, lignite bed 1.

* This would be lower Bridger of Nace.

* No columnar section measured, on Lost Creek at Chalk Banks.

* No columnar section measured, Bridger formation of Nace, from north side of Continental Peak, Sweetwater County.

388177 57 3
250 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

The proportion of shale to lignite varies from place to place in each 

lignite bed, but in general the lignite is of poor quality for use as fuel. 

Locally, as in bed 1 on High Point Eidge (southeast corner of the 

mapped area on pi. 16) and in bed 3 west of the mouth of Sourdough 

Creek (sample WNS-13 (S:18)), the lignite is free from clay. As 

noted in table 6, sample WNS-13 (S:18) contains only 9.1 percent 

ash. Considerable but variable amounts of gypsum occur in the lignite beds. No marcasite was observed. An appreciable amount of 

silicon and iron, and small amounts of magnesium, boron, titanium, 

zinc, calcium, barium, cerium, and lanthanum were found by spectrographic analysis of some of the lignite samples (table 5).'

Some of the lignite beds have been burned at the outcrop. The 

burning has converted the shale and lignite to clinker and to ash, 

respectively, and has baked the sediments above and below for a few 

inches or a few feet. As observed by the senior author in North 

Dakota, this burning takes place only if the lignite is relatively close 

to the surface and about 5 feet or more thick. In the Red Desert 

many of the outcrops of lignite have been burned back for a short 

distance. These beds of clinker and ash are not delineated on the 

maps because they occupy only local areas (pi. 17), but some of these 

areas are listed below:

(1) Bed 2(?) east of the road on the north side of anticline at Monument 

Lake.

(2) Bed 1 along the north side of Pleistocene Monument Lake.

(3) Bed 1 northwest of Sourdough Butte.

(4) Bed 3 for a short distance east of the mouth of Sourdough Canyom

RADIOACTIVITY

The amount of radioactivity of the lignite beds is indicated on 

plates 16 and 17. A. L. Slaughter and J. M. Nelson (unpublished report, 1946) found that radioactivity is not confined to the lignite 

seams; the interbedded layers of carbonaceous shale are also radioactive. For this reason, evaluation of the radioactivity of only the 

lignite seams, requires additional samples. Composite samples of 

the entire lignite bed were generally taken, in order to obtain a measure 

of the total radioactivity information required in the experimental 

airborne survey. Treated as units, the lignite beds provide radioactivity meter-readings at their best outcrop (pi. 17) that range from 

a fraction to more than six times the local background. When using 

the car-mounted Geiger-Mueller counter an increase in counting rate 

is easily discernible in crossing radioactive lignite beds, or the ash and 

clinker formed by the natural burning of the lignite beds. For example, in driving over the small outlier of lignite bed 2, half a mile 

east of the road intersections on High Point Ridge (pis. 16 and 17), 

the meter readings increase from about 9.5 scale divisions over the
URANIUM IN THE RED DESERT, WYOMING 251

sandstone on either side, to about 11.5 scale divisions directly over 

the small area of lignite.

Airborne equipment was successful in detecting the radioactive 

lignite beds. The test flights, methods, equipment, and results are 

given by F. W. Stead (unpublished report, 1949) and Nelson and 

others (1951) and will not be given here. Radioactivity^ measurements obtained by carborne and airborne Geiger-Mueller traverses 

and the geology are shown on figure 57. The intensity of the radioactivity varies from bed to bed, and over long distances along the 

strike, but in general is remarkably constant in all beds.

Note: Arrow indicates 

direction of flight

ACTIVITY AT 250 FEET

10 5

ACTIVITY AT GROUND LEVEL

JUSGS triin 

" std "Divide"

GEOLOGY ALONG FLIGHT LINE 

1 0 3 Miles

FIGURE 57. Records of gamma radiation obtained from carborne and airborne counters.
252 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Analyses of samples of lignite, carbonaceous shale, clinker, and ash 

from the flight-strip area over which the airborne equipment was used 

are shown in table 6.

Samples of lignite contain from 0.002 to 0.015 percent equivalent 

uranium and from 0.002 to 0.007 percent uranium. Most of these 

samples are composite samples of an entire bed and therefore include 

clay from interbedded carbonaceous shale. The combustion of lignite 

to an ash is a possible approach to the commercial production of 

uranium. Sample WNS-13 (S:18), representing 6 feet of highquality lignite with very little interbedded shale, produced ash containing 0.015 percent uranium, as compared to the 0.002 percent 

uranium contained in the original material.

Isolated outcrops of radioactive lignite and paper-thin shale, in 

part burned to clinker, were found about 1% miles north of the northwest corner of Lost Creek Dry Lake. Kadioactivity measurements 

at the outcrop suggest that the partly burned material contains about 

0.006 percent equivalent uranium. This bed of radioactive lignite was 

mapped by Smith (1909, pi. 12).

Equilibrium status. A sample of uraniferous rock in which radioactive equilibrium exists should contain as much uranium as equivalent 

uranium, unless elements of other radioactive series such as the thorium 

series are also present. Judged by the radioactivity of some samples 

not in radioactive equilibrium (table 6 and pi. 17), some of the lignites 

once contained more uranium than is indicated by the equivalenturanium (ell) content, or else disintegration products (principally 

radium) have concentrated in the lignite. Analytical work by the 

Geological Survey has demonstrated that radioactive equilibrium 

noted in analyses of the samples is caused by an abnormal radium-touranium ratio; there is about 60 percent more radium than needed for 

the equilibrium ratio (John Rosholt, written communication).

The measured radioactivity of sample WNS-4 (S :5) is equivalent to 

a uranium content of 0.015 percent, on the assumption that uranium is 

in equilibrium with its disintegration products. Chemical analysis, 

however, shows that it contains only 0.003 percent uranium. Because 

in this arid environment uranium salts are relatively soluble in comparison to radium salts (sulfate, chloride, and carbonate), it may be 

presumed that much of the uranium and its preradium disintegration 

products have been leached out. If this is true, material of the sample, 

before leaching, would have contained more uranium than the 0.015 

percent suggested by the equivalent-uranium content. Specifically, 

a uranium content of 0.026 percent would be required to give the 

observed radioactivity, if uranium and all its disintegration products 

were present and in equilibrium.

The simple calculations as evidence for this statement are shown 

below:
URANIUM IN THE RED DESERT, WYOMING 253

0.003X0.40=0.0012 Percent equivalent uranium due to uranium 

and its preradium disintegration products

0.015 0.0012=0.0138 Percent equivalent uranium due to radium 

and its disintegration products

0.0138-^-0.60=0.023 Percent uranium necessary for equilibrium 

with 0.0138 percent radium, and its disintegration products

0.023+0.003=0.026 Total percent uranium necessary for equilibrium

Sample WNS-17 (S:23), consisting of fragments of lignite, carbonaceous shale, and admixed surface debris, was picked from the sludge 

and cuttings of other rocks that accumulated in the sump during the 

drilling of a water well at the site of the California-Wyoming Development Co. oil well. This sample contained 0.011 percent equivalent 

uranium and 0.012 percent uranium. After burning hi the laboratory, 

it contained 73.7 percent ash and 0.014 percent uranium in the ash. 

The sample, although small and impure, demonstrates that beneath 

the surface at this locality radioactive lignite contains uranium 

essentially in equilibrium with its daughter elements. The high ash 

content, due largely to extraneous surface debris, suggests that 

samples of the lignite free from such diluting material may contain 

appreciably more uranium.

ORIGIN

The process by which uranium accumulated in uraniferous lignite 

is not known, but two alternative suggestions have been made: (1) 

uranium is syngenetic, that is, it was carried by ground and surface 

water into the swamps in which plants and plant debris were accumulating, and was fixed before coalification either by absorption in 

the tissues of live plants or by absorption or adsorption, or by chemical 

reaction with, the carbon and organic material of plant debris; or, (2) 

uranium is epigenetic, that is, it was leached from overlying source 

rocks, such as beds of volcanic ash, by ground or surface water and 

carried down to be precipitated in or be adsorbed by lignite (Tolmachev, 1943).

In support of the epigenetic origin of uranium in coal, N. M. 

Densen, G. O. Bachman, and H. D. Zeller (unpublished report, 1950) 

have observed that (1) beds of uraniferous lignite in North and South 

Dakota occur in several formations, but only in those underlying 

Oligocene rocks and only those beds of lignite nearest the unconformity at the base of the Oligocene rocks are uraniferous; (2) uranium 

is concentrated near certain fractures and near the tops of the lignite 

beds; and (3) lignite beneath relatively impermeable strata generally 

contains less uranium than lignite beneath relatively permeable 

strata. They believe the source of the uranium to be volcanic ash in 

the White River formation of Oligocene age.

In the Red Desert and surrounding region in Wyoming there are 

rocks derived from volcanic ash (parts of the Bridger, Continental
254 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Peak of Nace (1939), Chadron, and Brown's Park(?) formations of 

Eocene, Oligocene(?), and Miocene or Pliocene age), and also slightly 

radioactive igneous rocks (the rocks of the Leucite Hills).

The theory of epigenetic origin of the uranium in the lignite beds of 

the Ked Desert is, on the other hand, difficult to accept for the following reasons:

1. At the outcrop some of the lignite apparently has been subject 

to leaching (see analyses of samples, table 6), and has lost part of its 

uranium content. If we assume an epigenetic origin for the uranium, 

as outlined above, it is difficult to understand how the leaching could 

have taken place; the lignite of the outcrops should be enriched, 

rather than impoverished, in uranium.

2. Lignite buried about 100 feet beneath impervious shale in 

Monument Dry Lake, and beneath as much as 300-500 feet of 

impermeable shale and other Eocene rocks at the site of the CaliforniaWyoming Development Co. oil well, is uraniferous. If the uranium 

is epigenetic in origin, the lignite at these localities should not be 

uraniferous, because water carrying uranium could not percolate 

down through the shale. The lignite at the site of the oil well has 

apparently not been leached of its uranium content, as is indicated 

by the equilibrium relationship.

3. The radioactivity of the lignite beds is remarkably uniform along 

strike; no marked change in radioactivity was observed for 10 miles 

or more from High Point Ridge to Monument Dry Lake (pi. 17); the 

uranium content, however, is not uniform, a fact which could be 

attributed to differential leaching.

4. The evidence listed in support of an epigenetic mode of origin 

may be interpreted in several other ways; for example, in other types 

of uranium deposits secondary uranium minerals are commonly 

concentrated along fractures.

5. Autoradiographs of hard vitreous coal indicate a uniform 

distribution of radioactive material, a distribution difficult to explain 

by processes other than syngenetic processes.

It is the writers' opinion, therefore, that available evidence supports 

a syngenetic or at least pre-coalification origin for the uraniferous 

lignite beds in the Red Desert. However, a more thorough study of 

the region and of the physical chemistry of uranium and carbonaceous 

material is required before any theory of origin may be considered 

as demonstrated.

LOST CHEEK SCHROECKINQEBITE DEPOSIT

LX3CATION AND HISTORY

The Lost Creek schroeckingerite deposit (pis. 19 and 21) is 38 miles 

north of Wamsutter (index map, pi. 16) on the east side of Lost Creek, 

near the Kleber Hadsell shearing pens and cabin. The deposit is in
URANIUM IN THE RED DESERT, WYOMING 255

sees. 30 and 31, T. 26 N., K. 94 W., sixth principal meridian, and 

may be reached from Wamsutter, the nearest railroad station, by 

traveling 43 miles on a graded desert road.

The country surrounding the deposit, which occupies a broad open 

valley, is relatively flat but slopes gently southward. A mile north 

of the deposit a series of northwest-trending ridges rises a hundred 

feet or more above the general land surface. Farther west, these 

ridges are as much as 500 feet above the general land surface and form 

the Cyclone Run escarpment. About 13 miles north of the deposit 

.the Green Mountains and Antelope Hills form the northern rim of 

the Great Divide Basin.

Lost Creek rises in the Green Mountains, but a few intermittent 

streams from the east are tributary to it. It drains into Lost Creek 

Dry Lake when in flood, but is seasonally intermittent below the 

schroeckingerite deposit.

The schroeckingerite deposit was discovered in 1936 by the late 

Mrs. Minnie McCormick. The deposit is covered by the placer mining 

claims, Golden Arrow Nos. 1 to 9, filed by the late Mrs. Minnie 

McCormick and her associates, Louis A. McCormick, Mrs. Mabel 

A. McVae, Mrs. Emma J. Eversole, Mrs. Laura E. A. McCargar, 

Kleber H. Hadsell, and Tom W. Whelan. Since the tune of filing, 

C. A. Brimmer has been added to the list of owners. The property 

was leased with option to buy in January 1948 to Uranium Inc., 

Denver Colo., whose president is Walter Byron, and whose members 

include K. W. Robinson, R. D. Charlton, and Robert Swanson, also 

of Denver.

Many geologic examinations of the deposit have been made: (Knight 

and Gilbert, 1937 4 ; Dake, 1938; Harder and Wyant, unpublished 

report, 1944; Guillotte, G. B., unpublished report, 1945; Slaughter 

and Nelson, unpublished report, 1946; C. C. Towle, unpublished 

report, 1948; and D. G. Wyant, unpublished report, 1949).

The exploration work at the deposit carried out for Uranium Inc., 

by the Minerals Engineering Co. in 1948 consisted of about 3,900 

feet of trenches, 13 pits, a few bulldozer cuts, and many auger holes. 

The average maximum depth reached in this exploration was about 

5 feet beneath the surface, but most of the excavations were caved 

or filled by surface wash before the summer of 1949.

The field work in 1949 was done by D. G. Wyant, W. N. Sharp, 

and H. L. Bauer, Jr.; in 1950, D. M. Sheridan carried out the prelimary deeper auger testing. During about 2% weeks hi 1949, a 

planetable map and geologic sections of some of the trenches were 

made, and 39 shallow auger holes were bored. During about 8 weeks 

in 1950, 13 deeper auger holes, totaling 397 feet, were bored and|208 

samples were taken for analysis.

* The geologic occurrence, chemical composition, and optical properties of a new uranium mineral: unpublished paper presented before the chemistry section of the Am. Assoc. Adv. Sci. at Denver. Colo.
256 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGIC SETTING

The Lost Creek deposit, the largest deposit of schroeckingerite 

now known, is located within the Cyclone Rim fault zone, in an area 

predominantly of Wasatch-type green claystone, arkosic sandstone, 

and grit, and subordinately of thin interbeds of Green River-type 

platy shale. The Bridger formation and the Continental Peak formation of Nace (1939) are also possibly represented. The deposit is 

made up of several thin, irregular tabular mineralized bodies either 

in beds of platy shale of the Green River formation at their contact 

with beds of sandstone of Wasatch type, or in gray-green silty clay-, 

stone of Wasatch type. These beds have been folded, faulted, eroded, 

and covered by successive terrace deposits of Pleistocene to Recent 

gravel, silt, alluvium, and colluvium. The Pleistocene terrace deposits 

shown on plate 19 indicate at least two periods of terrace formation. 

The older, or upper terrace surface, is probably continuous along 

Lost Creek to a point where it leads into the delta-fan of Pleistocene 

Lost Lake in the vicinity of Eagles Nest.

About 1% miles north of the deposit, near Soda Lake (pi. 16), the 

northeast-dipping Eocene strata are overlain unconformably by the 

Oligocene(?) Chadron formation of Nace's usage (Nace, 1939, 

pp. 31-35).

Lithology. The deposit is very near the eastern margin of several 

thin tongues or lentils of the Green River formation and presumably, 

therefore, near the former fluctuating margin of one of the Eocene 

Green River lakes. Shale of the Green River formation ranging in 

thickness from 0.1 foot to about 30 feet, is exposed in units d and h of 

outcrop A (pi. 19), in the principal mineralized bodies (for example, in 

pit 8 and trench L), and in the bluff of Lost Creek. Plate 20 illustrates 

the repetition of the shale strata of the Green River at different 

stratigraphic positions in the trenches. Many of these thin beds are 

contorted, and weather to curved plates. In these beds ostracods 

were observed 60 feet east of the northeast corner of the Hadsell 

shearing pen (outcrop (a), pi. 19), and from them fragments of 

vertebrate fossils were collected (unit h, outcrop A, pi. 19).

Outcrops are sparse. The lithology of most outcrops is summarized in the following paragraphs. In outcrop A, west of the road 

fork in the south-central part of the mapped area, nine lithologic 

units are exposed: unit a is brown claystone containing some white 

sandstone; unit b is gray-green platy shale; unit c is white coarsegrained arkosic sandstone that is in fault contact with units d and e, 

which are respectively shale of the Green River and blocky gray 

shale (the sandstone is stained orange brown along the fault); unit/ is 

white coarse-grained sandstone, stained orange brown by iron oxides 

along its upper contact with unit g, a dark-brown claystone; unit h 

is brown shale of the Green River containing a few vertebrate fossils;
URANIUM IN THE RED DESERT, WYOMING 257

and unit i is gray-green claystone and gypsiferous sandstone, partly 

obscured by colluvium.

Outcrop B, shown near the center of the north edge of the mapped 

area, includes six stratigraphic units: unit a is light-green clayey 

sandstone; unit b is green gypsiferous claystone containing schroeckingerite; unit c is white-weathering brown conglomerate; unit d is 

green claystone and some sandstone, containing schroeckingerite 

pellets and gypsum; unit e is gray-green silty gypsiferous claystone; 

and unit/is arkosic conglomerate and green silty gypsiferous claystone 

that contains large pellets of schroeckingerite.

Outcrop C, west of outcrop B, is composed of 2 units: a, whiteweathering brown sandstone, and 6, medium-grained green sandstone 

and some claystone. Outcrop Z>, north of the Hadsell shearing shed, 

exposes brown claystone but may also include some shale of Green 

River type.

In addition to these outcrops, 8 outcrops too small to delineate as 

areas but plotted as points on plate 4 are as follows:

Outcrop (a), near the Hadsell shearing shed, contains platy brown 

shale of the Green River; in outcrop (6), near outcrop (a), green 

sandstone is exposed; outcrop (c), at the creek bank by the bridge, 

consists of green claystone in which pellets and flakes of schroeckingerite are concentrated in an irregular zone 2 inches thick adjacent 

to an overlying iron-stained solution zone in sandstone; outcrop (d), 

about 400 feet northeast of the bridge, exposes green-gray claystone 

containing schroeckingerite pellets; outcrop (e), north of Osborne 

Draw, exposes gray- and maroon-mottled claystone; outcrop (/), near 

outcrop (e), contains green, chocolate, or maroon sandy claystone; in 

outcrop (g), south of trench K in the west-central part of the mapped 

area, pellets of schroeckingerite are in gray-green platy shale above 

iron-stained sandstone; and in outcrop (h), 50 feet|east|of|outcrop (g), 

schroeckingerite pellets are iu green claystone.

The lithology as seen in, or as deduced from the material on dumps 

of shallow auger holes, pits, and bulldozer cuts is listed below:

Pitta and bulldozer cuts 

Reference no.

(pi. Iff) Lithologic description

1 _____________ Claystone, green, silty; contains schroeckingerite pellets.

2.______________ Claystone, gray-green; contains schroeckingerite pellets and

flakes; overlies iron-stained solution zone in green, clayey 

sandstone.

3..._____-______ Silt (terrace deposit).

4.._____________ Shale, gray-green, platy; contains schroeckingerite pellets and

gypsum.

5.._-____-______ Gravel, white to brown (terrace deposit).

6.______________ Gravel (terrace deposit).

7..-__-_-_______ Sand, white, and brown clayey sand and gravel (terrace

deposit). 

388177 57 4
258 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM 

Pits and bulldozer cuts Continued

Reference no.

(pi. 19) Lithologic description

S-.------------ Shale, gray, platy, weathering to curved plates; contains

schroeckingerite pellets; overlies iron-stained solution zone 

in white sandstone.

9___-_--__----_ Siltstone, green, sandy; contains schroeckingerite pellets; 

underlies basal boulder-gravel bed of terrace deposit.

10_____________ Sandstone, white to brown, clayey, and colluvium.

11_____________ Gravel, brownish white, clayey (terrace deposit).

12____.________ Gravel (terrace deposit).

13_____________ Claystone, gray; contains schroeckingerite pellets and white

efflorescent salt.

14_____________ Claystone, gray-green; contains schroeckingerite pellets, and

sandy siltstone. (Pit contains water.)

15_____________ Gravel of subrounded frosted quartz and feldspar grains (terrace deposit).

16______-______ Siltstone, green; contains schroeckingerite (dump material

from filled pit).

17_____________ Gravel, white to buff, and green sand (terrace deposit).

18__--____-___- Shale, gray-green and purple, platy; contains schroeckingerite 

pellets; overlies brown-stained solution zone in white sandstone.

19__---_-_--___ Siltstone, green, clayey; contains schroeckingerite pellets; 

overlies iron-stained solution zone in white micaceous sandstone.

20_____________ Shale, gray-green, platy; contains flakes of schroeckingerite;

overlies iron-stained solution zone in white sandstone and 

conglomerate (faulted).

21 ___-__.___-__ Claystone, gray-green, overlying orange-stained white sandstone; contains no schroeckingerite.

22_____________ Siltstone, green; contains schroeckingerite pellets, and overlies

iron-stained sandstone on west and north sides of pit; platy 

grey-green shale with no schroeckingerite, overlies siltstone on 

south and east sides of pit (faulted).

23_____________ Sand, green, clayey (terrace deposit); overlies gray-green

gypsiferous claystone.

24 _____________ Shale, gray, platy, weathers to curved plates; contains scbroeckingerite pellets; overlies iron-stained solution zone in white 

sandstone; claystone seams 10 and 17 inches below contact 

also contain schroeckingerite.

25_____________ Sand, gray-green, and clayey sand (terrace deposit).

26_____________ Sand, greenish white, and gravel (terrace deposit).

27_____________ Shale, gray-green, platy; contains schroeckingerite pellets;

overlies iron-stained solution zone in white sandstone.

28_____________ Shale, gray-green, platy; contains schroeckingerite pellets;

overlies iron-stained solution zone in white sandstone.

29_____________ Gravel (terrace deposit) fills pit.

30__________ Sand, white-weathering, brown (terrace deposit); fills pit.

Shallow auger holes

H-3_____ _ Claystone, maroon, sandy.

H-4___ __ Claystone, green, gravelly.

H-5________ Gravel (terrace deposit).

H-6___ ___ Gravel, white-weathering, brown (terrace deposit).
URANIUM IN THE RED DESERT, WYOMING 259

Shallow auger holes Continued 

Reference no.

(pi. 19) Lithologic description

H-7___________ Gravel, white-weathering, brown, and some white clay (terrace

deposit?).

H-8_ __________ Clay stone, light-green, silty.

H-9___________ Sand, white-weathering, buff and green, and gravel; gravel

contains fluorescent chalcedony (terrace deposit?).

H-10__________ Sand, green (terrace deposit).

H-11__________ Clay, green, and gravel (terrace deposit).

H-12________ Claystone, green.

H-13_-______ Claystone, green.

H-14__________ Gravel, green (terrace deposit).

H-15._________ Gravel (terrace deposit); hole is filled.

H-16__________ Gravel (terrace deposit); hole is filled.

H-17--_ r ______ Sand and gravel (terrace deposit); overlies green sandy siltstone; hole is filled.

H-18__________ Sand and gravel (terrace deposit); overlies green sandy siltstone; hole is filled.

H-19__________ Shale, gray-green, platy; contains schroeckingerite pellets,

and brown sandstone; hole is filled.

H-20_______ Silt, buff (terrace deposit).

H-2!__________ Sand, white (colluvium).

H-22__--__-___ Sand, white, coarse (colluvium and terrace deposit).

H-23__________ Gravel (terrace deposit); hole is filled.

H-24__________ Shale, gray-brown, platy; schroeckingerite?; hole is filled.

H-25__________ Gravel (terrace deposit, colluvium); hole is filled.

H-29________ Claystone, brown.

H-31 __________ Sandstone, green, silty.

H-33__________ Claystone, gray, silty; contains schroeckingerite.

H-34________ Claystone, gray, silty; contains schroeckingerite.

H-35__________ Sand and gravel (terrace deposit).

H-36________ Clay, green, sandy (terrace deposit?).

H-37__________ Claystone and sandstone, iron-stained.

Trenches F, G, H, /, and P (pi. 19) were filled or caved in the summer of 1949, although some information concerning lithology and ore 

zones was gathered by inspecting the dump material. Trenches Ii, J, 

t/i, MI were not deep enough to expose bedrock below the Pleistocene 

terrace deposit. Vertical sections were prepared of trenches C, E, E1} 

L, and N. The other trenches were open but were not mapped 

because the time was too short. The general relations between the 

various type of sediments and schroeckingerite in these five trenches 

are shown on plate 20.

Additional lithologic data obtained from cuttings of shallow auger 

holes drilled in 1949, and from deeper auger holes drilled in 1950 

are tabulated in the section Auger-hole data (tables 10 and 11).

Structure. The deposit is within the Cyclone Kirn fault zone 

that separates folded beds to the northeast from nearly horizontal 

beds to the southwest. (See cross sections A-A' and B-B', pi. 19.) 

Faults within the Cyclone Rim fault zone were first observed while 

measuring columnar section 9, about 8K miles northwest of the
260 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

deposit (pi. 16). These faults strike N. 50°-70° W., dip vertically or 

steeply to the south, and individual faults displace the beds on the 

southwest side downward as much as 33 feet. Within the schroeckingerit deposit, minor faults, ranging in strike from N. 70° to 85° 

E., and in dip from 25° to 53° SE., were mapped in trench C, trench 

A, pit 21, and outcrop A. Offsets on these faults appear to be small 

but were not positively demonstrated.

In general, the sediments within the deposit strike northwestward 

and dip northeastward. Their strikes, as determined in trenches and 

pits, range from N. 89° W. to N. 72° E. but average about N. 65° W.; 

dips range from 4° to 42° NE., and average about 20° NE. In 

trench L, pit 8, and in the bluffs of Lost Creek below the bridge, the 

beds strike northeastward and appear to be continuous between 

exposures, which suggests that they have been folded rather than 

faulted. The nearly east direction of strikes in pit 2, trench 0, pit 

4, and trench N, may also reflect the attitude of such a postulated 

fold rather than the effects of local faulting or "surface creep."

It is possible that most of the ore bodies are along fault surfaces 

that parallel bedding surfaces. Natural exposures are too few and 

exploration too shallow to afford adequate observation of this 

relationship.

MINERALOGY

The principal uranium mineral in the deposit is schroeckingerite, 

but fluorescent uraniferous opal, and undetermined minerals of 

uranium also occur.

SCHROECKINGERITE

Schroeckingerite, NaCa3 (UO2)(CO3) 3 (SO4)F-10H2O, is a bright yellowish-green mineral that contains about 27 percent uranium. Under 

ultraviolet light the mineral fluoresces an even brighter yellowishgreen than it appears in white light. Schroeckingerite, hand-picked 

from Lost Creek ore, and estimated to contain only 1 percent of 

impurities (sand, clay, etc.) contains 11.0 percent equivalent uranium 

and 24.5 percent uranium; the discrepancy between the analytical 

and theoretical uranium content may mean that the Lost Creek material analyzed contained nearly 4 percent impurities. The smaller 

equivalent uranium content reflects a relative deficiency in radium 

and indicates that the schroeckingerite formed so recently that the 

uranium and its disintegration products have not yet attained radioactive equilibrium. The optical properties determined by Joseph 

Berman correspond closely to those reported by Jaffe, Sherwood, and 

Peterson (1948). Other work concerning the mineralogy of this mineral has been done by Schrauf (1873), Larsen and Gonyer "(1937), 

Knight and Gilbert (see footnote 4, p. 255) (1937), Dake (1938), and 

Nova6ek (1939).
URANIUM IN THE RED DESERT, WYOMING 261

Some loose pellets of schroeckingerite, observed in the rock debris 

at the base of the bluff below the bridge and in the dumps of the 

trenches, appear to differ from normal schroeckingerite. These pellets 

are harder, slightly more yellow than the normal yellowish green, and 

are commonly encased by a reddish-brown shell; they may possibly 

be dehydration forms of the mineral or may be schroeckingerite 

slightly modified by the addition to or loss from the molecule of some 

components other than water.

In the Lost Creek deposit, schreockingerite has 3 characteristic 

modes of occurrence: 1, as round aggregates or pellets, as much as 

three-fourths of an inch in diameter, made up of platy crystals; 2, as 

individual, small flaky crystals; and 3, as 1 millimeter-thin layers made 

up of numerous small crystals that coat grains of quartz, calcite or 

other sandstone components or the surface of efflorescent salts. The 

mineral also occurs, rarely, in microscopic fibrous masses in silica and 

calcium carbonate.

The pellets, concentrations of which constitute the ore bodies, 

seem to occur preferentially within brown, gray, or varicolored shale 

of the Green River formation or in massive gray-green silty claystone 

or clayey siltstone of Wasatch type. Some pellets fill shrinkage 

cracks in the claystone. The commonly associated minerals, other 

than the predominant clay minerals of the montmorillonite group and 

quartz of silt-size, as determined by Joseph Berman in hand specimens 

of typical pelletal schroeckingerite ore, are gypsum, aragonite, calcite, 

and iron-oxides.

The individual thin flaky crystals of schroeckingerite that are 

commonly disseminated in loose sand or sandy clay, as well as the 

thin layers coating other minerals at the ground surface attest to the 

ready solubility and mobility of schroeckingerite in cold water. The 

mineral is periodically dissolved by rain and melting snow and carried 

down the slopes, where it recrystallizes upon drying as a surface 

incrustation. During the winter season of 1948-49, the individual 

crystals and pellets exposed on the dumps of the trenches dissolved 

and, during the dry season of 1949, recrystallized as thin efflorescent 

coatings of the ground below the dumps; these coatings cover areas as 

much as 20 feet square. Schroeckingerite is also readily dissolved 

and transported by near-surface ground water from which the mineral 

reforms on evaporation, so that a blanketlike thin layer of disseminated 

schroeckingerite flakes commonly coats shale beds or claystone that 

immediately underlie porous ten-ace sand and gravel, or colluvium. 

A specimen representative of this type of occurrence from the older 

terrace deposit (Qt2) at pit 18, overlying an ore body that was examined by Berman, consists of a friable, porous arkose composed 

predominantly of subrounded grains of microcline and a moderate 

amount of quartz; the grains are loosely bonded by small amounts of
262 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

clay and calcium carbonate. Small specks of fluorescent material 

are probably schroeckingerite. Such widespread dispersion of the 

mineral, although an aid in prospecting, hampers the finding of ore 

bodies; the thin coatings, although a spectacular sight under ultraviolet light, are not ore.

OTHER URANIUM MINERALS

Unknown uranium-bearing minerals or substances are present in 

the deposit and in the adjacent rocks, as was first noted by Slaughter 

and Nelson (unpublished report, 1946), who took samples of claystone 

that was radioactive but contained no visible schroeckingerite. One 

of these samples contained 0.018 percent equivalent uranium and 

0.004 percent uranium; another contained 0.019 percent equivalent 

uranium and 0.039 percent uranium. The presence in the first sample 

of a probable excess of radium (analogous to some of the radioactive 

lignite), and in the second of a probable excess of uranium, certainly 

indicates the presence of other uranium minerals or uranium-bearing 

substances. Sample WNS-5-233, of a 3-inch bed of white ashy 

material from trench K2 (pi. 21), contains 0.025 percent equivalent 

uranium, 0.011 percent uranium; the sample is composed of dolomitic 

calcite containing minor amounts of subrounded particles of partly 

devitrified volcanic glass (?) and quartz silt, Joseph Berman (written 

communication). A sample, DW-108-305, of gypsiferous sandstone 

from Arapahoe Creek contains 0.005 percent equivalent uranium and 

0.003 percent uranium (table 3). The sample, according to Berman, 

is composed of albite, gypsum, calcium carbonate, clay, some oligoclase and rose quartz, and small amount of microcline, altered rhyolite, and biotite. The oligoclase is largely altered to sericite. Fluorescent, radioactive agate pebbles occur at the Lost Creek deposit. 

In 1948 C. C. Towle and the senior author took samples of terrace 

deposits and of green clay in which no schroeckingerite was observed 

but which contained as much as 0.011 percent equivalent uranium 

and 0.006 percent uranium (sample TW-13, table 7).

Schroekingerite is associated with small amounts of fluorescent 

uraniferous opal, carbonate, and gypsum, and with nonfluorescent 

uranium minerals (or adsorptions on clay). During the program of 

auger-testing in the fall of 1950, material having fluorescent characteristics similar to those of schroeckingerite was found in all the holes 

bored. The fluorescent material was first thought to be schroeckingerite, but analyses show it does not contain as much uranium as 

schroeckingerite. M. E. Thompson determined the material to be, 

in part, opal; in part fluorescent calcite; and in part, an unidentified 

constituent. Examination of samples under ultraviolet light with 

a binocular microscope indicated that many fluorescent clots, which 

megascopically appeared to be small clots of schroeckingerite, are in 

reality grains and aggregates of other minerals with thin, irregular
URANIUM IN THE RED DESERT, WYOMING 263

coatings of schroeckingerite. Some of these other minerals, notably 

opal, calcite, and gypsum are also fluorescent.

Sample WNS-20 (S:28), of dull-yellow-fluorescent gypsiferous 

claystone from the west side of Lost Creek about 1% miles northwest 

of the Hadsell shearing sheds, contains 0.004 percent equivalent 

uranium, 0.002 percent uranium (table 3). The sample, as examined 

by Berman, is an argillaceous siltstone containing substantial amounts 

of gypsum. The clay is a physical mixture of an illite-type clay 

mineral and kaolinite. The silt particles are principally feldspar and 

quartz.

Some samples containing as much as 0.019 percent uranium contain 

only a relatively small amount of schroeckingerite. It is possible 

that uranium may be adsorbed in clay aggregates in some of these 

samples.

Semiquantitative spectrographic analyses of some of the augerhole samples have been made by Paul R. Barnett. Major constituents 

other than silicon and iron are calcium, barium, magnesium, and 

titanium. It is likely that barium and radium occur together. As 

much as O.OX percent vanadium, manganese, lanthanum, and cerium 

were found in some samples.

ORB BODIES

The schroeckingerite ore bodies at the Lost Creek deposit are shown 

on plate 19. The examination of the rock exposed in open trenches 

and pits and of the rock fragments in the dumps of auger holes and 

filled trenches and pits suggests that the more continuous ore bodies 

occur either in platy shale overlying sandstone or in gray-green 

massive silty claystone. The shale-sandstone type of ore body, 

which appears to predominate, is in detail, as follows: white friable 

sandstone of Wasatch type is overlain sharply by gray platy (commonly contorted) shale of Green River type. A thin zone, 1-8 

inches thick, largely but not entirely in the sandstone, at the contact 

of shale and sandstone is invariably stained brown, orange, or purple 

by iron and manganese (?) oxides. Pellets of schroeckingerite are 

commonly disseminated in the shale parallel to the iron oxide-stained 

zone and only occasionally within the zone, although flakes of schroeckingerite may be sparsely disseminated in it.

A typical ore body of the shale-sandstone type (pi. 20) is from 6 to 

15 inches thick, the average is 1 foot in thickness, and extends 5 feet 

or more vertically beneath the surface (pi. 19, trench D\\ pi. 20, 

trench L}. The maximum vertical depth to which schroeckingerite 

has been found is 8 feet, hi pit 18 and in trench C, and was a distance 

of 37 feet down the dip of the ore body.

The length of individual ore bodies is unknown. The longest 

distance explored along the strike of a bed is 150 feet in trench D\.
264 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

The schroeckingerite ore body in this trench extends, with a gap of 

about 100 feet, into pit 18 and is exposed by trench C. There is no 

apparent diminution in grade throughout the length explored. 

Therefore, it is reasonable to assume this body is continuous between 

exposures and that it is at least 270 feet long.

Schroeckingerite in shale overlying iron-stained sandstone (the 

shale-sandstone type of ore body) is found in nearly all trenches that 

are deep enough to expose bedrock. This shale-sandstone sequence 

of beds seems to be the most favored association for schroeckingerite, 

but this sequence is not invariably schroeckingerite bearing. In 

trench C, about 62 feet from the southeast end, and in pit 21 this 

characteristic favorable sequence of beds is barren of schroeckingerite.

The schroeckingerite body of the shale-sandstone type exposed hi the 

bluff of Lost Creek west of trenches K and L projects directly into 

the exposure of the body in trench L, thence into pit 8, and if the 

interpretation of structure is correct from pit 8 around a sharp fold 

into trench K. An auger hole, H-19, about 110 feet southeast of this 

shale-sandstone body in trench K, intersected the same deposit. 

From this point southeastward to trench / there are no exposures. 

The platy shale and schroeckingerite pellets in the dump at the southwest end of trench I are approximately on the trend of the schroeckingerite body and are assumed to be its southern extension. Two 

shale-sandstone ore bodies at the northeast end of trench A may be 

projected through trench E, possibly|as far as trench F.

The continental sedimentary rocks in this area are characteristically 

nonpersistent, lenticular, arid their contacts may be in part fault 

contacts; thus, the projection of shale-sandstone contacts and associated schroeckingerite bodies is somewhat questionable. In addition, 

the ore bodies are in the Cyclone Rim fault zone where the beds 

should be expected to be displaced by faults.

Schroeckingerite in gray-green silty claystone or clayey siltstone 

is exposed in trench L, pits 13 and 14, trench K2) the southwest end 

of trench F, trench C, pit 1, and outcrop (d).

Thin stringers or mantles of schroeckingerite pellets and flakes 

that are too thin and irregular to constitute potential ore occur along 

the bluff of Lost Creek below the bridge, and near the edge of the colluvium in outcrop -A; in a similar position in outcrop B; and in trench 

P. These occurrences are probably the result of the re-formation 

of schroeckingerite from ground and surface water that has passed 

over or through schroeckingerite-bearing material elsewhere.

GRADE

The grade of samples of schroeckingerite-bearing material that have 

been taken from the Lost Creek deposit since 1948 ranges from 0.013 

to 0.28 percent uranium.
URA3SFIUM m THE RID DESEBT, WTOMBfG 265

The analyses of samples of schroeckingerite-bearing material, water, 

plants, and soil taken by the Minerals Engineering Co. and by the 

Geological Survey are given in tables 7, 8, and 9. The analyses of 

rock samples (table 7) disclose discrepancies between equivalenturanium and uranium contents, and differences in the uranium content 

of samples taken by the Minerals Engineering Co. and those taken 

by Towle and Wyant. Some of the discrepancies may be attributable 

to sampling procedures. The report by George Petretic, Geological 

Survey, accompanying the analyses of the samples taken by Towle 

and Wyant (table 7) stated:

. . . the correspondence between the percent ell [equivalent uranium in table 

7] determined by reference to a standard in which uranium is in equilibrium with 

UXi and UXz only and percent uranium is good except for samples 5828 (TW-17), 

5836 (TW-25), and 5837 (TW-26). Although this agreement is not good, it 

can be attributed to the non-homogeneity of the samples. The schroeckingerite 

is dispersed throughout the matrix of feldspar, etc., and observation of the samples 

under an ultra-violet lamp clearly shows that a non-representative sample can 

easily be obtained, particularly if less than a gram is used for analysis.

The difference in analyses may be attributed in part to differences in 

the sampling procedure, and in part to the fact that schroeckingerite 

is erratically distributed in the ore bodies and that this soluble mineral 

is in process of being redistributed by ground and surface water. 

Bulk sampling probably is the only way to obtain representative 

samples.

The analyses of water samples (table 8) show an abnormal uranium 

content in the ground water underlying the deposit (as much as 0.88 

parts per million). The spring at the mouth of Osborne Draw (northwest part of map, pi. 19) is probably a seep of near-surface water, 

possibly localized by fracturing or faulting. It is of interest to note 

that there is a seasonal fluctuation of the uranium content of the 

spring water. Sample WNS-9-13 of water from pit 14 contains much 

more uranium (46 parts per million) than do many other water 

samples. This is not surprising, inasmuch as the schroeckingeritebearing material in this pit was exceptionally high grade, and as the 

water (in direct contact with this ore) had been stagnant in the pit for 

at least four months. The ground water is mildly alkaline (pH of 

7.8-8.3).

The plant and soil samples also show abnormally high uranium 

contents (table 8). A sample of greasewood roots (P 4) contains 7,400 

parts per million in the ash, according to Helen Cannon (written 

communication), who states ". . . so far as I know, this is the highest 

value for uranium ever reported in a plant." The greasewood plant 

was growing on a schroeckingerite body'(exposure d, pi. 19).

AUGHER-TESTESTQ PROGRAM! OF 1950

A program of auger drilling was begun at the Lost Creek schroeckingerite deposit on October 23, 1950, and was recessed on December 20,

388177 57 5
266 CONTRIBUTIONS TO THE -GEOLlQGY OF.URANIUM

1950. The drilling was done with a jeep-mounted auger-drill rig 

equipped with augers 4% inches in diameter.

The objectives of the auger-drilling program were (1) to determine 

the maximum depth at which schroeckingerite occurs, (2) to obtain 

preliminary data about the lateral distribution of schroeckingerite, 

and (3) to determine more accurately the relations of schroeckingerite 

to beds of different lithology and to the Cyclone Rim fault zone.

Because of contamination inherent in the auger-drilling method, 

assays of auger-samples were not expected to give representative 

grades of schroeckingerite ore bodies; it was hoped, however, that 

such bodies could be delineated by means of these assays.

SAMPLING AND LOGGING* PROCEDURES

Thirteen auger holes, totaling 397 feet, were drilled to depths ranging from 9 to 51 feet. The location of these holes is shown on plate 21. 

Eleven (holes ES-1 to ES-3 and ES-5 to ES-12), are along line of 

section C~Cr shown on plate 22 and are oriented approximately perpendicular to the average strike of the ore bodies. These holes were 

spaced at intervals of 2-23 feet apart near known ore bodies in the 

trenched area, and at intervals of 163-1,000 feet apart, where remote 

from known ore bodies. Hole ES-13 was collared at a point 2,000 

feet S. 60° E. from the northernmost end of section C-Cr and hole ES-4, 

at a point 2,200 feet N. 45° W. from the southernmost end of section 

0-C'.

Samples were taken from top to bottom of the hole at 2-foot intervals except where changes in lithology made a different sample interval preferable or where drilling difficulties required special sampling 

intervals. For example, drilling below the water table required large 

sample intervals, in order to save time and insure better recovery. 

Each sample for analysis consisted of all the rock recovered from the 

interval being drilled, except for small samples removed for lithologic collections. Whenever the sample was obviously contaminated, 

such information was noted. A total of 198 rock samples for analysis 

was taken from the 13 auger holes.

Samples of the dry rock above the water table were collected by 

Spinning the auger without lowering or raising the position of the bit, 

so that the rock traveled up the spiral auger and accumulated on a 

flat steel plate. This procedure was fairly satisfactory, but contamination by wall rock of the hole was unavoidable. For example, 

a 2-foot auger sample may consist entirely of clay mixed with sand and 

may assay 0.050 percent uranium. These data cannot be interpreted 

to mean that the sample represents an ore body 2 feet thick consisting 

of sandy claystone because the schroeckingerite may have been concentrated in any fraction of the 2-foot interval with a correspondingly 

higher grade in that fraction, and may all occur in the claystone and
URANIUM IN THE RED DESERT, WYOMING 267

not in the sandstone. By the time the sample reaches the surface it 

has undergone considerable mixing and the ore minerals may be 

scattered through the entire sample; caving may also add the ore 

minerals to succeeding samples.

In the drilling of holes below the water-table, sampling required 

the removal of rods after each sampling-run so that they could be 

stripped clean of adhering mud and ice.

Sample logs of each hole were made during the drilling and small 

representative samples of individual lithologic units were collected to 

preserve a record of each hole. A sample was taken of water in 

each of the 10 holes in which the water table was reached (all holes 

except ES-1, ES-11, and ES-13), and gamma-ray logs of each hole 

were made with a Geiger-Mueller counter to which a 2-foot gamma 

probe was connected by 50 feet of cable. In several holes caving 

prevented probing the total depth of a hole and the total footage of 

radiometric logging is only 326.5 feet, as compared to 397 feet of 

hole drilled.

Dry auger-samples were examined at night with an ultraviolet 

lamp having its highest efficiency at a wave length of 2540 angstrom 

units. The schroeckingerite content of each sample was estimated 

on the basis of yellowish-green to greenish-yellow fluorescence. 

Radioactivity examination of these dry samples was made with a 

Geiger-Mueller counter, using a small probe with the beta shield 

open. The lithology, depth of sample, the radioactivity of samples 

determined in the field, the laboratory analyses of samples, and the 

gamma-logs of the bore holes are given in table 11.

In summary, the auger-drilling program allowed the determination of the general sequence of subsurface lithology and the determination of approximate locations, but not specific dimensions of 

schroeckingerite ore bodies. The grade figures calculated from the 

analyses are, at best, of value only in determining the uranium content 

of large intervals of rock.

GEOLOGIC RESULTS

The subsurface lithology determined during the auger-testing program and tabulated hi the sample logs (table 11) has been plotted 

on geologic cross sections at scales of 1 inch to 200 feet (holes ES-2, and 

3, and ES-5-ES-12, pi. 22) and 1 inch to 20 feet (all holes except ES-1, 

pi. 23). The locations of all auger holes are shown on plate 21. 

Hole ES-1, abandoned at a depth of 9 feet, is only 2 feet from hole 

ES-2, and no section of it was prepared.

Holes ES-2, ES-3, ES-5, and ES-6 are near enough to each other 

to permit a general correlation of beds, aided in part by data from 

previous geologic mapping in the trenches. In the vicinity of these 

holes the lenticular beds of sandstone, siltstone, and claystone (trench
268 CONTRIBUTIONS TO T1B& GEOLOGY OP URANIUM

C, pi. 20, and pi. 23) show on a small scale the interfingering relationship that the Wasatch-type sandstone and claystone have to shale of 

the Green River formation elsewhere near Eagles Nest (pi. 16) on a 

larger scale. Faults, if present, were not recognized. The other 

auger holes were spaced too far apart to permit intercorrelation of 

the beds.

Hole ES-11, located just south of the southeastern limit of the 

Cyclone Rim fault zone, is mainly in brown, hard, platy shale and 

small amounts of interbedded sandstone. Holes ES-1 to ES-6, all in 

the trenched area, and holes ES-7, ES-8, and ES-10 are in a series 

of interbedded sandstone, siltstone, and claystone with scattered 

iron-stained zones at the contacts of sandstone and claystone beds, 

but hole ES-9, 29 feet in depth, is almost entirely in pebbly sandstone 

with only minor amounts of siltstone and no claysfcone. Hole ES-12 

cut beds of siltstone and claystone with only minor amounts of sandstone. Hole ES-13 penetrated sandstone and subordinate amounts 

of interbedded siltstone and claystone beds.

The most notable features of the general lithology described above 

are the thick sections of sandstone in holes ES-9 and -13, as compared 

with the sequence of siltstone and claystone in hole 12 and the sequences of sandstone, siltstone, and claystone in the other holes. 

Hole ES-9 is on the south flank of a ridge trending northwest (pi. 16), 

whereas hole ES-13 is on the north flank of the same ridge; hole 

ES-12 is at the foot of this ridge on its northeastern side.

Aerial photographs suggest that this ridge is formed of sandstone, 

and this is corroborated by the sandy character of the beds cut in 

holes ES-9 and ES-13. The shale penetrated in hole ES-12 suggests 

that a claystone sequence begins immediately north of the sandstone 

ridge. The data obtained by drilling indicate that the stratigraphic 

interval between the beds seen at the southwestern limit of the Cyclone Rim fault zone (pis. 16 and 19) and those cut in hole ES-9 

(pi. 21) is occupied by relatively thin sandstone beds with a high 

proportion of claysfcone, shale, and silfcstone beds, whereas the stratigraphic interval between the beds of hole ES-9 and those of hole 

ES-12 (pi. 21) is occupied by relatively thick sandstone beds with a 

low proportion of claystone and siltstone beds. Another sequence 

predominantly of shale and siltstone beds extends for an unknown 

distance northeast of hole ES-12.

DISTRIBUTION OF URANIUM

Visual estimates of the schroeckingerite content of each auger sample 

were made on the basis of fluorescence and auger samples were then 

analyzed by the Geological Survey (table 11). A comparison of 

uranium content determined by chemical analysis with the preliminary estimates of schroeckingerite content made in the field disclosed
URANIUM IN THE RED DESERT, WYOMING 269

several discrepancies: (1) in some samples the uranium content estimated from the amount of fluorescent material was much greater 

than that determined by chemical analysis, and (2) in some other 

samples opposite relationship was true.

For example, the average of estimates made by three observers of 

the schroeckingerite content of sample DS-2-10 (hole ES-2, table 11) 

is about 1 percent. Schroeckingerite contains about 27 percent 

uranium; therefore, this sample should have contained about 0.27 

percent uranium. Actually, it contained only 0.049 percent uranium. 

Three sources of error may account for this type of discrepancy: 

(1) errors in preparation or analysis, (2) errors in estimation of 

schroeckingerite content, and (3) the errors caused by the presence 

of fluorescent material other than schroeckingerite. Accordingly, an 

effort was made to check these possible sources of error. To check 

the methods of preparation, 6 representative samples were prepared 

by hand pulverized on a buckboard, ground in an agate mortar, 

mixed in a sampling cloth, and a representative split taken and were 

then analyzed. The results are shown in table 12. With one exception (sample DS-5-80), probably the result of an uneven original 

split, the resulting assays agree very closely with the original assays 

and the assays of the laboratory-prepared split, and indicate that 

neither the method of preparation nor the method of analysis (unless 

part of the uraniun is consistently lost in the chemical procedure) 

are the sources of error. Though visual estimates of the schroeckingerite content based on fluorescence are admittedly subject to error, 

it is believed that the discrepancies between estimates and assays are 

caused in part by the presence of fluorescent material other than 

schroeckingerite. (See under section headed Other uranium minerals.)

TABLE 12. Comparison of analyses (in percent) of six samples prepared by two 

different methods, Lost Creek schroeckingerite deposit, Red Desert, Wyo.

Original analyses

No. of sample

T>8-^-9.. .....................

DS-2-10 _ .... _ ..... _ ....

DS-2-11... _ ........... __ .

DS-5-80.... ..... ___ ....

DS-7-111-- ..................

DS-3-39-. __ - . . . 

Equivalent 

uranium

0.006 

.021 

.005 

.036 

.003 

.007

Uranium

0.007 

.049 

.007 

.063 

.001 

.007

Check test

Hand-prepared split

Equivalent 

uranium

0.006 

.023 

.005 

.037 

.004 

.007

Uranium

0.004 

.047 

.004 

.081 

.000 

.006

Laboratory-prepared 

split

Equivalent 

uranium

0.007 

.021 

.005 

.037 

.003 

.006

Uranium

0.004 

.044 

.006 

.080 

.000 

.005

Schroeckingerite was identified under the petrographic microscope 

in sample DS-2-10. In some other samples, however, containing 

little or no uranium and from 0.1 to 5 percent of fluorescent material, 

little or no schroeckingerite was observed. For example, on the
270 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

basis of fluorescence, sample DS-10-157 from hole ES-10 was estimated to contain from 1 to 2 percent schroeckingerite. Therefore, 

theoretically, it should have contained from 0.27 percent to 0.54 

percent uranium, but actually it assayed only 0.001 percent uranium. 

The fluorescent material in this and other similar samples, examined 

under the binocular microscope, fluoresces a slightly duller and more 

yellow color than does schroeckingerite (megascopic examination of 

the fine-grained material does not permit such fine color distinctions 

to be made) and is a very fine-grained aggregate with an index of 

refraction of less than 1.49; it is possibly allophane or opal. Some 

samples of this type contain very fine grains that are believed to have 

the true color of schroeckingerite in addition to the unknown material 

of lower refractive index.

Traces of fluorescent material which may be in part schroeckingerite 

were found at a maximum depth of about 34 feet in hole ES-13 and 

at various depths above the water table in all 13 auger holes. In 

trenches and pits schroeckingerite extends to a depth of at least 5 feet. 

The evidence obtained from the program of preliminary auger testing 

in 1950 suggests that schroeckingerite does not occur below the water 

table, and that schroeckingerite concentration in bodies of potential 

ore grade may not extend below a depth of about 8 feet.

Preliminary field mapping has indicated that rich concentrations 

of schroeckingerite in the shale are localized along some of the contacts between the shale and iron-stained sandstone. Iron-stained 

material was found as much as 35 feet beneath the water table. Data 

obtained from the auger drilling (table 11) and from investigations of 

the trenches suggest that the richest concentrations of schroeckingerite 

in the trenched area near holes ES-1, -2, -3, -5, and -6 are within 7.5 

feet of the surface. It cannot be concluded from assays, however, 

that rich concentrations do not persist to greater depths, because 

schroeckingerite pellets are erratically distributed within beds both 

horizontally and down dip. This has been shown by surface mapping 

and also suggested by some of the auger-testing data. Hole ES-7 

was drilled at a point determined by projection of an ore body from 

trench (73 so that the ore would be intersected at a depth of about 10 

feet. Samples in this hole, from depths of 5 to 12 feet, contain only 

0.001 percent uranium (Auger hole ES-7, table 11). In the field 

about 5 percent of the samples of damp rock directly above the 

water table (12 feet) fluoresced, but when this material was dried, no 

fluorescent material was observed; apparently the fluorescence was 

caused by efflorescent salts that contain little or no uranium and which 

lost their ability to fluoresce upon drying. Hole ES-4 was so located 

that an ore body projected from trench L and pit 8 would be intersected at a depth between 10 and 15 feet. Samples from this hole
URANIUM IN THE BED DESEET, WYOMING 271

(table 11) contain 0.007 percent uranium in the interval between 

depths of 10 to 12 feet and 0.005 percent uranium in that between

12 to 14 feet, compared to a general content of 0.002 percent uranium 

in samples from the rest of the hole. A very thin concentration of 

schroeckingerite diluted by wall rock during drilling may cause the 

abnormal uranium content in the interval 10-12 feet.

The lack of significant amounts of schroeckingerite at depths which 

are above the water table and along projections of ore bodies may be 

attributed to (1) its sporadic distribution in each ore body both 

horizontally and down dip, (2) the possibility that it does not occur 

below depths of 8 feet, (3) the possibility that favorable host beds 

either lens out or have been offset by faults, and (4) the possibility 

that schroeckingerite may be present in thin bodies that are insignificant in relation to the length of the sampled interval.

Radioactivity anomalies obtained from the gamma-ray logs of the 

auger holes (table 11), that do not correspond with the sample assays, 

such as the high radioactivity of the wall rock throughout hole ES-5, 

are not explained by existing data. It is possible that radon may 

cause some of the anomalies, or that imperfections of the instrument 

are to blame.

The uranium content of water samples (table 8) from 10 of the

13 auger holes ranged from 0.004 to 0.88 ppm. The analyses of 

water from holes ES-2, -3, -4, -5, and -6 indicate a fairly uniform 

abnormal uranium content in the ground water in the area near the 

trenches. Water from holes ES-7 and -10 contain, respectively, 0.50 

and 0.88 ppm, but rock samples from neither of these holes contained 

more than 0.006 percent uranium much less than the maximum 

uranium content of rock samples from holes ES-2, -3, and -5. The 

analyses of water from holes ES-8, -9, and -12 indicate that the 

ground water north of the fault zone contains relatively little uranium.

The limits of this near-surface uranium deposit are not known and 

will remain unknown until additional exploration is done. The gentle 

fold assumed to be in the vicinity of trench L and K (pi. 4) and the 

obscuring alluvial material along Lost Creek make it difficult to 

project positions of the beds which are the loci of ore bodies to the 

west side of Lost Creek.

Hole ES-7 cuts a sequence of interbedded sandstone, siltstone, and 

claystone and reached the water table at a depth of 12 feet. Although 

only one claystone bed was cut above the water table in this hole, 

many claystone beds were cut below the water table. These can be 

projected updip to positions above the water table in the area between 

holes 6 and 7, where it is possible that some may be schroeckingerite 

bearing. Additional auger-drilling or trenching, outlined on pi. 21, 

will be required to predict the total number of such loci for ore 

bodies in the deposit.
272 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ORIGIN

A thorough understanding of the source of uranium and the processes involved in the formation of the Lost Creek deposit the largest 

deposit of schroeckingerite now known in the world would have wide 

application in the continuing study of other deposits of secondary 

uranium minerals. Although the final stages in the formation of 

schroeckingerite are reasonably clear, data available are insufficient 

to do more than indicate several possible sources for the uranium.

The final stage hi the formation of schroeckingerite appears to be 

crystallization from alkaline ground- or surface-water solutions during evaporation of the water. The mineral must thus be deposited 

above the water table, near the surface. An arid or semiarid climate 

would thus seem to be a requirement for its accumulation, for under 

wet climatic conditions the mineral would tend to be flushed out of 

the area. The process of schroeckingerite deposition is thus conceived to differ from that of caliche deposition only in the quasistratigraphic control of the schroeckingerite. Another requirement 

for the formation of large pellets of the mineral appears to be a finegrained host rock, such as shale of the Green River formation.

An experiment performed by Guillotte (unpublished report, 1945) 

bears on this problem. He pulverized specimens of shale containing 

large pellets of schroeckingerite, added water and thoroughly mixed 

the slurry until schroeckingerite completely dissolved. The mud, left 

undisturbed until it had dried out, contained large pellets of newly 

formed schroeckingerite resembling in all respects those in the original 

specimens.

The observation that large pellets of schroeckingerite form in claystone, shale, or siltstone, whereas only disseminated flakes or surface 

incrustations of schroeckingerite form in adjacent sandstone and on 

the ground surface, may be explained by the difference hi the capacity 

of the different types of sediments to retain water. As the nearsurface rocks dry out, the finer grained sediments retain water for a 

longer tune than the coarser grained sandstone, or than any sediments 

at the ground surface, thus furnishing an environment hi which the 

mineral could crystallize relatively slowly and form large pellets or 

aggregates of crystals. If this is so, then one might expect to find 

pellets of schroeckingerite even in sandstone near the permanent 

water table.

Other known factors entering into the problem of the genesis of 

the schroeckingerite deposit are its localization within the Cyclone 

Rim fault zone, and the relationship between solution zones of ironstained sandstone and shale and schroeckingerite. Although the 

deposit has not been delimited, schroeckingerite is, with one exception, confined to the Cyclone Rim fault zone. The exception (the 

ore in exposure B and pit 1, pis. 19 and 21) might be explained by
- T7RANTOM IN THE RED DESERT, WYOMING 273

faulting subsidiary to the major fault zone, although such subsidiary 

faulting has not been established. Although exposures are poor, it 

seems remarkable that schroeckingerite has not been found anywhere else in the Red Desert. It is probable, therefore, that the 

zone of faulting is a major control in the localization of the schroeckingerite deposit.

The close though not constant association of zones of iron-stained 

sandstone and shale and the ore bodies of schroeckingerite suggests 

that they may be related in genesis. However, the fact that not all 

iron-stained zones contain schroeckingerite may only mean that the 

uranium mineral formed in the same environment as did iron oxides. 

The iron oxides were probably formed by the oxidation of ferrous 

hydroxide derived from ground water. Ferrous hydroxide may have 

been derived from distant source beds, such as beds buried beneath 

the stained zones, and transported relatively long distances, or may 

have been derived from local source beds, such as the shale beds at, 

the present sites of the stained zones, and transported laterally only 

a few inches or feet. The flow of ground water would tend to be 

localized in the permeable sandstone beds next to the relatively 

impermeable shale beds. On the other hand, water held in the shale 

would tend to migrate laterally into the adjacent sandstone as the 

level of the water table sank during dry seasons, for the sandstone 

would dry faster than the shale thus forcing the water held in the shale 

to migrate into the sandstone. Perhaps the relation in the iron content 

of samples closely spaced across an iron-stained zone, including both 

sandstone and shale and the adjacent minenalized shale bed might help 

resolve the problem of distant versus local source of the iron. Either 

postulation seems to require that the water table be low enough to 

permit air to enter the pore spaces of the sandstone beds. Present-day 

seasonal fluctuations of the water table permit the entrance of air 

only to a depth of about 20 feet. Therefore the iron-stained zones 

reached in auger-drilling at depths of as much as 35 feet beneath the 

water table probably were formed when the water table was much 

lower than it is now, possibly during dry interglacial stages of the 

Pleistocene epoch. The iron-stained zones that in places contain 

schroeckingerite beneath Recent colluvium, and beneath the Pleistocene terrace deposits are proof that iron oxides and schroeckingerite 

are still forming.

The source of the uranium carried by ground water remains problematical. Uraniferous lignite, however, is inferred to be the most likely 

source of the uranium for the following reasons:

1. Uranium apparently is leached from outcrops of uraniferous lignite near the 

area of the schroeckingerite deposit.

2. Uraniferous lignite, in which the uranium is in radioactive equilibrium, underlies the area south of the Cyclone Rim fault zone, as attested by the drill 

cuttings at the site of the California-Wyoming Development Co. oil well. 

The lignite, on the basis of geologic correlation (pis. 16 and 18). probably
274

is from 

fault zc 

would t 

schroec

Uraniuir 

lignite by 

and thenc 

fault zone, 

mentary re 

prevailed 

the level o 

Pleistocene 

ported up 

rium may 

ground wa 

carried 

probably 

formed, th 

transportec 

iron oxide

Some a] 

Lost Creek

1. Uranium, 

lated in 

the nea 

theloca 

nor the 

area w 

sedimen

and iron thus may have been leached from the uraniferous 

ground water circulating to depths of a few hundred feet 

carried upward in the porous rocks of the Cyclone Rim 

to precipitate preferentially in beds of fine-grained sedi- 

;ks above the low level of the ground-water table which 

during interglacial stages of the Pleistocene epoch. When 

the ground-water table rose during glacial stages of the 

and in Recent time, uranium was again dissolved, transard, and recrystallized as schroeckingerite. An equilibxist, as schroeckingerite may be currently deposited from 

er at about the same rate that the mineral is dissolved and 

Lost Creek by surface water. The iron-stained zones 

first formed during the Pleistocene epoch. Once

down

2.

and

minera 

Eocene 

Uranium 

such as 

Peak 

into th 

on eva] 

rence o 

for the 

3. Uranium 

ascendi 

Rim fa 

schroec 

The oc 

the fluo 

as in so hydrot' 

are known

The ava 

uranium a 

study and 

theory of t

Careful 

of little va

ONTRIBTJTIONS TO THE GEOLOGY OF URANIUM

00 to 500 feet beneath the surface at the southwestern edge of the 

e (cross section B-B', pi. 19) and if present in the zone of faulting, 

closer to the surface and could be the local source of uranium in the 

ngerite.

ere

relatively insoluble iron oxide was not dissolved and 

by the later rise of the ground-water table, although new

 obably is being deposited.

ernative theories that might explain the origin of the

schroeckingerite deposit, or some features of it, are:

derived from the surrounding crystalline basement rocks, accumuthe Eocene Green River lakes and schroeckingerite crystallized in 

shore muds as the lakes evaporated. This theory does not explain 

zation of the Lost Creek deposit within the Cyclone Rim fault zone,

absence of other schroeckingerite deposits elsewhere in the general 

;re the Green River formation interfingers with Wasatch-type 

ary rocks. Furthermore, it is difficult to understand, because the 

s readily soluble, how there would now be any evidence left of an

schroeckingerite deposit.

leached by descending ground water from overlying source rocks, 

le Pleistocene terrace deposits, or the volcanic ash of the Continental 

Chadron formations of Nace's usage (Nace, 1939), carried laterally 

Cyclone Rim fault zone to move updip and form schroeckingerite

 ration. This theory is plausible because of the widespread occurradioactive rocks in the Red Desert, although it does not account 

calization of the Lost Creek deposit.

leached from buried hydrothermal uraniferous vein deposits by 

ground water and carried upward into the rocks of the Cyclone 

t zone. In other areas, such as in the Marysvale district, Utah, 

ingerite is a secondary mineral, apparently derived from pitchblende, 

urrence of schroeckingerite in beidellite clays and the presence of 

ine atom in the schroeckingerite molecule raise the possibility that, 

ae other mining districts, beidellite and fluorite may be products of 

:rmal action. The theory is tenable, although no uraniferous veins 

to have been found in the area.

able evidence, therefore, points toward the source of the 

buried beds of uraniferous lignite, although additional 

xploration will be required to establish the validity of any 

e source of the uranium at the Lost Creek deposit.

AIDS TO PROSPECTING

bservation indicates that the Geiger-Mueller counter is 

in detecting schroeckingerite if the mineral is covered
- URANIUM IN THE RED DESERT, WYOMING 276

by even a thin mantle of overburden. The ultraviolet lamp is the 

most useful single tool to use in prospecting for schroeckingerite in the 

Re<lt)esert area and if these instruments are used together, reasonably 

certain identification of pellets of the mineral may be made. Small 

disseminated flakes of schroeckingerite are not so readily identified, 

and may easily be mistaken for opal or other material. It was 

observed that wherever efflorescent salts coating the surface of the 

ground had a decidedly greenish-yellow color under ultraviolet light, 

schroeckingerite could be found nearby by digging shallow pits.

The localization of schroeckingerite in shale of the Green River 

formation within the Cyclone Rim fault zone suggests that prospecting 

should be guided by this geologic association. Shale beds, and shalesandstone sequences of beds within the fault zone southeast and northwest of the deposit should be examined as well as similar beds in other 

fault zones hi the general area; for example, those in the Monument 

Dry Lake (pi. 17) might also be. worth prospecting. Schroeckingerite 

was found in pit 27 (pi. 19) at the southeast end of the area trenched 

in 1948, and in trench P at the northwestern edge of the area. The 

deposit, therefore, has not been delimited, and must extend farther 

both to the northwest and to the southeast.

FUTURE OUTLOOK

Very likely, more schroeckingerite will be discovered by further 

prospecting. The fact that schroeckingerite bodies are more or less 

continuous; the likelihood that the known limits of the deposit will 

be extended by more exploration; the fact that schroeckingerite is 

soluble in water; and the possibility that the mineral is constantly 

replenished by deposition from ground waiter, suggest that it might 

be possible to produce uranium from the Lost Creek deposit economically under present conditions. The deposit should be explored to its 

limits. At the time the present field work was completed, further 

exploration by the Geological Survey was planned to follow, in general, 

the lines of proposed trenches and auger holes shown on plate 6.

Beds of uraniferous lignite have a greater extent than the area 

shown on plate 2. The lignite beds crop out over much of the country 

east of that area, but the beds are folded and faulted, so that detailed 

mapping probably will be required to establish their location and 

relationships. Because of the general westward dip of the beds, the 

main lignite beds probably do not crop out much farther west than the 

west edge of the area. Some of the thin lignite seams may thicken to 

the west, however, and other beds may be found by subsequent 

mapping. North of High Point Ridge, the beds are covered by 

Pleistocene and Recent deposits. Accordingly, drilling or other subsurface methods would be required to prospect the country west and 

north of the area, and to obtain samples of unweathered lignite. 

Samples closely spaced across lignite beds of the principal lithologic
276

components (coal, carbonaceous shale, etc.), together with bulk 

samples c ' the entire bed should be taken for chemical analysis. 

Mapping and studies of lignite were being continued by the Geological 

Survey at the tune the present field work was completed.

Lignite that may be stratigraphically equivalent to that in the 

Red Desert area may be exposed hi the vicinity of the Leucite Hills, 

north of ! lock Springs, Wyo. and the uppermost lignite beds in the 

Washakie 3asin, south of Wamsutter, may be worth prospecting.

At present the possibility of commercial exploitation of the uraniferous lignite"beds is uncertain. Future need for uranium and other 

trace meti Is and the potential heat energy of the lignite may, when 

suitable methods of extracting the metals are developed, result in the 

utilization of the uraniferous lignite in the Red Desert area.

Blackwelde 

western

Bradley, W 

Sweetw

 1928 

Survey

 1945

Wyo.,

Prelim 

Dake, H. (

no. 3, p 

Dobbin, C.

possibi

Survey 

Evans, R.

Americ 

Fath, A. E

Ferris 

Fenneman,

Book C 

Jaffe, H. W

ingerite 

Kemp, J. E

Americ 

Larsen, E.

Wy 

Nace, R. L

and Fn 

Nelson, R.

survey

Survey

Ridge, 

NovdSek,

Minera

oming

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

LITERATURE CITED

E. B., 1915, Post-Cretaceous history of the mountains of central 

Wyoming: Jour. Geology, v. 23, no. 2, p. 97-117; no. 3, p. 193-217. 

H., 1926, Shore phases of the Green River formation in northern 

»ter County, Wyo.: TJ. S. Geol. Survey Prof. Paper 140-D, p. 121-131. 

Algae reefs and oolites of the Green River formation: U. S. Geol. 

Prof. Paper 154-G, p. 203-223.

Geology of the Washakie Basin, Sweetwater and Carbon Counties, 

nd Moffat County, Colo.: U. S. Geol. Survey Oil and Gas Inv. 

Map 32.

, 1938, The dakeite locality Wyoming: The Mineralogist, v. 6, 

7, 8, 23-25.

E., Hoots, H. W., and Dane, C. H., 1927, Geology and oil and gas 

ties of the Bell Springs district, Carbon County, Wyo.: U. S. Geol. 

Bull. 796-B, p. 171-201.

)., and Goodman, Clark, 1941, Radioactivity of rocks: Geol. Soc. 

Bull. 52, p. 459.

and Moulton, G. F., 1924, Oil and gas fields of the Lost Soldierstrict, Wyo.: U. S. Geol. Survey Bull. 756, 157 p. 

ST. M., 1931, Physiography of western United States: McGraw-Hill 

jmpany, Inc., New York and London, p. 143-144. 

Sherwood, A. M., and Peterson, M. J., 1948, New data on schroeckAm. Mineralogist, v. 33, nos. 3, 4, p. 152-157.

, and Knight, W. C., 1903, Leucite Hills of Wyoming: Geol. Soc. 

, Bull. v. 14, p. 305-336. 

, Jr., and Gonyer, F. A., 1937, Dakeite, a new uranium mineral from

Am. Mineralogist, v. 22, no. 5, p. 561-563.

1939, Geology of the northwest part of the Red Desert, Sweetwater 

tnont Counties, Wyo.: Wyoming Geol. Survey Bull. 27, p. 1-51.

Sharp, W. N., and Stead, F. W., 1951, Airborne radioactivity 

)f the Red Desert region, Sweetwater County, Wyo.: U. S. Geol. 

TEM-133, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak 

'enn.

1939, The identity of dakeite and schroeckingerite: Am. 

jgist, v. 24, no. 5, p. 317-323.

Ridim,
URANIUM IN THE BED DESERT, WYOMING 277

Schrauf, A., 1873, Schroeckingerite, ein neues Mineral von Joachimsthal: Tscherm.

Miner, mittheilungen, p. 137-138. 

Schultz, A. R., 1907 (1909), The northern part of the Rock Springs coal field,

Sweetwater County, Wyo.: in Coal fields of Wyoming: U. S. Geol. Survey

Bull. 341-B, p. 256-282. 

Sears, J. D., and Bradley, W. H., 1924, Relations of Wasatch and Green River

formations in northwestern Colorado and southern Wyoming: U. S. Geol.

Survey Prof. Paper 132-F, p. 93-107 (1925). 

Smith, E. E., 1907 (1909), The eastern part of the Great Divide Basin coal field,

Wyo.: in Coal fields of Wyoming, U. S. Geol. Survey Bull. 341-B, p. 220-242. 

Tolmachev, Ya. M., 1943, Adsorption of uranyl salts on solid adsorbents: Akad.

Nauk SSSR, Izv., in Nuclear Sci. Abs. no. 2063, no. 1, p. 28-34, (NP-742). 

Westgate, L. G., and Branson, E. B., 1913, The later Cenozoic history of the Wind

River Mountains, Wyo.: Jour. Geology, v. 21, no. 2, p. 144-159.

STRATIGRAPHIC SECTIONS

Stratigraphic section 1 (columnar section 1, pi. 18)

Distance 

Thick- above 

ness base 

Description (feet) (feet)

Siltstone, yellow, gypsiferous, clayey; ferruginous sand nodules__ 3. 0 110 

Claystone, varicolored (gray, yellow, maroon); uppermost 2

inches is maroon platy shale_______-_______--_______-__- 1.5 107

Lignite and papery carbonaceous shale; lignite bed 2___________ 1.0 105.5

Claystone, silty; weathers white.____________________________ 1. 0 104. 5

Sandstone, light-weathering, buff, micaceous, arkosic; the lowermost 2 feet is concretionary, gritty, and with no black 

minerals_________.___________..________ 10. 0 103. 5

Shale, poorly exposed, dark-green, hackly; weathers olive-gray to

yellowish______________________..______ 5. 5 93. 5

Sandstone, poorly exposed, coarse, buff; grades upward into siltstone________________________.._______ 11.0 88

Sandstone, silty, the uppermost 3 feet is clayey; weathers olivegray to buff; large quartz, feldspar, and mica grains______-_ 10. 0 77

Sandstone, yellow-buff to tan, lenticular, well-sorted; fine- to

coarse-grained, flaggy and calcareous from 62 to 64 feet_____ 12. 0 67

Claystone, green, yellowish in uppermost foot._________________ 5. 5 55

Sandstone, buff, silty, concretionary (may not be in place)__.___ 11. 0 49. 5 

Claystone, olive to yellow, silty, blocky-weathering___________ 1.0 38. 5

Sandstone, buff, well-sorted to silty, semiconsolidated (resembles 

sandstone of the Tongue River member of the Fort Union 

formation in North Dakota)___________..________ 7.5 37.5

Claystone, gray to black_____.______________________________ 5. 5 30

Lignite, vitreous, blocky-weathering (lignite bed 1)____________ 2. 5 24. 5

Sandstone, buff, clayey.______-_-__-_______-___..____-______- 4. 5 22

Claystone, carbonaceous_-__-_____-___--_-_-_-_.-___--___--_- 1. 0 17. 5

Siltstone, olive-green, tan weathering.___________-__--___--__- 7. 5 16. 5

Sandstone, varicolored; claystone; and silty claystone-_________ 3. 0 9

Sandstone, red, well-sorted, semiconsolidated, micaceous, brownstained on surfaces___-_..__-_--___------__--_----_------ 6.0 6
278

Sandstone, 

near th 

the noc 

Claystone, 

Shale, grayShale, lightlight-bi 

shale ii 

stone a 

Sandstone, 

Clinker, rec 

Poorly expo 

Sandstone, i 

Poorly expo 

Poorly expc 

siltston 

Sandstone, ] 

Sandstone, : 

and ere 

Siltstone, cr 

platy s' 

base__.

Siltstone, lij 

upwarc 

Sandstone, i 

bonacec 

carbon* 

Claystone, 

Sandstone, 

ferrugi

Sandstone, 

currem 

Sandstone, 

thin ca 

Shale, lightthin be 

Lignite, bla 

brown 

Sandstone, 

Siltstone, y 

and cl 

base

ONTRIBUTIONS TO THE GEOLOGT OF URANII

Stratigraphic section 2 (columnar section 2, pi. 18)

Description 

hite to yellow, fine-grained, with ferruginous nodules; 

top the unit becomes more clayey, more yellow, and 

ules become thin lenses____ __________________

gray, paper-thin in uppermost 0.5 foot, underlain by 

I sandstone and platy Siltstone above carbonaceous 

;er bedded with lignite; fine-grained, light-brown sandbase ____ ______ ____ __ _________ ___ ____

an to red, platy; overlain by bed of maroon ash____ 

and ash, white (lignite bed 3) _ ___ ___ ___ ___

ed_. ____ _ __ _ _______ _ ____ ______ .__

oarse-grained, white, well-cemented- _____ _ __ __

ed (probably sandstone grading upward into platy 

) __ ____ __ __ __ __ __ ____ _

aggy, calcareous, medium-grained, current-bedded. __ 

ne-grained, gray, with carbonate specks; olive shale 

m-yellow weathering siltstone ___ ______ __ __

am-yellow; 0.5 foot of black to brown carbonaceous 

ale; siltstone; 1.5 feet of coarse gray sandstone at

ht-gray, weathers to a cream color; becomes sandy

rkosic, weathers to a cream color, and maroon carus shale; 2.0 feet of maroon, micaceous, platy, 

ceous siltstone at base., _ ________ _ __________

ray-brown, silty______ _ __ __ _ _ _____ _ _

pray to buff, calcareous, nodular, arkosic, micaceous, 

ous__________________________ ___ __ __ ___

Stratigraphic section 8 (columnar section 8, pi. 18)

vhite, flaggy, calcareous, coarse-grained, micaceous, 

bedded _ __ _ __ _ ___ _ ____ _____ _____

)laty, fine-grained, and interbedded platy to paperarown, carbonaceous, and platy siltstone, with two 

Is of white sandstone. __ _____ _____ _________ _

c, platy, vitreous (lignite bed 3), overlying chocolateaper-thin shale and white, fine-grained sandstone___ 

rhite, coarse-grained, flaggy. __ _ _ ____ _ ____

How, sandy, interbedded with pale-green sandstone 

ystone; cream-yellow, current-bedded sandstone at

JM

Thickness 

(feet)

14. 0 

3.0 

3.0

4.0 

4.5 

2. 0 

2.5 

2.0 

6. 5

3. 5 

2.0

5. 5

7.0 

4. 0

7.5 

3.5

5.5

6. 5 

9. 5 

5.5

6.0 

1.0

10. 0

Distance 

above 

base 

(feet)

80.0 

66.0 

63.0

60.0 

56.0 

51. 5 

49.5 

47.0 

45. 0

38.5 

35.0

33.0

27.5 

20. 5

16. 5 

9.0

5.5

38. 5 

32.0 

22.5

17.0 

11.0

10.0
URANIUM IN THE RED DESERT, WYOMING 

Stratigraphic section 4 (columnar section 4t pi- 18)

279

Description

Sandstone, calcareous, fossiliferous, 

(fossil locality F-8) ; fine- to medium-grained, arkosic, micaceous; 

white, silty below; yellow above; 

caps butte _ ________________ ___

Shale, platy, sandy at top and base__ 

Sandstone, flaggy, calcareous, fossiliferous (fossil locality F-7); 

makes prominent ledge; fine- to 

coarse-grained. ____ ____... _

Sandstone, green; weathers buff; 

contains turtle plates and gar-pike 

scales; overlies blocky-weathering 

green shale; grades downward into 

white, micaceous fossiliferous 

sandstone (fossil locality F-6) __ _

Sandstone, white, micaceous; some 

ledges of calcareous, fossiliferous 

sandstone, and subordinate carbonaceous platy shale, and buff

Shale, paper-thin to platy; in part, 

chocolate-brown and with numerous plant fragments; in part 

silver-gray and with fish scales; 

contains 0.1- to 0.3-foot layers of 

silty, buff, fine-grained sandstone; 

becomes silty upward grading into 

silver to brown loess or siltstone

Sandstone, white, flaggy, calcareous;

Sandstone, coarse- to fine-grained, 

white to buff, ferruginous; interbedded with chocolate-brown platy

Siltstone, sandy; zone of vertebrate 

fossils _ __ ___ ____ __________

Sandstone, buff to yellow, in part, 

calcareous, ferruginous, micaceous, 

and nodular; becomes silty toward

tOD_______________ _________ _

Thickness 

(feet)

12.0 

10

4

6.0

24. 5

16.5 

2.0

1.0 

1.0

18. 0

Distance 

above base 

(feet)

106 

94.0

84.0

80.0 

74.0

49. 5 

33.0

31.0 

30.0

29. 0

Radioactivity (scale divisions) 

0.2 mr per hr*

Min

1 

0 

2 

2

0

2 

1

1 

^ 0

2 

3

Max

5 

6 

6

8

5

5

7

7 

4

8 

7

Avg

4 

3 

4 

5

2.5

3

4

4 

2

5 

5

 Radioactivity at the outcrop determined with standard survey Qeiger-Mueller counter, beta-gamma, 

0.2 mr per hr scale.
280 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Swatigraphic section 4 (columnar section 4, pi- 18) Continued

Claystone, < 

in beds 0. 

with oliv 

claystone 

Siltstone, b 

Shale, oln 

weatherir 

Sandstone,

Description

arbonaceous, paper-thin; 

foot thick; interbedded 

-gray silty, paper-thin

ff__ ___________________

e-gray, silty; blockysvhite, calcareous________

Thickness 

(feet)

5.5 

1.0

3. 5 

1.0

Distance 

above base 

(feet)

11.0 

5. 5

4.5 

1.0

Radioactivity (scale divisions) 

0.2 mr per hr*

Min

5

2

1

Max

10

8 

5

Avg

7

4 

2. 5

weatherir 

Sandstone,

*Radioactivi 

0.2 mr per hr sc

Sandstone, 

lain by 0 

sandstone 

taining ti 

of flaggy, 

Siltstone, br 

Shale, chocc 

Sandstone, 

siliferous 

Shale, graySandstone, 

Sandstone, 

claystone 

Sandstone, 

green an

Sandstone, 

arkosic__

Sandstone, 

Shale, choc 

Sandstone, 

Sandstone,

Sandstone; 

erous loc 

Sandstone; 

Shale; platy 

Sandstone;

g_____________________ 3.5 4.5 2

ivhite, calcareous________ 1. 0 1. 0 1

y at the outcrop determined with standard survey Qeiger-Mueller coi 

le.

Stratigraphic section 5^( columnar jsectionj), pi. 18)

Description 

platy, tan, less silty at top of lowest 4.5 feet; over5 foot of flaggy, white, calcareous, medium-grained 

overlain by 6.5 feet of buff, silty sandstone conrtle plates, some limonite cement; capped by 0.5 foot 

sparsely fossilif erous calcareous sandstone _________

own-green, ferruginous, sandy lenses; sandy at top__

jray, flaggy, fossiliferous, calcareous, micaceous (foslocality F-9) _______ _____ _ _ __ _ _ _ _

Irab, thin-bedded, and gray, blocky-weathering silty

;ray, micaceous, clayey, with ferruginous bands; olivemore clayey near the top; many turtle bones and

juff to white, with ferruginous layers, poorly sorted,

rellow-buff, silty____________ ___________ __ __ _

mff, grading downward into platy, gray shale. __

liver-gray, platy, and silty claystone. _____ _______

Stratigraphic section 6 (columnar section 6, pi. 18)

vhite to buff, flaggy, fossiliferous, calcareous (fossiliflity F-10) _________ __ ___ ___ _____ __ _ _____

ine-grained, buff- weathering, white to yellow, silty __

?reen-gray, calcareous, fossiliferous (ledge-former) __

8 

5

4 

2. 5

inter, beta-gamma,

Distance 

nhick- above 

ness base 

(feet) (feet)

11. 5 54. 5 

3. 0 43. 0 

1. 5 40. 0

3. 0 38. 5 

1. 0 35. 5 

1. 0 34. 5

1. 0 33. 5

10. 5 32. 5

11. 0 22. 0 

3.0 11.0 

2. 5 8. 0 

2. 5 5. 5 

3. 0 3. 0

11. 5 35. 5 

10. 0 24. 0 

11. 0 14. 0 

3. 0 3. 0
URANIUM IN THE EED DESERT, WYOMING 281

Stratigraphic section 7 (columnar section 7, pi. 18)

Distance 

Thick- above 

ness base 

Description (feet) (feet)

Sandstone, arkosic, salmon-pink, poorly sorted, coarse-grained, 

current-bedded (channel axes trend S. 75° W.), with some flaggy 

masses and white zones; a zone of log-shaped concretions in 

uppermost foot_______-____-_____________________________ 15. 5 101

Sandstone, white, fine-grained, micaceous in part calcareous;

overlain by carbonaceous paper-thin shale__________________ 1. 0 85. 5

Sandstone, coarse, white-weathering, buff with sparse, poorly preserved fossils; red to orange in basal foot.______--_---_____-_ 5, 5 84. 5

Shale, silver-gray to olive-green, paper-thin___________________ 11. 0 79. 0

Poorly exposed, steep local flexure, offset(?)___________________ 5. 5 68. 0

Sandstone, white to light buff, flaggy, variable amounts of calcareous cement from bed to bed; basal 3 feet white, coarsegrained, arkosic_--______-..___-__________-______-______ 21. 5 62. 5

Shale, drab to olive-green, paper-thin, petroliferous and fossiliferous; 0.1-foot layers of buff, gypsiferous bentonite at 12.0 

feet, 15.0 feet, 35.0 feet, and 36.0 feet. Ostracods and small 

pelecypods collected at 16.5 feet; (fossil locality JBR-2)____ 38. 0 41. 0 

Sandstone, green or white calcareous with 0.5-foot bed of coquina 

at top; (fossiliferous locality F-ll)_______________ 3. 0 3. 0

Stratigraphic section 8 (columnar section 8, pi. 18)

Poorly exposed, probably gray-brown, oolitic limestone, algal reef; 

this unit with the underlying unit forms cap rock of the land 

surface to the south and north__-___________--__-_-______- 4.0 44.0

Limestone, sandy, and subordinate sandstone; the limestone is 

brown flaggy, and contains oolitic grains and pale gray-green 

clay galls; the sandstone is buff and flaggy.________________ 5.0 40.0

Oil shale, paper-thin, chocolate-brown to gray, interbedded with 

gray, calcareous, oolitic sandstone, becomes platy, more gray, 

and silty claystone in uppermost 3 feet; abundant ostracods; 

abundant vertebrate fossils (turtle plates and bones, gar-pike 

scales) from 33 feet to 35 feet._____________________ 27. 0 35. 0

Siltstone, gray-brown____________________________________ 2. 0 8. 0

Sandstone, white, gray siltstone, silty sandstone, capped by 0.5-foot

gray medium-grained sandstone (bench-former) ______________ 6. 0 6. 0

Stratigraphic section 9 (columnar section 9, pi. 18)

Not exposed. The base of the Chadron formation is within this 

interval---_____________________________ 28 534. 0

Sandstone, coarse-grained buff, and some mudstone; poorly exposed 

from 451 to 506 feet; sandstone has torrential current-bedding 

from 451 to 506 feet and contains pebbles of green chalcedony; 

fossil of large turtle at interval 439 feet to 441 feet- -____- __ 77. 0 506. 0

Conglomerate, gravel and boulder; unit caps and forms Cyclone 

Rim; poorly exposed; pebbles and boulders are predominantly 

brown to black chalcedony and white agate; subordinately 

granitic, volcanic, and metasedimentary rocks._____________ 71. 5 429. 0
282

8t

Poorly exp< 

ing vert< 

green cal 

Sandstone; 

salmon-ci 

in part f< 

consolida 

unit map 

Shale, brow 

Sandstone, 

careous. 

to 195.0 

This is tl 

Shale, gray 

of sandy 

Sandstone, 

Claystone, 

buff silts 

green, p] 

clayey sil 

Sandstone, 

Claystone, 

gray-gree 

to 110.0 

Sand, finestone; sp 

Sandstone, 

Limestone, 

Shale, olive 

Limestone 

Sandstone, 

Sandstone, 

oolitic 1 

crosses f 

displaceir 

paper-thi 

Limestone, 

Claystone 

Siltstone, c 

basal foo 

Sandstone, 

degree o 

ledge-for 

siltstone 

Claystone 

gypsifero 

top____

Sandstone, 

Conglomer 

rocks, ch 

Shale, gree

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

atigraphic section 9 (columnar section 9, pi. 18) Continued

Thick- . 

ness 

Description (feet)

ed (probably blocky brown shale, sandstone containarate remains; also probably includes pale-yellowthe uppermost 8 feet is fine-grained, calcareous, 

ored, or brown; the lower part is micaceous, white, 

siliferous, calcareous and ledge-forming, in part uned, poorly exposed. This is the upper sandstone 

ed(pl.!6)_ ___________ . ___ ___. __ . __ 41. 0

white to gray, arkosic, in part fossiliferous and calFossil localities JBR-5, JBR-4, and JBR-3 at 196 

eet, 183.0 to 185.0 feet, and 170 feet, respectively, 

e lower sandstone unit mapped (pi. 16)___ __ _____ 26. 5

to brown, paper-thin to platy; some ^i-inch beds 

imestone__ _ ________ __ __ _ _ _______ ______ 10.0

alcareous, and sandy limestone __ _______________ 2. 0

ray, platy; interbedded with 1-foot beds of white to 

one or sandstone in upper 11 feet; overlying oliveaty to paper-thin shale that grades upward into 

stone ________________ __________ 22.5

alcareous, platy, current-bedded; weathers white. __ 2. 0 

andy and claystone; blocky-weathering, light-tan, 

, maroon, or buff; bentonitic in interval from 104.5 

et _ ____________ ___ ____________ 34.0

;rained, in part cemented by calcite to form sandkrsely fossiliferous_______________________________ 5. 5

ight gray-green, clayey__________________________ 3.5

slayey__ ___________________ _______ 3. 0

 green, paper-thin. ___ _____ __ _ _ __ ___ _ 4 5

fossiliferous, and 0.2 foot of paper-thin shale. __ ___ 2. 5

Sne-grained micaceous flesh-colored. _______________ 6. 2

white, ashy(?), fine-grained, highly gypsiferous; and 

nestone containing abundant ostracods; (section 

ult striking N. 80° E., dipping steeply, stratigraphic 

ent is 3 feet down on southwest side) ; overlies gray, 

i shale with abundant ostracods __ _ ______________ 3. 5

live-green, sandy ____ _ _____ __ _______________ 5.0

ayey, platy, gray-green (weathers light green); the 

is buff-yellow. __ _ _____________ ___ _ 10.0

irkosic, poorly sorted, buff, weathers white; varies in 

cementation; the uppermost foot is a calcareous, 

ling micaceous sandstone that grades laterally into 

_____ __ ____ _ ______________________________ 11. 0

,nd shale, poorly exposed; gray (weathers white), 

:s; more gypsiferous, gritty and lighter in color near 

_ __ _ ___ ____ ___ ___ _ _________ __ ______ 17. 5

>oorly exposed, light-brown, silty _______ __ ___ _ 15. 5

;e, brown, containing pebbles, boulders of granitic 

rt, feldspar, quartzite; weathers white _ ___________ 11. 0

blocky, poorly exposed _ __ _ _____ _ ___ ___ 2. 0

Distance 

above 

base 

(feet)

357.5

255.5 

2145

198.0

171.5 

161.5

159.5 

137.0

135. 0

101. 0 

95. 5 

92.0 

89.0 

845 

82.0

75.8 

72. 3 

72.0

67.0

57.0

46.0 

28.5

13.0 

2.0
URANIUM IN THE EED DESERT, WYOMING

ANALYSES

283

TABLE 3. Analyses of material other than lignite, carbonaceous shale, schroeckingerite, or water, Red Desert, Wyo.

No. of sample

DW-102 (S:294) . 

DW-112 (8:295). 

DW-108 (8:305) .

WNS-2(S:2)__ _

WNS-3(S:4)_ 

WNS-6(S:8)._ .

WNS-8(S:10)_ 

WNS-9(S:11)- .

WNS-12(S:17) .

WNS-15(S:20)- 

WNS-17 (S:24) 

WNS-19(S:27)- 

WNS-20(S:28)- 

WNS-23(S:31) _

WNS-24(S:32)_ _ 

WNS-25-33- . 

Locality of sample 

(pi. 16 unless otherwise noted)

Center of Lost Creek Dry 

Lake. 

 do _. 

Bank of Lost Creek, 1 mile

north of Hadsell shearing 

pens. 

Chain Lake ____ . _____

Dry-lake bed (pi. 17) ... ... .

shearing pens.

kingerite deposit.

Nest. 

Monument Dry Lake (pi. 17) -

In sump of water well at site 

of Cafifornian-Wyoming Development Co. oil well. 

Antelope Hills, about 20 miles 

northwest of Hadsell shearing pens. 

Bank of Lost Creek, IJi miles 

north of Hadsell shearing 

pens.

A wide area northwest of the 

Lost Creek schroeckingerite 

deposit. 

Trench Kz (pi. 21), Lost Creek

schroeckingerite deposit.

Material of sample

Moist clay, about 1 foot beneath surface. 

Dry crust of mud and silt,

about 3 inches beneath surface.

sandstone and clays tone.

sat). 

Clay- - ..

Clay.........................

Gray and brown clay with 

specks of lignite.

Qabbro dike intruding graniteFluorescent, gypsiferous, silty, 

claystone and sandstone.

halite, and gypsum). 

Selected pebbles of fluorescent 

agate-chalcedony.

and volcanic glass).

Equivalent 

uranium 

(percent)

0.004 

.003

nnfi

.006

.005

.008

.005

nftfi

.003

.003

.007 

.000 

.004 

.001

.010 

.025

Uranium 

(percent)

0.001 

.002

.003

.002

.002

.001

.001

.002

.002

.002

.004 

.001 

.002 

.001

.006 

.011

TABLE 4. Analyses of water samples (in parts per million), Red Desert, Wyo. 

(Does not include samples taken from auger holes in 1950}

No. of sample

DW-102 (8:296) 

DW-85 (8:264) 

WNS-10(S:14)--. 

WNS-22 (8:30) 

DW-85 (8:265) -

WNS-3(S:3)--__. .

WNS-7(S:9)_-_ 

WNS-9 (8:13) .. 

WNS-17 (8:25) 

WNS-21 (8:29)- 

Locality of sample 

(Pi. 16)

Draw. (Sampled May 5, 

1949.) 

Spring at mouth of Osborne 

Draw. (Sampled July 29, 

1949.)

(Sampled October 6, 1949.)

schroeckingerite deposit. 

Chain Lake (muddy water) ...

voir in part on lignite bed 1. 

Pit 14, Lost Creek schroeckingerite deposit.

Wyoming Development Co. 

oil well.

23 miles northwest of Hadsell shearing pens (not 

shown on pi. 16) .

Uranium

0.00

44

.01 

.13

00

.03

.01

46.00 

.03

.01

HCOr

70

83

136

114

2,147

102

486

C08

2

7

6

17

242

0

34

SOr103

127

78

54

1,956

28

6,590

ci19

20

20

5

1,960

68

40

Total 

solids

294 

110

8,290

173

14,120 

640

200
284

TABLE 5.-

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Spectrographic analysis (in percent) of samples of uraniferous lignite,

Red Desert, Wyo. 

[Paul R. Barnett, U/S.'GeologicalJSurvey, analyst]

No. of sami 

(locality on pi,

DW-103 (8:291 

DW-103 (S:29! 

DW-103 (S:29< 

WNS-1 (S:l) _

WNS-4(S:5). 

WNS^(S:6). 

WNS-5(S:7).

No.

DW-103 (S:29; 

DW-103 (S:29J 

DW-103 (S:29J 

WNS-1 (S:l).. 

WNS-4(S:5).. 

WNS-4(S:0).. 

WNS-5(S:7)..

No.

DW-103 (8:297 

DW-103 (S:29J 

DW-103 (8:295 

WNS-1 (S:l)_. 

WNS-4(S:5).. 

WNS-4(S:6).. 

WNS-5(S:7)-

e

7)

---

Lignite 

bed

1 

1 

1

1

2 

2 

2

Material of sample

Lignite _ - ..

Carbonaceous sh 

Shale and lignite 

Lignite and cs 

ceous shale. 

Lignite and shah

ale.-.--

irbona-

^

Lignite and carbonaceous shale.

of sample

 

of sample

Ti

O.OX 

.X 

.X

.OX

.X

.ox

Sr

O.OOX 

.OOX 

.OOX

.OOX 

.OOX 

.OOX

Mn

O.OX 

.OX

.ox

.OOX

.OOX

.ox

Ca

o.x

.X 

.X

.X 

.X 

.X

Uranium 

in ash

0.019 

.004 

.008 

.022

.008 

.015

.011

V

O.OOX

.ox 

.ox

.ox

.ox 

.ox

Ce

O.OX

.ox 

.ox

.ox 

.ox 

.ox

Cu

0. OO'X 

.OOX 

.OOX

.OOX 

.OOX

.OOX

Cr

O.OOX 

.OOX

.OOX

.OOX

.OOX 

.OOX

La

O.OX

.ox 

.ox

.OOX

.ox

.OOX

Pb

0)

O.OOX

.ox

.OOX

.ox

Y

O.OOX 

.OOX 

.OOX

.ooox

.OOX

.ooox

Fe

O.X 

X 

X 

X 

X 

X

.ox

Co

0.001 

.001 

.001

.ooox

Be

Tr. 

Tr. 

Tr.

Tr.

Mg

O.X 

X 

.X 

.X

.ox 

.ox 

.ox

Ni

0.003 

.002 

.003

.001 

.001

.001

Mo

O.OOX 

.OOX 

.OOX

.OOX 

.OOX

.ooox

B

O.OX

.ox 

.ox

.X

.ox 

.ox 

.ox

Zn

0) 

O.X 

.X

Sc

O.OOOX 

.OOX 

.OOX

.OOX 

.OOX

.ooox

Oa

O.OOOX 

.OOX 

.OOX

.ooox

.OOX

Zr

(')

O.OOX 

.OOX

.OOX

Ba

O.OOX 

.OX 

.OX

.OX 

.X

.ox

Si

O.X 

X 

X 

X 

X 

X 

X

Looked for b 

i Looked for

TABLE 6. 

t not found: As, Tl, In, Ge, Be, Sn, Nd, Ta, U, Nb, Pt, W, Bi, Sb, Cd, Au, Ag. 

ut not found.

Analyses (in percent) of radioactive lignite, carbonaceous shale, clinker, 

and ash, Red Desert, Wyo.

No. of sam] 

(locality on p

WNS-1 (S:l). 

DW-103(S:2T 

DW-103 (8:29 

DW-103 (8:299

WNS-4(S:5)

WNS-4(S:6). 

WNS-5(S:7).

WNS-11(S:15 

WNS-13(S:18

WNS-1 (S:12) 

WNS-11 (S:16

WNS-16(S:21 

WNS-16(S:22 

WNS-14(S:19

e 

17)

Thickness of 

sample 

interval 

(feet)

Type of sample

Lignite bed and 

material of sample

Equivalent uranium

Uranium Ash

Uranium in 

ash

Lignite and carbonaceous shale (map symbol)

.....

12 

0.7 

3.3

2.0 

15-20

10 

10 

6

Composite grab 

sample 

Composite chip 

sample

-...do...... ..

 _do . 

Grab sam pie.. .. 

Chip sample ....

.....do.. ......

.....do ........

Bed 1, lignite and 

carbonaceous shale. 

Bed 1, lignite ....

Bed 1, caroonaceous 

shale. 

Bed 1, carbonaceous 

shale, with thin lignite seams. 

Bed 2, lignite and 

carbonaceous shale. 

Bed 2, lignite only . 

Bed 2, lignite and 

carbonaceous shale. 

Bed 2(?), lignite and 

carbonaceous shale. 

Bed 3, lignite 

0.010 

.007 

.008 

.010

.015

.005 

.003

.004 

.002

0.007 

.003 

.003 

.004

.003

.003 

.003

.003 

.002

38.7 

24.1 

85.7 

69.1

74.7

32.2

26.0

9.1

0.022 

.019 

.004 

.008

.008

.015 

.011

.015

Clinker and ash (map symbol A)

.....

----

3

3 

3

Grab sample ....

Composite of 10 

feet. 

Grab sample....

 .do... ........

Bed 1, clinker, ash, 

baked clay. 

Bedl or 2, clinker ..

Bed 1, clinker ___ ... 

Bed 1, ash... .__ 

Bed 3, clinker and ash.

0.014

.007

.007 

.013 

.012

0.005 

.003

.003 

.006 

.005
URANIUM IN THE EED DESERT, WYOMING 285

TABLE 7. Analyses of rock samples, Lost Creek schroeckingerite deposit, Red

Desert, Wyo.

[The prefix ME to the sample number indicates the sample was taken by the Minerals Engineering Co., 

In 1948 and analyzed by the Brown Engineering Co., Grand Junction, Colo.; the prefix TW Indicates 

the sample was taken by C. C. Towle and D. Q. Wyant in 1949 and analyzed by the U. S. Geological 

Survey. Equivalent uranium was determined by reference to a standard uranium sample in which the 

uranium is in equilibrium with all Its decomposition products. Corrected equivalent uranium was 

determined by reference to a standard uranium sample hi which the uranium is in equilibrium with UXi 

(Thorium 234) and TJXi (Protoactinlum 234) only.]

No. of sample

ME-1925 .. 

ME-1927 .

TW-30 ... .

ME-1936 ..

ME-1935 -

TW-33 .

ME-1938 . 

ME-1939 ..

ME-1929 ._

ME-1931 ..

TW-35.. _

ME-1930 - 

ME-1919... ..

TW-28.......

ME-1923 .-

ME-1921. 

TW-23 

ME-1934 ..

TW-24 

ME-1933 ..

ME-1941 ..

TW-22 

ME-1940 

TW-21 

ME-1952 

TW-20 ....

TW-18 

TW-15 

TW-17 ...

TW-14 .

TW-13 .

TW-10- 

TW-11 

TW-6 

ME-1948 -

TW-5 .....

ME-1945 -

ME-1946- 

TW-7A 

TW-7B......

TW-8 . 

ME-1943-... 

TW-9 .. 

Locality of 

sample 

(Pi. 21)

 do 

 do-.- 

 do _ 

 do.- 

Trench C.. ...

 -do 

 .do-.. 

 ..do.---..

.....do........

..... do.... .

 . .do.. ......

..... do..- 

 do 

- do .... -

 -do- .

 do.. ...

 do.--- 

..... do.-- -

Trench .H _

 -do 

 do.. .

 . .do ....

 do..- .

Trench !?_- 

 do. .

 -do ... ...

. do- .

..... do ...

 -do 

 -do ...

Trench K\.. ..

.. do... ......

Material of sample

Clayey conglomerate, claystone, sparse schroeckingerite, efflorescent white 

salts.

Gravel, no schroeckingeriteClaystone and schroeckingerite.

Claystone and schroeckingerite.

Claystone, schroeckingerite, 

and efflorescent white salts.

Claystone and schroeckingerite.

Claystone, sandstone, and 

sparse schroeckingerite.

Green claystone and schroeckingerite.

Green claystone and schroeckingerite. 

Claystone, sandstone, and 

gravel (Qta) (includes 0.8 

foot of claystone and 

schroeckingerite) . 

Terrace material (Qts) and 

clay; no schroeckingerite. 

Green claystone and gravelly 

claystone; includes 1 foot of 

claystone and schroeckingerite. 

Green clay and white salt, 

terrace material (Qtj); no 

schroeckingerite. 

Terrace material (Qts); no 

schroeckingerite . 

 ..do 

Terrace material (Qtj) trace 

schroeckingerite. 

Composite sample, terrace 

material, (Qta) and clay.

Green siltstone, schroeckingerite.

Green claystone, sparse 

schroeckingerite.

Terrace material (Qta) and 

some clay.

Dimensions of 

sample

Length 

(ft)

5 

2.5

8 

4 

5 

5 

16 

6 

5

5 

30

4 

20

12

12 

4

8

12

25

14

35

?

Thickness 

(ft)

0.67 

.25

1.7

1 

.5

.83 

.5 

.8 

.5 

.5

.5 

.75 

1.3

.3 

1

1

.83 

1.3

.83 

.5 

1.5

.82

1

.83 

.8

4

4.5 

3

3.5

4

4.5

5

4.5

1

.5

.75 

.42 

1.3

.5 

.8

1.0

4.0

Equivalent 

uranium 

(percent)

0.041

.005

.15

.082

.018

.020

.048

.070

.067 

.054

.004 

.11

.005

.007

.004 

.009

.007

.37

.004 

.058 

.029

.007

Corrected 

equivalent 

uranium 

(percent)

0.066

.008

.24

.13

.029

.032

.077

.11

.11 

.086

.006 

.18

.008

.011

.006 

.014

.011

.059

.006 

.093 

.046

.011

Uranium (percent)

0.11 

.19 

.055

.10 

.02 

.005 

.05 

.19 

.14 

.06 

.21

.13 

.15 

.11

.11 

.10 

.024

.13 

.022

.08 

.07 

.054

.18 

.095

.17 

.10

.075

.004 

.14

.004

.006

.002 

.010

0.004

.11 

.053

.14 

.14 

.002 

.091 

.046

.13 

.008
286 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 7. Analyses of rock samples, Lost Creek schroeckingerite deposit, Red

Desert, Wyo. Continued

No. of sample

ME-1909 .. 

ME-1950 

TW-4 

TW-3 .....

TW-39 .

TW-1.. ......

TW-2.. ______

ME-1906 

TW-32 .

TW-34 ......

TW-31 ...

TW-29..____.

ME-1905 _.

ME-1901 __ 

ME-1902 

ME-1903.....

TW-27... 

TW-36 _. 

ME-1907 . _

TW-26 .

ME-1904._.__ 

TW-25__.____

ME-1908 _. 

TW-19 __-

ME-1917 _. 

TW-16 

ME-1918 

TW-12A. 

ME-1913 . 

TW-12B.....

ME-1910 __

ME-1911.__._

TW-38 __ 

ME-1914 _.

TW-37 . 

ME-1916 .

Locality of 

sample 

(Pi. 21)

Trench .K. ....

Trench L .....

. .do ..._._

___._doTrench M~ ...

Lost Creek 

bluff. 

.....do ......

Pit27.-..._..

.....do ......

Pit23.........

Pit 24. ....__._

 -.do.. ....

Pit 18 (north 

side). 

Pit 18 (south 

side), 

 ..do -_-. 

_ do. ...

Pit 18 __ . 

Pit 21. ..__..._

Pit 20. 

Pit 19.- ...

 .do. .....

Hole 38 

 do 

Pit 16 (west 

side). 

Pitl6._ ____

Pit 16 (east 

side). 

Pit 14 (north 

side). 

Pit 14 (south 

side). 

 .. do....... ..

Pit8 ._.

Pit 4... .......

 do 

Pit 2.. ........

 do 

Pit 1. _________

Material of sample

Sandy green claystone with 

schroeckingerite. 

Green claystone with schroeckingerite. 

Green claystone with schroeckingerite. 

Claystone and schroeckingerite. 

Sandstone, claystone; no 

schroeckingerite.

Claystone and sparse schroeckingerite.

Clayey conglomerate, claystone, salts, and sparse 

schroeckingerite. 

Green claystone and schroeckingerite.

Claystone, some sandstone 

with schroeckingerite. 

Grab sample of ore pile from 

pit. .

Claystone and schroeckingerite.

Claystone and schroeckingerite.

Green claystone with schroeckingerite.

Terrace material (Qts) and 1 

foot clay.

Green siltstone with schroeckingerite.

Claystone, no schroeckingerite.

Claystone, sparse schroeckingerite.

Claystone, white salts, sparse 

schroeckingerite.

Dimensions of 

sample

Length 

(ft)

27

Thickness 

(ft)

0.75 

.8

.5 

.8 

1 

1.3

.7

1.3

1

.8

1.3

1.5

.8

1

3

1.3

.8

.8

.5

Equivalent 

uranium 

(percent)

0.081 

.041 

.070 

.015 

.006

.039

.005 

.015

.050

.041 

.046

.12

.14

.097

.008

.034

.007

.038

.016

Corrected 

equivalent 

uranium 

(percent)

0.13 

.066 

.11 

.024 

.010

.062

.008 

.024

.080

.066 

.074

.19

.22

.16

.013

.054

.011

.061

.026

Uranium (percent)

0.08 

.09 

.11

.064 

.091 

.013 

.009

.13 

.049

.004 

.022

.055

.14 

.20

.14

.03 

.063

.065

.04 

.14

.09

.17

.03 

.15

.28 

.008 

.14 

.048 

.24 

.004

.08 

.11 

.058

.04 

.018

.08
URANIUM IN THE RED DESERT, WYOMING 287

TABLE 8. Analyses (in parts per million) of surface- or ground-water samples, 

Lost Creek schroeckingerite deposit, Red Desert, Wyo.

No. of 

sample

DW-S5-264 .

WNS-10-14. 

WNS-22-30. 

DW-S5-265 .

WNS-9-13..

DS-2-199-... 

DS-3-200 . 

DS-4-201 - 

DS-5-202 . 

DS-6-203 . 

DS-7-204 . 

DS-8-205-... 

DS-9-206 . 

DS-10-207 

DS-12-208 

Locality of sample 

(pl. 21)

Spring at mouth of 

Osborne Draw. 

 .do.... , 

 ..do.. ...

Lost Creek below 

bridge. 

Pit 14.. ........

Auger-hole ES-3.. 

Auger-hole ES-4.. 

Auger-hole ES-5..

Auger-hole ES-8.. 

Auger-hole ES-9__ 

Auger-hole ES-10. 

Auger-hole ES-12.

Date of 

sampling

May 5, 1949-

July 29, 1949 . 

Oct. 6, 1949...

IQdQ

1949. .. 

1950 .

1950. ___ 

1950 

1960 ___ 

1980 

1950 

1950. ... 

1950 .... 

1950 . . .-

1960 ..... ..

U

0.44

.01 

.13 

.00

46.00 

.66 

.42 

.60 

.48 

.48 

.50 

.14 

.04 

.88 

.07

coj~

7 

6

"17"

3411.1

18.5 

18.5 

6.6 

8.7 

10.0 

10.6 

7.4 

9.2 

14.5

HCOf

83 

136 ""Iii"

486 

144.2 

190.3 

134.0 

162.1 

135.9 

123.8 

126.0 

134.5 

138.0 

100.5

so7"

127 

78 

""54"

6,590 

998.0 

932.0 

2,035.0 

893.4 

800.0 

184.4 

751.0 

823.0 

6,521.0 

2,566.0

ci20

20

... ...

40

22.6 

30.8 

31.2 

16.4 

15.2 

28.7 

19.5 

19.9 

78.3 

35.9

Total 

solids

294 

110

14,120

U> in 

sludge

.......

1 

820.0 

30.0 

20.0

PH

7.85 

8.35 

8.00 

8.00 

8.20 

7.90 

8.00 

7.90 

8.10 

8.00

i Based on dried weight of sludge. 

* Insufficient sludge for analysis.

TABLE 9. Analyses (in parts per million) of plant and soil samples, Lost Creek 

schroeckingerite deposit, Red Desert, Wyo.

[Analyst, Helen Cannon]

Locality of sample

(PL 21)

Osborne draw.

Do... .........

Do....-..... . .

Do... ...

Do... .... . 

Do.... ..... ..... .

Do ... .........

No. of

sample

P la.......

Plb... 

P 2 

P 3 .... .

SI........

P 3a ....

P 4. ..

82. . 

Material of sample

Qreasewood (Sarcobatus eermiculatus) roots

in schroeckingerite-bearing clay.

Uranium

28

36

1.7

39

10

14

7,400

270

Vanadium

oxide

(V20«)

80

40

00

500

40

00

400

100
288 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

AUGER-HOLE DATA

TABLE 10. Lithology of cuttings from shallow auger holes drilled by the U. S. 

Geological Survey in 1949, Lost Creek schroeckingerite deposit, Red Desert, Wyo.

Reference no. 

(pi. 19)

H 1.. ............

H-2 ...... ......

H-26 . . 

H-27-....-..--....

H-28 ...... ... ..

H-30 .... ... ....

H-32 .. ...

Description

Claystone, gray-green, silty, gypsiferous 

Claystone, siltstone, and green to buff 

sandstone.

Claystone, green; contains schroeckingerite and gypsum.

Claystone, platy, purple.. ________

Sandstone, white _____________

Claystone, gray to brown, containing 

schroeckingerite siltstone.

Claystone, gray, silty, and gray Claystone. 

Gravel and green, white, and buff sand ...

Siltstone, gray-green, and flakes and pellets of gray platy shale.

Trench fill..... _ . ____ . ____ ...

Siltstone, green, clayey, and some sandstone.

Depth 

in feet

0-1.3

1. 3-3. 0 

3. 0-5. 0

5. 0-6. 0 

0-0.5

0. 5-1. 3

1. 3-2. 3 

0-2.0

2.0-3.0

3. 0-4. 0

4.0-4.5

0-1.0

1. 0-2. 0

2.0-3.5

3.5-4.5

4.5-4.8

4. 8-5. 2 

5. 2-5. 6

0-2.0

2. 0-2. 5

2. 5-3. 0 

0-9.7

9. 7-10. 2

10. 2-10. 5

10. 5-11. 2

11. 2-13. 4

13. 4-16. 0 

0-4.0

4.0-6.1 

6. 1-7. 4

7. 4-7. 6

7.6-8.0

Remarks

Radioactivity: 2 scale divisions (milliroentgens per 

hr) above background 

which averages 2.5 scale 

divisions.

Radioactivity: 32 scale divisions above background. 

Terrace deposit(?), colluvium(?).

No schroeckingerite.

Iron-stained zone at 3.3 feet.

No schroeckingerite.

Terrace deposit(?).

Shale is the ore-bearing bed 

in trench F. No schroeckingerite.

Platy shale fragments at 6.8

feet. 

Radioactivity: average of 10

scale divisions above background. 

Solution zone. Radioactivity: 5 scale divisions above 

background. No schroeckingerite.
0 °>

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URANIUM IN THE RED DESERT, WYOMING 289

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URANIUM IN THE RED DESERT, WYOMING 291

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292 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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DS-4-60.- 

51. .

52........

63........

64. 

65........

66.. ......

57..... _

58........

69........

60-- .

61. .......

62........

63.. ......

64........

65.. 

66. _ ....

67. 

68.. 

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71-.. 

green claystone; traces of fluorescent material.

with a small amount of coarse sandstone, 

4.5-5.8 feet; brown siltstone, 5.8-6 feet.

of gypsum(?) which fluoresces pale yellowwhite.

brown iron-stained sandstone; trace of gypsuin (?).

siltstone with subordinate sandstone, claystone, and gypsum(?), 8.1-10 feet.

gray to gray silty claystone with sparse gypsum (?), 11-12 feet.

feet; red-brown sandy claystone, 12.9-13 feet; 

brown -gray to white, clayey, medium-coarse 

sandstone, 13-14 feet; 0.01 percent fluorescent 

material.

of fluorescent material.

amounts of gray claystone, 14.5-15.5 feet; 

gray clayey siltstone, 15.5-16 feet.

silty claystone; traces of fluorescent material. 

Siltstone, brownish gray-green, with minor

amounts of claystone and fine sandstone.

sandy siltstone, intermixed; traces of fluorescent material.

white, fine sandy siltstone, 22-22.5 feet; 

brown-gray siltstone with some claystone 

and sandstone, 22.5-24 feet; water table at 

22.5 feet.

stone and sandstone. 

 ..do... . . _ 

. do 

. do 

. .do . . .-..--. . _ ... ... 

0-2

2-4

4-4.6

4.5-6

6-7

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8-10

10-12

12-14

14-14. 6

14. 5-16

16-18

18-20

20-22

22-24

OJ_O/l K

24.5-26.5

26.5-28

28-29

29-30

30-32

32-53

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1

0

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1

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2

1

0

0

0

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7

6

7

7

6

6

6.6

7

9

8.5

5

8

5

7

3.5

3

3.5

3

3

3.6

3.6

3.5

4.5

4

3

3.6

3

3.5
294 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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claystone and sandstone, 2-3.5 feet; brown 

sandy claystone, 3.5-4 feet; sample contains 

6 percent fluorescent material (including 

schroeckingerite in pellets).

brown pebbly sand, 4.3-4.5 feet; gray-green 

clayey siltstone, 4.5-6 feet; 0.5-1 percent 

fluorescent material (including schroeckingerite).

stone, 6-6.5 feet; brown to green-gray clayey 

siltstone with a little sandstone, 6.5-7 feet; 

0.1 to 0.5 percent fluorescent material. 

Siltstone, brown-gray sandy clayey, 7-7.2 feet;

gray-white silty pebbly sandstone, 7.2-8 

feet; brown to green-gray clayey siltstone, 

8-9 feet; 0.1 to 0.5 percent fluorescent material. 

Siltstone, green-gray sandy, 9-9.8 feet; brown

silty claystone, 9.8-10 feet; brown sandy 

siltstone, 10-10.6 feet; green-gray siltstone 

with subordinate yellow-brown sandy siltstone, 10.5-11 feet.

brownish-gray-green claystone, 11.3-11.7 

feet; brown gray-white silty clayey sandstone, 11.7-12.5 feet; gray-white silty sandstone, 12.5-13 feet; traces of fluorescent 

material.

13-14.7 feet; gray-green to brown-gray, 

sandy clayey siltstone, 14.7-15 feet. Water 

table at 14.7 feet.

green-gray clayey siltstone with some sandstone, 16-17 feet.

green-gray sandy siltstone with some pebbles, 

19-20 feet.

bles, 20-20.2 feet; brown-gray sandy clayey 

siltstone, 20.2-21 feet. (Caved at 20 feet.)

material.

0.01 percent fluorescent material.

2-4

4-6

6-7

7-9

9-11

11-13

13-15

15-17

17-20

20-21

21

0-1

1-2

711

0.6 01

Auger-hoi 10

2078667

eES-676

124

3.5 333

3.5

3.5
296 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

04

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101. . 

102- 

103........

104 ___ ...

105 _ .....

amount of claystone, 15-15.7 feet; maroonbrown sandy clayey siltstone, 15.7-15.8 feet; 

gray-green sandy siltstone, 16.8-16 feet; 

brown clayey siltstone, 16-16.2 feet; graygreen claystone, 16.2-17 feet; (water table at 

16.2 feet). 

Sand, gray sllty pebbly, 17-18 feet; brown

sandy clayey siltstone, 18-19 feet; green-gray 

silty sandstone, 19-19.5 feet; gray -green sandy 

clayey siltstone, 19.5-20 feet; brown sandy 

siltstone, 20-20.6 feet; green-gray sllty sandstone, 20.5-21 feet.

to brown-gray sandy silty claystone, 22-23 

feet; gray sandy clayey siltstone, 23-23.5 feet; 

brown-gray silty sandstone. 23.5-24 feet.

24-25.5 feet; gray-brown silty sandstone, 

26.5-26 feet; gray to brown-gray sandy silty 

claystone, 26-27 feet: gray sandy clayey siltstone, 27-29 feet.

stone, 29-32 feet; brown-gray sandy clayey 

siltstone, 32-33 feet. (Caved at 31 feet) .

15-17

17-21

21-24

24-29

29-33

33-34

14.

105 _ --.-.

sUtstone, 32-33 feet. (Caved at 31 feet) .

33-34 

34

Auger-hole ES-7 

DS-7-106.. ...

107 ........

108 ........

109 ........

110 _ . __

Sand, brown silty, 0-1 foot; brown sandy silty 

clay, 1-2.5 feet; pale-buff sandstone with 

some siltstone, 2.5-3 feet. Sample contains 

some gypsum. 

Sandstone, pale-buff to pale-brown silty, 3-4 

feet; brown-red sandy silty claystone, 4-5 

feet. Traces of fluorescent material in addition to minor amount of gypsum. 

Sandstone, pale-gray with some siltstone; 

0.5-1 percent fluorescent material in addition to very small amount of gypsum. 

Sandstone, white to pale-gray with a little 

siltstone; 0.5-1 percent fluorescent material 

in addition to minor amount of gypsum. 

Sandstone, pale-buff to pale-gray silty pebbly, 

with some gray siltsone intermixed from 

10.5-11 feet.

0-3 

3-6

5-7 

7-9 

9-11

0.6 

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1 

0 0

87

7 

6 6

3.6 3

3.5 

2.5 3
298 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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148.

149.

150- 

151.

152.

Sandstone, brownish pale-buff to brown-gray 

pebbly and a little siltstone; 0.5-1 percent 

fluorescent material.

In part caved rock from 20-22 feet. Brownish 

pale-buff to brown-gray pebble sandstone 

with subordinate Duff-gray-white sandy 

siltstone; sample contains 0.1-0.5 percent 

fluorescent material.

Siltstone, buff gray-white sandy, with traces of 

fluorescent material.

Sandstone, pale-buff to pale-brown, very silty; 

sample contains 0.1 percent fluorescent 

material.

Siltstone, light-gray sandy, and intermixed 

pale-buff silty sandstone from 26-27 feet; 

water table reached at 27 feet; pale-buff silty 

sandstone with minor amounts of light-gray 

sandy siltstone, 27-29 feet; sample contains 

traces of fluorescent material. (Caved at 

27 feet.)

End of hole..________________.

20-22 

20-23

22-24 

24-26

29

0 

0.5

7.5

6.5

4 

3.5

3.5 

3.5

Auger-hole ES-10

DS-10-153..._. Sandstone, brown silty with a few pebbles; 0-2 

sample contains 0.1-0.5 percent fluorescent 

material.

154.--_. Sandstone, buff-brown silty,2-2.7 feet;brown 2-4 

sandy siltstone with some claystone, 2.7-3 

feet; brown-red to grayish-red-brown silty 

claystone with some sandstone, 3-4 feet; 

0.5 percent fluorescent material and minor 

gypsum(?).

155----..- Siltstone, red-brown to brownish-gray-buff 4-6 

with intermixed claystone and sandstone; 

sample contains -about 0.5 percent fluorescent material.

156.. .. Siltstone, brown-gray to buff-gray with some 6-8 

claystone and sandstone from 6-7.5 feet; 

green-gray siltstone with some sandstone, 

7.5-8 feet; 2-5 percent fluorescent material.

157-. Siltstone, green-gray sandy, 8-10.5 feet; brown- 8-11 

ish-green-gray sandy siltstone, 10.5-11 feet;

I-2 percent fluorescent material. 

158. - .. Siltstone, brown-gray to green-gray sandy, 11-13

II-12 feet; gray-green siltstone with a small 

amount of sandstone, 12-13 feet; 0.5-1 percent fluorescent material.

6.5

14

3.5 

4

4.5

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302 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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URANIUM IN THE RED DESERT, WYOMING 303

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TABLE 11. Lithology, content of uranium and equivalent uranium, and radioactivity of r

drilled by the U. S. Geological Survey in 1950, Lost Creek schroeckingerite de

Sample No. Lithology (sample log)

Field radioa

Samples

Depth 

(ft)

Scale divisions 0.2 mr per hr

Miu Max Avg

Auger-hole ES-12 Continued 

DS-12-180... __

181

182 

183.......

184

Siltstone, gray-green to buff-green clayey, with 

traces of fluorescent material. 

Siltstone, gray-green to green-gray, very clayey, 

contaminated with overlying rock; sample 

contains less than 0.1 percent fluorescent 

material. 

SUtstone, gray-green to green-gray, very clayey, 

contaminated with overlying rock; sample 

contains traces of fluorescent material. 

Claystone, gray-green silty water-bearing, 

20-21.5 feet; gray-green clayey siltstone, dry, 

21.6-23 feet; sample is contaminated with 

material from above and contains traces of 

fluorescent material. 

(Water table at 23 feet.) Gray-green silty 

claystone, 23-23.5 feet; brownish-gray -green 

very silty claystone, 23.5-24.5 feet: light 

brown silty claystone, 24.6-25 feet. (Caved 

at 23.5 feet.)

14-16 

16-18

18-20 

20-23

23-25 

25

2

Auger-hole ES-13 

DS-13-185 ____

IRft

187. 

188

Sand, brown or buff silty, with a few pebbles.. 

Sandstone, buff pebbly, with subordinate 

siltstone.

Sandstone, buff to pale-buff silty pebbly (pebbles as much as half an inch in diameter).

0-2 

2-4

4-6 

6-8
189.. 

190... _ .

191.. ..

192... ....

193.......

194.- -

19S... ....

196.- 

197.......

198... ....

do

Sandstone, pale-buff silty pebbly (pebbles as 

much as three-fourths of an inch In diameter) . 

Sandstone, pale-buff silty pebbly (some pebbles 

are as much as 1 inch in diameter; some 54- 

inch grains are feldspar). 

Sandstone, yellowish pale-buff silty pebbly, 

14-15.7 feet; gray-green and maroon-brown 

silty claystone, 15.7-16 feet (trace of fluorescent material). , 

Sandstone, brown-buff, silty pebbly (some 

gray -green claystone). 

Sandstone, pebbly, brown to gray, silty, with 

some brown siltstone, 18-19.5 feet; graybrown sandy siltstone, 19.5-21.5 feet; palebuff sandy siltstone, 21.5-22 feet (trace fluorescent material). 

Sandstone, pale-gray, silty, 22-23 feet; pale-buff 

sandy siltstone, 23-24 feet; sample contaminated with caved rock. 

Sandstone, gray-buff to pale-buff silty, with 

some pebbles; sample contaminated. 

Sandstone, gray-buff silty 29-32 feet; maroon 

and gray-green waxy claystone with minor 

sandstone, 32-33 feet; buff-brown clayey 

siltstone, 33-34 feet (trace of fluorescent 

material). Sample contaminated. 

Siltstone. gray-buff; sample contaminated. 

(Caved at 34 feet.) 

Bole abandoned at 35 feet without reaching 

water table.

8-10 

10-12

12-14 

14-16

16-18 

18-22

22-24

24-29 

29-34

34-35

INDEX

Page

 - . _.__.. 252,265,268-260,283 

spectrographic._____________ 250,263 

Antelope Hills.......................... 240,255,283

Ash, lignite, uranium content_________ 252 

volcanic........ ................. 242,253,274

Auger holes, deep..... ............__.. 265,271

shallow _______________ 258,59

Bachman, G. 0., Densen N. M., and Zeller,

H. D., work cited.......... --. 253

Barnett, P. B., work cited... -.--..- ---- 263

Basement complex.. ____________ 242,283 

Berman, Jos., work cited__________ 261,262 

Bridger formation______________ 240,256 

Brown, B. W., cited .. . 248

Browns Park formation____________ 242

Calcite. . 262^

Cannon, Helen, cited_____________ 265 

Chadron formation. ......____ .. 242

Chain Lakes. . . 240,242,245, pis. 16,17 

Claystone-. ..... 241,245,248,256,257,263,268,272

Clinker and ash.. ._............... 250,252

Continental Peak formation of Nace- ------- 241,

244,256,274

Correlation, radioactivity measurements__ 244 

, rock units 242,248,268

Cyclone Bim__.........._......... 240,243,255

Cyclone Bim fault zone.... . 243,272,273,274

Densen, N. M., Bachman, Q. 0., and Zeller,

H.D., work cited........ 253

Eocene lakes.........__._.____ 243,244,274

Eocene rocks. . - . 240-241,242,264 

history... .._._____....__ 243

Equilibrium, radioactive... . 252,253,261,262,265 

Equivalent uranium_ 244,246,252 

Evans, B.D., and Goodman, Clark, work cited. 245

Fades, transition in. _________ . 241,245 

Faults 243,259-260,264,273,28S, 286

Field work. ..................... 239,255,257r260

Fluorescence_ 261,262-263,267,269,270

Folds 242,243,259,260,264

 ... .... 248,249,256

Granite Mountains... ... ...... 240,242

Great Divide Basin- __......... 229,243

Green Mountains-. _________:_ 240,255 

Green Biver Basin... ~ 240 

Green Biver formation....______- 240,241; 245

Ground water, flow.._ 273; 274 

Guillotte, G. B., work cited. . 272 

Gypsum_ - ... 250

Lake basins, Pleistocene.. . 240,241,245

Page

Leaching of uranium..____________ 254 

Lenticularity of rock units__.______.. 241 

Leucite Hills, lava of. _____________ 245 

Lignite, associated rocks.. 248 

beds..._._ __ 246-247

extent. - . 3846 

formation of.. __.. 243 

in test well_-.... _... 246,254

in seismic-survey shotholes.............. 248

quality for fuel...____________.. 250 

radioactivity of~ -~-------------._ 246,250

Lithologic units__ 256

Logging of auger holes_____________ 271 

Lost Creek schroeckingerite deposit, associated

minerals______________ 261 

control by faults_ __________.. 273 

description.. ...___._...__.. 266 

exploratory work________ 255,265-271,276 

geography ... ....___....... 255

grade of ore..___.- ____. _. __ 264,265 

iron-stained zones..______ 257,263,273,274 

ore bodies 266,261,263,264 

ownership . .. 255

Masursky, Harold, and Pipiringos, G. N.,

work cited ..__........ 242,243

Nace, B. L., work cited... ............ 241,242

Nelson, J. M., and Slaughter, A. L., work 

cited__......_....___..

Oil-and-gas tests.. . 243 

Oligocene rocks (See also Chadron formation). 263 

Outcrops 250,262,265-256

Petretic, Geo., work cited.._...... . 265

Pipiringos, G. N., and Harold Masursky,

work cited.... _...._- 242,243

Pits__ __........... ... 267-258,265

Pleistocene rocks .. 242 

Prospecting. ._____ ___-___ .. 276

Radioactivity measurements___.___.. 244

anomalies in auger-hole, logs 271

comparison. 244-245

in auger holes 267

with airborne equipment. 251

with car-mounted equipment_ _ 250

Recent sediments______________ 242,244

Bed Desert, description 239-240

Roads- - - - - 240,256

Bock Springs uplift__...._ . 240

Bosholt, John, cited. 262

Samples, rock_ 262, 

253,265,268,269,283-286,289-305 

plant 265,287

water. . 265,271

307
308 INDEX

Sampling.. ...- i. .... 245,

246,250,252-253,262,263,266-267,268-269,271

Sandstone 248,250,256,257,262,263,268,272,273

SchroecMngerite- _.__ 257,260-61

accumulation_... __________ 272

deposition.. ... ...... 261,264,272

detection of. ..... __. 275

flakes... . _ 261,272 

in eolluvium. . .........__. 264

pellets 261,263

formation.... ... 272

relation to iron oxide-stained zones___ 273 

relation to water table_______ 270,273,274 

transportation. ..... .... 261,273

Shale. .__ 241,242,248,256,257,263,273,274 

lacustrine or Green River-type. 241,256 

carbonaceous, uranium in....___ 246,250,252

with lignite. 248,249,250

Sierra Madre Range.. ....... . 240

Siltstone. . . 263,264,268,272 

Slaughter, A. L., and Nelson, J. M., work

cited..... 246,250,262

Source of uranium____."________ 273-274 

Supply points . . .... ........__ 240

Sweetwater Mountains___________ 240,242

Terraces 244,256,261,274

Page

Thickness of rocks 242 

Thompson, M. E., work cited . 262 

Topographic features 240 

Towle, C. C., and Wyant, D. G., work cited- 262 

Trenches . . . . - 259

Uraniferous lignite, origin . .. 253-254 

Uranium, in lignite, epigentetic origin 253

syngenetic origin 254 

Uranium content, fluorescent chert 245

lignite.__...-.. ___ .... 252-253

sludge from test well 253 

Uranium minerals, schroeckingerite....__. 260-61

unknown minerals . 262-263

Vegetation__. . 240 

Volcanic rocks of the Leaucite Hills. .. 242,245

Wasatch formation-. 240,241,248 

Water supply_ .... __ ... . 240, pi. 16

Water table. . . - - 271

movements.. .- - 273-274

Wyant, D. G., and Towle, C. C., work cited.. 262

Yen, T. C., cited .- 248

Zeller, H. D., Densen, N. M., and Bachman,

G. O., work cited .- ._------ 253
Stratigraphy of the 

Morrison Formation 

lii Part of Northwestern 

New Mexico

By V. L. FREEMAN and L. S. HILPERT

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-J

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE* WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 15 cents (paper cover)
CONTENTS

Page

Abstract_______________________________________________ 309

Introduction._____________________________________________________ 309

Previous stratigraphic work_______________________________________ 310

Morrison formation in northwestern New Mexico._____________________ 313

Recapture member._ __________________________________________ 313

Westwater Canyon member___________________________________ 314

Brushy Basin member________________________________________ 314

Stratigraphy of the Morris on formation near Laguna_ ____________ __ 315

Conclusions__________________________________________________. 318

Literature cited.__________________________________________________ 319

Stratigraphic sections of the Morrison formation.__________________ 320

ILLUSTRATIONS

FIGUKE 58. Index map of part of New Mexico-___--__-_____________-_ 311

59. Nomenclature of the Morrison formation in northwestern

New Mexico..________________________ 312

60. Nomenclature of the Morrison formation in the Laguna area. 315

61. Interrelationship of the members of the Morrison formation._, 316

in

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

STRATIGRAPHY OF THE MORRISON FORMATION IN PART 

OF NORTHWESTERN NEW MEXICO

By V. L. FREEMAN and L. S. HILPEKT

ABSTRACT

In the summer of 1954 while investigating the uranium resources of northwestern New Mexico, the writers noticed that the stratigraphic nomenclature of 

the Morrison formation in use in the Laguna area was not consistent with that 

in use elsewhere in the region. A review of the literature led to the agreement 

that the nomenclature currently in use elsewhere in the area, such as near Grants, 

is satisfactory. This usage divides the Morrison formation into three members; 

in ascending order they are the Recapture, the Westwater Canyon, and the 

Brushy Basin members. These members may be recognized and have been 

correlated throughout northwestern New Mexico. In the Laguna area the Recapture, Westwater Canyon, and most of the Brushy Basin members, as correlated by the writers, are present .in the stratigraphic interval that has previously 

been considered as Recapture. The sandstone previously considered as Westwater Canyon is in our opinion at the top of the Brushy Basin. This sandstone 

is of economic importance and is informally called the Jackpile ore-bearing bed.

INTRODUCTION

The field work on which this report is based was done during the 

summer of 1954 when the writers were engaged hi investigating the 

uranium resources of northwestern New Mexico on behalf of the 

U. S. Atomic Energy Commission. While studying the uranium 

potential of the stratigraphic units, a discrepancy between the nomenclature of the Morrison formation of Late Jurassic age in the 

Laguna area and in other parts of northwestern New Mexico became 

evident. As correct correlations were a necessity in evaluating the 

resource potential of the stratigraphic units, a stratigraphic study 

was undertaken to assure proper correlations. Eleven stratigraphic 

sections were measured in northwestern New Mexico, four sections 

measured by others were examined, and a review of the literature was 

undertaken. This report reviews the names that have been proposed for the members of the Morrison formation in northwest New 

Mexico, describes them, and presents the results of the writers' work 

in correlating the members near Laguna with adjacent areas. The 

work was aided by the cooperation of the staffs of the mining companies in the area and the Atomic Energy Commission. Use was

309
310 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

made of stratigraphic sections measured by L. C. Craig and T. E. 

Mullens of the Geological Survey.

PREVIOUS STRATIGRAPHIC WORK

The nomenclature of the formations of Jurassic age in northwestern 

New Mexico was summarized, and a complete bibliography of the 

Jurassic literature was presented, by Baker, Dane, and Reeside (J936, 

p. 43). This report, together with a revision by them (1947), is the 

standard reference on Jurassic stratigraphy in the region. In the 

earlier paper the Morrison formation in northwestern New Mexico 

included the Todilto limestone member at the base, overlain in 

ascending order by a sandstone member and a shale member (Baker, 

Dane, and Reeside, 1936, table 8). In the revision the Todilto limestone was not included in the Morrison formation (1947, p. 1668). 

No attempt was made in these reports to subdivide the Morrison 

formation above the Todilto limestone into formal members.

The first subdivision of the Morrison formation on the Colorado 

Plateau was made by Lupton (1941) who gave the name Salt Wash 

sandstone member to a basal conglomeratic sandstone unit in eastcentral Utah. At Bluff, Utah (fig. 58), a massive sandstone that 

forms the cliffs along the San Juan River, and locally referred to as 

the Bluff sandstone, was considered by Baker, Dane, and Reeside 

(1936, p. 21) as a member of the Morrison formation. Gregory 

(1938, p. 58), in the same area, recognized four members of the 

Morrison formation: the Bluff sandstone at the base, overlain by the 

Recapture shale, the Westwater Canyon sandstone, and the Brushy 

Basin shale.

In. 1947 the Geological Survey began a study of the stratigraphy 

of the Morrison formation on the Colorado Plateau (Craig and others, 

1955). The study resulted in the definition of the distribution of the 

members of the Morrison formation in the Colorado Plateau region. 

As this study ceatered on the then known uranium ore deposits in 

the Morrison formation in western Colorado and eastern Utah, the 

Morrison formation of northwestern New Mexico was not investigated 

in detail. Craig tentatively assigned the Bluff sandstone, as a formation, to the upper part of the San Rafael group but retained as 

members of the Morrison formation in ascending order: the Salt Wash, 

Recapture, Westwater Canyon, and Brushy Basin. These assignments have been accepted by the Geologic Names Committee of the 

Geological Survey. The Salt Wash member was shown (Craig and 

others, 1955, p. 135, 138) to extend from southeastern Utah a short 

distance into New Mexico, where it intertongues southwardly with, 

the Recapture member and is absent elsewhere in New Mexico. The 

remaining members of the Morrison formation, the Recapture, West-
STRATIGRAPHY, MORRISON FORMATION, ; ; MEXICO 31J.

J

* T' i ii i - >

 ___ UTAH

/ J__| __ 1 __ _| _ /

COLORADO! \ / _ _L

\ A&ZONA 1 "NEW MEXICO^ " ~~ "~ 1 ~~ T "" ' 1

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AREA SHOWN ON FIG. «f 1 j - ^ ____ _ \ ____ . 1 _ ,

-| Gallup . II \ 1 

LMPton^o ° 0Tboreau ! Ysidro I r~~'

1 f ~ ogTuewater \ _ 1_ _^ . _ .s* ~~ \ 

I Qrantso \oCanoncito^ | _ f J

 1 Laguna0 ALBUQUERQUF" ~ I I I

y

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 ' _j i1 "" V-U.-!

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L

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l 50 0 100 Miles

__ .' 1 . . . . 1 . 1

1

FIGURE 58. Index map of part of New Mexico and adjacent States showing localities referred to in text.

water Canyon, and Brushy Basin, were shown to extend to and 

beyond the Laguna area.

Before the extension of the Recapture, Westwater Canyon, and 

Brushy Basin members of the Morrison formation into New Mexico, 

a set of informal member names was suggested by Kelley and Wood 

(1946) and adopted by Silver (1948) in the Laguna area. These 

names were, in ascending order: the buff shale, the brown-buff sandstone, the white sandstone, and the variegated shale. Craig considered the buff shale to be an equivalent of the Summerville formation 

and the brown-buff sandstone and the white sandstone to be equivalents of the Bluff sandstone (Craig, oral communication). The variegated shale apparently contains equivalents of the Recapture, Westwater Canyon, and Brushy Basin members.

The discovery of commercial quantities of uranium ore in northwestern New Mexico in 1950, resulted in a study of the sedimentary
312 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

rocks of Jurassic age by the Atomic Energy Commission (Rapaport, 

Hadfield, and Olsen, 1952). The geologists of the Atomic Energy 

Commission recognized the presence of the Summerville formation 

and Bluff sandstone in the area of northwestern New Mexico east of 

Gallup (Rapaport, Hadfield, and Olsen, 1952, p. 20) and followed 

Craig's (Craig and others, 1955) terminology for the Morrison formation (fig. 59). This terminology has been widely accepted by the 

mining companies.

Smith (1951, p. 13; 1954, p. 15) recently proposed a partly new 

set of names for the members of the Morrison formation (fig. 59). 

In the area near Thoreau, N. Mex., he divides the Morrison formation 

into the Chavez at the base, stating that it may be equivalent to the 

Recapture; an overlying Prewitt sandstone member, equivalent to the 

Westwater Canyon; and the Brushy Basin at the top. The writers 

believe that the similarity of the members of the Morrison in the

1

Baker, Dane, and Reeside 

1936, 1947 

Northwest New Mexico

Cretaceous

jj

S

s

Shale member

Sandstone 

member

Todilto 

limestone 

member

Kelley and Wood 

1946 

Lucero uplift, 

New Mexico

Dakota(?) sandstone

g 

* 

5

§

Variegated 

shale 

member

White 

sandstone 

member

Brown-buff 

sandstone 

member

Buff 

shale 

member

Todilto 

gypsum 

member

Harshbarger, Repenning, 

and Jackson 

1951 

Navajo Country

Dakota sandstone

Brushy Basin 

shale member

Westwater Canyon 

.1 sandstone member

S

Cow Springs 

sandstone

Recapture 

shale 

member

Salt 

Wash sandstone 

member

Bluff 

sandstone

Summerville 

formation

Absent

This report; modified from Craig 

and others, 1955; and 

Rapaport, Hadfield, and 

Olsen, 1952 '

Dakota sandstone

1 

&

1

o

S

Brushy Basin 

member

Westwater Canyon 

member

Salt 

Wash 

member

Recapture 

member

Bluff 

sandstone

Summerville 

formation

Todilto limestone

Smith, C.T. 

1954 

Thoreau quadrangle

Dakota sandstone

|

£

o

5

£

i

£

Brushy Basin 

shale member

Prewitt sandstone 

member

Chavez 

member

Upper member

Lower member

Todilto formation

FIGURE 59. Nomenclature of the Morrison formation in northwestern New Mexico.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 313

Thoreau-Grants area with those in southeast Utah could only be 

possible if they are continuous beneath the San Juan Basin. It, 

therefore, seems desirable to use the same terminology, especially as 

it is in general use by the mining companies in northwest New Mexico, 

rather than adopt the new terminology of Smith. In summary, the 

Morrison formation throughout most of northwestern New Mexico is 

considered to consist of the Recapture at the base, the Westwater 

Canyon, and the Brushy Basin. A summary of the terminology is 

presented in figure 59.

MORRISON FORMATION IN NORTHWESTERN 

NEW MEXICO

In the belt of outcrop of the Jurassic rocks between Gallup and 

Albuquerque, the Morrison formation as used here consists of three 

conformable members: the Recapture, Westwater Canyon, and the 

Brushy Basin. To the west, on the Navajo Indian reservation, several 

upper Jurassic units grade into\ a sand facies that has been named the 

Cow Springs sandstone (Harshbarger, Repenning, and Jackson, 1951). 

At Lupton, Ariz., the Recapture and Westwater Canyon members of 

the Morrison are recognizable although with difficulty. Farther to the 

south the Recapture grades into the Cow Springs sandstone leaving 

only the Westwater Canyon as a recognizable member of the Morrison 

formation because the Brushy Basin is missing, probably due to preDakota erosion. About 3 miles east of Gallup where the Jurassic 

section crops out on the flank of the Zuni uplift, the Recapture is 

recognizable although it is very sandy. A few miles farther east the 

Brushy Basin appears beneath the Dakota sandstone of Cretaceous 

age, and in the area of this report the Morrison formation consists of 

the three members listed above.

RECAPTURE MEMBER

The Recapture member in the Gallup-Albuquerque area ranges 

from about 20 to about 170 feet in thickness, in general thinning 

southward. It consists largely of grayish-red sandy claystone and 

clayey sandstone with limy nodules and white, clean, fine- to mediumgrained sandstone in alternating units 5 to 10 feet in thickness. The 

clean sandstone beds are most common in the western part of the area 

and probably represent tongues of the Cow Springs sandstone. 

Clayey sandstone is the dominant rock type in the eastern and southern parts of the area. The Recapture in most of the area is conformable with the underlying Bluff sandstone, but to the north near San 

Ysidro it rests directly upon the Summerville formation. In general 

the upper part of the usually clean Bluff sandstone is clayey, but the 

contact with grayish-red clayey sandstone of the overlying Recapture

402655 56 2
314 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

is sharply marked. In the Laguna area the Recapture interfingers 

with the Bluff sandstone. On Haystack Butte, near Bluewater, the 

basal unit of the Recapture member is a conglomeratic sandstone that 

rests on a slightly channeled surface cut into the Bluff sandstone; they 

are distinguished by grain size and type of crossbedding.

The Recapture generally is overlain by the Westwater Canyon from 

which it is easily distinguished. A few miles south of Laguna the 

Recapture is composed of clayey sandstone beds that, because of the 

absence of the Westwater Canyon, are directly overlain by Brushy 

Basin strata of similar lithology. Near Acoma, farther to the southwest, the two members could not be separated with certainty.

WESTWATER CANYON MEMBER

The Westwater Canyon member ranges from about 50 to 190 feet 

in thickness in the Gallup-Albuquerque area, except near Laguna 

where it is locally absent. In general, the Westwater Canyon thickens from the Laguna area toward Gallup to the west and toward San 

Ysidro to the north* The Westwater Canyon is a yellowish-gray to 

light-grayish-red, locally conglomeratic, fine- to coarse-grained sandstone that is characterized by scour-and-fill crossbedding and by 

angular grains of unweathered feldspar. Discontinuous lenses of 

grayish-green sandy claystone are present. The Westwater Canyon 

interfingers with the underlying Recapture and the overlying Brushy 

Basin members.

BRUSHY BASIN MEMBER

The thickness of the Brushy Basin member is largely determined by 

the amount of deformation and erosion before deposition of the Dakota 

sandstone. The details of the pre-Dakota deformation are not known, 

but, in general, it consisted of northeastward tilting and local broad 

folding. Subsequent erosion resulted in a southwestward irregular 

thinning of the Brushy Basin. In northwestern New Mexico the 

member ranges in thickness from a knife edge to about 370 feet. The 

Brushy Basin consists of partly variegated but dominantly light 

greenish-gray, slightly swelling, locally saody claystone containing 

limy nodules. Thick sandstone units lithologicaUy similar to the 

Westwater Canyon, thin hard green sandstone beds, and thin clayey 

limestone beds are rare to common in occurrence. Pinkish-orange 

jasper commonly occurs, especially near the base, as crack fillings and 

as cement in thin sandstones. As the Brushy Basin and the Westwater Canyon members interfinger, the contact between the members 

may be difficult to determine. The writers placed the contact at the 

base of the lowest recognizable claystone in the Brushy Basin and 

acknowledge that some of the sandstone beds placed hi the Brushy 

Basin may laterally be equivalent to the Westwater Canyon member.
STRATIGRAPHY, MORRISON; FORMATION, NW. NEW MEXICO 31 f>

STRATIGRAPHY OF THE MORRISON FORMATION NEAR

LAGUNA

The Morrison formation in the Laguna area became of economic 

importance with the discovery of uranium in 1951. As a consequence, 

a great deal of geologic work is in progress in the area. The nomenclature of the Morrison formation in general use is that used in this. 

report, but it is not being applied to the same stratigraphic units. 

Figure 60 compares the terminology in previous use with that proposed

Previous usage

Dakota sandstone 

~\__^ ---

Westwater Canyon member

Recapture member

Bluff sandstone

This report

Dakota sandstone 

^_^~^-\_

Jackpile ore-bearing bed

Brushy Basin member

Westwater Canyon member

Recapture member

Bluff sandstone

FIGUKE 60. Nomenclature of the Morrison formation In the Laguna area, New

Mexico.

now. The correlation of the members of the Morrison formation 

between Laguna and adjacent areas is difficult because of: the similarity of the ore-bearing sandstone unit, informally caEed Jackpile 

ore-bearing bed in this report, with the Westwater Canyon member; 

the local absence of the Westwater Canyon; the unusual thickness of 

the Brushy Basin member; and the thinness and incomplete exposures 

of the Recapture member. The Salt wash member is not present in 

this area.
816 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Figure 61 shows the location of some of the measured sections studied 

and the relationship of the members of the Morrison between the 

sections. The sections used are presented following page 319. The 

Haystack Butte and Red Bluff sections are in the Grants area where 

there is general agreement on the nomenclature. At Haystack 

Butte the contact between the Westwater Canyon and the Brushy 

Basin is placed at the base of the lowest persistent claystone unit. 

Ledges of sandstone that could not be distinguished from the Westwater Canyon are present throughout the entire thickness of the 

Brushy Basin. Eastward toward the Red Bluff section the Westwater Canyon interfingers with the Brushy Basin and to a lesser extent 

with the Recapture, resulting in a considerable thinning of the WestHAYSTACK 

BUTTE 

.Sec. 13, 

T. 13 N., 

R. 11 W. RED 

BLUFF 

Sec. 3, 

T. 12 N., 

,R.9W.

XV

ACOMA SHEEP\\\ 

Sec. 8. CAMP \\\ 

T.8N., Sec. 2. \\\, ^ 

R.7 W. T.8N., V *-- 

R.6W

FIGTTKE 61. Interrelationship of the members of the Morrison formation.

water Canyon. Interfingering of the Recapture with the Bluff 

sandstone was not seen but may be present and may account for some 

thinning of the Recapture. The Morrison formation is not exposed 

in the area between the Red Bluff and Laguna sections.

At the Laguna section, only the uppermost 29 feet of the Bluff 

sandstone is exposed. It is overlain by about 20 feet of reddishbrown and minor greenish-gray, very clayey sandstone with limy 

nodules that is typical of the Recapture member. Above the slope 

formed on the Recapture is a prominent ledge, about 55 feet thick, 

of the Westwater Canyon member. As no exposures of the Recapture 

exist between the Red Bluff and Laguna section, the manner of its 

thinning is not known. Silver (1948) showed that in this area the
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 317

entire Jurassic section thins southward by overlap against a Jurassic 

highland, and the writers believe the thinning of the Recapture is 

probably due to the same cause.

The Westwater Canyon is similar lithologically at the Laguna 

section and in the southeastern Utah area. It contains angular grams 

of unaltered feldspar, is moderately to poorly sorted, medium grained 

to coarse grained, and is scour-and-fill crossbedded. These features 

are in marked contrast to the dominantly well-sorted, fine-grained, 

and sweeping crossbedded Bluff sandstone that is not known to contain the angular grams of unaltered feldspar. South of Laguna the 

Westwater Canyon is not present; it probably disappears by interfingering with the Recapture and Brushy Basin members.

At the Laguna section the Brushy Basin member is about 370 feet 

thick. It consists of grayish-green, slightly swelling, clay-rich beds 

with some pinkish variegations near the base and lenticular sandstone 

units lithologically similar to the Westwater Canyon. The Brushy 

basin in the Laguna area is similar to the Brushy Basin in the Grants 

area and in southeastern Utah but distinctly different from the 

Recapture member in these areas. At the Laguna section the uppermost 65 feet of the Brushy Basin is the so-called Jackpile ore-bearing 

bed. It is a very pale orange and locally white sandstone that is 

dominantly fine grained to medium grained with minor coarse grains 

at the base. Feldspar grains, as well as specks of a white clay mineral, 

probably kaolin, are present. The sandstone is characterized by scourand-fill crossbedding, but some parallel bedding, often marked by 

claystone partings, is present also.

Toward Acoma, beyond the limit of the Westwater Canyon member, the Recapture and Brushy Basin members are considerably 

thinner (fig. 61). The contact of the Recapture and Brushy Basin 

can be placed with reasonable certainty as far southwest as the Sheep 

Camp section (fig. 61), but farther to the southwest the contact is 

indistinct. The Brushy Basin becomes more variegated, grayish-red 

colors are prevalent, and it is similar to the Recapture. At the 

Acoma section a reddish zone at the base of the Morrison may correlate with the Recapture, but this zone is gradational with the upper 

part of the formation which also contains thin reddish zones.

The West Mesa Gigante section is similar to the Laguna section; 

but, proceeding from the section southward along the west side of 

Mesa Gigante the Westwater Canyon disappears in a few miles. It 

reappears for about a half a mile along the south face of the mesa 

where it has a thickness of 58 feet; it does not reappear again until 

about 3 miles north of Canoncito along the east face of the mesa 

where it is 47 feet thick. At this locality, S^ sec. 27, T. 11 N., R. 

3 W., tfre pinching out of the Westwater Canyon is well exposed. In
318 CONTRIBUTIONS TO THE GEOLOGY OF TTEANITJM '!

a distance of about 50 feet along the outcrop, the entire member, 

consisting of 47 feet of sandstone disappears by interfingerjing with 

sandy claystone beds similar to the Recapture and Brushy Basin 

(fig. 61). North of the Canoncito section, less than half a mile from 

the disappearance of the Westwater Canyon, the Recapture includes 

several sandstone beds similar to those in the Westwater Canyon. 

Between the Canoncito area and the Cuchillo Arroyo section, only 

the upper part of the Morrison is exposed locally. At Cuchillo 

Arroyo 170 feet of the Westwater Canyon is well exposed in a vertical 

 cliff. It interfingers at top and base with the Brushy Basin and 

Recapture, respectively. The Recapture rests directly upon the 

Summerville formation from which it is distinguished with difficulty. 

The manner in which the Bluff sandstone has disappeared is not 

known, but as the Bluff has been seen by the writers to interfinger 

with both the Recapture member and the Summerville formation, a 

gradual thinning by interfingering with these units is at least partly 

responsible.

CONCLUSIONS

The Morrison formation in the area of Laguna, N. Mex., consists 

of a 20-foot unit at the base assigned to the Recapture, a 55-foot 

sandstone assigned to the Westwater Canyon, and a 370-foot unit 

assigned to the Brushy Basin. The upper 65 feet of the Brushy 

Basin is a sandstone that has been considered by others as the Westwater Canyon to which it is lithologically similar; the entire underlying Morrison, in consequence, was considered as Recapture. The 

members of the Morrison formation near Laguna are lithologically 

similar to the members in the area near Grants, where there is general 

agreement of nomenclature, and in the San Ysidro area, where they 

are so typical as to preclude disagreement. The Recapture and the 

Westwater Canyon, however, are thinner near Laguna because of 

proximity to the edge of their areas of deposition; and the Brushy 

Basin is much thicker, probably because of less removal before 

deposition of the Dakota sandstone.

The sandstone occupying the uppermost part of the Brushy Basin 

member has been traced from the Laguna section, in nearly continuous exposures, into the ore-bearing sandstone at the Jackpile 

mine of the Anaconda Copper Mining Co. It ranges in thickness 

from a knife edge, where cut out by pre-Dakota(?) erosion, to about 

175 feet at the Jackpile mine. Because of the economic importance 

of this sandstone bed, it has been informally named the Jackpile 

ore-bearing bed of the Brushy Basin member.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 319 

LITERATURE CITED

Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., 1936, Correlation of the Jurassic 

formations of parts of Utah, Arizona, New Mexico, and Colorado: II. S. 

Geol. Survey Prof. Paper 183.

 1947, Revised correlation of Jurassic formations of parts of Utah, Arizona, 

New Mexico, and Colorado: Am. Assoc. Petroleum Geologists Bull., v. 31, 

p. 1664-1668.

Craig, L. C., and others, 1955, Stratigraphy of the Morrison and related formations, Colorado Plateau region, a preliminary report: U. S. Geol. Survey 

Bull. 1009-E.

Gregory, H. E., 1938, The San Juan country, a geographic and geologic reconnaissance of southeastern Utah: U. S. Geol. Survey Prof. Paper 188.

Harshbarger, J. W., Repenning, C. A., and Jackson, R. L., 1951, Jurassic stratigraphy of the Navajo country: N. Mex. Geol. Soc. Guidebook, 2d field 

conf., p. 95-99.

Kelley, V. C., and Wood, G. H., 1946, Lucero uplift, Valencia, Socorro, and 

Bernalillo Counties, N. Mex.: U. S. Geol. Survey Oil and Gas Inv. Prelim. 

Map 47.

Lupton, C. T., 1914, Oil and gas near Green River, Grand County, Utah: U. S. 

Geol. Survey Bull. 541-D.

Rapaport, Irving, Hadfield, J. P., and Olsen, R. H., 1952, Jurassic rocks of the 

Zuni uplift, New Mexico: U. S. Atomic Energy Comm., Tech. Inf. Service, 

RMO-642.

Silver, Caswell, 1948^ Jurassic overlap in western New Mexico: Am. Assoc. 

Petroleum Geologists Bull., v. 32, p. 68-81.

Smith, C. T., 1951, Generalized nomenclature chart for formation and member 

names used in road logs: N. Mex. Geol. Soc. Guidebook, 2d field conf., 

p. 13.

 1954, Geology of the Thoreau Quadrangle, McKinley and Valencia 

Counties, N. Mex.: N. Mex. Bur. Mines and Min. Res., Bull. 31.
STRATIGRAPHIC SECTIONS OF THE 

MORRISON FORMATION

VALENCIA COUNTY

Laguna section, NW}£ sec. 28, T. 10 N., R. 5 W. 

[Measured by L. C. Craig, V. L. Freeman, and T. E. Mullins]

Top of measured section. Peei 

Dakota sandstone:

Sandstone, white (2V9) 1 , to very pale orange (10YR 8/2), weathering 

grayish-orange (IOYR 7/4), fine- to medium-grained, well-sorted; 

composed of subrounded to rounded clear quartz with rare white 

accessory grains; well-cemented, calcareous; subparallel laminations filling shallow erosion troughs, thin- to medium-bedded, some 

ripple laminations. Conglomeratic sandstone near base, pebbles 

of gray and black chert, pebbles subangular to subrounded. Abundant plant impressions; some carbonaceous material. Unit forms 

vertical cliff__________ ________________-__-__-_-________- 16. 5

Morrison formation: 

Brushy Basin member:

Sandstone, very pale orange (IQYR 8/2), locally white (2V9) in upper 

part, predominantly fine- to medium-grained with rare coarse 

grains at base, well-sorted; composed of subangular to subrounded clear quartz with abundant pink feldspar grains and much 

interstitial kaolin; coarse grains are quartz, feldspar, granite, and 

rare red and brown chert; moderately well cemented; channeling 

with subparallel laminations filling erosion troughs; minor clay 

partings; unit forms ledgy slope with upper 16 feet forming a vertical cliff. (Jackpile ore-bearing bed)________________----___-- 64. 5

Claystone, grayish-red (10R 4/2) and light greenish-gray (5GY 8/1), 

very sandy (to fine-grained); earthy weathering; slightly fissile; 

forms banded slope-_______-_____--____----_--------_---_-- 17. 8

Sandstone, very pale orange (IOYR 8/2) to yellowish-gray (5Y 8/-0, 

medium- to coarse-grained, moderately sorted; composed of subrounded to rounded clear quartz with abundant pink and white 

accessory grains; friable, weakly cemented; bedding not visible; 

forms steep slope________________________________________ 12. 7

Claystone, grayish-red (10 R 4/2), very sandy (to fine-grained); earthy

weathering; slightly fissile______-______-----_---------_-_--- 11. 8

Sandstone, with claystone and limestone near top; sandstone grayishyellow (5Y 8/4) to white (N9), medium-grained with some very 

coarse grains at top, moderately sorted; composed of subrounded 

quartz with common pink and white accessory grains; very coarse 

grains at top are predominantly clear to white quartz, pink feldspar, and granite; well-cemented to friable; cross-laminations 

filling erosion troughs. Eight-foot claystone and limestone unit 

below 10-foot top ledge same as in unit below. Unit forms ledgy to 

rounded slope___________.________________________ 33. 7

i The colors and color numbers are from the Rock-color chart of the National Research Council, Washington, D. C., 1948.

320
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 321

Brushy Basin member Continued *"«*

Clay stone, (90 percent) and limestone (10 percent). Clay stone, 

dominantly light greenish-gray (5GY 8/1), with some yellowishgray (5F8/1) and at base pale-red (5R 4/2) to grayish-red (IQR 

4/2), silty to sandy (fine-grained). Limestone, very light gray 

(JV8), weathers white C/V9), dense to finely crystalline. Unit 

weathers to steep rubble-covered slope _______________________ 46. 4

Sandstone, conglomeratic, very pale orange (10 YR 8/2) to yellowishgray (5F8/1) very fine- to coarse-grained, poorly sorted; composed of subangular and subrounded clear quartz with abundant 

pink feldspar and uncommon white and green accessory grains. 

Conglomerate consists mainly of tan, brown, gray, and red chert 

pebbles and granules averaging % inch with maximum 1J>_ inches 

in diameter, and abundant pink feldspar and white to clear quartz 

grains averaging % inch with maximum Yz inch in diameter; crosslaminations filling erosion troughs; locally forms prominent ledge. 

Coarser material concentrated at base of unit _________________ 14 4

Claystone (85 percent), sandstone (10 percent), and limestone (5 percent). Clay stone, yellowish-gray (5F8/1) to light greenish-gray 

(5G 8/1) and yellowish-gray (5 Y 7/2), slightly silty to slightly sandy 

(to fine-grained); frothy weathering, forms pastel green and pink 

slope. Sandstone, light greenish-gray (5G 8/1) to very light gray 

(JV8), very fine grained; forms beds as much as 2 feet thick, 

bedding not visible; weathers to slabby ledges. Limestone, very 

light gray (N8), dense: forms nodular beds to hackly ledges 1 foot 

thick. Pink bands in clay stone due to formation of pink cherty 

spots____-_______-.:____________________-_____-__________ 64. 5

Sandstone (65 percent) and claystone (35 percent). Sandstone, yellowish-gray (5F 8/1), fine- to medium-grained, moderately sorted; 

composed of subangular to subrounded clear quartz with common 

red, green, and white accessory grains; well-cemented with coarse 

crystals of calcite; unit, is lenticular, beds 1 to 5 feet thick of wavy 

laminations and cross-laminations filling erosion troughs. Weathers to prominent ledges. Claystone, very light gray (N8), sandy 

(very fine- to fine-grained); hackly to earthy weathering, forms 

narrow slopes between ledges. Locally the sandstone contains 

dinosaur bones, gastroliths, and stringers of granule to pebble 

size reddish-brown subangular chert________________________ 48. 5

Claystone (70 percent), sandstone (15 percent), and limestone (15 percent). Claystone, variegated, dominantly yellowish-gray (5F 

8/1), to light greenish-gray (5GF 8/1) containing thin beds of grayish-purple (5P 4/2) and grayish-red purple (5RP 4/2) near the base, 

sandy; in part calcareous; frothy weathering. Sandstone, yellowish-gray (5F 8/1), fine- to very fine-grained, well-sorted; composed 

of subangular clear quartz with abundant pink and white and 

uncommon green accessory grains (pink probably feldspar); forms 

lenticular beds 1 to 10 feet thick pinching out laterally within 300 

feet, cross-laminations filling erosion troughs. Limestone, very 

light gray (2V8), weathers white (M)); forms hackly to concretionary rubble-covered slt>pe______________________________ 58. 0

Total Brushy Basin member____________________________ 372. 3
322 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Westwater Canyon member: *"«* 

Sandstone, yellowish-gray (5 Y 7/2) to grayish-yellow (5 Y 8/4), mediumto coarse-grained with rare grains as much as one-eighth inch in 

diameter, poorly sorted; composed of subangular clear quartz 

with common pink feldspar, uncommon red and white accessory 

grains; firmly cemented, calcareous; medium scale wedging crosslaminations; forms prominent cliff above ledgy slope below. 

A lenticular bed at base is 1 foot thick, containing pebbles of red 

and gray chert and limy claystone. Limonite staining common- 56. 7

Total Westwater Canyon member.______________________ 56. 7

Recapture member:

Sandstone, clayey, and claystone, sandy, reddish-brown (WR 3/4) and 

greenish-gray (5GF 7/1), fine- to medium-grained, poorly sorted; 

composed of subrounded stained quartz with uncommon orange 

and black accessory grains; calcareous; locally stained with 

limonite. At top of unit is zone of large (1 foot) nodules of 

radiating calcite__--__________---_------_-_--------_------- 20. 1

Total Recapture member.______________________________ 20. 1

Total Morrison formation._____________________________ 449. 1

Bluff sandstone (part):

Sandstone, clayey, grayish-yellow (5F 8/4) to light greenish-gray 

(5GY 8/1), medium-grained, fair sorting; composed of subrounded 

grains of quartz with uncommon black and orange accessory 

grains; calcareous; bedding obscure.- Becomes increasingly 

clayey upward. Limonite staining common. Weathers to 

gentle slopes or rounded ledges._____________--_____-_-_-_-_- 29. 0

Base of measured section.

VALENCIA COUNTY

Acoma section, NW}4 sec. 8, T. 8 N, R. 7 W.

[Measured by V. L. Freeman, November 1954] 

Dakota sandstone:

Not measured or described. 

Top of section.

Morrison formation: feet 

Sandstone, clayey, dusky red (5R 3/4) (30 percent) and light greenishgray (5GY 8/1) (70 percent), gypsiferous, some limy nodules 

present. Unit contains minor sandstone beds like unit below. 

Unit forms slightly frothy surface__________________________ 36. 1

Sandstone, yellowish-gray (5F 8/1), medium- to fine-grained, wellsorted, subrounded, grains of quartz with uncommon red and 

orange accessory grains; friable, calcareous; very lenticular beds 

with minor beds of argillaceous sandstone like below except 

entirely dusky red; crossbedding is contorted low angle and 

medium scale, filling scour features._________________________ 7. 8

Sandstone, clayey, like top unit but 25 percent dusky red and 75

cent light greenish-gray.__ ____.______________-____-_-__--_- 23. 7
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 323

Morrison formation Continued #«*

Sandstone, white (NQ), medium- to coarse-grained, conglomeratic, 

poorly sorted, grains of quartz with orange, red, and gray 

accessory grains, pebbles to one-half inch are of chert and clay 

(chert is mostly red with gray and green present); slightly friable, 

calcareous; crossbedding is low angle and medium scale, filling 

scour features__________________________________-__________ 3. 3

Sandstone, clayey, dusky red (5R 3/4) and light greenish-gray 

(5GY 8/1) in about equal amounts, fine-grained, poorly sorted, 

some limy nodules, minor amounts of sandy claystone and sandstone like below, forms slightly frothy surface _________________ 65. 4

Sandstone, yellowish-gray (5F 8/1), medium-grained, well-sorted, 

subrounded, grains of quartz with uncommon red and orange 

accessory grains; friable, calcareous; very lenticular beds with 

some argillaceous sandstone like below near center of unit; 

contorted crossbedding is low angle and medium scale, filling 

scour features__-_____________-_______-__________-__-___-__ 12. 0

Sandstone, clayey, dusky red (572*3/4), fine-grained, poorly sorted;

forms slightly frothy surface________________________________ 7. 0

NOTE. At least lowest unit is probably equivalent to Recapture

member._________________________________________________ _____

Total Morrison formation.___________________________ 155.3

Bluff sandstone (part):

Sandstone, pale yellowish-green (WGY 8/2), fine-grained, well-sorted, 

subrounded grains of quartz with rare orange and red accessory 

grains; friable, some calcareous cement, some unknown white 

cement; unit weathers into rounded knobs; bedding not visible

Not measured 

Base of section.

SANDOVAL COUNTY

Cuchillo arroyo section, sec. 36, T. 17 N., R. 1 W. 

{Measured by L. C. Craig and V. L. Freeman, 1950]

Top of measured section.

Morrison formation (part):

Brushy Basin member (part): Feet 

Sandstone, very pale orange (1QYR 8/2), fine-grained, subangular, 

grains of clear quartz with uncommon orange and black accessory 

grains; hard, siliceous cement; lenticular strata, forms prominent 

local capping ledge_______________________________________ 2.5

Claystone, light greenish-gray (5GY 8/1), pale yellowish-brown (IOYR 6/2), 

and pale reddish-brown (10R 5/4), silty to medium-grained sandy, 

with common 1-inch to 1-foot beds of pale reddish-brown (10R 

5/4) and greenish-gray (5G 6/1) silicified claystone, several light 

gray (A77) dense lenticular limestone units; weathers to pastel 

green and pink; forms earthy to frothy slope._________________ 58.3

Sandstone, light greenish-gray (5(r'F 8/1) to yellowish-gray (5F 8/1), 

fine-grained, subangular, well-sorted, grains of clear quartz with 

common orange, green, and black accessory grains; massive, forms 

resistant ledge, is locally highly lenticular___________________ 2.4
324 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Brushy Basin member (part) Continued F&* 

Claystone, light greenish-gray (5G 8/1) to light-gray (NT) with minor 

pale reddish-brown (1QR 5/4) and pale yellowish-brown (WYR 

4/2) at top, silty to very fine grained sandy; weathers to earthy 

light greenish-gray slope with a few pale reddish-brown bands at 

top; one 6-inch lens of pale reddish-brown silicified clay stone or 

limestone near top_________________________________________ 42.1

Total measured Brushy Basin member.__________________ 105.3

Total Brushy Basin member 2 _______________________ 180.0

Westwater Canyon member:

Sandstone, light olive-gray (5F5/2) to yellowish-gray (5F8/1) to light 

greenish-gray (5GF 8/1), very fine-grained at top and coarsegrained at bottom, predominantly medium-grained, subangular 

to subrounded, grains of clear quartz with rare orange and black 

accessory grains; medium-scale cross laminated, scour bedding.

NOTE. Top four Westwater sandstone units appear transitional to

Brushy Basin member..____________________________________ 22.5

Claystone, pale grayish-yellow (5F9/4) to pale greenish-gray (5G 6/1),

slightly silty to medium-grained sandy; weathers to earthy slope_ 5.4

Sandstone, grayish-orange (10 YR 7/4) to yellowish-gray (5F 8/1), 

very fine-grained to medium-grained, subangular to rounded, 

poorly sorted, grains of clear quartz with rare orange and gray to 

black accessory grains; weakly cemented with streaks and bands 

of firm calcareous cement; medium-scale cross lamination indicated, scour bedding; forms ledgy slope._____________________ 31.8

Claystone, greenish-gray (5(7 F 6/1), silty to slightly fine-grained 

sandy; weathers to earthy sandy slope, abundant very light gray 

(NS) dense to very fine-grained limestone nodules on surface____ 8. 6

Sandstone, pale yellowish-orange (IOYR 8/6) to yellowish-gray 

(5F 8/1) to white, fine- to medium-grained, subangular to subrounded, moderately sorted, grains of clear quartz with uncommon orange and white accessory grains, locally has specks 

of unknown white cement; medium-scale cross-laminated, channeling; lateral to section contains thin lenses of greenish claystone-___________________________________________________ 85. 5

Claystone, grayish-red (10R 4/2) and light greenish-gray (5G 8/1)

with minor very fine- to fine-grained sandstone lenses._________ 2. 5

Sandstone, pale yellowish-orange (IOYR 8/6) to yellowish-gray 

(5F 8/1) to white (N9), fine- to medium-grained, subangular to 

subrounded, moderately sorted, grains of clear quartz with uncommon orange and white accessory grains, locally has specks 

of unknown white cement; medium-scale cross-laminated, channeling_______ ________________________________________ 15. 0

Total Westwater Canyon member__-_____-__-__-__------ 171. 3

2 Measured by E. H. Baltz, Jr., oral communication.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 325

Recapture member: Feet

Claystone, and sandstone (20 percent). Claystone, very dusky red 

(10/2 2/2), silty to slightly fine-grained sandy, structure partly 

masked, some thin irregular parallel beds; sandstone, light 

greenish-gray (5GY 8/1) to yellowish-gray (5F 8/1), fine-grained, 

subaflgul«r; moderately to poorly sorted, some interstitial clay, 

grains of clear quartz with uncommon orange and black and 

minor green accessory grains; in structureless beds 6 inches to 

3.5 feet thick;unit forms steep earthy slopes except under overlying cliff where it stands vertical___________________________ 25. 5

Sandstone and claystone, grayish-orange pink (WR 8/2) and very 

minor greenish-gray (5GY 6/1), fine- to medium-grained, subangular to rounded, moderately sorted, grains of clear quartz 

with abundant orange and black and rare green accessory grains; 

medium-scale cross-lamination is indistinct; claystone, very 

dusky red (WR 2/2) to grayish-red (WR 4/2), silty to slightly 

sandy, structureless to thin parallel bedded; unit weathers to 

steep ledgy slope of white and yellowish gray with grayish-red 

bands______________________________________________ 94. 0

Sandstone, and claystone (25 percent). Sandstone, grayish-orange pink 

(IOR 8/2), very fine- to medium-grained, moderately sorted, 

subangular to subrounded, grains of clear quartz with common 

black and orange accessory grains; several biotite flakes noted; 

medium-scale cross-laminations indistinct, local channeling; claystone, very dusky red (WR 2/2) to grayish-red (WR 4/2), very 

slightly sandy up to fine-grained, finely micaceous, contains 

some thin sandstone beds, light greenish-gray (5GY 8/1) to 

grayish-red (WR 4/2), very fine- to fine-grained, subangular, 

moderately sorted, grains of clear quartz with abundant orange 

and black accessory grains; structureless; unit as whole weathers 

to pale-red and grayish-red ledgy slope_______________________ 96. 5

Sandstone, white to moderate orange-pink (5YR 8/4), very fine- to 

medium-grained, moderately sorted, subangular to subrounded, 

grains of clear quartz with abundant orange and common black 

and rare green accessory grains; medium-scale cross-laminations 

indicated; unit weathers to sandy ledgy slope_________________ 13. 4

Claystone, very dusky red (WR 2/2), grayish-purple (5P 4/2) and 

grayish-red (WR 4/2); very fine- to medium-grained sandy; 

sandstone, light greenish-gray (5G 8/1) mottled grayish-red 

(5ft 4/2), very fine- to fine-grained, rare medium grains, interstitial clay common, moderately to poorly sorted, subangular 

to rounded, grains of clear quartz with common orange, red, and 

black accessory grains; unit weathers to steep earthy slope____ 47. 0

Total Recapture member_____________________________ 276. 4

Summerville formation (part):

Claystone and sandstone. Claystone, dark reddish-brown (WR 3/4) 

to pale reddish-brown, (10K5/4) pure to very sandy, very fine- to 

fine-grained, earthy weathering; sandstone, pale reddish-brown 

(10.B 5/4) to grayish-orange pink (WR 8/2), very fine- to finegrained, moderately sorted, subangular, weak to firm calcareous 

cement, grains of clear quartz with common black and orange 

accessory grains; units weathers to earthy slope_____._Not measured

Base of section.
326 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

McKINLEY COUNTY

Haystack Butte section, sec. 13, T. 13 N., E. 11 W. 

[Measured by L. S. Hilpert and V. L. Freeman, August 1954],

Top of measured section.

Dakota sandstone (part): Feet

Sandstone, light reddish-orange (1QR 7/6), medium-grained, wellsorted, subrounded, grains of quartz with some white chert 

grains; friable, quartz overgrowths___________---_----_--_--__ 40. 0

Shale, carbonaceous. Some interbedded clayey sandstone, grayish-red

(5R 4/2), medium-grained, poorly sorted, angular to subrounded-. 17. 8 

Morrison formation: 

Brushy Basin member:

Poorly exposed. Local outcrop of claystone, silty and sandy, light 

greenish-gray (5GY 8/1); and sandstone, pale yellowish-brown 

(IQYR 6/2), medium-grained, poorly sorted, subangular to subrounded, grains of quartz with red and white accessory grains; 

friable, calcareous cement and specks of white unknown cement. _ 67. 2

Sandstone, slightly conglomeratic, pale yellowish-brown (IQYR 6/2) 

with local greenish-gray (5GY 6/1), medium- to coarse-grained, 

poorly sorted, subangular to subrounded, grains of quartz with 

red and white accessory grains, granules and pebbles (% inch); 

friable, calcareous cement and specks of unknown white cement; 

crossbedding is medium scale and low angle filling shallow erosional troughs_______-______--___--_---__--_--_------------ 2. 7

Claystone, silty and sandy., very dusky red (IQR 2/2) and greenishgray (5GF6/1)_.______._____________________ 9.6

Sandstone, like second unit below_______________________________ 23. 2

Sandstone (at base) and claystone, silty. Sandstone, very pale orange 

(WYR 8/2), fine-grained, poorly sorted, subrounded, grains of 

quartz with orange, black, and white accessory grains, possibly 

some silica cement; claystone, dusky red (1QR 3/2) ________ 6. 0

Sandstone, pale yellowish-brown (IQYR 6/2), very coarse-grained at 

base grading upward to medium-grained at top, poorly sorted, 

subangular to subrounded, grains of quartz with red and white 

accessory grains; very friable, calcareous near base, specks (1 to 

3 mm across) of unknown white cement scattered throughout; 

crossbedding is medium scale and low angle filling shallow erosional troughs________________._________-_____-_---___-_-__- 18. 1

Claystone, silty, pale reddish-brown (IQR 5/4), mottled with yellowish

gray (5F 8/l).__......_.......__ _ . 24.5

Total Brushy Basin member________-__---------_--____- 151. 3

Westwater Canyon member:

Sandstone, grayish-red (IQR 5/2) to light-brown (5YR 7/4) in lower 

part and grayish-orange (IQYR 7/2) with some limonite stain near 

top, poorly sorted, subrounded to rounded, grains of quartz with 

white, black, and orange accessory grains; locally calcareous in 

lower part; crossbedding is large scale and low angle filling shallow 

erosional troughs; mud pods and partings near base; this unit 

forms a prominent cliff_______________._____________________ 106. 0

Total Westwater Canyon member_____________--____-___ 106. 0
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 327

Recapture member: &*&

Sandstone, very clayey, dark reddish-brown (IOR 3/4) and light 

greenish-gray (5GY 8/1), fine-grained, poorly sorted with some 

coarse grains, subrounded, grains of quartz with orange, red, and 

black accessory grains; very calcareous near middle.___________ 2. 5

Sandstone, yellowish-gray (5F 8/1) and light olive-gray (5F 6/1), finegrained, well-sorted, subrounded, grains of quartz with orange and 

black accessory grains; slightly calcareous, locally clayey; bedding 

obscure_________________________________________________ 5. 5

Sandstone, very clayey, dark reddish-brown (IOR 3/4) to grayishred (5R 5/2) with interbeds of pale olive (10Y 6/2) near top, 

medium-grained, poorly sorted, subrounded, grains of quartz 

with orange and black accessory grains; calcareous with nodules 

near top_---_-_---_--__-________________-_-_-_______-_-_ 18. 0

Sandstone, very light greenish-gray (5GY 9/1) to light pinkish-gray 

(5YR 9/1), fine- to medium-grained, poorly sorted, subrounded, 

grains of quartz with orange accessory grains; fria,ble, calcareous; 

bedding obscure_________________________________________ 11. 2

Sandstone, very clayey, dark, reddish-brown (10 R 3/4), fine-grained,

poorly sorted, subrounded__________________________________ 10. 3

Sandstone, light yellowish-gray (5F 9/1), medium- to coarse-grained, 

moderately sorted, subrounded to rounded, grains of quartz 

with white, orange, and black accessory grains; friable, slightly 

calcareous; at base are granules and pebbles ()_ inch) of red, black, 

and green chert; bedding mostly obscure, some crossbedding is 

medium scale, low angle, and some is straight in tabular sets____ 5. 9

Sandstone (75 percent) and claystone, sandy. Sandstone, yellowishgray (5F 8/1) and pinkish-gray (5YR 8/1), fine-grained, moderately sorted, rounded, grains of quartz with orange and black 

accessory grains, locally green clay pods in sandstone at base, 

locally calcareous; claystone, pale yellowish-green (10(?F 7/2) 

with mottling of dark reddish-brown (IOR 3/4)________________ 15. 7

Claystone, sandy, like second unit below, contains some thin sandstone beds near top______-_________________-____--___-_---_ 6. 9

Sandstone, light yellowish-gray (5F 9/1), medium-grained, moderately 

sorted, subrounded, grains of quartz with orange, red, and black 

accessory grains; very friable, calcareous especially near top and 

base; rare scattered pebbles near base; bedding obscure__-_____ 5. 8

Claystone, sandy, mottled dark grayish-red (IOR 3/2) and greenishgray (5GY 7/1), calcareous. Near middle of unit is 8-inch bed 

of sandstone, greenish-gray (5GF 7/1), very fine grained; friable, 

calcareous; thin parallel laminations-___________________-_---- 7. 0

Sandstone, pale-red (IOR 6/2) and pinkish-gray (SYR 8/1), mediumgrained with scattered granules and pebbles (1 inch) locally 

concentrated along laminae; moderately to poorly sorted, 

rounded; grains of quartz with orange, red, black, and green accessory grains; very friable, calcareous; claystone parting about 

7>_ feet above base; bedding mostly parallel but near base is crossbedding of medium to large scale and low angle that fills shallow 

erosional troughs____________________________-____-__-----__44.4

Total Recapture member______________________________ 133. 2

Total Morrison formation______________________________ 390.5
328 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Bluff sandstone: Feet 

Sandstone, moderate orange-pink (10/2 7/4) to light-brown (5YR 7/4), 

fine-grained, well-sorted, subrounded, grains of quartz with 

orange accessory grains; friable, calcareous; crossbedding is 

large scale and low angle in tabular sets; forms nearly vertical 

cliff________________________________.______________ Not measured

Base of section.

BERNALILLO COUNTY

North of Canoncito section, EH sec. 34, T. 11 N., R. 3 W. 

[Measured by V. L. Freeman, October 1954]

Top of section. 

Dakota sandstone:

Not measured or described. 

Morrison formation:

Brushy Basin member: Feet 

Claystone, sandy, light greenish-gray (56? 8/1), minor amounts of 

sandstone and limy nodules, forms frothy surface. Poorly exposed, especially near top__________________________ ____ 176.0

Sandstone, yellowish-gray (5F 8/1), medium-grained, moderately 

sorted, subrounded, grains of clay coated quartz with orange, 

black, and white accessory grains, quartz, clay, and calcite 

cement; bedding indistinct but in part is crossbedded on medium 

scale_____________________________________________________ 11. 7

Claystone, sandy, and sandstone, clayey, yellowish-gray (5F 8/1) to 

light brownish-gray (5FR 6/1) with minor greenish tint; some 

limy nodules and chert; forms slightly frothy surface.___________ 52. 6

Total Brushy Basin member__-__--___------_----------- 240. 3

Gradational contact

Recapture member (probably includes equivalents to Westwater Canyon 

member):

Sandstone, partly clayey, yellowish-gray (5F 8/1) with limonite stains 

near base, fine- to medium-grained, moderately sorted; friable, 

calcareous especially near base; bedding not visible____________ 14. 5

Claystone, very sandy (to medium-grained), grayish-red (IQR 4/2), 

calcareous. Unit contains one thin hard green sandstone bed; 

forms slightly frothy surface______---_-------------------__- 24. 2

Sandstone, moderate orange-pink (5YR 8/4) to yellowish-gray (5F 

8/1), medium-grained, poorly sorted, rounded, grains of quartz 

with uncommon black and orange accessory grains; friable, calcareous cement and uncommon specks of unknown white cement; 

crossbedding is small to medium scale________---_-------_--_- 10. 1

Claystone, very sandy and sandstone, clayey; grayish-red (WR 4/2), 

calcareous; sandstone in thin irregular beds totaling about half of 

unit_____________________________________________--- 20.0

Sandstone, yellowish-gray (5F 8/1), medium-grained, moderately 

sorted, rounded, grains of quartz with common black, orange, 

red, and white accessory grains; alternating hard and friable 

zones, calcite cement; bedding not visible.____________________ 5. 4

Claystone, very sandy, like second unit below_____________---___-- 10. 5
'STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 329

Recapture member Continued Feet 

Sandstone, yellowish-gray (5Y 8/1), fine-grained, poorly sorted, 

rounded, grains of quartz with uncommon orange, red, black, 

and white accessory grains; slightly friable, calcareous; structureless; common limonite staining. Unit grades into unit above. __ 18. 0 

Claystone, very sandy (to medium-grained), grayish-red (IQR 4/2), calcareous, several irregular thin beds of sandstone.______________ 12. 6

Total Reqapture member and probable equivalents of Westwater Canyon member_____________-_________----_- 115. 3

Total Morrison formation________-..-______------------_ 355.6

Bluff sandstone (part):

Sandstone, grayish-yellow (5F7/4), fine-grained, well-sorted, rounded, 

grains of quartz with black, white, and orange accessory grains; 

friable; bedding indistinct but in part is extremely large-scale 

crossbedding____________________________________ Not measured

Base of section.

Red Bluff section, WJ4 sec. 3, T. 12 N., R. 9 W.

[Measured by V. L. Freeman and L. S. Hilpert, August 1954]

Top of measured section.

Dakota sandstone (part): *"«* 

Sandstone, very pale orange (10 YR 8/2), to dark yellowish-orange 

(10FR 6/6), the yellow coloring caused by limonite staining generally along bedding, .medium-grained, poorly sorted with local 

scattered granules and pebbles of red and black chert and vein 

quartz, subangular to rounded, grains of quartz with rare chert 

and white accessory grains; abundant quartz overgrowths; parallel bedded with some tabular crossbedding __________________ 49. 0

Morrison formation: 

Brushy Basin member:

Claystone and sandstone, clayey, poorly exposed; greenish-gray 

(5(rF 6/1) at base and pale-olive (10F 6/2); local calcareous thinbedded sandstone lenses, greenish-gray (5GY 6/1), fine-grained-- 88. 0 

Sandstone, pale yellowish-brown (10FR 7/2), medium- to coarsegrained, poorly sorted with local granules and small pebbles, 

subangular to rounded, grains of quartz with uncommon orange 

and black accessory grains; crystal calcite cement at top and 

specks of unknown white cement throughout; cross-laminatiojos 

are medium scale and low angle filling shallow erosion troughs. _ 14. 4 

Mostly covered; some clay stone, yellowish-gray (5F 8/1) and light 

greenish-gray (5GY 8/1), free of sand grains, some limy nodules, 

some seams of gypsum_____________________________-_--_-_- 42. 6

Sandstone, yellowish-gray (5F 8/1), medium-grained, poorly sorted, 

rounded, grains of quartz with white, black, green, and orange 

accessory grains; friable, calcareous; forms surface coated by 

small nodules____________________________________________ 4. 0

Claystone, slightly sandy, grayish-yellow green (5<?F 7/2) and light

grayish-red (WR 5/2) in lower part, common limy nodules____ 10. 6
330 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM ;

Westwater Canyon member: . Fe$ 

Sandstone, grayish-orange (10YR 7/4) with widespread limonite 

specks, medium- to coarse-grained, moderately to poorly sorted 

with scattered granules, subrounded, grains of quartz with 

common white (kaolin?) and rare black (chert?) accessory grains; 

friable, local crystal calcite cement; cross laminations are medium 

scale and low angle between planar erosion surfaces. Locally 

claystone, pale yellowish-green (1QGY 7/2) occurs near the base 

in irregular pods_________________________________________ 62. 2

Total Westwater Canyon member_____________ _______ 62. 2

Recapture member:

Sandstone, clayey, and some claystone, sandy, dusky red-purple 

(5.2P3/2) and greenish-gray (56? F 6/1), sandstone is fine grained, 

claystone locally contains limy nodules; unit forms mostly 

covered slope_-___-___________-___-_-__------_-_-----____- 25. 9

Sandstone, light yellowish-gray (5F9/1), fine- to coarse-grained, local 

conglomeratic lenses with pebbles dominantly of chert, moderately to poorly sorted, subrounded, grains of quartz with white, 

orange, and black accessory grains; crystal calcite cement; crossbedding filling scours_______________-_----_--___ _________ 7. 4

Sandstone, clayey, and claystone, sandy. Claystone mostly light

greenish-gray (56?F 8/1) and brownish-gray (5YR 4/1) with some , ' *

grayish-red purple (5RP 4/2) and dusky yellow (5 Y 6/4); sandstone

is fine grained and poorly sorted; local limy nodules_______ , 3. 0

Sandstone, light yellowish-gray (5F 9/1), medium-grained, poorly 

sorted, rounded, grains of quartz with white and orange accessory 

grains, scattered granules and green clay chips; friable, locally 

calcareous; bedding obscure; weathers to rounded ledge_______ 9. 0

Sandstone, clayey, very dusky red purple (5RP 2/2), very fine- to 

fine-grained, moderately sorted, grains of quartz with black and 

orange accessory grains; local small limy nodules. Unit contains 

local thin beds of sandstone, greenish-gray (1Q6?F 5/2); hard, 

clay cement___-_________________-_______________________ 7. 5

Sandstone, light yellowish-gray (5F 9/1) and very light greenish gray 

(5(r F 9/1), fine- to medium-grained, poorly sorted, subrounded, 

grains of quartz with white, orange, red, green, and black accessory grains; friable; crossbedding is small to medium scale and 

low angle in tabular sets between planar erosion surfaces______ 8. 5

Sandstone, lenticular with thin irregular lenses and pods of claystone; 

claystone, dark reddish-brown (10/2 3/4) mottled light greenishgray (56?F 8/1); sandstone, light pinkish-gray (SYR 9/1), mediumto coarse-grained with scattered granules, poorly sorted, subrounded to rounded, grains of quartz with orange and black 

accessory grains; friable, calcareous; crossbedding is small scale 

and low angle in wedge-shaped sets___._-_________________-_ . 3. 9

Sandstone, light pinkish-gray (5FJ? 9/1), medium- to coarse-grained 

with rare granules, poorly sorted, subrounded to rounded, grains 

of quartz and chert with white and orange accessory grains; friable; in part is parallel bedded and in part is crossbedded, medium 

scale, low angle. This unit fills a channel in underlying unit that 

is 2 to 4 feet deep and about 20 feet wide___________________ 11. 0
(STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 331

Recapture member Continued feet 

Sandstone, slightly clayey, greenish-gray (5GF6/1), medium-grained, 

moderately sorted, rounded, grains of quartz with uncommon 

orange and red and rare black accessory grains; forms slope. ____ 1. 3

' Claystone, slightly silty, very dusky red (10R 2/3); some limy nodules

and gypsum; forms rounded slope._--_______-__^____________ 4. 3

Sandstone, slightly clayey, pale olive (10 Y 6/2) with some limonite 

stains, fine- to medium-grained, moderately sorted, rounded, 

grains of quartz plus common orange and rare black accessory 

grains; very friable; forms slope. Unit appears gradational 

with Bluff sandstone_____________________________________ 8. 8

Total Recapture member_____________-____________ 90. 6

Total Morrison formation._____________________________ 312. 4

Bluff sandstone (part):

Sandstone, grayish-yellow (5F 8/4), fine- to medium-grained; very 

friable, calcareous concretions locally present; cross-laminations 

are medium to large scale and high angle in wedge-shaped sets. _ Not

measured 

Base of section.

VALENCIA COUNTY

Sheep Camp section, S}_ sec. 2, T. 8 N., R. 6 W.

[Measured by V. L. Freeman, September 1954] 

Top of measured section. 

Dakota sandstone (part): Feet

Sandstone, like basal Dakota unit, two silicified 6-inch bands, also a few

very thin carbonaceous claystone partings___________________ 15. 0

Claystone, carbonaceous, sandy. Along strike, unit becomes sandstone h'ke below with very thin partings of carbonaceous claystone. Unit forms reentrant in cliff_________________________ 1.0

Sandstone, light-yellow (5F 8/6), medium-grained, poorly sorted, 

granules common, rounded, grains of clay-coated quartz with 

white (chert?) accessory grains; one 6-inch band is highly silicified 

and white; very thin crossbedding is medium scale and low angle. 

Plant remains present. ___________l_________________________ 4. 9

Morrison formation:

Claystone, slightly fine-grained sandy, pale-olive (10F6/2) and minor

grayish-red purple; forms slightly frothy surface.______________ 43. 5

Sandstone, white (NQ), medium-grained, well to moderately sorted, 

subrounded, grains of quartz with orange and white accessory 

grains; slightly friable, calcareous cement; indistinct crossbedding 

is medium scale and low angle_____________________________ 6. 0

Claystone, like second unit below with two thin beds of sandstone,

like below, that total 3 feet_______________________ 25. 7

Sandstone, white (JV9), medium-grained, well to moderately sorted, 

subrounded, grains of quartz with orange and white accessory 

grains; slightly friable, calcareous cement; indistinct crossbedding 

is medium scale and low angle______-_-_-___-___-_------___- 4. 6

Claystone, slightly fine-grained sandy, pale-olive (10 F 6/2) and minor

grayish-red purple (5RP 4/2); forms slightly frothy surface____ 13.0
332 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Morrison formation Continued ***

Sandstone, very light greenish gray (5GY 8/1), fine- to mediumgrained, well- to, .moderately sorted, subrounded, grains of quartz 

with orange and white accessory grains; slightly friable, calcareous 

cement; crossbedding is medium scale and low angle. Uncommon 

limy nodules. Unit is lenticular and interfingers with unit above. 8. 5

Sandstone, clayey, very dusky red (between 5RP 2/2 and 10R 2/2) and 

light greenish-gray (5GY 8/1) in about equal amounts in alternating bands, medium-grained, moderately sorted, subrounded, 

grains of quartz and rare orange accessory grains; hard when 

fresh; unit forms soft slope. Laterally unit contains lens like 

unit above________________________________________________ 16. 8

Sandstone, clayey, dark reddish-brown (WR 3/5), fine-grained, 

moderately sorted, subrounded, grains of stained quartz with 

rare black accessory grains; hard when fresh; unit forms soft 

slope. Unit grades into Bluff sandstone and locally interfingers 

with Bluff...__________________________--______ 3. 7

NOTE. Lower two units of Morrison probably are equivalent to Recapture member and remainder probably equivalent to Brushy 

Basin member___________________________________________ ____

Total Morrison formation._____________________________ 121. 8

Bluff sandstone (part):

Sandstone, light greenish-yellow (WY 7/2) slightly h'ghter near top, 

medium- and fine-grained in gradationally alternating 6-inch 

beds, well sorted to moderately sorted, subrounded to rounded, 

grains of green clay coated quartz with common white chert and rare 

orange accessory grains; friable, zones of heavy h'monite cement. 

Poorly defined parallel bedding underlain by crossbedding of 

extremely large scale and low angle__________________ Not measured

Base of section.

VALENCIA COUNTY 

West Mesa Gigante section (composite) 

[Measured by V. L. Freeman, September, October 1954]

Section A., sec. 10, T. 10 N., R. 4 W. 

Top of section.

Dakota sandstone: &#& 

Not measured. Sandstone, conglomeratic, with minor carbonaceous

shale. Siliceous cement. 

Morrison formation: 

Brushy Basin member:

Sandstone, yellowish-gray (5F 8/1) to white (JV9), medium-grained, 

well to poorly sorted, subrounded to subangular, grains of clay 

coated quartz with rare pink and black accessory grains, green 

clay chips locally abundant but usually rare; friable, some calcareous cement and specks of white unknown cement; crossbedding is medium scale and low angle filling shallow erosion 

troughs. This is the Jackpile ore-bearing bed________________ 90. 9

Claystone, silty, and siltstone, clayey, light greenish-gray (5GY 8/1) 

and minor grayish-red (1QR 4/2), limy nodules common. Near 

top is 2-foot bed of sandstone, clayey, light grayish-green 

(5GF6/2)______________________________________________ 105.7
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 333

Brushy Basin member Continued Fe&

Sandstone, yellowish-gray (5F 8/1), medium-grained, poorly sorted, 

subrounded to subangular, grains of clay coated quartz with 

orange, red, black, and rare green accessory grains; granules 

and pebbles 04 inch) scattered in sandstone, include feldspar; 

crossbedding is medium scale and low angle, filling shallow 

erosion troughs____________________________________-______ 20.0

Claystone, silty; siltstone and very fine sandstone, both very clayey; 

all light greenish gray (5G 8/1), some hard calcareous beds, 

weathers to frothy surface__________________________________ 71. 7

Sandstone, very pale orange (10 YR 8/2) to dark yellowish-brown 

(10 YR 3/4), medium-grained, moderately sorted, grains of quartz 

with green, orange, red, and black accessory grains; hard; crossbedding is medium scale and low angle. Three beds with clay 

chips at base of each_______________________________________ 3. 0

Siltstone and very fine sandstone; both clayey, pinkish-gray (5YR 8/1) 

and light greenish-gray (5GY 8/1), calcareous; also claystone, 

silty, light greenish-gray (5GY 8/1) and minor pale-purple 

(5P 6/2), hard, calcareous; some units weather to frothy surface- 81. 2

Total Brushy Basin member__________________________ 372. 5

Section B, SW}i sec. 23, T. 10 N., R. 4 W.

Morrison formation Continued 

Westwater Canyon member:

Sandstone, very pale orange (10 YR 8/2) to dusky yellow (5F 6/4), 

medium- to coarse-grained, poorly to moderately sorted, subrounded to angular, grains of quartz and feldspar (angular and 

as much as granules in size) with common red and white (chert?) 

accessory grains; some beds clayey; friable except for local 

crystal calcite cement. Indistinct crossbedding______________ 31. 1

Sandstone, like purple part of third unit below________________^___ 1. 5

Sandstone (75 percent) and claystone with limy nodules (25). Sandstone, very pale orange (10 YR 8/2), medium- to coarse-grained, 

moderately sorted, rounded to subrounded, grains of quartz and 

feldspar wath common red and white and uncommon green and 

gray accessory grains; friable, calcareous, locally crystal calcite 

cement; crossbedding is small to medium scale, low angle, lenticular type; claystone like below but pale purple (5P 7/2) and with 

large (1 foot) nodules that form bed_______--___________-__ 19. 5

Total Westwater Canyon member__________£_________ _ 52. 1

Note. On section A where base is not exposed, the incomplete Westwater Canyon is 62 feet thick. 

Recapture member:

Claystone, slightly fine-grained sandy, light greenish-gray (5G 8/1) 

with purplish tints locally, limy nodular beds total 2.0 feet. 

Claystone is slightly calcareous______________________________ 8. 3

Sandstone, very clayey, pale yellowish-green (10GY 7/2) in middle 

third, rest is grayish red-purple (5RP 4/2). Medium-grained, 

poorly sorted, rounded, grains of quartz with common orange 

and red and rare black and white accessory grains. Purple part 

is calcareous. Bedding obscure_____________________________ 5.8
334 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Recapture member Continued Feet 

Claystone, very sandy (fine-grained) (50 percent) and sandstone (50 percent). Claystone, reddish-brown (10R 4/4), slightly calcareous but not 

containing limy nodules here; sandstone, yellowish gray, mediumgrained, moderately sorted, rounded, grains of quartz with 

uncommon orange, black, and red accessory grains; bedding 

obscure. Sandstone and Claystone thickly (2 to 3 feet) interbedded. Claystone beds weather to slightly frothy surface- __ 31. &

Total Recapture member_____________________________ 45. 7

Total Morrison formation______________________________ 470. 3

Bluff sandstone (part):

Sandstone, grayish-yellow (5Y 8/4) to moderate yellow (5Y 7/6), 

medium-grained, well to moderately sorted, rounded grains of 

quartz with black, orange, and white accessory grains; friable, 

local crystal calcite cement. Crossbedding is large scale and 

poorly defined_____________________________________ Not measured

Base of section.

o


Uranium Deposits in 

Oolitic Limestone Near 

Mayoworth, Johnson 

County, Wyoming

By R. R. GUILINGER and P. K. THEOBALD

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-K

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of the 

Commission.

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 15 cents (paper cover)
CONTENTS

	Page 

Abstract________________________________________________________ 335

Introduction._____________________________________________________ 335

Stratigraphy. ___-__--__-__--___-_____-_____-_-______-___-__.-___-_ 335

Structure__-___-_---_----_-___--_--_______---__-_-__--__-_--_-__-_ 338

Uranium deposits______--__-_______________--____-___---____-__-_-_ 340

i. *: Mineralogy and mode of emplacement._--_________--____--_----_ 340

Economic potential.___________________________________________ 342

Literature cited- ___________-_________________-______--__-_---_.-... 342

ILLUSTRATIONS

FIGURE 62. Map showing distribution of radioactive localities in the Sundance formation near Mayoworth,____________-_---___-_ 336

63. Photomicrograph of limestone showing radial and concentric

oolite growth...______________________________________ 337

64. Photomicrograph of limestone showing a metatyuyamunitefilled fracture ---_-------------_-__--_--_--_-------- 338

65. Map showing lithologic units and structure of part of the Sundance formation near Mayo worth-__ ____________________ 339

66. Photomicrograph of limestone showing opaque uranium(?)

mineral veining an oolite_____________________________ 341

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIUM DEPOSITS IN OOLITIC LIMESTONE NEAR 

MAYOWORTH, JOHNSON COUNTY, WYOMING

By R. R. GUILINGEE and P. K. THEOBALD

ABSTRACT

The uranium deposits of the Mayoworth area, Johnson County, Wyo., are in 

oolitic limestone at the base of the Sundance formation of Late Jurassic age. The 

uranium mineral has been identified as metatyuyamunite, a hydrous calcium 

uranium vanadate that coats joints and fractures and replaces calcite in both the 

cement and the oolites. In the largest area of measured radioactivity, the 

deposits are coatings on joint surfaces, but in the other areas, replacement of 

oolites and cement is most common. Some of the uranium may be syngenetic. 

Secondary metatyuyamunite has been concentrated along ground water channels. 

The uranium content ranges from 0.017 to 0.32 percent and the V2Os content 

ranges from 0.06 to 0.17 percent. The known deposits of the area are of sub-ore 

grade and are not of economic importance at this time.

INTRODUCTION

The uranium deposits of the Mayoworth area are 2.2 miles south of 

the abandoned postoffice at Mayoworth, Johnson County, Wyo. 

The area is accessible by a dirt road from Mayoworth, which is reached 

by a paved secondary road from U. S. Highway 87 at Kaycee.

The stratigraphy and structure of the area surrounding the uranium 

deposits have been mapped and described by Richardson 1 and the 

general area to the north by Hose (1954). Love (1954) described the 

uranium deposits of the Mayoworth area.

To evaluate the economic potential and to study controls of deposition of the uranium, the writers examined the deposits in August 

1954 and mapped the area by plane table methods in September 1954. 

This work was done by the U. S. Geological Survey on behalf of the 

Division of Raw Materials of the U. S. Atomic Energy Commission.

STRATIGRAPHY

Sedimentary rocks of Triassic and Jurassic age are exposed in the 

immediate vicinity of the Mayoworth uranium deposits. The Chugwater formation of Triassic age is composed of massive red sandstones

1 Richardson, A. L., 1950, Geology of the Mayoworth region, Johnson County, Wyoming: Univ. of 

Wyoming, M. A. thesis, unpub.

405342V 57 335
336 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

and shales. The Sundance formation of Late Jurassic age unconformably overlies the Chugwater formation. In the mapped area 

(fig. 1), the Sundance formation is divided into three units. The 

basal unit, in which the uranium deposits occur, is a gray oolitic

EXPLANATION

lugwater formation

Contact 

Dashed where indefinite

: /2

Strike and dip of beds

Strike and dip of joints

t »o

Strike of vertical joints

Radioactivity greater 

than 0.05 mr per hr

500 Feet

Contour interval 20 feet

Geology and base by P. K. Theobald. 1954

FIGURE 62. Map showing distribution of radioactive localities in the Sundance formation near Mayoworth,

Johnson County, Wyo.
URANIUM DEPOSITS IN OOLITIC LIMESTONE 337

limestone, 8 to 10 feet thick. Conformably overlying the limestone 

is 30 feet of soft gray fossiliferous shale, and directly overlying the 

shale is white to buff sandstone. Isolated patches of gravel of late 

Cenozoic age uncomformably overlie both the Triassic and Jurassic 

rocks.

The limestone of the Sundance formation is composed of oolites 

formed primarily around elongate cores of colorless calcite. The 

oolites are generally uniform in size, averaging about 0.5 mm in 

diameter but ranging from 0.1 mm to 2 mm in diameter. They tend 

to follow the form of the cores, with elongated shapes predominant. 

Radial and concentric growth is evident around the cores, and in 

many oolites both kinds occur (fig. 63). Where both forms of growth

FIGURE 63. Photomicrograph of limestone near Mayoworth, Wyo., showing radial and concentric 

oolite growth. Crossed nicols. X100.

are present in a single oolite, the radial growth is on the inside, surrounded by the concentric rings and separated from the concentric 

rings by a thin layer of clay. This suggests two stages and two 

processes of oolite formation with a slight interruption between the 

stages. Another interruption in the oolite formation is suggested by 

some corrosion and clay accumulation on a concentric ring at about 

the same position in several oolites.

Though most of the cores consist of colorless calcite, there are other 

kinds. Of these, fossils are the most common. They include small 

pelecypod shells, Foraminifera(?), or shell fragments. Opaque black 

minerals form the cores of some oolites. Most of these black minerals 

are hematite or goethite, but some have not been positively identified. 

The cores of some oolites are quartz grains, but grains of this mineral
338 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

are generally larger and occur as clastic grains free of oolite forming 

calcite.

The oolites are imbedded in a cement of colorless coarsely crystalline 

calcite. At the time of cementation some solution of the oolites 

occurred, and their outer edges appear corroded and partly replaced 

by the cementing calcite. Later solutions, apparently moving along 

the interfaces between the cement and the oolites, introduced iron 

oxide that replaced both the cement and oolites. In some places the 

cement is completely replaced by iron oxide, and an unidentified 

green mineral replaces the edges of some oolites. In places finely 

divided iron oxide gives a reddish color to the oolites and cement. 

Hematite and metatyuyamunite have filled fractures that cut both 

the cement and oolites (fig. 64).

FIGURE 64. Photomicrograph of limestone near Mayo\vorth, Wyo., showing a rr.etatyuyamunite-fllled

fracture. X100.

STRUCTURE

The Mayoworth area is on the southeast flank ol the Bighorn arch. 

The sedimentary rocks in the Mayoworth area are separated from 

Precambrian crystalline rocks to the north by a northwest-trending 

thrust fault about 6 miles north of the mapped area. South of this 

thrust fault, the east limb of the major arch is warped into smaller 

anticlines and synclines. The uranium-bearing limestone is exposed 

on the east limb ol an anticline that forms the eastern limit of exposure 

of the minor folds.

The structure in the vicinity of the uranium occurrences is shown 

on figure 65. The strike of the Chug water formation and the sandstone of the Sundance formation is uniform. The Chugwater forma-
URANIUM DEPOSITS IN OOLITIC LIMESTONE 339

r /-v'7 x7 ^*£" ,</(H'i Jsh

Geology and base by P. K. Theobald, 1954

FIGURE 65. Map showing lithclogic units and structure of part of the Sundance formation near Mayoworth,

Johnson County. Wyo.

tion has an average strike of N. 23° W., and an average dip of 15° 

NE.; the sandstone unit of the Sundance formation has an average 

strike of N. 28° W., and an average dip of 14° NE. The structure 

of the oolitic limestone is complex; bedding planes are warped, and 

there is some crossbedding. The erratic strike and dip symbols on 

figure 63 reflect these features.
340 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Three sets of joints are conspicuous in the limestone; one is essentially parallel to bedding and strikes from N. 15 to 20° W., and two 

are vertical with strikes of N. 70° E. and N. 30° W. (fig. 62). The 

joints probably were formed during the Laramide orogeny. No 

faults were observed in the area mapped.

Metatyuyamunite, a hydrous calcium uranium vanadate, was 

identified by W. F. Outerbridge of the Geological Survey by X-ray 

methods in a selected sample of oolitic limestone. It occurs as 

coatings on joints and small fractures and as replacements of calcite 

in the cement and oolites. In zones of highest radioactivity, metatyuyamunite is prominent as joint coatings, particularly in the north 

half of the mapped area. The coatings are most conspicuous along 

joints striking N. 70° E. and N. 15° W.

In the less radioactive rocks, replacement was the most common 

mode of emplacement. Uranium-bearing solutions entered the 

limestone along small fractures, and replaced cement or oolites 

adjacent to the fractures. Where fractures are absent the solutions 

appear to have moved along the interfaces between crystals of the 

cement or more commonly between cement and oolites. In the latter, 

both cement- and oolite-forming calcite were replaced, but the ooliteforming calcite seems to be more susceptible to replacement. In 

several thin sections only the oolites or oolite cores were replaced 

but there is no evidence of channels through which replacing solutions 

could have entered. In one polished section an unidentified black 

mineral formed the core of the oolite. This black mineral has a 

dark-gray or black streak in contrast to the red and brown streak of 

the iron minerals. Immediately surrounding this black mineral is 

an orange alteration product, which is surrounded in turn by a 

concentration of a yellow uranium mineral. The black mineral may 

be a syngenetic primary uranium mineral, but it is too small to be 

positively identified. An autoradiograph of this polished section 

gave inconclusive results. The same polished section also showed a 

black mineral, with orange and yellow alteration halos, veining an 

oolite (fig. 66).

Association of the radioactive rocks with present water courses is 

evident from figure 62, suggesting some geomorphic control of the 

deposits. The relations of the Quaternary gravel shown at the north 

end of the map and similar occurrences at about the same altitude 

north of the mapped area suggest that the present trunk stream, 

which parallels the road shown at the north edge of figure 62, developed 

its course after the gravel was deposited. The small streams shown
URANIUM DEPOSITS IX OOLITIC LIMESTONE 341

FIGURE 66. Photomicrograph of limestone near Mayoworth showing opaque uranium (?) mineral veining

an oolite. X132.

on figure 62 are entrenched along their lower reaches. Along most of 

the stream that flows parallel to the strike along the contact of the 

limestone and shale there is no flood plain though there is a welldeveloped flood plain near its head in the south half of the map.

Anomalous radioactivity is confined to areas as high or higher than 

the Quaternary gravel and the patch of alluvium at the head of the 

strike valley. This suggests that at least some of the uranium concentration took place along the courses of mature streams as they 

entered the limestone at the two gaps in the flatirons shown on the 

west side of figure 62. Channels of flow would be northeast along 

the bedding-plane joints and the vertical joints parallel to the stream 

flow, and not along vertical northwest-striking joints perpendicular to 

the flow. Thus greater uranium concentrations should occur along 

the joints striking N. 70° E. and N. 15° W., as they do.

In the discussion of the uranium mineralogy it is suggested that 

some of the uranium minerals may be syngenetic. If this is true, 

syngenetic uranium could have been leached from the limestone up 

dip and reconcentrated as secondary metatyuyamimite along ground 

water channels such as joints and fractures in the limestone. Love 

(1954) suggests that solutions bearing uranium could have been 

derived from tuffaceous rock in the White River formation of Oligocene 

age, which may have covered this area. Also, streams entering the 

Mayoworth area could have derived uranium from known bodies of 

radioactive rocks higher in the Bighorn Mountains (Hose, 1954, and 

Jones, 1952).
342 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ECONOMIC POTENTIAL

About 20,000 square feet within the area mapped is more radioactive than 0.05 milliroentgens per hour (mr per hr). Maximum radioactivity is 2 mrperhr in the large mineralized zone in the north half 

of the area (fig. 62) where the background is 0.1 mrperhr. There are 

several areas of high radioactivity in the south half of the mapped 

area where a maximum radioactivity of 0.25 mrperhr was noted. The 

average background for the southern area is 0.025 mrperhr. Radioactive localities also occur in the limestone north and south of the 

area mapped.

Analyses of samples from the Mayoworth deposits indicate that 

the radioactivity ranges from 0.04 to 0.16 percent equivalent uranium 

(see table below). The uranium content ranges from 0.017 to 0.32 

percent. The V2O5 content ranges from 0.06 to 0.17 percent. The 

CaCO3 content of sample 214833 is 96.3 percent.

Analyses of samples from the Mayoworth area

Laboratory 

sample No.

D-97107 i

D-97108 i

RW-5132 2

214833 l

eU

(percent)

0. 16

.039

.040

U

(percent)

0. 21

.052

.32

.017

V2 05 

(percent)

0. 17

.06

. 10

Description of sample

Selected sample of

oolitic limestone.

Grab sample of

oolitic limestone.

Selected sample of

oolitic limestone.

Grab sample of

oolitic limestone.

Location

Radioactive deposit 500 feet

south of road.

Do.

Do.

Yz mile south of

mapped area.

1 Analysts: S. Furman, W. Mountjoy, J. Wilson, H. Lipp, J. Schuch, U. S. Geological Survey. 

Analyst: J. J. Warr, U. S. Geological Survey.

The known uranium deposits of the Mayoworth area are of sub-ore 

grade, and of small size. Vanadium content of the deposits is too 

small to provide a by-product. From the available information it is 

unlikely that large, high-grade deposits occur in the oolitic limestone.

LITERATURE CITED

Hose, R. K., 1954, Geology of the Crazy Woman Creek area, Johnson County,

Wyo.: U. S. Geol. Survey Oil and Gas Map OM 142. 

Jones, E. E., 1952, Airborne radiometric survey of the east flank of the Big Horn

Mountains, Wyoming and Montana: U. S. Atomic Energy Commission

RME-4006, Tech. Inf. Service, Oak Ridge, Tenn. 

Love, J. D., 1954, Uranium in the Mayoworth area, Johnson County, Wyo. A

preliminary report: U. S. Geol. Survey Circ. 358.

o
Copper and Uranium 

Deposits of the Coyote 

District, Mora County 

New Mexico

Sy C. M. TSCHANZ, D. C. LAUB, and G. W. FULLER

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-L

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1958
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C.
CONTENTS

	Page 

Abstract________________________________________ 343

Introduction ______________________________________________________ 344

Location and accessibility___________________________________--_ 344

Topography. _________________________________________________ 344

Previous work_______________________________________________ 345

Purpose and methods___-__-___________________________--__-___ 345

Acknowledgments _____________________________________________ 346

Geology. ____ __________________________________________ 346

Geologic history.-_____________________________________________ 346

Stratigraphy-_________________________________________________ 347

Precambrian rocks-____-_-_________________________--_----_ 347

Magdalena group______________________________________ 349

Description.._________________________________________ 349

Fossils. ________________________________ 349

Sangre de Cristo formation_________________________-_______ 350

Description.__________________________________________ 350

Fossils. _______________________________________ 354

Conditions of deposition__^_____________________________ 354

Yeso formation___________________________________________ 355

San Andres formation (Glorieta sandstone member)__________ 355

Bernalformation __________________________________________ 355

Santa Rosa sandstone__________^__.________________________ 355

Quaternary(?) basalt_______________________________________ 355

Structure____________________________________________________ 356

Mineral deposits_____________________________________________ 356

Copper deposits_-_________________________________--_____- 357

Description._ _________________________________________ 357

Mineralogy.__________________________________________ 369.

Uranium deposits________________________________________ 370

Uranium deposits in sandstone__________________________ 370

Area B, Bias Medina property. _____________________ 370

Area F, Arturo Le Deux property_______-_-_----_-_- 378-

Uraniferous siltstone and shale._________________________ 379'

Mineralogy of uranium deposits.________________________ 379-

. Chemical characteristics of uranium-bearing sandstone. _____ 380

Geochemical prospecting ___________________________________ 382

Origin________________________________________________ 383

Copper deposits_______________________________________ 383

Uranium deposits-_____________________________________ 385

Uraniferous siltstone_______________________________ 386

Uranium-vanadium deposits in sandstone______-_--_-_ 388

Summary ____ _________________________________________ 391

Comparison with other copper-uranium deposits--_____________ 391

Guides to ore deposits___-________________________________________ ___ 392

Conclusions-______________________________________________________ 393

Literature cited ___________________________________________________ 394

Index._______________________________________________________ 397

III
IV CONTENTS

ILLUSTKATIONS

[Plates 24-32 in pocket]

PLATE 24. Generalized geologic map. ..

25. Geologic map of area A.

26. Geologic map of area B.

27. Geologic map of area C.

28. Geologic map of area E.

29. Geologic map of area F.

30. Geologic map of area G.

31. Geologic map of area H.

32. Geologic map of area 7.

33. Photomicrographs of copper ores___________----___ Facing 378

34. Photomicrographs of uraniferous sandstone.________ Facing 379

FIGURE 67. Index map of Mora County, N. Mex____________________ 344

68. Columnar section of sedimentary rocks.___________________ 348

69. Columnar section of Sangre de Cristo formation.___________ 351

70. Columnar section of main ore-bearing interval _____________ 352

71. Section showing relationship of copper to rock types, area H- _ 367

72. Section showing concentration of copper and uranium in carbonaceous shale, area ff___-___--------_-----_-_------- 368

73. Section along ore sandstone, Bias Medina property.________ 370

TABLES

TABLE 1. Description of the Sangre de Cristo formation._____________ 363

2. Marine fossils of the Sangre de Cristo formation ____________ 354

3. Analytical data for samples from area A (pi. 25)____________ 357

4. Analytical data for samples from area B (pi. 26)____________ 359

5. Analytical data for samples from area C (pi. 27)____________ 360

6. Analytical data for samples from area E (pi. 28)____________ 361

7. Analytical data for samples from area F (pi. 29)____________ 362

8. Analytical data for samples from areas G and H (pis. 30 and

31)--._________________________-__-_-___--__-_.__ 364

9. Analytical data for samples from area 7 (pi. 32)_____________ 365

10. Analytical data for samples outside areas of large-scale maps. _ 366

11. Spectrographic, chemical, and radioactivity analyses of

selected copper and uranium samples._______.__--____.__ 372

12. Chemical characteristics of uraniuna-bearing sandstone-- _ _ - - - 381
CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

COPPER AND URANIUM DEPOSITS OF THE 

COYOTE DISTRICT, MORA COUNTY, NEW MEXICO

By C. M. TSCHANZ, D. C. LAUB, and G. W. FULLER

ABSTRACT

The copper and uranium-vanadium deposits of the Coyote district, Mora 

County, N. Mex., are confined to the lower 2,000 feet of the Sangre de Gristo 

formation of Pennsylvanian and Permian (?) age. A narrow belt of deposits 

in steeply dipping or overturned rocks extends for 7 miles along Coyote Creek 

south of Guadalupita.

Earlier studies showed that the copper deposits contained uranium, but the 

reserves and the uranium content of the copper-bearing shale are too small 

to justify any attempt to recover uranium. Several small, commercial-grade 

uranium deposits have been discovered in sandstone, however.

Small isolated lenses of copper-bearing carbonaceous shale, siltstone, limestone or sandstone, interbedded with predominantly red rocks, are present at 

12 or more stratigraphic levels. The better deposits, in carbonaceous shale, 

average about 2 percent copper. The copper content of the other rocks is usually 

lower, but small concentrations may contain 6 percent copper. The principal 

copper minerals are chalcocite and malachite. Chalcocite replaces wood and 

forms nodules that contain small, variable amounts of pyrite, bornite, covellite, 

and, rarely, uraninite.

The uranium deposits occur as small, closely spaced pockets that are commonly localized by sedimentary structures within one or more fluviatile arkosic 

sandstone beds near the middle of the formation, particularly where carbonized 

wood and clay and rock fragments are abundant. The uraniferous sandstone 

is commonly stained pink by hematite that was probably introduced with the 

uranium. The color increases in intensity with the radioactivity.

The outcrops of the uranium deposits are typically inconspicuous, but close 

inspection reveals malachite, chalcopyrite, black vanadium minerals of micaceous 

habit, metatyuyamunite, and microscopic grains of an unidentified black uraniferous substance. The proportion of copper, uranium, and vanadium is 

variable and any of these metals may be dominant in the ore.

The metals probably were derived from Precambrian granitic rocks. Copper 

and minor amounts of uranium were deposited in local stagnant basins by 

reaction with hydrogen sulfide and decaying organic material. The uraniferous 

shale and the copper deposits are probably syngenetic, or nearly so, but the 

uranium deposits in sandstone are epigenetic and probably were deposited from 

ground waters with a possible hydrothermal admixture. The uranium and 

vanadium may have been reconcentrated from earlier, low-grade, syngenetic 

deposits.

The average copper ore body assays about 1.5 percent copper and contains less 

than 1,000 tons. The small size of known, commercial-grade uranium pockets

843
344 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

and the small total uranium reserves will permit small-scale mining only under 

favorable conditions. Further exploration probably would result in an increase 

of uranium reserves, but no large deposits are expected.

INTRODUCTION

LOCATION AND ACCESSIBILITY

The Coyote district is in Mora County in the north-central part of 

New Mexico (fig. 67). The district can be reached from Las Vegas,

MORA

I COUNTS ,,

I Santa Fe. 1^^ J

I . Las Vegas 

(Albuquerque :

I NEW I

MEXICO |

I i

Lr- I i-1

INDEX MAP

'Las Vegas

FIGURE 67. Index map of Mora County, N. Mex.

N. Mex., by traveling 28 miles north on State Route 3 to Mora, 8 miles 

north on State Route 38, and 2 miles east on an unimproved road. 

The district can also be reached by turning off State Route 3 at 

La Cueva and following State Route 21 for 6 miles, 2 miles west to 

Lucero on an unimproved road and 3 miles north along Coyote Creek. 

The roads in the district are ungraded and in poor condition. The 

nearest railroad shipping points are Watrous and Las Vegas. The 

nearest uranium mill and buying station is at Ship Rock, N. Mex. 

Sufficient water is probably available in Coyote Creek to operate a 

small mill.

TOPOGRAPHY

The narrow north-south valley of Coyote Creek approximates the 

boundary between the gently dipping Permian and Mesozoic rocks 

of the High Plains to the east and the Pennsylvanian and Precambrian
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 345

rocks of the Southern Eocky Mountains to the west. The district is 

on the east flank of a north-south hogback between Coyote Creek 

on the east and Turquillo Valley on the west.

PREVIOUS WORK

The copper deposits of the district have been known for 50 years. 

Brief descriptions of the district have been published by Lindgren, 

Graton, and Gordon (1910, p. 109); Lasky and Wooton (1933, p. 84); 

Harley (1940, p. 42-43). In 1944 Kead, Sample, and Shelton (written 

communication, 1954) examined the deposits and described them. 

Bachman and Kead (written communication, 1952) discovered radioactive material in the district in 1951. Gott and Erickson (1952) 

visited the district and showed that the radioactivity was caused by 

uranium. As a result, the Geological Survey began an intensive 

study of the district for the Atomic Energy Commission, first by 

Zeller and Baltz (1954) and later by the writers of this report.

The district is shown on a geologic map of the Ocate area by Bachman (1953). A generalized topographic and geologic map of most of 

the district on a scale of 1:12,000 is included in a report by Zeller and 

Baltz (1954, fig. 4).

PURPOSE AND METHODS

Preliminary work in the Coyote district in 1952 showed that widespread copper-bearing carbonaceous shale contained small amounts of 

uranium, indicating the possibility of very large reserves of low-grade 

copper ores from which uranium might be recovered as a byproduct. 

The present study was begun primarily to explore this possibility. A 

secondary objective was the gathering of data on the origin of the ore 

deposits and the relationship between the copper and uranium deposits. As work progressed, the uranium content of the copper-bearing shale was found to be negligible and the plan was revised to include evaluation of newly discovered uranium-vanadium deposits in 

sandstone.

The most promising areas were mapped on a scale of 1 inch to 200 

feet. Two small areas were mapped on a scale of 1 inch to 50 feet. The 

total area mapped was about 1.5 square miles. The most promising 

deposits were explored by about 200 shallow hand-dug trenches and 

25 shallow jeep-mounted-auger holes. The trenches were sampled and 

mapped on a scale of 1 inch to 5 feet. A total of 339 soil samples and 

457 botanical samples were collected. Wherever possible, soil and botanical samples were collected at the same site to permit comparison 

of the results of the two prospecting methods.

Three hundred fifty-one samples were collected from the copper and 

uranium deposits of which 210 samples were submitted for chemical
346

analyses, 22 for semiquantitative spectrographic analyses, and 5 for 

mineral identification by X-ray diffraction techniques. About 70 

polished sections, 6 thin sections, and several heavy-mineral concentrates were studied. Four autoradiographs were made and studied. 

Several samples of uranium ore have been submitted for age determination but the results are not yet available. The field work was accomplished during 5 months in the summer and fall of 1953 and 2 

weeks in the following spring.

ACKNOWLEDGMENTS

All analytical work was done in the laboratories of the U. S. Geological Survey. The spectrographic analyses were made by G. W. Boyes 

and P. J. Dunton, the X-ray analyses by W. F. Outerbridge, the 

equivalent uranium determinations by S. P. Furman and E. J. Fennelly, and the selenium analyses were made by J. L. Siverly. Chemical 

analyses for copper, uranium, and vanadium were made by E. C. 

MaUory, J. W. Patton, W. D. Goss, J. F. Wahlberg, J. P. Schuch, 

Wayne Mountjoy, D. L. Stockwell, E. J. Fennelly, H. E. Bivens, 

J. E. Wilson, D. L. Skinner, and R. F. Dufour. Rapid colorimetric 

analyses for trace amounts of copper and zinc were made by H. E. 

Crowe and J. H. McCarthy.

The plant and soil samples were collected by W. R. Martin. The 

writers are indebted to H. D. Zeller and E. H. Baltz, Jr., who kindly 

loaned their maps, notes, and specimens, and to J. G. McGrath for 

operation of the jeep-mounted auger.

This work is part of the program of exploration for radioactive 

raw materials undertaken by the Geological Survey on behalf of the 

U. S. Atomic Energy Commission.

GEOLOGY

GEOLOGIC HISTORY

During Pennsylvanian and early Permian time, the Ocate-Guadalupita area was part of a geosyncline, the Rowe-Mora trough, which 

was flanked by rising geanticlines of Precambrian rocks that were part 

of the Colorado Mountains or ancestral Rocky Mountains (Read and 

Wood, 1947, p. 266). The axis of the geosyncline, which trends northwest, was about 12 miles west of the district. The rising positive areas 

furnished large volumes of sediments to the basin, which was occupied 

by a sea during the deposition of most of the Magdalena group. 

Marine sedimentation recurred intermittently during the deposition 

of the lower part of the Sangre de Cristo formation, but most of the 

sediments were deposited under subaerial conditions.

The sea invaded the region repeatedly after the deposition of the 

Sangre de Cristo formation. Bachman (1953) believes that the
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 347

Glorieta sandstone member of the San Andres formation of late 

Permian age is probably a beach sand deposited as the sea transgressed 

northward. Triassic and Jurassic sediments are partly shallow marine and partly continental in origin. A major marine transgression 

lasted during most of Cretaceous time.

In early Tertiary time, regional compression deformed the rocks 

in the district and buckled the site of the present Sangre de Cristo 

Mountain system into a broad anticlinorium. Precambrian rocks 

were moved eastward over the Pennsylvanian rocks along steep reverse faults on the east flank of the rising mountains. The rocks 

within and immediately east of the zone of reverse faults were steeply 

tilted or overturned to form the series of hogbacks in which the district 

is located (Northrup, Sullwold, MacAlpin, and Rogers, 1946; Bachman, 1953). This narrow, upturned belt parallels the east flank of 

the mountains northward and as far south as Las Vegas.

The sedimentary rocks farther east were gently folded to form 

the Jarosa syncline and the Ocate anticline. The axes of these northtrending folds are 3 miles and 6 miles east of Coyote Creek.

Basalt flows belonging to two periods of activity in late Tertiary 

or early Quaternary time covered all older rocks. The older flows 

originally covered most of the district, but only scattered erosional 

remnants exist today.

STRATIGRAPHY

Four main groups of rocks in the Coyote district are: (1) igneous 

and metamorphic rocks of Precambrian age; (2) sandstone, arkose, 

siltstone, limestone, and shale of Pennsylvanian, Permian, and 

Triassic age; (3) basalt flows of late Tertiary or early Quaternary 

age; and (4) quaternary gravel and alluvium. Their distribution 

is shown in the general geologic map of the district in plate 24. A 

graphic section of the sedimentary rocks from Precambrian to the 

Benton formation of Cretaceous age is shown in figure 68. The rocks 

of Jurassic and Cretaceous age are included in figure 68 to provide 

comparison of the stratigraphy of the Coyote district with that of 

other uranium districts. Bachman (1953) gives descriptions of these 

units.

PRECAMBRIAN ROCKS

Precambrian rocks in fault contact with the Magdalena group 

crop out along the west side of the district. These Precambrian rocks 

are chiefly quartzite, containing minor amounts of pegmatite, schist, 

and gneiss. Coarse-grained pink granite, diabase, diorite, amphibolite, pegmatite, and quartz veins are common in the Precambrian areas 

of northern New Mexico and Colorado. Fragments of many of these 

rocks are found in the Pennsylvanian and Permian sedimentary rocks.

417829 58 2
348 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

3

O

PERMIA

Si

UJ <

CARBON PENNSYL

iz

Benton formation

Dakota sandstone

Morrison formation

Wanakah formation ^-

Naranio formation /

Chinle formation

Santa Rosa sandstone

Bernal formation

San Andres formation 

Glorieta sandstone 

member

Yeso formation

Sangre'de Cristo

formation

Magdalena group

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~o O 

.c 0 

i; o

~ £

-D <=

0 JT

II

£? CL

O '

in

en

Shale, brown to gray, fissile marine; and limestone

Sandstone, buff to gray, medium-grained

Sandstone, brown, and variegated shale, mterbedded

Shale, gray and brown, sandstone, and limestone

Sandstone, gray, massive, cross-laminated, probably correlative with

Entrada sandstone 

 Sandstone, brownish-red, siltstone, and shale, mterbedded

Shale, brownish-red and maroon, and siltstone, with a few discontinuous sandstone lenses

Sandstone, brownish-red in part conglomeratic, and shale

Siltstone, brownish-red and fine-grained sandstone

Sandstone, gray to light-brown, medium grained, cross laminated in 

part, may mtertongue with Sangre de Cristo formation

Siltstone, brownish-pink, mtertongues with Sangre de Cristo formation, generally absent north of Lucero

Pebble conglomerate, brownish-red, arkosic. sandstone, and shale 

with minor gray shale and limestone: generally correlative with Abo 

formation; basal part intertongues with upper part of Magdalena 

group

Sandstone, brown and buff, arkosic pebble conglomerate and shale 

interbed'ded with gray marine limestone, base of exposed section 

in fault contact with Precambnan rock

Quartzite and minor schist, gneiss, pegmatite in area. Granite 

abundant elsewhere

FIGDEK 68. Generalized columnar section of tbe sedimentary rocks of tbe Coyote district

and surrounding region.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 349

MAGDAUENA GROUP 

DESCRIPTION

A regional angular unconformity separates the Precambrian rocks 

from the Magdalena group of Pennsylvanian age. The Magdalena 

group 12 miles west of Guadalupita near Chacon consists of four 

units (Bachman, 1953). The basal unit, 3,800 feet thick, is equivalent 

to the Sandia formation and consists of sandstone and arkose, containing minor amounts of shale and limestone. The next higher unit, 

about 1,000 feet thick, is bituminous and slightly calcareous friable 

and fissile shale. The third unit consists of 2,800 feet of interbedded 

arkose, sandstone, shale, and limestone. The upper unit, 3,000 feet 

thick, consists of brownish to reddish-brown sandstone, arkose, and 

shale interbedded with gray marine limestone.

The section at Chacon is more than 10,000 feet thick and is dominantly marine. Only about 3,500 feet of the upper part of the Magdalena group is exposed in the Coyote district, however. Bachman 

(1953) believes a large part of the Magdalena group is cut out by 

reverse faults along the west side of the district (pi. 24).

The marine sedimentary rocks of the Magdalena group in the 

Coyote district are yellow-brown, buff, or gray in contrast to the 

predominantly reddish continental sedimentary rocks of the Sangre 

de Cristo formation. On a regional scale the marine sedimentary 

rocks of the Magdalena group grade laterally and vertically into red 

beds of the Sangre de Cristo formation (Northrup and others, 1946). 

K. G. Brill (1952, p. 821-823, 826-827), G. O. Bachman (1953), and 

C. B. Read and G. H. Wood (1947, p. 223-227) give further details 

on the regional stratigraphic relationships of both Pennsylvanian 

and Permian formations.

The contact of the Magdalena group and the overlying Sangre 

de Cristo formation in the district was arbitrarily placed at the change 

from gray or brown to red about 140 feet above a 25-foot fossiliferous 

limestone bed. In other parts of New Mexico the upper contact of 

the Magdalena group is at the top of the highest marine limestone bed, but in this area several thin marine limestone beds occur 

in the lower 950 feet of a red-bed sequence that is indistinguishable 

from the Sangre de Cristo formation.

FOSSILS

The 25-foot-thick limestone bed 140 feet below the contact contains 

abundant marine fossils, including algae (?), sponges, corals, crinoids, 

bryozoans, brachiopods, and mollusks. The fossils listed here were 

identified by members of the Geological Survey (written communications, 1954).
350 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Corals (identified by Helen Duncan)

Caninoid corals (Pseudozaphrentoides as interpreted by Moore

and Jeffords) 

Clisiophyllid corals (Neolconinckophyllum as interpreted by

Moore and Jeffords) 

Bryozoans (identified by Helen Duncan) 

Fistulipora sp., massive form 

Polypora sp. 

Rhdbdomeson sp.

Brachiopods (identified by Mackenzie Gordon, Jr.) 

Meekella striatocostata (Cox) 

Dictyoclostus sp.

Linoprodn^tus cf. L. platyumbonus. Dunbar and Condra 

Echinoconchus semipunctatus (Shepard), var. 

Neospirifer cf. N. latus. Dunbar and Condra 

Composita subtilita (Hall) 

Compositaf sp.

Mollusks (identified by Mackenzie Gordon, Jr.) 

Pteria sp. 

AUorisma sp. 

Worthenia sp. (identified by Ellis Yochelson and Brookes

Knight)

The over-all affinities indicate about middle Pennsylvanian or at 

least post-Morrow age (Mackenzie Gordon, Jr., arid Helen Duncan). 

The range of the species is little known in New Mexico but there is no 

evidence of a late Pennsylvanian or Permian age.

The species to which Linoproductus and Neospirifer are compared 

are confined to the Kansas City and Lansing groups of the Missouri 

series in Kansas and Nebraska, according to Dunbar and Condra 

(Mackenzie Gordon, Jr.). The corals resemble species from the upper 

Marble Falls limestone and Smithwick shale (post-Morrow lower 

Pennsylvania) of Texas more than other described species (Helen 

Duncan). A scale tree, probably Lepidodendron, found in arkose in 

the upper part of the Magdalena group indicates that marine conditions were not universal.

SANGRE 1KB CBISTO FORMATION

The Sangre de Cristo formation of Pennsylvanian and Permian (?) 

age overlies the Magdalena group with .apparent conformity in the 

Coyote district, but it interfingers with the upper part of the Magdalena group on a regional scale.

DESCRIPTION

In the Guadalupita area, the Sangre de Cristo formation is between 

3,000 and 3,200 feet thick (fig. 69); along the Mora River 6 miles south
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 351

Glorieta sandstone member of 

San Andres formation

Thickness 

in feet

Limestone

Sandy lirnec'.one 

Shaly limestone

Shale

Uranium-vanadium Conglomeratic sandstone 

deposits in sandstone ____

Silty sandstone

rincipal copper 

deposits

Marine gastropods

Uranium deposits in 

siltstone or shale

Vertical scale 

in feet

Fusulinids, brachiopods

FIGURE 69. Composite columnar section of the Sangre d« Cristo formation, Coyote district,

Mora County, N. Mex.

of the district, the thickness is 3,300 feet (Bachman, 1953). The formation is divided into six units for convenience of description. These 

units are not shown on the large-scale maps because of the uncertainty 

in tracing individual lenticular beds across faults, covered areas, and
352 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Top

Siltstone and shale, reddish

Sandstone, reddish, arkosic

Siltstone and shale, maroon and 

purple

Sandstone, gray, arkosic 

Covered

Sandstone, yellowish-brown, arkosic, 

copper-bearing, some limy beds

Covered

Siltstone, mottled gray and red

Limestone, mottled red and gray, 

sandy

Sandstone, gray and yellowishbrown, thin bedded, copper-bearing and thin limestone pebble 

conglomerate beds

Siltstone, gray

Shale, gray

Sandstone and Siltstone, gray and

yellowish-brown 

Covered

Sandstone, gray, arkosic 

Covered

Sandstone, brown, thin-bedded 

Shale('), gray, covered 

Sandstone, brown, arkosic

Sandstone, gray and brown, thinbedded, fine-grained, with thin 

gray shale and limestone pebble 

conglomerate beds

Limestone pebble conglomerate, 

grayish-brown, sandy

Siltstone and shale, mottled red. 

purple, and gray

Pebble conglomerate, reddish, 

arkosic

Covered, chiefly shale and siltstone, red, with discontinuous 

reddish sandstone and arkosic 

pebble conglomerate lenses

Limestone, mottled red and gray. 

with minor shale

Pebble conglomerate, arkosic

Sandstone, red, thin-bedded, finegrained

Pebble conglomerate, arkosic

Covered

Pebble conglomerate, arkosic

Sandstone and Siltstone, red, very

fine grained 

Pebble conglomerate, arkosic

Sandstone, Siltstone, and limy 

shale, reddish, thin-bedded. 

fine grained

Limestone, gray, massive

Pebble conglomerate, arkosic. 

massive

Shale and siltstone, red

Siltstone. gray, containing malachite

Covered, chiefly Siltstone, sandstone, shale and limy shale, red

Siltstone, red

Pebble conglomerate, arkosic. thinbedded

Covered, chiefly siltstone. red 

Pebble conglomerate, arkosic

Shale, siltstone and nodular limestone, red'

Pebble conglomerate, reddish.

arkosic 

Shale, red

Pebble conglomerate, reddish, 

arkosic, massive

Shale, red, with limestone nodules 

Pebble conglomerate, reddish.

arkosic 

Covered 

Pebble conglomerate, reddish,

arkosic, massive

Covered, probably chiefly red shale. 

y shale, and siltstone

Pebble conglomerate, red, arkosic. 

massive

FIGURE 70. Columnar section of the main ore-bearing interval, Sangre de Cristo formation,

area D.

areas not mapped in detail. A lithologic description of these units is 

given in table 1.

A detailed columnar section of the middle, or principal ore-bearing 

part, of the formation in area D is given in figure 70. Further details 

of the lithology are shown on the large-scale geologic maps of areas 

AtoO and E to /, plates 25 through 32. Two notable characteristics
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 353

of the Sangre de Cristo formation shown on these maps are: (1) the 

many abrupt facies changes and (2) the small stagnant basins in which 

the gray and black shale beds were deposited. No bed extends the 

length of the district.

TABLE 1. Description of the Sangre de Cristo formation

Thickness 

(feet)

Conglomeratic sandstone unit 200-280 

Sandstone, reddish gray, friable, massive and crossbedded, conglomeratic, with abundant well-rounded sand grains and chert and 

quartzite pebbles up to 3 inches in diameter. Interbedded with 

some mottled silty limestone and shale. Sandstone in upper half 

weathers to smooth, rounded rim. May include beds equivalent 

to Yeso formation and lower part of the Glorieta sandstone member of San Andres formation. Unmineralized.

Variegated sandstone unit 200-250 

Sandstone, gray, brown, and red; medium- to coarse-grained, poorly 

sorted, arkosic, fluviatile. Interbedded with thin red shale, siltstone, and limestone. Many cut-and-fill structures and abundant 

fragments of limestone, quartz, quartzite, siltstone, greenstone, 

and vein quartz. Unmineralized.

Red siltstone unit 530-640 

Shale and siltstone, predominantly red, maroon, or chocolate; limy 

or micaceous. Many thin beds of silty limestone and fine-grained, 

red, silty sandstone. Some silicified wood at base. Unmineralized.

Fluviatile sandstone unit 140-300 

Sandstone, gray or brown, well-sorted, thin-bedded, cross-bedded, or 

massive, fine- to medium-grained. Interbedded with thin gray 

shale, limy shale, and limestone pebble conglomerate. Sand-filled 

scours and channels common. Beds lenticular; some beds, limy; 

poorly sorted, coarse, with abundant clay fragments, carbonized 

wood, and foreign rock fragments. Uranium, vanadium, and 

copper deposits (pis. 26 and 29).

Transition unit 670-940 

Arkosic pebble conglomerate, reddish gray, massive, alternating 

with red, gray, or black, micaceous, carbonaceous, or limy shale 

and siltstone. Many thin limestone and limy shale beds in upper 

part. Carbonized or silicified wood locally abundant. Copper in 

local gray or black lenses at 10 horizons; some uranium (pis. 27 

and 31).

Red arkose unit 630-950 

Arkosic pebble conglomerate, reddish gray, 20 to 80 feet thick. 

Coarse, massive Beds alternating with red, chocolate, or maroon, 

shale, limy shale, and micaceous siltstone. Few thin limestone 

beds, some fossiliferous and marine. Arkose contains abundant 

angular quartz, feldspar, and granite fragments up to % inch in 

diameter, carbonized, silicified or calcitized wood and magnetite 

seams along the bedding. A thin gray micaceous uraniferous 

shale or siltsone bed in areas A and C. Some copper-bearing carbonaceous shale (pis. 25 and 32).
354 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FOSSILS

Carbonized plant remains and fossil wood replaced by silica, calcite, chalcocite, or, rarely, pink barite are the most common and 

widely distributed fossils in the Sangre de Cristo formation. Especially well-preserved plant remains are found in pit G2 and in the 

uraniferous siltstone in area A.

A Permian (?) conifer, Lebachia, was reported by Zeller and Baltz 

(1954, p. 3) in the northernmost pit in area (7, and Calamites and 

Lepidodendron have been tentatively identified by the writers.

Some fossiliferous marine limestone or siltstone occurs in the lower 

950 feet of the formation. Brachiopods, pelecypods, crinoids, nautiloids, and gastropods, chiefly bellerophontids, have been collected. 

The marine fossils have been identified by members of the Geological 

Survey as follows:

TABLE 2. Marine fossils of the Sangre de Cristo formation

Fossil Locality Identified by

Linoproductus sp________________. i!2 (pi. 32)____ Mackenzie Gordon, Jr.

Myalina sp_-_________-__________ BZ-21 (pi. 24)_ S. A. Northrup

Pelecypods indet_________________ i6 (pi. 32)___._ E. L. Yochelson

Hypselentomal sp_________________ 16 (pi. 32)_____ Do.

Bellerophontid gastropods indet____ 16 (pi. 32)_____ Do.

Pseudorthoceras cf. P_---__________ 16 (pi. 32) _____ Mackenzie Gordon, Jr.

knoxense (McChesney)__.__. 16 (pi. 32)____. Do.

Some of the copper-bearing shale either contains marine fossils or is 

overlain by fossiliferous limestone. The genus Hypselentoma is known 

only from the upper Pennsylvanian in the mid-continent region 

(Yochelson, written communication, 1954). If the range is the same 

in the Coyote district, at least the lower 950 feet of the formation is 

Pennsylvanian.

CONDITIONS OF DEPOSITION

Most of the Sangre de Cristo formation appears to be first-cycle 

sediments deposited in a deltaic, flood plain, or fluviatile environment 

near the source areas, which were high during the deposition of the 

lower units of the formation. Thin, marine limestone beds show that 

the basin of deposition was intermittently below sea level. The thickness and grain size of the coarser beds decreases upward, and the 

proportion of limestone or shale increased as the relief of the source 

areas became lower. The lower two units show a cyclic sequence of 

sediments; these have been called cyclothems of the piedmont type.

Locally, especially during deposition of the transition unit, swamps, 

lagoons, and stagnant ponds existed on the flood plain. According 

to Yochelson (written communication, 1954), the abundance of 

Hypselentoma(?) in a limestone bed at pit i6 and the presence of
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MBX. 355

very few other marine fossils could indicate a shallow-water environment with restricted circulation of sea water.

The sandstone of the fluviatile sandstone unit (table 1) was apparently deposited in the channels of meandering streams on a flood 

plain. The coarse, poorly sorted, conglomeratic sandstone beds abovethe red siltstone unit may indicate renewed uplift or a new source area. 

The uppermost unit appears to be a series of beach deposits on an area 

being gradually inundated.

TESO FORMATION

The Yeso formation of Permian age pinches out near Lucero and 

is not present in the mapped area. It consists of brownish-pink siltstone that is lighter and finer than the Sangre de Cristo formation. 

The description of this and succeeding units is from Bachman (1953).

SAN ANDRES FORMATION (GLORIETA SANDSTONE MEMBER)

The Glorieta sandstone member of the San Andres formation of 

Permian age is the only member of the formation exposed in the district. The member consists of about 266 feet of gray to light-brown, 

medium-grained sandstone. It forms the prominent cliff along the 

east side of the district.

BERNAL FORMATION

The Bernal formation of Permian age consists of interbedded 

brownish-red siltstone and fine-grained sandstone about 100 feet thick. 

A disconformity separates the Bernal formation and the Glorieta 

sandstone member of the San Andres formation.

SANTA ROSA SANDSTONE

The Santa Rosa sandstone of Late Triassic age is exposed in the 

southeast corner of the area (pi. 24), lying disconformably on the 

Bernal formation. It consists of 425 feet of brownish-red shale and 

sandstone. The units above the Santa Eosa sandstone are not exposed in the district and are not described although they are included 

in figure 68.

QUATERNARY(?) BASALT

Five volcanic centers are present a short distance northeast of 

the Coyote district. The nearest is less than a mile east of the north 

end of the district. Two ages of extensive basalt flows (Bachman, 

1953) cover large areas along the east and north sides of the district. 

The older flows originally covered the Coyote district but only remnants now exist as mesa cappings on vertical beds of older rocks 

(pi. 24). The five volcanic plugs and the flow rocks (Bachman, 1953) 

in the Ocate area are products of the later period of eruption. No 

evidence has been found of a genetic relationship between the basalt 

and the mineral deposits.

417829 58 3
356 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

STRUCTURE

The Coyote district is in a Laramide( ?) belt of deformation along 

the east flank of the Sangre de Cristo Kange. The rocks east of the 

district are warped into gentle folds; the rocks west of Coyote Creek 

are turned up sharply along a north-south axis. In the mineral belt 

the dips are steep to overturned and farther west the beds are overturned and cut by steep reverse faults. Bedding attitudes within the 

mineral belt indicate that the forces of deformation were torsional, 

increasing in intensity northward. The strike changes progressively 

northward from N. 20° W. to N. 20° E. (pi. 24). At the south end 

the beds dip 80° E. Northward the dip passes through the vertical, 

and the overturned beds in the northern part dip 50°-756 W. The 

degree of overturn increases westward throughout most of the district.

Several high-angle reverse faults were mapped by Bachman (1953) 

in Precambrian and Pennsylvanian rocks along the west side of the 

district. The Precambrian rocks have been thrust eastward several 

thousand feet over Pennsylvanian rocks, cutting out a large part of 

the Magdalena group.

Several northwest-striking oblique faults with lateral displacement of less than 300 feet were mapped in areas A, E, and F (pie. 25, 

28,29). Several minor northeast-striking oblique faults were mapped 

in area H (pi. 31). Some faults clearly offset the ore zones; however, 

the lack of marker beds makes correlation across the faults difficult. 

The arkose is sheared and bleached in areas of closely spaced faulting. 

Although several ore deposits are near major faults there'is no evidence of mineral deposition along the faults (pis. 28 and 29).

MINERAL DEPOSITS

The mineral deposits of the Coyote district (pi. 24) are confined 

to lenticular beds of gray, brown, black, or pink sedimentary rocks 

in the lower 2,000 feet of the Sangre de Cristo formation. Copper 

and uranium minerals have not been found in the red, chocolatecolored, or maroon rocks that make up most of the formation.

The ore minerals are sparsely distributed, and individual deposits 

are small. Copper deposits typically contain negligible amounts of 

uranium and the uranium deposits contain small but variable amounts 

of copper.

Uranium deposits occur in sandstone and micaceous siltstone; copper 

deposits .occur in several rock types, but most of the ore bodies are 

in black carbonaceous shale. The fluviatile sandstone unit (table 1) 

contains most of the uranium deposits. Most of the copper deposits 

are in lower units, particularly the transition unit.

The location of the mineral deposits and samples are shown on 

the large-scale maps, plates 25-32. The analytical data for samples
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 357

from each area are given in tables 3-9. The location of the scattered 

samples outside these areas are shown in plate 24 and analyses are 

given in table 10.

COPPER DEPOSITS 

DESCRIPTION

Copper deposits occur in four types of rock: (1) carbonaceous shale 

orsiltstone, (2) arkosic pebble conglomerate, (3) micaceous sandstone, 

and (4) nodular limy shale or limestone. The deposits are richest 

and most abundant in black, carbonaceous shale lenses and in adjacent 

parts of gray shale or arkosic pebble conglomerate beds. Sandstone 

normally contains low-grade disseminated deposits, and copper deposits in limestone are rare and unimportant.

TABLE 3. Analytical data for samples from area A (pi. 25)

[Radioactivity analyses by S. P. Furman and E. S. Fennely. Chemical analyses by H. E. Bivens, R. F. 

Dufour, E. C. Mallory, C. E. Thompson, D. C. Stockwell, J. H. McCarthy, J. F. Wahlberg, and W. D. 

Gossj

Field

no.

92

93

94

195

19fi

197

198

199

?nn

?oi

?02

ms

204

205

206

207

208

?09

210

211

212

213

?14

Width (ft.)

2.0

2.7

3.2

.6

2.8

2.3

2.5

1.4

1.0

2.4

2 4

3.0

1.5

2.7

2.4

2.1

2.1

3.5

3.5

2.8

q

2.0

eU

0.007

.004

.007

.013

.004

.008

.011

.004

.044

.005

.011

.010

.008

.011

.008

.012

.015

.009

.009

.002

.003

.019

Percent

U

0.005

.004

.008

.003

.006

.029

<. 005

.006

.005

.004

.007

.005

Cu

5.07

.13

.07

. 10

. 15

. 10

. 10

.15

. 10

. 10

.20

.20

.15

.07

. 15

. 10

.07

.07

. 10

. 10

Se

(ppm)

2

Lithologic description

Green sandstone and shale.

Black carbonaceous shale.

Altered limonitic sandstone.

Buff siltstone, brown shale.

Gray-brown siltstone.

Yellow-brown siltstone and shale.

Yellow-brown shale and siltstone.

Yellow-brown siltstone with plant

remains. 

Do.

Do.

Yellow-brown shale and siltstone.

Olive-brown siltstone.

Do.

Gray-green and olive-brown shale

and siltstone. 

Gray-green shale and siltstone.

Gray shale and yellow-brown siltstone with carbon seams.
358 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 3. Analytical data for samples from area A (pi. 25) Continued

Field

no.

215

216

917

219

220

221

222

223

224

225

226

231

233

234

235

236

237

238

239

240

241

242

243

244

245

400

401

402

403

404

405

412

228

Width

(ft.)

1.6

1.4

1. 9

. 9

1.8

2.7

.8

1.6

1.6

1.2

.9

.7

1.2

.9

1. 7

1.6

2.6

1.0

3.3

2.1

1.8

.8

.8

2.0

1.0

2.0

6.0

3.5

2.5

3.3

2.0

eU

0. 004

.019

.006

.004

.004

.007

.006

.006

.022

.016

.013

.018

.021

.011

. 012

.026

.006

.020

.011

.006

.012

.008

.012

.002

.002

.005

.004

.002

.002

.004

.008

Percent

U

.021

.011

.007

.012

.014

.008

. 009

.015

.015

.009

.007

.002

.007

Cu

0.07

. 15

. 10

.03

.06

.05

.02

.36

.17

.29

. 16

.20

.54

.29

60

3.92

1.75

. 14

.05

.18

Se

(ppm)

2

5

Lithologic description

Gray and black silty sandstone.

Yellow-brown siltstone and shale.

Do.

Do.

Gray-green and olive shale.

Yellow-brown siltstone and shale.

Gray micaceous siltstone and shale.

Chalcocite nodules.

Fossiliferous limestone.

Gray-green shale.

Gray-green shale with carbon seams.

Siltstone with calcite, quartz, plagioclase, nontronite, and kaolinite. 

Gray-green micaceous siltstone.

Black siltstone with carbon seams.

Gray-green shale and yellow-brown

sandstone. 

Dark gray-green siltstone with carbon. 

Do.

Yellow-green micaceous sandstone.

Micaceous sandstone.

Do.

Dark-green micaceous shale, yellowbrown sandstone. 

Gray-green shale and carbon seams,

yellow-brown sandstone. 

Dark-green and black shale.

Fine-grained sandstone.

Blue-gray shale.

Blue-gray arkosic sandstone.

Black shale and arkosic sandstone.

Composite of 401 and 402.

Gray-green shale.

Dark gray-green micaceous shale.

Yellow-brown micaceous siltstone.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 359

TABLE 4. Analytical data for samples from area B (pi. 26)

[Radioactivity analyses by S. P. irurman. Chemical analyses by E. C. Mallory, J. F. Wahlberg.Wayne 

Mountjoy, S. P. Schuch, H. E. Crowe, W. D. Qoss, and J. H. McCarthy]

Field 

no.

247

248

249

251

330

331

332

333

334

335

336

352

Width 

(feet)

1.0

.6

.6

' 

.8

1.2

1.2

.4

.5

.5

Percent

eU

0.051

.058

.061

. 11

.052

.022

.043

.048

.030

.024

.26

u

0.036

.049

.041

.10

.044

.017

.033

.024

.033

.018

.29

Cu

0.79

1.37

1.22

.01

.77

.02

.62

1.66

.25

.63

.47

VjOs

_

0.32

<.l

.12

.15

<.l

<.l

.22

Lithologic description

Coarse gray-brown arkosic sandstone

with malachite.

Brown and yellow-brown, fine-grained,

thin-bedded arkosic sandstone with

malachite.

Same as 248 with sulfides.

Gray-brown arkosic sandstone with

chalcopyrite and calcite cement.

Carbonized-ocherous log.

Pink arkosic sandstone with chalcopyrite.

Pink-gray arkosic sandstone.

Gray arkosic sandstone.

Black and brown sandstone.

Arkosic sandstone.

Pink feldspathic sandstone.

Pink arkosic sandstone with chalcopyrite and metatyuyamunite.
360 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABIJE 5. Analytical data for samples from area 0 (pi. 27)

[Radioactivity analyses by S. P. Furman and E. J. Fennelly. Chemical analyses by D. L. Skinner, J. H. 

McCarthy, W. N. Niles, Wayne Mountjoy, J. P. Schuch, H. E. Bivens, R. F. Dufour, E. C. Mallory, 

C. E. Thompson, D. L. Stockwell, and J. F. Mallory]

Field 

no.

58 

59 

60 

65

66 

67 

68 

69 

70 

71 

72 

73 

337

338 

339 

340 

341 

342 

414 

415

416

417

418 

419 

420

BZ-1 

BZ-2

BZ-3 

BZ-4

Width 

(feet)

3.4 

2.0

4.0

1.0 

1.3 

1.7 

1.7 

.6 

2. 1 

.6

4. 1 

2.1

1.5 

.9 

.6

2.0

Percent

eU

0.004

.004

.006

.008 

.005

.01

.008 

.005 

.004 

.005 

.007 

.016

.019 

.034

.010 

.023 

.003

.009 

.007

.020 

.007

u

0.004

.005 

.003

.004

.002 

.001 

.001 

.001 

.004 

.009

.012 

.016

.006 

.011 

.002

.006 

.007

.004 

.003

Cu

0. 15

.88

2.38 

2. 14

2.63

1.01 

1.91 

1.61 

1. 94 

1.04 

.09

.08 

.56

.02 

.20 

.05

2.21 

1.73

2.51 

2.72

VjOs

<0. 1

<.l

<. 1

<. 1

. 17

Se 

(ppm)

2

2 

2

Lithologic description

Chalcocite nodules. 

Gray-green shale. 

Do. 

Dark gray micaceous siltstone. 

Black carbonaceous shale. 

Wood replaced by chalcocite. 

Chalcocite nodules. 

Large chalcocite nodules. 

Black carbonaceous shale. 

Gray-green shale. 

Chalcocite nodules. 

Do. 

Black shale with chalcocite 

nodules. 

Do. 

Do. 

Do. 

Do. 

Do. 

Cross-bedded sflty*sandstone. 

Yellow - brown micaceous 

sandstone. 

Yellow sandstone. 

Gray-green shale and yellow 

sandstone. 

Micaceous sandstone. 

Do. 

Yellow - green micaceous 

sandstone. 

Dark - gray carbonaceous 

shale. 

Arkosic sandstone with chalcocite and malachite. 

Black carbonaceous shale. 

Black carbonaceous shale 

with chalcocite nodules 

and carbonized plant remains.
COPPEE AND TTRANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 361

TABLE 6. Analytical data for samples from area E (pi. 88)

[Radioactivity analyses by S. P. Furman and E. J. Fennelly. Chemical analyses by D. 1. Skinner, 

J. H. McCarthy, W. N. Niles, Wayne Mountjoy, J. P. Sehuch, W. D. Qoss, H. E. Bivcns, R. F. Dufour, 

E. O. Mallory, and C. E. Thompson]

Field no.

40 

41 

42 

43 

44 

45

46

47

48 

91

97 

98

99 

100

101 

102 

103 

104

BZ-7 

B&-8

BZ-9 

BZ-10 

BZ-11 

BZ-12

BZ-13 

BZ-14

Thickness 

(feet)

5.5

5.0

2.4 

.5

.9 

1.7 

1.1

Percent

eU

0.008

.003

.006

.005

.003

.005

.004 

.002

.005 

.010

.004 

.005 

.011

.014 

.065

.039 

.001 

.001 

.011

.018

U

0.002 

.009

.004 

.009

.010 

.048

.018 

.001 

<. 001 

.008

.015

Cu

2.74

4.08

1.46

.49 

.15

.22

4.65

.91 

1.34 

5.81

4. 16 

6.39

14.38

.03 

3.72

4. 65

V,0s

<0.1 

< 1

<M

.26

.30 

.18 

<.l

Se 

(ppm)

<2 

<2

<2

10

<2 

3 

3

Lithologic description

Gray carbonaceous shale. 

Black arkosic sandstone. 

Chalcocite in sandstone. 

Do. 

Arkosic sandstone. 

Black arkosic sandstone 

with malachite and 

volborthite. 

Chalcocite nodules. 

Green shale and sandstone. 

Gray sandstone with 

malachite and volborthite. 

Chalcocite and metatyuyamunite in sandstone. 

Gray silty sandstone. 

Yellow-brown silty 

sandstone. 

Gray micaceous silty 

sandstone. 

Green micaceous siltstone. 

Do. 

Do. 

Do. 

Argillized arkosic sandstone. 

Arkosic sandstone. 

Arkosic sandstone with 

metatyuyamunite. 

Do. 

Barren olive clay shale. 

Barren gray clay shale. 

Shale and arkosic sandstone. 

Black carbonaceous 

shale. 

Radioactive coaly fragment may contain 

uraninite(?).

1«c <np
362 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 7. Analytical data for samples from area F (pi. 29)

|Radioactivity analyses by S. P. Furman and E. J. Fennelly. Chemical analyses by D. L. Skinner, 

J. H. McCarthy, H. E. Bivens, R. F. Dufour, E. C. Mallory, C. E. Thompson, J. E. Wilson, D. L. 

Stockwell^W. D. Qoss, J. F. Wahlberg, and J. L. Silverly]

Field 

no.

14 

17 

18 

33

34

35

36 

61

74

75 

76

77 

81

82 

83

84 

85

86

87 

88

89 

90 

95 

96

107 

108 

109 

110

111 

112

Width 

(feet)

2.0

2.0

2.3

.8 

.7 

1.4 

.9

1.8 

.8

Percent

eU

0.002 

.062

.001 

.081

.082

.005

. 014

.005 

.009 

.005 

.002

.025 

.013

tr

0.008

.002 

.006 

.003

.017 

.012

Cu

0.06

.02

.45

1.23

.66

.17 

.60 

.33 

1.72

2.09 

1.33

V2 05

0.45

< 1 

< 1

< 1 

< 1

<-l 

< 1

Se 

(ppm)

10

2

2 

2 

2

10 

2

Lithologic description

Green shale with carbon. 

Coaly seam in sandstone. 

Red micaceous siltstone. 

Metatyuyamunite specimens. 

Gray arkosic sandstone with 

metatyuyamunite. 

Chalcocite nodules. 

Green nodular limestone. 

Black and green arkose. 

Reddish arkose and sandstone. 

Weathered carbonaceous material. 

Black vanadiferous(?) sandstone. 

Do. 

Nodular recrystallized limestone. 

Gray sandstone with bornite. 

Black sandstone with vitrain 

and metatyuyamunite. 

Ocherous-orange core of log. 

Radioactive limonitic sandstone. 

Radioactive carbonized log. 

Do. 

Black and yellow-brown 

sandstone. 

Limonitic sandstone core of 

log. 

Green sandstone with 

carbon. 

Green siltstone and sandstone. 

Yellow-green uranium mineral. 

Black and red shale. 

Black carbonaceous shale. 

Do. 

Gray-green micaceous siltstone. 

Black shale and arkosic 

sandstone. 

Olive siltstone and black 

shale.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 363 

TABLE 7. Analytical data for samples from area F (pi. 29) Continued

Field 

no.

113 

114 

116 

176 

177

178 

179 

186

187

188 

343

344

345

346

347 

349

350 

351 

353

354 

355

356

357 

BZ-15

BZ-16

BZ-17 

BZ-18

BZ-19

Width 

(feet)

3. 5 

3.5

1.4

3.4 

1. 1 

2. 0

1.8

1.3 

2. 1 

1.2

2.0 

2.2 

1.3

1.0 

1.2 

1.3

1.4

.6 

1.6

Percent

eU

0. 004 

.005 

.007

.003 

.005

. 18

.063

.009 

.015 

.042

.075 

.046

.038 

.20

.038 

.044 

.068

.025 

.81

.035

.010

.068

.004 

.054

.039

u

0. 004 

.005

.004 

. 004 

.20

.042

.006 

.006 

.027

.038 

.041

.024 

. 18

.033 

.036 

.019

.019

.85

. 026

.003 

.067

. 0002 

.032

.026

Cu

0.06 

.3 

.58

.2 

1.27

.89

. 72 

.02 

. 10

. 17 

.09

.09 

.20

.02 

.02

13.65

57.33 

.66

.41

V205

<. 1

.29 

.90

1.22 

1.36

.32 

2.07

<. 1 

< 1

2.92

Se 

(ppm)

<2

3

50

Lithologic description

Chalcocite nodules. 

Black shale. 

Red, gray, and green shale. 

Gray, black, and olive shale. 

Olive and gray-green siltstone. 

Olive, gray, and black shale. 

Olive and black shale. 

Pink arkosic sandstone, micaceous siltstone with 

metatyuyamunite. 

Pink sandstone and black 

shale. 

Olive-brown and black shale. 

Arkosic sandstone. 

Conglomeratic sandstone 

with black clay fragments. 

Pink conglomeratic arkosic 

sandstone. 

Gray-brown arkosic sandstone. 

Pink feldspathic sandstone. 

Selected high grade, abundant metatyuyamunite. 

Pink arkosic sandstone. 

Do. 

Pink arkosic micaceous sandstone. 

Arkosic sandstone and black 

shale. 

Selected high - grade ore, 

abundant metatyuyamunite. 

Pink arkosic micaceous sandstone. 

Arkosic micaceous sandstone 

Sandstone with carbonized 

wood. 

Acicular limestone nodules 

with malachite. 

Chalcocite nodules. 

Sandstone with disseminated malachite and metatyuyamunite. 

Sandstone with disseminated metatuyuamunite.

417829 5E
364 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 8. Analytical data for samples from areas G and H (pis. 30 and 31}

[Radioactivity analyses by S. P. Furman and E. J. Fennelly. Chemical analyses by D. L. Skinner, W. 

N. Niles, Wayne Mountjoy, J. P. Schuch, W. D. Qoss, E. C. Mallory, J. L. Siverly, C. E. Thompson, 

and D. L. Stockwell]

Field

no.

1

2

3

4

5

6

7

8

9

10

11

12

14

15

16

166 

167

168

169

170

171

172

174

175

184

185

189 

190 

191

192 

193 

BZ-25

BZ-26

BZ-30

Thickness

(feet)

6.0

7.0

2.0

.5

4.2 

2.0

2. 4

40

2.5

2.5

2.0

3.5

6.5

6. 3

3.2

. 4 

1.5 

3.8

3.2 

2.0 

1.5

eU

0.003

.015

.005

.011

.001

.004

.002

.002

.009

.001

.006

.004

.002

.005

.006

.007 

.003

.005

.004

.003

.003

.002

.003

.004

.002

.003

.022 

.005 

.003

.008 

.007 

.008

.048

.015

Percent

U

0.015

.005

.006

.019 

.001

.005 

.006 

.004

.041

.008

Cu

0.63

6.07

.03

1. 40

1. 97

55. 73

.49

.06

1. 27 

.37

1. 21

.06

. 60

1.49

.05

.03

.015

.005

.005

1. 09 

3. 53 

. 1

1. 05 

. 58 

7.49

32. 85

. 80

Lithologic description

Chalcocite nodules.

cocite. 

Barren micaceous sandstone.

Dark-gray sandstone.

Chalcocite nodules.

Barren limestone.

Gray silty carbonaceous sandstone.

Gray carbonaceous siltstone.

Do.

Chalcocite nodules.

Gray and black shale. 

Gray brown siltstone.

Black carbonaceous shale.

Gray limy shale.

Do.

Gray and red shale.

Gray shale.

Black shale and arkose. 

Black carbonaceous shale. 

Gray green siltstone.

Gray and black shale. 

Green and black shale. 

Gray shaly siltstone with carbon and 

chalcocite.

with uraninite. 

Black shale with copper and limestone

nodules.
COPPER AND URANItrM DEPOSITS, COYOTE DISTRICT, N. MEX. 365

TABLE 9. Analytical data for samples from area I (pi. 32)

[Radioactivity analyses by 8. P. Fiirman and J. H. Patton. Chemical analyses by D. L. Skinner, W. N. 

Niles, Wayne Mountjoy, S. P. Sehuch, H. E. Bivens, W. D. Qoss, R. F. Dufour, J. L. Siverly, and 

E. C. Mallory]

Field

no.

122

123

124

125

126

127 

128

129

130

131

132

133

134

135

136 

137

138

139

141

142

143

144

145

146

147

148

149

150

151

152

153

154 

155 

156

157

158

159

160

161

162

BZ-28 

BZ-29

Width

(feet)

2.5

3.5

1.7

2.0

1.3

2.0 

3.0

2.0

1.2

1.3

2.0

2.7

2.0

3.4

1.5 

2.7

2.0

1.0

1.9

4.8

2.0

5.0

. 8

.6

4.2

3.5

2.4 

2.0 

1. 6

1.0

2.7

1. 1

2.2

3.0

.3 

.5

eU

0.004

.004

.003

.004

.005

.009 

.003

.003

.004

.005

.005

.002

.004

.004

.012 

.005

.004

.003

.004

.003

.004

.003

.004

.002

.005

.008 

.008 

.007 

.005

.003

.005

.007

.003

.004

.054 

.011

Percent

U

0.006

.008

.005 

.005 

.005

.061 

.003

Cu

0. 14

.32

.05

.02

.03

.75 

.02

.02

.01

.01

<.01

<.01

.01

. 65

2. 10

.81

1. 52

1.47

1.79

.01

.07

.01

. 54

.66

1. 57

1.74 

1. 46 

1.85 

5.20

.02

2. 04

1. 55

1.44

.05

3. 84 

2. 23

Lithologic description

Do.

Olive-brown micaceous shale.

Light-gray thin-bedded arkose.

Gray-green micaceous siltstone.

Do.

Olive clay shale and siltstone.

Do.

Gray-green siltstone.

Poorly sorted arkose with malachite.

Coaly, iron-stained log with copper.

Log, partly replaced by chalcocite.

Green and brown clay shale.

Carbonaceous shale and siltstone.

Do. 

Carbonaceous sandstone and siltstone. 

Carbonaceous shale. 

Gray-green carbonaceous shale.

Dark-gray and brown shale.

Gray-green carbonaceous shale.

Gray shale and arkose.

Gray shale with red mottling.

tropods. 

Gray shaly sandstone. 

Carbonaceous siltstone and shale.
366 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 10. Analytical data for samples outside areas of large-scale maps

[Samples listed In order of appearance on map (pi. -24) from south to north. Radioactivity analyses by 

8. P. Furman and E.J. Fennelly. Chemical analyses by D. L. Skinner, J. H. McCarthy, W. X.Xiles, 

Wayne Mountjoy, J. P. Schuch, and W. D. Goss]

Field

no.

BZ-31

BZ-32

8

163

164

165

BZ-27

BZ-21 

20

21 1

BZ-22

BZ-23

BZ-21

25

BZ-20

26 »

27

28

29

31

32

53

54

52

49 J

50 »

sa

BZ-6

BZ-5

55

56

57

Width

(feet)

1.5

1.0

1. 4

2.0

1. 2

1.2

3.0

5. 7

3.0

8.7

ell

0.003

.004

. 002

. 002

.003

.003

.003

.003

. 003

.005

.001

.009

.003

.004

.001

.003

.003

.003

.004

.005

.003

.003

.003

.002

. 018

.009

.005

Percent

U

0.002

. 003

.002

<.001

.003

. 004

.001

.014

Cu

5. 24

6. 76

1 Q7

.01

. 19

. 06

. 02

.005

1. 06

. 005

1.81

2. 00

3.46

1. 27

.08

0.84

.02

.76

.005

6. 13

Lithologic description

Sandstone with carbon.

Light and dark-gray shale.

Gray shale with carbon.

Barren greenish-gray clay shale. 

Unaltered chalcocite nodules.

Fossiliferous limestone.

Marine fossils in sandy limestone.

Do.

Gray-green and red shale.

Carbonaceous shaly sandstone.

Do.

Light arkosic sandstone.

Mineralized carbonaceous wood.

Gray carbonaceous shale.

Red siltstone, gray micaceous shale.

Brown fine-grained sandstone.

Green shale with copper.

Do.

Gray-green shale with copper.

Black carbonaceous shale.

Carbonaceous shale.

Gray-green shale from dump.

Chalcocite nodules and replaced wood.

1 Semiquantitatlve spectrographic analyses given in table 11.

The copper deposits are confined to sedimentary rocks that probably were deposited in small, stagnant basins. The association of 

the copper deposits and this sedimentary f acies is so distinct that a 

genetic relationship is indicated. Most of the copper deposits are 

in black shale lenses in the transition unit. The black shale lenses are 

enclosed in gray-green shale that contains a small amount of copper 

and grades into barren red shale or limestone. Detailed sections 

of two typical ore bodies are shown in figures 71 and 72. The sequence 

of rock types shown in figure 71 probably marks successive stages
PIT

Chalcocite in limestone 

nodule

N. 10° W.

Horizontal and vertical scal

40 0 

I___________i I_______________L

PIT 

h!5

Field 

no.

166

167

168

169

170

171

172

175

Thickness 

in feet

4.2

2.0 

2.4 

4.0 

2.5 

2.5 

2.0 

6.5

SAMPLE DATA

Percent 

eU U Cu

0.007 0.006 1.27

.003

.005

.004

.003

.003

.002

.004

.37

1.21

.46

.60

1.49

.05

.015

PIGCEE 71. Section along copper lens, area H, showing typica
N. 10° W 40

Horizontal and vertical scale

0

_J______________L_

193.

Feather edge ___~^== 

of arkose lens

191'

PIT

h8

\

*£

PIT P 

h9 h

L ._, 1

: v $':

Sslg 

^

Mass v

2.;££

3t-': :&

=&

e r

d"'

 «liii

T 

10 

kos c p bble

iJiSr

A.-.:.vv-;-.-.-.v.-:V

.Gray shale / 

Black carbonaceous shale

190

SAMPLE DATA

Field 

no.

189

190

191 

192 

193

Thickness 

in feet

0.4

1.5

3.8 

3.2 

2.0

P e

eU

0.022

.005

.003 

.008 

.007

r c e n 

U

0.019

.001

.005 

.006

t 

Cu

1.09

3.53

.10 

1.05 

.58

FIGURE 72. Section along copper lens, area H, showing concentration o
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 369

in the filling of a local basin. The limited extent of the favorable 

host rock, the black shale, limits the size of the ore bodies.

The ore bodies are tabular bedded deposits 100-300 feet in diameiter and 1 to 6 feet thick. The copper content ranges from 1 to 

6 percent. The average ore lens is 2 or 3 feet thick and contains 

about 1.5 percent copper. None of the deposits contains more than 

about 7,500 tons of ore, and few contain more than 1,000 tons.

The ore contains chalcocite nodules less than 2 inches in diameter, 

but some as large as a man's head have been reported. Most nodules 

are not radioactive, although a few highly radioactive ones were 

found at pits G2, E15, and E16.

MINERALOGY

The principal copper minerals are blue and gray chalcocite, 

malachite, and azurite. Azurite and malachite commonly occur as 

disseminated grains or coatings on chalcocite nodules or mica flakes. 

The chalcocite nodules contain small amounts of pyrite, bornite, 

covellite, and vitrain. Uraninite was identified in a chalcocite nodule 

from pit G2, plate 30, by Abraham Rosenzweig of the Atomic Energy 

Commission (Zeller and Baltz, 1954, p. 5). Volborthite is present 

with malachite in a micaceous arkosic sandstone in pit e5, plate 28.

A woody cell structure and even the form of the woody fragments 

are well preserved in many chalcocite nodules (pi. 33), and all stages 

of replacement by chalcocite can be found. Normally the cell walls 

are vitrain and the cores are filled with sulfide minerals. A few 

nodules have a concentric banded structure that may be marked by 

slender groups of pyrite crystals radiating from the center.

Chalcocite also occurs in dense limestone nodules near pits b!4 

and a62. In a few places the dense limestone core of the nodules is 

surrounded by concentric layers of coarse, acicular brownish calcite 

that contains malachite. Chalcocite is rare in sandstone but the outer 

edge of a pebble conglomerate bed adjacent to copper-bearing shale 

may contain as much as 14 percent copper, chiefly chalcocite.

Many coalified woody fragments were composed entirely of vitrain 

and pyrite before pyrite was replaced by copper sulfides. Bornite 

and chalcopyrite are most abundant in nodules that still contain 

abundant pyrite. Covellite and chalcocite are the important minerals 

where replacement is nearly complete (pi. 33). The paragenetic 

sequence is: (1) vitrain and pyrite, (2) chalcopyrite and bornite, 

(3) chalcocite, and (4) covellite. Malachite and azurite are believed 

to be products of weathering. The paragenetic sequence is in the 

order of increasing copper content and decreasing iron content of 

the sulfide minerals. The chalcocite (possibly digenite(?)) is distinctly blue in some nodules where it has almost completely replaced 

pyrite, bornite, and chalcopyrite (pi. 33). The blue color is typical
370 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

of a chalcocite-covellite solid solution, which may contain as much 

as 8 percent covellite at room temperature. The blue chalcocite is 

interpreted by some to indicate a temperature of formation above 

75°C (Edwards, 1947, p. 74-76). Copper-bearing samples contain 

less vanadium, lead, and rare earths than uranium samples (table 11, 

page 372).

URANIUM DEPOSITS

URANIUM DEPOSITS IN SANDSTONE

The uranif erous shale and siltstone are of very low grade and all 

commercial-grade uranium deposits are in sandstone. The uranium 

deposits may or may not contain significant amounts of copper or 

vanadium.

Uranium and vanadium minerals are commonly concentrated in 

scours filled by sandstone that contains abundant clay and rock fragments and carbonized wood (fig. 73). Most of the ore pockets are less 

than 2 feet thick and 10 feet long. A group of several closely spaced 

deposits within a favorable sandstone generally are separated from 

other groups by long stretches of barren sandstone. The ore pockets 

are surrounded by lower grade material, and radioactivity may be 

continuous between adjacent deposits. The outcrops of the ore bodies 

are inconspicuous. Metatyuyamunite is locally abundant, but recognizable uranium minerals are not visible in many deposits.

The uranium deposits in sandstone are described below.

Area B, Bias Medina property. All the uranium deposits in area B 

are probably in the same gently dipping arkosic sandstone about 1,670 

feet above the base of the formation. Uranium was found in all the

N. 15° E.

Festoon crossbedding in 

3-ft channel Strike 

N 10° W.

S. 15°W.

Thin-bedded red silty sandstone and siltstone 

Crossbeddin| Fine-grained gray 

;ilty sandstone

\ reading 6 on 2~0 scale 

Sample 352, 0 5 ft thick. 0 26 percent eU 

0 29 percent U, 0 22 percent V2 0 5 , 047 

percent Cu

EXPLANATION

GEIGER COUNTER READINGS

More than 0 10 mi per hr More than 0.15 mr per hr 

Note Outcrop in pit bl shown on pi 26 

0

More than 0 5 mr per hr

Geology by D C. Laub and C M Tschanz, 1953 Radioactivity 

analyses by S. P. Furman. Chemical analyses by C. E. 

Thompson, D. L Stockwell, and E. C Mallory 

10 Feet

Horizontal and vertical scale

FIGURE 73. Section along outcrop of ore sandstone, Bias Medina property, Coyote district,

Mora County, N. Mex.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 371

trenches except b5 and b7, but ore was found only in trenches bl, b4, 

and the new shaft. The map of these deposits is given in plate 26 and 

the sample analyses are given in table 4.

The ore in pit b4 is in a hard, limy, massive, medium-grained, pink 

sandstone which fills a scour about 10 feet in diameter. The ore, 4 to 6 

inches thick, contains abundant small grains of disseminated chalcopyrite; metatyuyamunite is rare. Chalcopyrite has been found only in 

area B.

In the summer of 1955 a 15-foot shaft was sunk by lessees about 25 

feet behind the outcrop at pit b4. They reported that the lowest part 

of the shaft cut through several feet of ore containing abundant 

chalcopyrite and as much as 1 percent equivalent uranium. A grab 

sample (360) analyzed in the laboratories of the Geological Survey 

contained 0.78 percent equivalent uranium and 0.41 percent uranium 

(table 11), and duplicate analyses confirmed these figures. The difference between the radiometric and chemical values was surprisingly 

great compared to sample 251 from the nearby outcrop which was 

nearly in equilibrium. Radiochemical analyses for uranium daughter 

elements were made by J. N. Eosholt, Jr., to determine the cause of 

the disequilibrium. The radiochemical data (table 11) are interpreted 

to mean that uranium probably has been selectively leached from 

sample 360 even though the sample contains abundant chalcopyrite. 

This conclusion is surprising because uranium has apparently not 

been comparably leached from the surface outcrop (251). If this interpretation is accepted, the ore must have originally contained more 

uranium, perhaps as much as the 1.34 percent required to form the 

ionium in the sample. The indicated subsurface leaching of uranium 

suggests that uranium is readily soluble under certain conditions where 

chalcopyrite is relatively stable. The uranium leached from the ore 

might possibly be redeposited in minable concentrations downdip. 

The only alternative interpretation permitted by the radiochemical 

data would have ionium extracted by the sample from ground waters 

by some mechanism such as coprecipitation with or adsorption on 

ferric hydroxides. This alternative is unlikely.

In pit bl, figure 73, several sets of cross strata in the sandstone 

are separated by curved, troughlike erosion surfaces. Uranium 

is concentrated along clay seams, in clay fragments, or along discontinuities between cross strata. In the spring of 1954, radioactive 

material was discovered in two massive, grayish-pink arkosic sandstone beds from 1,000 to 1,300 feet north of pit bl. The sandstone 

beds, 6-8 feet thick, are separated by 20 feet of siltstone. Fine-grained 

malachite, the only visible ore mineral, is probably derived from 

chalcopyrite. The radioactive layer in the center of each sandstone 

bed is 1-2 feet thick. Readings as much as 0.2 milliroentgens per hour 

on the Geiger counter were obtained, but samples were not collected.
372 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

£ *> 

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analyses Semiquantitative in percent spectrographic 

1fe PL,

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Lithologic description

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Pink micaceous sandstone, abun- dant carbon, metatyuyamunite 

O.OOX- Ge.............. Micaceous sandstone andshale, carbonaceous shale, metatyuyamunite- ... ____. 

Pink arkosic micaceous sandstone, 

metatvuvamunite

1-1 '"' £

IO CD CO 

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Pink arkosic sandstone withchalcoand blackpyrite uranium mineral

3

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Coarse pink arkosic sandstone wihclay black glls and metatyuyamunite-- _____ ...... -do--... ............... Nonmagnetic heavy mineral con-pink, centrate ofarkosic sand- black stonewith uranium mineral andchalcopyrite ..... 

Limonitic sandstone from ofcenter carbonized log. O.X; P As O.X..

Carbonized log replaced by chalco2 § §S £ -3

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Buff micaceous siltstone and shale._ Buff micaceous siltstone and sanstone

V

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Buff and siltstone shal gray ... Black carbonaceous shale with

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.......do . ...... 

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Green coarse-grained arkosic sandFossillferous limestone with chal-

.003

.002

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2.00

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4.08

1.06

XX 

XX

XX

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XX

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x+

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See footnotes at end of table.
TABLE 11. Spectrographic, chemical, and radioactivity analyses of selected copper and 

N. Mex. 1 Continued

Field 

no.

355

186

33

352

3602 

349

346

251

89

149A 

201 

416 

216 

70

337 

40

60 

49

Trench 

no.

fll 

fll

f9 

bl

near b4 

f26

f26

b4

F9

115 

a!9 

c6 

a!7 

C6

C6 

E15

C19

Lithologic description

Pink micaceous sandstone, 

abundant carbon, metatyuyMicaceous sandstone and shale, 

carbonaceous shale, metaPink micaceous arkosic sandPink arkosic sandstone with 

chalcopyrite and black uraniDo., bottom new 15 ft. shaft, 

25 ft. from b4_____ ............

Coarse pink arkosic sandstone 

with black clay galls and

Nonmagnetic heavy mineral 

concentrate of pink, arkosic 

sandstone with black uranium mineral and chalcopyrite. 

Limonitic sandstone from center of carbonized log. PO.X; 

As O.X - - 

Carbonized log replaced by 

chalcocite. Bi O.OOX- .. -

Buff micaceous siltstone and

Buff micaceous siltstone and

Buff and gray siltstone and

Black carbonaceous shale with

.. do.........................

Gray or green shale with fine 

carbonized plant remains

 -do.. .... ... ... ._ 

 do.......... .-, ..

Semiquantitative Spectrogr

Ti

O.X-

.X 

.X

.OX+ 

.OX+

.ox

.X

X-

.X-

.ox

.X 

.X 

.X

X 

'.X

.X 

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Mn

O.X-

.OX+ 

.X-

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.X

-OX+ 

.OX+

.x+ 

.ox

Tr. 

.OX- 

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.OX 

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Or

O.OOX

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Tr.

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X

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x+

X 

XX

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X 

X

X 

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0 

0
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 375

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376 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 377

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.do..... ................ .......

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spectrographic sensitivity Standard ................

theldaughter required produce PW0The figures the ofuranium notation, in XX,> O.+,.X, amounts tExample percent: 10;0.464 to1.0; 0.215 i ofare .

isotope threshold conditions andnormal uranium Tr., elements assuming equilibrium present 0.464; O.X-,0.100 to0.215; amount. anear

C. Eshow teiscausd by leaching of uranium by H. ECrowe, and Thompson abundance. Thedata indicate disequilibrium analyses R. BeinsColorimptric * 

been high Mo, Seand O.Radiochemical thateoriginal uranium could have1.34 percent, 4approximately As,120 50content 150 as ppm 

Jr., show daughter elements by J.N. Rosholt, Th"° Assay figures fo bulksample, analyses 1.34 percent * uranium ofare 

shown Ra plate and Locations Pa'", 1.08 SM24. 0.92 Rn«', 0.94 4 ionium), percent 1.22 on, 
378 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Area F, Arturo Le Deux property. Massive pink medium-grained 

limy micaceous arkosic sandstone contains uranium and vanadium between pits f9 and f!2 (pi. 29). The sandstone ranges in thickness 

from a featheredge to 4 feet and crops out sporadically at the surface. 

This sandstone is about 770 feet above the base of the formation and 

is enclosed in copper-bearing gray shale containing thin seams of black 

shale. Metatyuyamunite is concentrated in micaceous seams at the 

contact of the sandstone and the shale in pit fll and disseminated 

through the sandstone in pit f9. A high-grade ore pocket found 2 

feet below the surface in the featheredge of the sandstone hi pit fll 

probably extends to the north end of pit f 12. The ore between depths 

of 2 and 4 feet is less than 2 feet thick. The radioactivity is not above 

background count south of pit f!2 and north of pit f8, and no other 

uranium deposits were found in this zone. The analyses in table 7 indicate that uranium has been leached from the uranif erous shale and 

redeposited in the adjacent sandstone. The lack of control by sedimentary structures within the sandstone and the close association with 

copper-bearing shale are exceptional.

Three nearly vertical fluviatile sandstone beds between 1,920 and 

1,960 feet above the base of the Sangre de Cristo formation contain 

uranium or vanadium deposits in the eastern part of area F. The 

middle or main uranium-bearing sandstone is a gray-brown poorly 

sorted, massive limy sandstone about 6 or 8 feet thick. This sandstone 

contains isolated concentrations of uranium in each pit between f 19 

and f26. Pockets of uranium ore occur chiefly in poorly defined lenses 

of coarse, pink, limy sandstone that contains carbonized wood and gray 

or black clay and limestone fragments. The pink color is distinctive 

and becomes more intense as the radioactivity increases. Black micaceous vanadium minerals impregnate the sandstone along bedding 

planes and partly surround the uranium pockets. The black color of 

clay fragments in ore of high vanadium content probably is the result 

of adsorbed vanadium, but at least part of the vanadium is in the clay 

mineral structure. The ore-grade material is less than a foot thick 

except in pits f23 and f26 where metatyuyamunite is abundant.

Several vertical slickensided joints cut the sandstone between pits 

f23 and f26. One joint contains nonradioactive caliche and iron 

oxides. A narrow zone of sandstone adjacent to this joint is barren; 

beyond this a zone impregnated with black vanadium minerals is 

parallel to the joint and partly envelops a small uranium pocket.

The lowest of the three sandstone beds contains small vanadium 

deposits, but the uranium content is low. The highest of the three 

sandstone beds is represented by a group of small isolated hard white 

massive fine-grained limy sandstone lenses at about the same stratigraphic position above the main ore-bearing sandstone. Several of
GEOLOGICAL SURVEY BULLETIN 1030 PLATE 33

A. Polished longitudinal section of carbonized wood (dark gray) replaced 

by blue chalcocite (gray) containing residual grains of pyrite and bornite (not visible). X 50.

B. Polished cross section of carbonized wood (dark gray) replaced by gray chalcocite (gray) and 

minor covellite (not visible). Shows cell structure and growth rings. X 50.

PHOTOMICROGRAPHS OF COPPER ORES, COYOTE DISTRICT, MORA

COUNTY, N. MEX.
GEOLOGICAL SURVEY BULLETIN 1030 PLATE 34

A. Polished section of uraniferous sandstone, Bias Medina property, pit b-4. Quartz and 

feldspar (high relief) and calcite (low relief) replaced by chalcopyrite (cp) and black uraniferous substance (u). X 50.

B. Thin section of hematitic uraniferous sandstone, Bias Medina property, pit b-4. Quartz (<;), 

hematite-impregnated feldspar (/), and calcite (c), replaced by chalcopyrite and black uraniferous substance. X 70.

PHOTOMICROGRAPHS OF URANIFEROUS SANDSTONE, COYOTE 

DISTRICT, MORA COUNTY, N. MEX.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 379

these lenses contain uranium but no copper or vanadium. The part of 

the lenses that contains uranium is pink, as in pit f28, f32, and f33.

An ore-grade layer 3 to 5 inches thick parallels a slickensided bedding plane in the middle of a 3-foot massive limy sandstone bed in 

pits f32 and f33. The layer is apparently continuous between these 

pits and may extend 50 feet farther north. The deep pink ore-grade 

material grades into barren white sandstone.

TTRANIFEROTTS SILTSTONE AND SHALE

A uraniferous micaceous marine siltstone and shale bed overlain by 

a thin bed of f ossilif erous marine limestone in area A is correlated with 

a similar uraniferous rock sequence in area C. If this correlation is 

correct, the basal 330 feet of the Sangre de Cristo formation is missing 

in area C because 670 feet of beds intervene between the uraniferous 

siltstone and the apparent base of the formation in area A, but only 

340 feet intervene in area C. If the uraniferous siltstone beds are 

correlated, the uraniferous sandstone beds in area F can be correlated 

with those in area C. The discrepancy in thickness of the basal beds 

may be due to nondeposition or, more probably, faulting that has cut 

out the basal part of the formation in area C.

The uraniferous siltstone averages 2 feet in thickness and can be 

traced more than 5,000 feet in area A and 1,500 feet in area B. The 

bed is exposed downdip for 200 feet. Samples from many trenches 

show that the lithologic character and the uranium content are remarkably uniform (see table 3). Nine segments of this bed in area 

A (pi. 25) and one in area C (pi. 27) contain an average of 0.01 percent uranium. Elsewhere the uranium content is about half as much.

The uraniferous beds cannot be traced between areas A and C. 

Near the south end of area A the siltstone grades into radioactive 

sandstone that contains some malachite. In places the siltstone f acies 

between areas A and G is replaced by sandstone.

MINERALOGY OF URANITTM DEPOSITS

The chief ore minerals in the uranium deposits in sandstone are 

metatyuyamunite, an unidentified uraniferous substance, black 

micaceous vanadium minerals similar to "roscoelite," chalcopyrite, and 

malachite. Uraninite has not been identified in any of the uranium 

deposits in sandstone. No other uranium and vanadium minerals 

have been recognized in the uraniferous siltstone.

Most of the uranium in area B is apparently in hematite(?) and 

especially in a black uraniferous ferric (?) substance that gives positive tests for uranium, iron, and copper but does not give an X-ray 

diffraction pattern. Not all the black "mineral" contains uranium but 

it is difficult to distinguish between the two varieties visually. In 

oblique light fragments or irregular surfaces of the uraniferous substance appear black, but polished surfaces in a light source perpendicu-
380 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

lar to the surface appear gray. Grains viewed under either oblique 

or vertical light commonly show a red internal reflection. Under the 

microscope the uraniferous substance is seen to be interlocked with 

chalcopyrite, which it apparently replaces (pi. 34). Both minerals 

replace calcite and, to a lesser extent, quartz and altered feldspar. 

Both minerals occur chiefly as finely disseminated grains that clearly 

were formed later than calcite, which was formed later than the sand 

grains. A few detrital grains contain chalcopyrite and a black substance, but the amount of metal so deposited is negligible.

A heavy-mineral concentrate, sample 251, is composed of chalcopyrite (50 percent), the unidentified substance (30 percent), and small 

amounts of quartz, feldspar, tourmaline, and accessory minerals. This 

sample was submitted for semiquantitative spectrographic analyses 

after crusher steel was removed (table 11). The unidentified uraniferous substance is probably a metamict or amorphous ferric oxide. 

Calculations from semiquantitative spectrographic data indicate that 

the uranium content of the uraniferous ferric oxide is less than 3 

percent. It is suggested that the difference in physical properties between the black uraniferous ferric substance and the hematite may be 

the result of changes caused by radiation from a much greater 

uranium content.

Most of the sedimentary rocks of the Sangre de Cristo formation are 

feldspathic. The composition, in percent, of the ore-bearing sandstone is quartz (30-40), feldspar (30-40), calcite (20-30), muscovite 

(0-5), rock fragments (0-20), and a little hematite and nontronite. 

The feldspar is chiefly oligoclase and microcline. Although potash 

feldspar was not detected in the five samples studied by X-ray diffraction techniques, much of the feldspar shows the characteristic gridiron 

pattern of microcline, and orthoclase may be present.

Except in the upper uraniferous sandstone in area F, the calcite content of the radioactive sandstone generally is higher than the content 

of nonradioactive sandstone. Calcite replaces altered feldspar and 

quartz; it also fills fractures in these minerals. Where replacement is 

advanced, the detrital grains are represented by corroded remnants 

that are no longer in contact. Some of the calcite in area F is high in 

manganese. The genetic significance of these facts is discussed on 

page 388.

The pink color of some uraniferous sandstone ore is caused by 

"dusty" grains of hematite (?) which coat quartz grains and impregnate altered feldspar grains and foreign rock fragments. Most of the 

"dusty" hematite (?) tested gives a positive test for uranium.

CHEMICAL CHARACTERISTICS OF URANIUM-BEARING SANDSTONE

The amount and relative proportions of uranium, vanadium, copper, and certain minor constituents vary greatly, as shown by the 

selected analytical data in tables 11 and 12.
COPPEE AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 381

In general, the uraniferous sandstone of the Coyote district has a 

higher content of copper, lead, rare earths, and other minor constituents than the uranium ores in the Morrison and Shinarump formations of the Colorado Plateau. Lead and the rare earths are concentrated with uranium in the radioactive sandstone and in the heavymineral fraction (sample 251, table 11). The highest rare-earth content is found in the limonitic sandstone core of a carbonized log, 

sample 89. The rare-earth content of this sample exceeds the uranium 

and vanadium content. The few selenium analyses (tables 7 and 12) 

suggest that the selenium content is higher in the uraniferous rocks, 

particularly in the most uraniferous sandstone, but the data are not 

conclusive.

TABLE 12. Chemical characteristics of uranium-bearing sandstone

tRadioaetivity analyses by S. P. Furman, chemical analyses by C. E. Thompson, D. L. StockweH, E. O. 

Mallory, J. F. Wahlberg, Wayne Mountjoy, J. P. Schuch, W. D. Goss, J. H. McCarthy, H. E. Bivens, 

R. F. Dufour, and J. L. Siverly]

Field 

no.

Pit 

no.

Lithologic description

Percent

eU U Ou V20s

Se 

(ppm)

Ratios

eU/U V/eU

Uranium "ore"

251

351 

350

332

b4

f33 

132

b3

pink, limy arkosic sandstone. May

uraniferous iron oxide(?).

0.11

.044 

.038

.022

0.10

.036 

.033

.017

0.01

.02 

.02

.02

<0.1 

<.l

<-l

3

1.10

1.22 

1.15

1.30

<1.27 

<1.45

<2.64

Uranium-copper "ore"

360» 

352

186

1 353

187

249

248

247

334 

333

near 

b4 

bl

fll

m

f!2

blO

blO

blO

b7 

b4

Coarse massive pink sandstone, chalcopyrite. 

Do.

Do.

Do.

Do.

Limy arkosic sandstone.

0.78 

.26

.18

.068

.063

.061

.058

.051

.048 

.043

0.41 

29

.20

.019

.042

.041

.049

.036

.024 

1033

H

<0.46

.47

1.27

.89

1.22

1.37

TO

1.66 

.62

<0.2 

.22

.15 

.12

50

9

1.90 

.76

.90

9.58

1.60

1.49

1.14

1.42

2.00 

1.30

<0.28 

.47

1.74 

1.56

Uranium-vanadium "ore"

355 

349

345

346

344

343

fll 

-fl6

128

f26

f*<

m

Metatyuyamunite in micaceous sandstone.

0.81 

.20

.075

046

fld9

.015

0.85 

.18

.038

041

.027

.006

0.25

.17

.09

.10

.02

2.92

2.07

1 22

1.36

on

.29

50 0.95 

1.10

1.97

1.10

2.55

2.50

2.0 

5.66

8.97

10.95

11.95

10.8

1 Colorimetric analyses by H. E. Crowe, R. R. Beins, and C. E. Thompson show approxunately 150 ppm 

JLs, 120 ppm Mo, and 4 ppm Qe.

The eU/U ratio (table 12) may give an indication of the amount of 

uranium that has been leached from the sample. The thorium content 

of these rocks is below O.OX, the spectrographic threshold, and can 

be ignored because the radioactivity of thorium is only about onefifth that of the same amount of uranium. Where uranium is in
382 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

equilibrium with its daughter products, the ratio is 1.0. If selective 

leaching or precipitation of daughter products can be ignored, ratios 

much greater than 1.0 indicate recent leaching of uranium and ratios 

less than 1.0 indicate that uranium has been reprecipitated recently. 

This interpretation is less hazardous where the uranium content is 

appreciable (more than 0.05 percent), where the ratio is greater than 

2.0, and where there is corroborating field evidence.

The eU/U ratios (table 12) and the field evidence indicate that 

some leaching and redeposition of uranium occurs locally. The eU/U 

ratio changes from 2.0 to 4.0 in siltstone and shale, and apparently 

uranium is leached from the uraniferous shale and redeposited in 

adjacent sandstone in some areas.

GEOCHEMICAL, PROSPECTING

Geochemical prospecting techniques were used in the hope that 

deposits hidden under alluvium might be detected. A total of 457 

botanical and 339 soil samples were collected. Wherever possible, soil 

and botanical samples were collected from the same place to determine 

which prospecting method was more satisfactory; the botanical 

samples were obtained from plant foliage to insure approximate 

uniformity of metal content and age of growth.

In general, the results were disappointing and neither geochemical 

nor botanical testing appears to be well suited to detecting small 

deposits of this type. A poor correlation between plant and soil data 

was obtained. This may be partly the result of the extraction of 

metals from the soil by plant roots. Several trenches dug beneath 

trees having a high copper or uranium content failed to disclose copper 

minerals or radioactivity in the bedrock. In area I, plant and soil 

data gave an entirely different pattern even though only the needles 

of ponderosa pine were sampled. The anomalies in content of copper 

in ponderosa pine outlined most of the copper deposits but neither, the 

lead and zinc anomalies for ponderosa pine nor the anomalies for any 

of the three metals in soil samples were related to the ore bodies.

The reasons for the failure are: (1) prevalent surface wash, 

(2) different metal content of each rock type, and (3) the small size 

of rock units and ore bodies which caused the root circle of plants to 

overlap several beds of different metal content. Samples of the foliage 

of ponderosa pine, piny on, juniper, and scrub oak were collected. The 

metal content varied greatly but was higher in the pines than in the 

other trees.

The soil and ashed plant samples were analyzed for copper, lead, 

and zinc by rapid colorimetric methods. All three metals were determined in plant samples but only lead and zinc were determined in 255 

soil samples. Uranium was determined by the fluorimetric method in 

159 representative botanical samples.
COPPEE AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 383

ORIGIN

In this section is postulated a tentative theory of origin of the 

mineral deposits that is consistent with the mineralogical, chemical, 

and field relationships. Such a theory is of necessity speculative; 

whether the ores were formed by the processes postulated remains to 

be demonstrated and depends on the correctness of assumptions that 

appear reasonable in the light of current physico-chemical knowledge 

but cannot be proved. The senior writer is primarily responsible for 

the ideas expressed in this section.

Briefly, the metals now concentrated in the mineral deposits are 

considered to have been derived from the Precambrian terrane and 

to have been concentrated by syngenetic sedimentary processes and, in 

the case of the uranium deposits in sandstone, reconcentrated by warm 

chemically active ground water with a possible juvenile component. 

Copper and uranium were partly separated because they were 

deposited in different chemical environments by different mechanisms. 

Copper was deposited as a sulfide by H2S, but uranium probably was 

adsorbed on a ferric hydroxide precipitate. The origin of each type 

of deposit is discussed separately in detail below and a summary is 

given at the end of the section.

COFFER DEPOSITS

The copper and associated uranium in the copper-bearing shale 

probably were derived chiefly from Precambrian rocks. Many small 

copper deposits of pre-Pennsylvanian age are found in the Precambrian rocks of northern New Mexico. The metal probably was 

derived partly from these deposits but chiefly from acidic igneous 

rocks, which contain an average of 16 grams of copper per metric 

ton (0.0016 percent), according to Rankama and Sahama (1950, p. 

697).

The carbonaceous copper deposits are local stagnant basin shale 

facies characterized by abundant carbonized plant remains and ferrous 

iron. The enclosing barren red rocks are colored by ferric oxides; 

they do not contain carbonaceous material, although plant imprints 

remain. The highest content of copper and uranium in the shale is 

found in shale with the most carbonaceous material. Copper probably was deposited in local swamps, lagoons, or lakes in an oxygendeficient environment which favored the carbonization of plant material and reduced iron to the ferrous state.

Copper, iron, and a little uranium from the Precambrian terrane 

probably were transported in solution by surface or ground waters 

to local anaerobic basins where copper and iron were precipitated as 

sulfides by hydrogen sulfide generated by the decay of organic material or the reduction of sulfates by anaerobic bacteria. A small 

part of the uranium was precipitated as uraninite. A little was
384 CONTKIBUTIONS TO THE GEOLOGY OP URANIUM

probably adsorbed on carbon, ferric hydroxide, or humic compounds, 

but much of the uranium may have remained in solution or suspension 

to be deposited elsewhere.

The metal content and the form in which the metals were transported in solution are unknown but the metal content need not have 

been high if the process was long continued.

Microscopic study shows that carbonized wood was replaced first by 

pyrite and then by copper sulfides in the following order: chalcopyrite, bornite, chalcocite, blue chalcocite with excess CuS, and 

covellite. Only pyrite and chalcocite are important quantitatively. 

The proportion of copper progressively increases and the proportion 

of iron and sulfur progressively decreases in each succeeding member 

of the series with the exception of sulfur in covellite. The amount 

of sulfide ion in solution seems to have been the critical factor determining the mineral content. The concentration of iron in solution 

was probably always greater than the concentration of copper because 

of its greater abundance in rocks and because it would be regenerated 

as iron-bearing sulfides were replaced by copper-bearing sulfides. 

Sulfide ion would be generated continuously by decay of organic 

matter or by reduction of sulfates by anaerobic bacteria, but the 

sulfide ion content of the solution fell as deposition of sulfides continued if the sulfur content of the minerals formed at each stage 

is a fair indication of the sulfide ion content of the solution. The 

solubility of iron sulfide is less than the solubility of copper sulfide, 

therefore pyrite began to precipitate first. Once the solubility 

product of copper sulfide was reached, however, mixed copper-iron 

sulfides began to precipitate and, as the sulfide ion concentration fell, 

sulfides progressively richer in copper were precipitated as a result 

of the greater affinity of copper for sulfide ion in acid aqueous solution. The mineralization process would be terminated by the exhaustion of sulfide or copper ion in solution or by changes in pH or 

oxidation potential. The very low uranium content (less than 0.01 

percent) of the black copper-bearing shale beds can be explained 

partly by the low concentration and relatively high solubility of 

uranium in acid swamp water (pH 4.0-4.5) and partly by precipitation of iron as a sulfide rather than as a flocculent hydroxide that 

could adsorb uranium. The near-absence of pitchblende, which might 

be expected to form in this environment, probably indicates that the 

solubility product was seldom exceeded because the oxidation potential 

was low enough. It must be tentatively concluded that the uranium 

and iron remained in solution or colloidal suspension in the excurrent 

waters to be deposited elsewhere. The writers are aware that many 

factors are ignored in the foregoing analysis.

The deposition of copper probably began with the establishment of 

anaerobic conditions, but it may have continued after the enclosing
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 385

sediments were buried and during the period of diagenetic changes. 

Many chalcocite nodules have a concretionlike structure that indicates slow, gradual growth. Isolated masses of chalcocite occur in the 

cores of some limestone nodules. In strict terminology, these deposits 

are not syngenetic but rather semisyngenetic or penecontemporaneous 

with sedimentation and diagenetic processes. The presence of sulfide 

concretions, the association of copper with rocks deposited in an environment of putrefaction (Faulnis) regardless of type, and the absence of copper in these same rock types deposited under other conditions strongly support a penecontemporaneous origin for the copper 

deposits. An alternate and, to the writers, less likely hypothesis 

would have the metals extracted from, ground waters by adsorption 

or reduction after burial of the enclosing rocks. A third, and untenable, hypothesis would have the copper deposits formed by the 

accumulation of detrital grains of copper minerals derived from preexisting deposits. The association of copper with carbonaceous sedimentary rocks deposited in foul water is unmistakable whatever the 

origin of the deposits.

URANIUM DEPOSITS

Uranium and vanadium in addition to copper were probably derived from Precambrian rocks, but unlike the copper deposits the deposits of uranium and vanadium are, in part, epigenetic.

Precambrian pegmatite and (or) quartz veins contain uraniumbearing minerals in the Petaca, Ojo Caliente, Elk Mountain, Kociada, 

and Gallinas Canyon districts. The uranium-bearing minerals include uraninite, gummite, uranophane, samarskite, betafite, f ergusonite, euxenite(?), and hatchettolite (Jahns, 1946, p. 61-68, 267, 277). 

These minerals contain niobium, tantalum, thorium, lithium, beryllium, or bismuth. The nearest of these districts, the Rociada district, 

is about 15 miles south of the Coyote district. Several radioactive 

anomalies have been detected in Precambrian and Pennsylvanian rocks 

by radioactivity surveys along the west side of the Coyote district. 

Part of the uranium came from the pegmatite but most of the uranium 

probably was derived from granitic rocks. Studies of the arkose derived from granite in the Powder River Basin of Wyoming show that 

possibly as much as two-thirds of the uranium in granitic rocks is 

present in disordered intergranular phases or is loosely held on the 

surface of mineral grains and can be released by mechanical disintegration without much chemical weathering (Harold Masursky, oral 

communication). Rankama and Sahama (1950, p. 634) report 3.963 

grams of uranium per metric ton in granitic rocks and the wide distribution of radioactive anomalies in the granite and simple granite 

pegmatite of the Precambrian areas near Guadalupita suggests that 

this average figure may be too low for this granite. Investigators 

report the average vanadium content of igneous rocks to be 150 and
386 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

315 grains of vanadium per metric ton (Eankama and Sahama, 1950r 

p. 596). The vanadium content of granite is much lower; investigators report between 1 and 30 grams per metric ton for granite or 

acidic igneous rocks (Eankama and Sahama, 1950, p. 596). The 

vanadium content is highest in gabbro and dolerite and part of the 

vanadium may have been derived from these rocks in the Precambrian 

terrane rather than for granite. Erosion of the source areas furnished 

enough uranium and vanadium to account for the amount concentrated in the deposits if an efficient process of concentration were 

available.

The uranium content of natural waters is very low except in the 

vicinity of uranium mines or districts where it may be from several 

hundred to several thousand parts per billion (109 ). The uranium 

content of natural waters is very sensitive to changes in pH. On the 

basis of present information, waters with a pH of 6.5 do not contain 

more than 1 to 6 parts per billion (Philip Fix, oral communication, 

1954) but waters with a pH of 5.5 may contain several hundred parts 

per billion although the average in areas of uraniferous rocks probably is on the order of 10. The uranium content of waters derived 

from the Precambrian terrane must have between the extreme limits 

of 1 and 100 parts per billion. A sample of domestic water from a 

Avell in the Guadalupita district contained 15 parts per billion and 

this figure does not seem unreasonable for natural waters from which 

the uraniferous shale beds were deposited. Considering the widespread occurrence of uraniferous rocks and sulfide deposits in the 

source areas, the waters in restricted drainages may have had a 

uranium content as high as 50 parts per billion and a pH as low as 

4.0 for short periods of time where oxidizing sulfide deposits lowered 

the pH. A large flow from an old tunnel draining the several square 

miles of a gold district has 80 parts per billion uranium and a pH of 

2.5 (Philip Fix, oral communication, 1954). Using a figure of 10 parts 

per billion, the syngenetic uranium deposits in shale or siltstone represent a concentration ratio of 10,000 to 20,000 and the epigenetic deposits in sandstone represent a ratio higher than 100,000. Such highconcentration ratios require efficient mechanisms of concentration operative in extremely dilute solutions. The adsorption mechanism 

postulated in this paper is believed adequate, although the adsorption 

of ferric hydroxide has not been fully tested. The scavenging power 

of activated charcoal and other compounds used in the laboratory to 

remove traces of deleterious ions from water shows the ability of some 

adsorptive compounds to remove metallic ions from extremely dilute 

solutions.

Uraniferous siltstone. These deposits, though generally similar to 

the copper-bearing shale, differ from it in several ways. The uraniferous siltstone has a higher uranium (0.01 to 0.02 percent) and
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 387

iron content and a much lower content of copper and carbonaceous 

matter than the black shale. The vanadium content is generally less 

than a few hundredths percent, only slightly higher than that of the 

copper-bearing shale. Copper is present as malachite, but sulfides or 

uranium minerals have not been found. Some uranium may be in 

detrital minerals containing rare earths, but most of it is probably 

adsorbed on iron oxides or on clay, mica, and carbonaceous material.

There is no reason to doubt a syngenetic or penecontemporaneous 

origin for the uraniferous siltstone. The uranium-bearing beds are 

persistent and the uranium content is relatively uniform. The differences in metal content between the uraniferous siltstone and the 

copper-bearing shale probably reflect differences in the conditions of 

deposition.

The hypothesis outlined in the following paragraph is suggested 

to explain the observed separation of uranium and copper and to 

indicate a direction for further research.

The uraniferous siltstone probably was deposited in a lagoon which 

had limited access to the sea. Anaerobic conditions were much less 

extreme than in the black shale and consequently the lagoonal water 

was more nearly normal. Both the pH and the oxidation potential 

were probably higher than in the stagnant-water environment in 

which the black shale was deposited. The absence of sulfide minerals, 

the lower copper content, and the higher uranium content of the siltstone probably are all indirect consequences of the low content of 

carbonaceous matter and hence the near absence of hydrogen sulfide. 

Under these conditions an effective mechanism for the precipitation 

of copper did not exist and the iron probably was precipitated as 

ferric hydroxide which readily adsorbs uranium rather than as a 

sulfide which does not. Uranium and copper minerals probably could 

not precipitate from the dilute near-neutral or slightly acid, mildly 

oxidizing waters and uranium was probably adsorbed on or coprecipitated with iron compounds such as ferric hydroxide that later dehydrated to form limonite. The precipitation of iron hydroxide and 

uranium was probably initiated by the mixing of excurrent water 

from the swampy flood plain and the stagnant-water basins in which 

the copper was deposited with the marine water of the lagoon. 

Colloids tend to be flocculated by sea water and recent data indicate 

that uranium is effectively removed from an acid, iron-rich solution 

(pH 2.9) from which ferric hydroxide is precipitating when the solution is neutralized (pH 6.0). The acidity of swamp water (pH 

4r-4.5) would be neutralized by mixing with sea water (pH 8.1-9.6) 

and the uranium would be adsorbed on colloidal ferric hydroxide 

coagulated by sea water. If the sedimentation rate in the lagoon was 

low, a considerable concentration of uranium might occur over a 

long period of time.
388 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Uraniwm-vanadiiim deposits in, sandstone. The uranium-vanadium deposits in sandstone differ in several important respects from 

the copper deposits and the uraniferous siltstone, notably in the much 

higher uranium and vanadium contents. The metals, like those in 

the other deposits, are believed to have been derived from Precambrian rocks, but these deposits are epigenetic and probably formed 

long after the sandstone was deposited. .A two-stage epigenetic origin 

is postulated.

Three processes by which the deposits could have formed are: (1) 

extraction and reconcentration from earlier low-grade syngenetic deposits by ground waters or hydrothermal solutions, (2) direct derivation from previous deposits or igneous rocks in the Precambrian 

source areas, or (3) addition of uranium and vanadium from a 

magnetic source. None of these possibilities can be disproved but the 

first is most probable and the last is unlikely.

The absence of uranium, vanadium, and copper along the major 

faults and the lack of a known magmatic source for these metals argue 

against a simple hydrothermal origin; however, hydrothermal solutions probably were active in the district as shown by the sericitization 

of sheared arkose and the replacement of detrital quartz and feldspar 

by calcite and hematite. No indication of the source of the hydrothermal solutions has been found; they may have been derived from 

the basalt plugs east of the district or from an unknown body at 

depth. A relationship cannot be demonstrated between sericitized 

ground and uranium deposits and the role of a hydrothermal component in the formation of the deposits can be questioned if the less 

clear-cut alteration changes described in the following paragraphs can 

be explained in another way.

Normal surface or ground water probably could not cause the 

replacement of quartz and feldspar by calcite. If calcite were introduced by a normal cementation process the sand grains should be 

nearly in contact, but the grains are corroded and isolated where 

replacement is advanced. The high manganese content of some calcite 

and the extensive replacement of quartz and feldspar in most uranium 

deposits seem to require the introduction of some calcite by chemically 

active fluids, perhaps at a higher temperature than normal for ground 

water. If this conclusion is correct it. is reasonable to ascribe the 

calcitization to an early effect of the solution responsible for the 

deposition of iron and uranium.

A direct relationship between the degree of hematitic alteration 

and the uranium is shown by the field and laboratory evidence. Hematite, nontronite, and the uraniferous ferric oxide are considered 

products of warm, chemically active ground water with a possible 

juvenile component. The presence of fresh feldspar and chalcopyrite 

on the outcrops suggests that the hematitic alteration is not related
COPPER ,AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 389

to surface oxidation. The iron in nontronite, a montmorillonite-type 

clay with ferric iron, cannot be added without destroying the structure 

of the clay mineral, for example, by the adsorption of iron on a 

montmorillonite clay in normal ground water. The iron must have 

been introduced at the time nontronite was formed and the formation 

of nontronite, except by the weathering of ferromagnesian minerals, 

probably requires a high ferric iron concentration and temperatures 

higher than those of normal ground waters.

To explain the field and laboratory evidence the writers tentatively 

postulate a two-stage epigenetic theory of origin: that the uranium 

deposits in sandstone are epigenetic and were leached and redeposited 

from earlier syngenetic uranium deposits containing from 0.005 to 

0.03 percent uranium. The evidence is not conclusive and the 

hypothesis is necessarily speculative.

Barren chemically active hydrothermal (?) solutions are believed 

to have migrated along the Laramide(?) faults and through permeable beds. The warm, active acid solutions sericitized the arkoses 

near the channels and leached iron, uranium, vanadium, and calcium 

from the low-grade uraniferous rocks through which they moved. 

Much of the uranium in the shale probably was loosely held by adsorption and hence was readily removed from the shale adjacent to 

the faults. The ability of such hydrothermal solutions to sericitize the 

rocks and to leach iron and uranium is shown by Phair's study (1952) 

of the altered radioactive quartz bostonite in the Front Range of 

Colorado. Phair found that an appreciable part of the uranium and 

iron were leached from the altered quartz bostonite dikes near the 

pitchblende deposits.

The acid solutions spread out in permeable sandstone beds and 

merged with the ground-water system whose circulation may have 

been reactivated by folding. The ground water with its juvenile (?) 

component flushed the sandstone and picked up more metal. The 

movement of the ground water was controlled by the permeability, 

porosity, and structure of the aquifers. In favorable sedimentary 

structures, uranium-vanadium and iron were deposited by change in 

pH, oxidation potential, complex-ion destruction, or flocculation of a 

colloidal suspension by dilution or mixing of solutions of different 

characteristics. It is suggested that uranium compounds could not 

form under the existing conditions and the uranium and rare earths 

were adsorbed on or coprecipitated with ferric hydroxide formed when 

the originally acid solution was neutralized by dilution or by reaction 

with calcite. The ferric hydroxide might have remained in suspension 

and continued to move with the ground waters until flocculated by 

some mechanism, such as mixing with waters containing dissolved salts 

or strained out by decrease in pore size of the sandstone. The flocculent precipitate may have continued to adsorb uranium from mi-
390 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

grating ground waters until the unbalanced charges were fully 

neutralized. Precipitation of ferric hydroxide begins at a pH of 

3.0-3.5 and virtually all the uranium will be removed from an ironrich solution by the time a pH of 6 is reached. The marked concentration of rare earth in uraniferous iron oxides (samples 251 and 89, 

table 11) might also be explained by adsorption or coprecipitation on 

ferric hydroxide because their behavior is generally similar to the 

behavior of uranium. Vanadium, where present, seems to be in the 

clay minerals or adsorbed on carbonized wood. Probably most of the 

vanadium is in a vanadium hydromica formed by incorporation of 

vanadium in the structure during the recrystallization of an existing 

clay mineral. The proportions of uranium, vanadium, and copper 

were controlled by the characteristics of the sediments and the density, 

temperature, pH, oxidation potential, and metal content of the 

solution.

The principal evidence against a syngenetic origin for the uraniumvanadium deposits in sandstone is the difficulty in explaining the 

sericitization of sheared arkose, the extensive replacement of quartz 

and feldspar by calcite and hematite, and the presence of both early 

sulfides containing ferrous iron and late ferric iron oxides containing 

uranium and rare earths. The uranium content of the uraniferous 

siltstone probably represents the maximum that can be expected in 

syngenetic deposits formed under conditions that existed in the 

Coyote district, unless the uranium content of the water was abnormally high at certain times. An abnormally high uranium content in 

water can be expected only where the water is acid and waters more 

acid than those that deposited the black shale (pH 4.0-4'.5) could 

hardly be expected in a terrane containing limestone. The uranium 

content of the black shale and uraniferous siltstone is low as comared to that of the sandstone deposits but the total amount is much 

greater. The uranium content of a syngenetic uranium deposit is 

limited by the sedimentation rate and by the suggestion that uranium 

is readily removed by absorption in slightly acid or neutral waters and 

hence is dispersed. The uranium content of the syngenetic deposits 

in the Coyote district is comparable to that of most other syngenetic 

deposits except for a few deposits like the presumably syngenetic 

Swedish kolm (ash-rich coal(?)) that have a much higher organic 

content.

Given a sufficient volume of solution and an efficient mechanism of 

concentration, uranium deposits might be formed from very dilute 

solutions, even from the ground waters existing in the district today. 

A water sample from a well in the central part of the district contained 

0.015 parts per million uranium (Zeller and Baltz, 1954, p. 11). Several high uranium concentrations in ponderosa pine in area E were not 

paralleled by anomalies in the bedrock and the uranium probably
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 391

was extracted from dilute ground water percolating through the 

sheared ground.

Although a few clastic grains containing chalcopyrite and a black 

substance have been seen in the uranium ore, microscopic examination 

reveals that virtually all the uranium is later than the calcite cement. 

The absence of niobium, tantalum, thorium, and other elements derived from the uranium-bearing pegmatite and the scarcity of the 

resistant minerals of these elements proves that the amount of uranium, vanadium, and rare earths contributed by the heavy minerals is 

negligible and indicates that most of the uranium was not derived 

from the pegmatite.

SUMMARY

Copper and smaller amounts of uranium and vanadium freed by 

erosion of the Precambrian terrane were transported to the basins of 

depositions in solution. The metals were removed from solution by 

different mechanisms operating under different conditions and this 

caused a partial separation of metals. The copper and part of the 

iron in solution were precipitated as sulfide in local anaerobic basins 

where carbonaceous shale was accumulating but most of the uranium 

and some iron remained in the still-acid excurrent water, either in solution or suspension until the pH approached 6 by dilution in lakes or 

lagoons or by reaction with limy sediments. A large part of the uranium probably was dispersed upon neutralization by absorption in 

clays but a considerable concentration of uranium occurred where the 

still-acid excurrent waters mingled with sea water in a marine lagoon 

where the sedimentation rate was slow. Here colloidal suspensions 

of ferric hydroxide would be coagulated and the remaining iron 

would be precipitated as ferric hydroxide. The uranium forced out 

of solution by increase in pH upon dilution would be absorbed on or 

coprecipitated with the iron hydroxide, which later dehydrated to 

form hematite or limonite.

Following Laramide( ?) orogeny warm acid ground waters with a 

chemically active (hydrothermal?) component migrating through 

sheared ground and along faults leached lime, iron, uranium, vanadium, and rare earths from the uraniferous sedimentary rocks and 

mingled with the ground waters in the sandstone aquifers. The 

waters were neutralized by dilution by reaction with the calcite cement 

of the sandstone, and uranium and rare earths were adsorbed on 

ferric hydroxide precipitated in favorable sedimentary structures.

COMPARISON WITH OTHER COPPER-URANIUM DEPOSITS

Copper-uranium deposits similar to the deposits in the Coyote district have been found in arkosic red beds, at least partly equivalent 

to the Sangre de Cristo formation, in several areas marginal to the 

ancestral Rocky Mountains.
392 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The Cutler formation contains small copper-uranium deposits in 

the Big Indian Wash district and the Lockhart Canyon-Indian Creek 

area of Utah (G. P. Dix, written communication, 1953). The Abo formation, equivalent in part to both the Cutler formation and the Sangre 

de Cristo formation, contains copper deposits in the Scholle, Zuni 

Mountain, and Jemez Springs districts of New Mexico. Uranium 

has been reported from the Scholle and Jemez Springs district. Small 

copper-uranium deposits have been found in the Maroon formation, 

a partial equivalent of the Sangre de Cristo formation in the Huerfano 

Park and La Veta Pass areas, Huerfano and Costilla Counties, Colo. 

The Garo property, Park County, Colo. (Gott, written communication, 1951), has produced a small tonnage of uranium ore from sandstone in the Maroon (?) formation. The Cutler, Abo, Sangre de Cristo 

and Maroon formations form a continuous arkosic red bed unit. The 

deposits in the Lockhart Canyon-Indian Creek area of Utah and the 

deposits in the Maroon formation of Colorado resemble the sandstone 

deposits in the Coyote district. The deposits near Garo and La Veta, 

Colo., and in the Coyote district have a similar structural setting 

along the flanks of the Sangre de Cristo Mountain system.

The occurrence of similar deposits in arkose deposits on the flanks 

of areas of Pennsylvanian uplift in widely separated areas suggests 

that other similar deposits exist. The similarities to the deposits 

of the Coyote district further suggest that ore guides at Guadalupita 

may be applicable to prospecting in other areas.

Copper deposits of the red-bed type, some of which contain small 

amounts of uranium, are present in the Poleo or Aqua Zarca sandstone lentils of the Chinle formation of Triassic age in the Cuba, 

Abiquiu, Cobre Basin, Copper City, and Gallinas districts, all of 

which surround the Nacimiento uplift in New Mexico. Uranium has 

been reported from the Chinle formation near Coyote north of the 

Nacimiento uplift and near Sabinosa along the Canadian River east 

of Las Vegas, N. Mex. These deposits are similar to those described 

in this report. Uranium deposits might be found in sandstone which 

does not contain appreciable quantities of copper in other red-bed 

copper districts.

GUIDES TO ORE DEPOSITS

The ore guides described below pertain to the Coyote district but 

they may have a wider application as indicated in the preceding 

section.

In prospecting for copper deposits special attention should be directed to parts of the Sangre de Cristo formation that contain abundant limestone or gray shale beds, because the ore-bearing black shale 

lenses are enclosed in gray shale and may grade into limestone.
COPPER AHD trRANTUM DEPOSITS, COYOTE DISTRICT, H. MEX. 393

The uranium deposits are in one or more brown or gray fluvial 

sandstone beds near the middle of the Sangre de Cristo formation. 

The outcrops are inconspicuous and a radiation counter is necessary 

for prospecting. Chalcopyrite, malachite, or black vanadium minerals 

and the distinctive pink color of the sandstone are the best ore guides 

but are easily overlooked. The most favorable places in sandstone 

are cut-and-fill structures, especially where the sandstone is coarse 

and contains abundant gray or black clay and foreign rock fragments, 

and carbonized wood. The red (or maroon) sediments probably can 

be ignored because evidence of mineralization has not been found in 

them.

CONCLUSIONS

The uranium content of the copper deposits and the uraniferous 

siltstone is too low to permit the recovery of uranium under presentday conditions. The uranium deposits in sandstone are small, but 

some production might be expected under favorable conditions. Further exploration probably will result in an increase of uranium 

reserves but no large deposits are expected. Geochemical prospecting 

methods are not suitable because of the steep dip of the beds and 

small size of the mineral deposits,

A large part of the value of the present investigation, in the opinion 

of the writers, lies in the genetic implications and practical application 

of the relationships discovered between copper deposits and the 

uranium-vanadium deposits. Some of the more important relationships, chosen for their possible application to the search for uranium 

deposits in other areas, are:

(1) The largest copper deposits are in local black carbonaceous 

shale lenses and contain a negligible amount of uranium.

(2) The only commercial-grade uranium deposits are low in 

copper. They occur in several gray or brown fluvial sandstone beds 

and are localized by small sedimentary structures similar to those in 

the Morrison and Shinarump formations. It is suggested that 

uranium deposits may be found in fluvial sandstone in other "redbed" copper districts but that the conditions favorable for the formation of commercial-grade uranium deposits are not the same as those 

favorable for red-bed copper deposits.

(3) The copper-bearing shale and the uraniferous siltstone are 

essentially syngenetic but the uranium-vanadium deposits in sandstone 

probably are much younger and may have formed from low-grade 

syngenetic deposits by ground water having a hydrothermal (?) 

component following Laramide( ?) orogeny. If this theory of origin 

is correct, the search for uranium deposits in arkosic red-bed units 

should be directed to areas where favorable sandstone beds are folded
394 <!ONTRIBUTIONS TO THE <SEOW)GY OF

or faulted, particularly where they surround younger intrusives. It is 

suggested that undiscovered uranium deposits may exist along the 

flanks of the present mountains where limy sandstone beds in sedimentary rocks of the Cutler, Abo, Sangre de Cristo, and Maroon 

formations or formations of similar lithology are exposed.

(4) It is suggested that the coprecipitation with or adsorption 

on ferric hydroxide offers a mechanism by which uranium deposits 

can form even where uranium compounds (minerals) cannot form. 

This process is operative in acid oxidizing solutions between a plj of 

3 and 6 and applies equally to syngenetic and epigenetic deposits. It 

is suggested that the ferric hydroxide is usually precipitated by 

reaction with calcite. The same adsorption process is believed to 

cause the concentration of the rare earths. The uranium in both the 

siltstone and the sandstone probably was concentrated by this mechanism. If the foregoing is true, the search for large low-grade uranium 

deposits need not be limited to sedimentary rocks rich in organic 

material but should be extended to certain fine-grained sedimentary 

rocks containing iron oxides formed in the manner described.

(5) The distinct pink color imparted by hematite introduced with 

uranium is the best ore guide to the sandstone deposits. The difference 

between it and the red, chocolate, or maroon color of the barren red 

beds is slight but distinctive.

LITERATURE CITED I

Bachman, G. O., 1953, Geology of a part of northwestern Mora County, N. Mex.:

U. S. Geol. Survey, Oil and Gas Inv. Map, OM137. 

Brill, K. G., Jr., 1952, Stratigraphy in the Permo-Pennsylvanian Zeugogeosyncline

of Colorado and Northern New Mexico: Geol. Soc. America Bull., v. 63,

p. 809-880. 

Edwards, A. B., 1947, Textures of the ore minerals and their significance:

Australasian Inst. Min. Metallurgy, Melbourne, 185 p. 

Gott, G. B., and Erickson, R. L., 1952, Reconnaissance of uranium and copper

deposits in parts of New Mexico, Colorado, Utah, Idaho and Wyoming:

U. S. Geol. Survey Circ. 219. 

Harley, G. T., 1940, The geology and ore deposits of northeastern New Mexico:

New Mexico Bur. Mines Bull. 15,104 p. ; 

Jahns, R. H., 1946, Mica deposits of the Petaca district, JRio Arriba County, N.

Mex.: New Mexico Bur. Mines Bull. 25,294 p. 

Lasky, S. G., and Wooton, T. P., 1933, The metal resources of New Mexico and

their economic features: New Mexico Bur. Mines Bull. 

Lindgren, Waldemar, Graton, L. C., and Gordon, C. H.,

7,178 p.

1910, Ore deposits of

New Mexico: U. S. Geol. Survey Prof. Paper 68, 361 p. 

Northrup, S. A., Sullwold, H. H., Jr., MacAlpin, A. J., and Rogers, C. P., Jr., 

1946, Geologic maps of a part of the Las Vegas basin,and of the foothills of 

the Sangre de Cristo Mountains, San Miguel and Mora Counties, N. Mex,: 

U. S. Geol. Survey, Oil and Gas Inv. Prelim. Map 54.
COPPER AND URANIUM DEPOSITS, COYOTE DISTRICT, N. MEX. 395

Phair, George, 1952, Radioactive Tertiary porphyries in the Central City district,

Colo., and their bearing on pitchblende deposition: U. S. Geol. Survey Trace

Elements Inv. Rept. 247, U. S. Atomic Energy Tech. Inf. Service, Oak Ridge,

Tenn. 

Rankama, Kalervo, and Sahama, T. G., 1950, Geochemistry: Chicago, Univ.

Chicago Press, 911 p. 

Read, C. B., and Wood, G. H., 1947, Distribution and correlation of Pennsylvanian

rocks in late Paleozoic sedimentary basins of northern New Mexico: Jour.

Geol., v. 55, p. 220-237. 

Zeller, H. D., and Baltz, E. H., Jr., 1954, Uranium-bearing copper deposits in the

Coyote district, Mora County, N. Mex,: U. S. Geol. Survey Circ. 334.

INDEX

Page

Abiquiu district_____.___________ 392 

Abo formation__________________ 392,394 

Abstract______________________ 343 

Adsorption of uranium____.. 383,386-387,389-391 

Aluminum____________________ 372-373 

Amphibolite 347

Analyses, chemical... .... 357-366,372-377,381

radiochemical ______._____.- 377 

rapid colorimetric______ _ __ __ 377

spectrographlc. ___ . _________ 372-377 

Aqua Zarca sandstone lentils_________ 392 

AlkoSK................. 349,351-353,356,385,388,390

Arkosic pebble conglomerate- _____. 352-353,357

sandstone__________ 352,370-372,378-379

Arsenic. ..__ _...._. 372,374,376,377,381

Azurite __ _-________________ 369

Barite-_ __.__.._...._._ 354

Barium______________________ 372-373 

Basalt flows__________________ 355 

Bernal formation _____________ 355 

Beryllium._.___ .... 376-377,385

Betafite.... . ........__....._____ 385

Big Indian Wash district____________ 392 

Bismuth.......................__... 372,376,385

Bornite -_____ __-____ __ 369,384 

Boron ..._....__ ..__.__.__ 374-375

Brachiopods. ...__ ... 350,354 

Bryozoans . ______________ 350

Calcite.._____.__ 354,369,380,388,389,390,391 

Calcium________________._ 372-373,389 

Carbonaceous shale ______ 356,357,367-368 

Carbonized wood _...'..... 369-370,383-384,393

Chacon______________________ 349 

Chalcocite .__............ 354,369,377,384,385

Chalcopyrite. _._ 371,379,380,384,388,391,393 

Chinle formation________________ 392 

Chromium.____._____________ 374-375 

Cobalt-.. _ - 374-375

Cobre Basin district.______..___.__ 392 

Copper 356-370,379,380-385,387,388,390-393 

Copper City district______________ 392 

Corals_______________________ 350 

Covellite.---___.______._._ 369,377,384 

Coyote Creek-... _____________ 344 

Cuba district_._____________.__ 392 

Cutler formation_______________ 392,394 

Cyclothems__________________ 354

Diabase_____________.__.___ 347

Digenite ____. ._.. 369

Diorite -- ._ _____ 347

Elk Mountain district 385

Equivalent uranium (ell)_________. 357-368,

371,372-373,381-382

Euxenite _.___.____________ 385

Page

Feldspar--. 380,388,390 

Fergusonite. .. _____.___ 385 

Fluviatile sandstone unit___________ 355,356

Gallinas district_____.______.____ 392 

Gallium _......... 374-375

Garo uranium property _____. ___ 392 

Geochemical prospecting anomalies. .. . 382 

Germanium.... 372,381 

Glorieta sandstone member...________ 347,355 

Gneiss.. - _ -__ __ 347 

Granite- 347 

Gummite_____ __________ 385

Hatchettolite_.___-_.___ ...._ 385 

Hematite ___ - 379,380,388,390,391,394 

Huerfano Park. __________ 392 

Hydrothermal leaching_____________ 389 

Hypselentoma................................. 354

Ionium.._ ...... 371,376

Iron._ _._.__ 371,372-373,383,388,389,391

Jarosa syncline . 347 

Jemez Springs district __________ 392

Kolm__________....________._ 390

La Veta Pass area___ _________ 392 

Leaching of uranium.. _________ 371 

Lead_......__.__.___... 372-373,377,381

Limestone.. _-_ -__ 349,354,357,366,392 

Limonite_____________________ 391 

Lithium _._. ........_...._ 385

Lockhart Canyon-Indian Creek area, Utah.... 392

Magdalena group__________ 346,349-350,356 

Magnesium__________________ 372-373 

Malachite 369,371,379,387,393

Manganese--_____ ______ 374-375,388 

Marble Falls limestone_____________ 350 

Maroon formation___.__________ 392.394 

Metatyuyamunite. _-__ 370,371,378-379 

Micaceous sandstone ..._______._- 357 

Mollusks.__________________._ 350 

Molybdenum.... _............ .... 374-375,381

Montmorillonite_________________ 389 

Morrison formation ______ .. 381,393 

Muscovite_______-___-_____. 380

Nacimiento uplift.. ._____-_ ... 392 

Nickel __........ 374-375

Niobium. _...... ........ .... 385,391

Nontronite___ ..... _____ 3

Ocate anticline__________________ 347

area.-______.- ___ .. . 345

Ojo Caliente district __________ 385

Paragenetic sequence 385

397
398 INDEX

Page 

Pegmatite - .. 347,385,391

Petaca district--.- 385

Phosphorus _________________ 372 

Pitchblende . 384

Potassium.. .____.............._.. 372-373

Poleo sandstone lentils.. ___________ 392 

Pyiite . . . 369,384

Quartz... . 380,385,388,390 

Quartzite.. ..._ . - __ 347

Radioactive equilibrium________ 371,381-382 

Rare earths ...................... 372,381,389-391

Rociada district.. . _ 385

Rocky Mountains_______________ 345 

Roscaelite - - 379 

Rowe-Morageosyncline-.---_..___...... 346

Samarskite__._______......___._ 385

San Andres formation_____________ 347 

Sandia formation . . . - 349 

Sandstone .... 349,356,371,372,379,381,388-394

Sangre de Cristo formation . 346, 

347,349-355,356,378,391-394

Santa Rosa sandstone - 355 

Scandium ...._........ . ..._ 376-377

Schist.. _ _._ 347

Scholle district...._ .... ..... .. 392

Selenium. 357-358,360-363 

Shale. 349,366,369,371,378,379,386,387,391,392 

Shale, copper-bearing carbonaceous 345

Page

Shlnarump formation____________ 381,393 

Silicon. 372-373

Siltstone 354,356,357,370,379,386-387,393 

Silver. 374-375

Smithwick shale ____._-___..__ 350 

Sodium... . 372-373

Strontium............... .._.__.._.._.._ 374-375

Tantalum . .... . .. 385,391

Thorium 385,391

Titanium... 374-375

Tourmaline . . . .. . ... .. 380 

Turquillo Valley- ___.___....... 345

Unconformity ...___________ 349 

Uraninite -_ - - 369,379,385 

Uranium_...... - _ ._ 356,

370,371,378-380,382,383,385-386,388-394 

Uranium daughter elements . 377 

Uranophane ____._______ 385

Vanadium . 370,376-377,378,379,381,385-391,393 

Vanadium oxide 359-363,381

Vitrain. . . 369

Volborthite. __ _ ......_ 369

Volcanic plugs. ______________ 355

Water, uranium content___________ 386

Zinc _._........ 374-375

Zirconium___________________ 374-375 

Zuni Mountain district____________ 392

o
Description of Indicator 

Plants and Methods of 

Botanical Prospecting for 

Uranium Deposits on the 

Colorado Plateau

By HELEN L. CANNON

A CONTRIBUTION TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-M

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 50 cents (paper cover)
CONTENTS

Page

Abstract_____-____--_________-_-_-_____________________-_-___--- 399

Introduction-_____________________________________________________ 399

Colorado Plateau soils and ground-water conditions___________________ 400

Plants in relation to ground water________________-_______-----_-_-_- 401

Plant associations and indicator plants on the Colorado Plateau-________ 402

How to prospect by plant analysis.__________________________________ 405

How to use indicator plants in prospecting____________________________ 407

Selected bibliography ______________________________________________ 411

Illustrations and descriptions of indicator plants.______________________ 413

Glossary__ _ _____________________________________________________ 514

Plant index_______________________________________________________ 515

ILLUSTRATIONS

Page 

FIGURE 74. Dead plants of Astragalus paltersoni useful in fall and

winter in deciding where to drill. _______________ 409

75. Index map of part of the Colorado Plateau showing

location of mining districts. _ ____________________ 410

76,77. Astragalus pattersoni A. Gray, or Patterson poisonvetch___________________________________ 414, 415

78, 79. Astragalus preussi A. Gray, or Preuss poisonvetch.. 416, 417 

80, 81. Astragalus thompsonae S. Wats., or Thompson loco 418, 419 

82, 83. Astragalus confertiflorus A. Gray, or blue poisonvetch- 420, 421 

84, 85. Astragalus bisulcatus (Hook.) A. Gray, or two-grooved

poisonvetch.___________________________ 422, 423

86, 87. Astragalus missouriensis Nutt., or Missouri milkvetch- 424, 425 

88, 89. Astragalus lonchocarpus Torr., or long-seeded milkvetch. ________________________________ 426, 427

90, 91. Astragalus dodgianus Jones, or Dodge milkvetch_____ 428, 429

92, 93. Astragalus tenellus Pursh, or looseflower milkvetch- 430, 431 

94, 95. Astragalus aculeatus A. Nels., or spiny milkvetch__ 432, 433 

96, 97. Allium acuminatum Hook., or tapertip onion, and related species_-_______--__-___--__-__-----____ 434, 435

98, 99. Calochortus nuttalli Torr. & Gr., or Sego lily, mariposa_____________________________ 436,437

100, 101. Zigadenus gramineus Rydb., or grassy deathcamas 438, 439 

102, 103. Stanleya pinnata (Pursh) Britt., or desert princesplume. 440,

441

104, 105. Lepidium montanum Nutt., or mountain pepperweed.. 442,

443

106, 107. Lepidium lasiocarpum Nutt., or hairy-pod pepperweed. 444,

445

108, 109. Sisymbrium altissimum (L.) Britt., or tumblemustard. 446,

447

in
IV CONTENTS

Page 

FIGURE 110, 111. Cryptantha flava A. Nels., or cryptanth, and related

species______________________________________ 448, 449

112, 113. Oenothera caespitosa Nutt., or tufted evening-primrose- 450,

451

114, 115. Oenothera albicaulis Pursh, or whitestemmed eveningprimrose. ____________________________________ 452, 453

116, 117. Eriogonum inflatum Torr., or deserttrumpet eriogonum _ 454,

455 

118, 119. Eriogonum fusiforme Small, or deserttrumpet______ 456, 457

120, 121. Eriogonum ovalifolium Nutt., or silver plant or cushion

eriogonum___________________________________ 458, 459

122, 123. Eriogonum umbellatum Torr., or sulfur eriogonum __ 460,461 

124, 125. Eiymus salina Jones, or salina wildrye_____________ 462, 463

126, 127. Stipa comata Trin. & Rupr., or needleandthread_____ 464, 465

128, 129. Oryzopsis hymenoides (Roem. & Schult.) Ricker, or

Indian ricegrass______________________________ 466, 467

130,131. Aster venustus Jones, or woody aster_______________ 468,469

132, 133. Townsendia incana Nutt., or hoary townsendia-_____ 470,471

134, 135. Aplopappus armeriodes A. Gray, or goldenweed_____ 472, 473

136, 137. Grindelia squarrosa (Pursh) Dural, or curlycup gumweed______________________________________ 474, 475

138, 139. Senecio longilobus Benth., or threadleaf groundsel __ 476,477 

140, 141. Euphorbia fendleri Torr. & Gr., or sandmat or fendler

euphorbia and related prostrate species __________ 478, 479

142, 143. Mentzelia multiflora (Nutt.) A. Gray, or desert blazingstar_-______________--_____-___----_------ 480, 481

144, 145. Solidago petradoria Blake, or rock goldenrod_ _______ 482, 483

146, 147. Tetradymia spinosa Hook. & Arn., or cottonthorn

horsebrush._________________________________ 484, 455

148, 149. Cowania stansburiana Torr., or Stansbury cliffrose___ 486,487 

150, 151. Purshia tridentata (Pursh) DC., or antelope bitterbrush_______________________________ 488, 489

152, 153. Hedysarum boreale Nutt., or northern sweetvetch __ 490, 491 

154, 155. Castilleja integra Gray, or Indian paintbrush or paintedcup_______________________________________ 492, 493

156, 157. Plantago purshi Roem. & Schult., or woolly indianwheat_ 494,495 

158, 159. Atriplex confertifolia (Torr.) S. Wats., or shadscale

saltbush_________________________________ 496, 497

160, 161. Atriplex canescens (Pursh) Nutt., or fourwing saltbush- _ 498,499 

162, 163. Sarcobatus vermiculatus (Hook.) Torr., or black greasewood-__________________--__--____--___-_-_- 500, 501

164, 165. Ephedra sp., or jointfir or mormon tea____________ 502, 503

166, 167. Opuntia engelmanni Salm-Dyck, or Engelmann pricklypear, and other species_______________________ 504, 505

168, 169. Mirabilis multiflora A. Gray, or Colorado four-o'clock. 506,507 

170, 171. Fraxinus anomala Torr., or singleleaf ash___________ 508, 509

172, 173. Hymenopappus filifolius Hook., or fineleaf hymenopappus_____-_______-___-_____-----_---_---_---_ 510,511

174, 175. Actinea acaulis (Pursh) Spreng., or stemless actinea 512, 513
DESCRIPTION OF INDICATOR PLANTS AND METHODS

OF BOTANICAL PROSPECTING FOR URANIUM DEPOSITS

ON THE COLORADO PLATEAU

By HELEN L. CANNON

ABSTRACT

Two methods of botanical prospecting for uraniferous deposits on the Colorado Plateau are useful in semiarid country in prospecting for ore-bearing beds 

at depths as much as 70 feet. By one method, tips of tree branches are sampled 

and analyzed for uranium content. Generally more than 1 part per million of 

uranium in the ash indicates favorable ground for further geologic exploration. 

The second method, that of mapping indicator plants, is used in semiarid parts 

of the Plateau at low altitude. The distribution of indicator plants is controlled by the availability of chemical constituents of the ore, such as selenium, 

sulfur, and calcium. Plants of the genus Astragalus are most useful in prospecting for uranium deposits of high selenium content; plants of the genera Allium 

and Eriogonum are most useful as indicators of deposits with a high sulfur 

content. Fifty indicator plants commonly associated with carnotite deposits 

and plants tolerant of mineralized ground are described and illustrated.

INTRODUCTION

Two methods of botanical prospecting for uranium deposits have 

been applied on the Colorado Plateau. One method is based on a 

chemical analysis for the uranium content of deep-rooted plants that 

absorb uranium from the ore bodies; the other is based on distribution 

studies of indicator plants that are commonly associated with uranium 

deposits. A third method, that of determining morphological or 

physiological changes in plants growing in ore deposits, has been discarded in this area. The general principles on which methods of prospecting were developed are described in earlier reports (Camion, 1952; 

1953).

The first method makes it possible to detect uranium-bearing material through a maximum of 70 feet of barren rock by means of tree 

root-systems, which act as conduits for the upward migration of 

soluble salts to the ground surface. The method is applicable where 

the mineralized bed crops out in a broad, flat bench so that plant 

samples can be collected on a grid pattern to outline mineralized zones 

at depth; and also where the mineralized bed crops out in a sharp cliff 

that is commonly obscured by talus or slump. Here a line traverse

399
400 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

parallel to the cliff may be desirable. The samples are either analyzed 

in the field by a quick test for uranium or are sent to a chemical laboratory for quantitative assay.

Prospecting by indicator plants is the less expensive of the two 

methods and consists of mapping the areal distribution of key indicator plant species. Indicator plants and also plants tolerant of 

mineralized ground, and therefore common in uranium districts, are 

described, illustrated, and evaluated in this report. The information 

has been compiled not as a key for species identification but as a sorting 

device that will enable geologists and prospectors to identify, in a preliminary way, the plants that may be useful in prospecting an area. 

The information was gathered while botanical prospecting studies 

were being made on the Colorado Plateau by the U. S. Geological 

Survey on behalf of the Division of Kaw Materials of the U. S. 

Atomic Energy Commission.

A part of the section on the use of absorber plants was taken from 

unpublished reports by Albert J. Froelich of the Geological Survey. 

The plants collected during the study were identified by T. H. Ivearney, 

formerly of the U. S. Department of Agriculture; A. H. Holmgren, 

Utah State Agricultural College; R. J. Davis, University of Idaho; 

and E. F. Castetter, University of New Mexico. The line drawings 

were made from pressed plant specimens by Maxine Heyl, Ann Pettigrew, and Catherine B. Hayes. The plants were photographed in the 

field by the writer, with the part-time assistance of Edward Clebsch.

COLORADO PLATEAU SOILS AND GROUND-WATER

CONDITIONS

Plant associations on the Colorado Plateau depend on soil and 

ground-water conditions. Because the climate of the Plateau is semiarid, little residual soil forms except in the mountains and on the 

higher mesas. The sandy and clayey soils are commonly closely related to the alternating beds of sandstone and shale from which they 

are derived (Shreve, 1951, p. 16). The texture and salinity of the 

soil associated with the various stratigraphic Units at lower altitudes 

largely determine the plants that grow in them. The most common 

soluble salts in a desert soil are carbonates, chlorides, and sulfates of 

calcium, magnesium, and sodium (Shreve, 1951, p. 16). Many desert 

plants tolerate large amounts of these compounds.

In the semiarid Colorado Plateau the dependence of plants either 

directly or indirectly on ground water requires a study of the ground 

water in areas where plants are studied. Water beneath the ground 

surface occurs in the zone of saturation and the zone of aeration 

(Meinzer, 1923, p. 29-95). The upper surface of the ground water 

occurring in the zone of saturation is called the water table. Owing 

to capillarity, however, the earth is moist for a distance of several
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 401

feet above the water table. The thickness of this capillary fringe 

may range from 8 or 10 feet in fine silt or sand to 3 or 4 feet in coarse 

clean sand. Roots of most phreatophytes terminate in the capillary 

fringe (White, 1932, p. 3-1). The zone of aeration extends from the 

water table to the surface. Other zones of saturation may occur above 

the main water table where lenses or layers of impermeable material 

prevent movement of water down to the main water table. Such 

zones are termed "perched water tables" and may be temporary or 

permanent.

Perched water tables are common on the Colorado Plateau where 

the ore-bearing sandstone beds are underlain by impervious clay (D. A. 

Phoenix, written communication, 1952). Locally, clay seams may 

prevent the downward movement of ground water and thus prevent 

the oxidation of primary ores even at relatively shallow depths.

PLANTS IN RELATION TO GROUND WATER

Perennial plants that obtain water from the water table, especially 

in arid regions, in contrast to plants that utilize soil moisture above 

the water table are called phreatophytes (Meinzer, 1923, p. 95; 1927, 

p. 1; Robinson, in preparation). Plants that utilize soil moisture 

where it is available in the zone of aeration but can withstand long 

periods of drought are called xerophytes. Many, like the cactus, have 

short roots and thickened stems or leaves that are well protected from 

evaporation and designed for water storage. A third group, called 

ephemeral, endures adverse periods as bulbs or as seeds beneath the 

soil, bursts into bloom suddenly after a period of heavy rainfall, sets 

fruit, and disappears. All three groups grow in uranium districts of 

the Colorado Plateau and are described in this report.

Such phreatophytes as Salix (willow), Tamarix (tamarisk), Cowania (cliffrose), /Shepherdia (buffaloberry), Sarcobatus (greasewood), Chrysothwmnus (rabbitbrush), and Hedysarum (sweetvetch) 

are typical indicators of ground water. Normally, on the Colorado 

Plateau juniper and piny on are also phreatophytes and, in areas 

where the ore-bearing bed contains water, are useful for uranium 

analysis.

Generally xerophytes are tolerant of soils that have a high salt 

content, and these are therefore tolerant of and in some cases indicative 

of shallow uranium deposits. Where the water table is below the ore 

zone, Atriplex confertifolia (shadscale), a xerophyte, may be used as 

the sampling medium.

In areas where the capilliary fringe extends nearly to the surface 

and soluble salts from sulfide ore bodies have migrated in large quantities to surface soils, ephemeral indicator plants may flourish and 

become useful in prospecting. For example, wild onions, which are
402 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

sulfur indicators, have indicated uranium at depths of 20 to 30 feet 

beneath the surface.

PLANT ASSOCIATIONS AND INDICATOR PLANTS ON 

THE COLORADO PLATEAU

The distribution of major plant associations on the Colorado Plateau 

is controlled by many factors including slope, altitude, ground-water 

conditions, and texture and salinity of the soil. Few uranium deposits occur at altitudes of more than 9,000 feet in the spruce-fir and 

alpine life zones. At altitudes of 7,400 to 9,500 feet ponderosa pine 

and Douglas-fir forests predominate. These include the following 

shrubs and trees:

Pinus ponderosa, ponderosa pine 

Abies concolor, white fir 

Pseudotsuga taxi-folia, Douglas fir 

Juniperus scopiilontm, Rocky Mountain juniper 

Populns tremuloides, quaking aspen 

Quercus gamltetti, Gambel's oak 

ArctostapJiylos pungens, manzanita 

Ceanothus fendleri, buekbrush 

AmelancMer alnifolia, shadbush 

Sympltoricarpos oreophilus, snowberry

Lack of sunlight causes a poor distribution of herbaceous plants and 

consequently of indicator plants in this association. Here tree sampling has been used successfully as a method of prospecting.

From 5,000 to 7,400 feet pinyoii and juniper forests predominate 011 

foothill pediments and on mesas capped with sandstone that contains 

sufficient water. The shrubs that occur in or near the fringes of these 

forests prefer a light sandy soil and water of low salt content. They 

include:

Cowania stanslmriana, cliffrose 

Cercocarpus montanus, mountain mahogany 

Ephedra viridis, Mormon tea 

HaJwnia fremontU, holly grape 

Rtius trilobata, skunkbush

They also include low growth of Gambel's oak. The herbs in this 

altitude range include many of the plants described in this report. 

Pinyon and juniper have been used commonly in plant analysis 

prospecting.

From altitudes of 3,500 to 5,000 feet the plants are characteristic of 

the northern desert flora and are divided into two major groups; 

namely, those that are tolerant of alkali soils and those that are not. 

In loose soils of low-salt content, sagebrush predominates. Sagebrush is frequently associated with or replaced in drier areas by:
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 403

Atriplex canescens, saltbush 

Grrayia spinosa, liopsage , 

Coleogyne ramosissima, blackbrush 

Chrysothamnus puberulus, little rabbitbrush

The sagebrush association is common on pediments and alluvial fans 

at the base of mountains and is the characteristic flora in areas underlain by the Dakota sandstone.

In low areas of drier soils and of higher salt content within this 

altitude range, the shadscale association is dominant. Atriplex confertifolia, or shadscale, is shallow rooted and depends upon moisture 

in the surface soils for its water supply. Woody plants belonging to 

the association include:

Tetradymia spinosa, horsebrush 

Artemisia spinescens, budsage 

Gutierresia sarothrae, snakeweed 

Eurotia lanata, winterfat.

The shadscale association is characteristic of sandstone exposures of 

the Summerville, Chinle, and Mancos formation at lower altitudes. 

In heavy saline soils of high moisture content, an association of Sarcobatus vermicul-atus, or greasewood, prevails. The association is 

generally restricted to low, poorly drained salt flats, and the presence 

of greasewood indicates saline ground water at depths of not much 

more than 15 feet. In areas where the water table is at or near the 

surface, seepweed or pickleweed may be the only plants able to grow 

in the highly alkaline environment.

The importance of these associations in prospecting lies not in 

their normal association with a given geologic formation of the Colorado Plateau but in their abnormal occurrences as island communities 

indicative of greater or less soil salt or moisture content than the 

endemic association. On the higher benches where ground water of 

low alkali content is available in the sandstone, little change in the 

general appearance of the juniper-pinyon flora can be seen around 

carnotite deposits. In drier areas at lower altitude, however, the 

general appearance of the flora in the carnotite districts is commonly 

similar to the flora of a salt flat. Instead of an association in which 

sagebrush (Artemisia tridentata) , hop sage (Grayia spinosa), or 

saltbush (Atriplex canescens} is dominant, it is largely a shadscale 

(Atriplex confertifolia] association capable of growing in soils of 

high salt content.

Patches of indicator plants, controlled in distribution by the availability of specific chemical elements, are commonly found within 

areas of shadescale and snakeweed. These plants that indicate mineralized ground are not all controlled by the same chemical element
404 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

and are usually common weeds rather than unusual plants. The 

control of the species may be pH variations; a change in the availability of phosphorus, calcium, or other major constituent necessary 

for plant growth; or a true dependence on a minor element, such as 

selenium or sulfur.

Selenium-indicator plants are the only group definitely known to be 

completely dependent on the presence or absence of a single element. 

The selenium indicators described by Trelease and Beath (1949) include a tribe of Astragalus species, Stanleya, Aster venustus, Oryzopsis, and several other plants. These indicators absorb large amounts 

of selenium, sufficient to poison sheep and cattle. Because selenium 

is present in many uranium ores, these plants are in some places useful 

guides to the location of uranium deposits.

The distribution of many sulfur and calcium-absorbing plants reflect the presence of gypsum in the soil. Plants that require large 

amounts of these elements for their growth include the lily and mustard families, at least a part of the buckwheat family, and various 

isolated genera. Because uranium ores commonly contain sulfides 

from which gypsum may be produced in the surface soils, gypsumindicators may also be found in the vicinity of uranium deposits.

Both selenium and sulfur occur in all sedimentary rocks, but the 

concentration varies greatly between different stratigraphic units and 

in different regions. For instance, the selenium content of western 

shales of Cretaceous age is high and remains relatively constant in 

particular beds or strata for several hundred miles. Both elements 

may also be concentrated in tuff, coal, or sulfide ore deposits. The occurrence of selenium and sulfur, on the other hand, in amounts less 

than 10 ppm in barren sandstones of Triassic and Jurassic age contrasts sharply with concentrations of 100 to 1,000 ppm in ore deposits 

in the same formations. For this reason, the distribution of indicator 

plants along the outcrops of these sandstones forms conspicuous 

patterns.

Besides an increase in total selenium in camotite ore, experimentalplot studies indicate that the proportion of water-soluble selenium 

is increased in the presence of camotite. This results in a marked 

tendency for the Astragalus group to grow in the vicinity of ore 

deposits where it is possible for them to absorb selenium in concentrations of several hundreds or perhaps thousands of parts per million 

from ground containing only 2 ppm total selenium. Stanleya, however, appears to substitute selenium for sulfur in the plant metabolism 

and is capable of extracting and concentrating large quantities of 

selenium from gypsum containing only small amounts, but it is not
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 405

capable of extracting large amounts of selenium from a carnotite ore. 

For this reason Stanleya is not a primary indicator of seleniferous 

uranium ore but may be used in some areas as a secondary indicator of 

mineralized ground water.

Many of the other plants found near uranium deposits probably 

reflect changes in acidity and in the availability of major plant nutrients. Experimental studies show that larger amounts of calcium and 

phosphorus are available to plants in the vicinity of carnotite deposits 

than in barren ground. This favors an increase in the number of the 

calcium absorbers, Afentselia, Cryptantha, and Oenothera, around ore 

deposits. The phosphorus absorbers, Eriogonum, Allium, Calochortus, and mustards, are encouraged by the increase in available phosphorus and sulfur as indicators of uranium ore.

In addition to those plants that act as indicators of mineralized 

ground or can be used in alluvial prospecting, many plants are tolerant 

of mineralized ground. Sixteen of these plants are described in this 

report. In general, the plants best adapted to soils of high mineral 

content are those having an acid cell sap that enables the plant to 

absorb and neutralize alkali elements. For example, shadscale absorbs large quantities of salts without harm to the plant growth. 

Plants of the goosefoot, rose, and cactus families are also tolerant of 

highly mineralized ground on the Colorado Plateau.

HOW TO PROSPECT BY PLANT ANALYSIS

Trees or shrubs of extensive root habit may be analyzed for uranium 

content to denote areas of mineralized ground. Basic information 

on the rate of absorption of uranium by plants must be gathered for 

control in the area to be prospected. Commonly a collection of 

samples from a variety of species in close proximity is made in an area 

that is known to be mineralized from drill-hole data or surface outcrop 

but is uncontaminated by surface workings. This collection is compared with similar collections in an area known by past exploration 

to be unmineralized.

In general, uranium is best absorbed by plants with a fairly acid 

cell sap and high cation exchange capacity in the root. Experimental 

work shows that plants belonging to this category absorb large 

amounts of calcium, selenium, and (or) sulfur along with uranium, but 

very little potassium. Conversely, potassium absorbers absorb only 

small amounts of uranium. Plants that have been used in sampling 

programs belong largely to the rose and pine families.
4,000-6,000

406 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The trees and shrubs commonly sampled on the Colorado Plateau 

are as follows:

Altitude

(feet) 

Pinus ponderosa Dougl. (ponderosa pine)______________

Pseudotsuga taxifolia Britt. (Douglas fir)___________. 7Oftn_onnn 

AUes concolor Lindl. (white fir)_______________ ' 7,000-9,000

ShepJierdia rotundifolia Parry (buffaloberry)___________

Pinus edulis Englm. (pinyon) , 

T -, n /-^ i ...-,... t \ b,UUU 7,UUU Jumperus scopulorum Sarg. (Rocky Mountain juniper)_ '

utahensis Sarg. (Utah juniper)____________________

monosperma Engelm. (oneseed juniper)______ 

Coivania stansburiana Torr. (cliffrose)________________

Atriple® confertifolia (T. & F.) S. Wats (shadscale)__

The sampling medium and sampling interval are determined after 

a study is made of the extent of mineralized outcrop, size, and habits 

of the known ore bodies, and the relation of the ore-bearing bed to 

the water table and to plant roots. A plant species that has an extensive root system which penetrates to the ore horizon is chosen as the 

sampling medium. If information concerning the absorption of 

uranium by that species is not available, preliminary samples are collected to determine the lowest value indicative of mineralized ground. 

Several trees are also selected for periodic sampling to test the consistency of laboratory results and seasonal variation. Branches on a 

given side of the tree are connected directly with roots on that side of 

the tree; thus the uranium content may vary greatly from one side of 

the tree to the other. To obtain the most representative sample, 

therefore, it is recommended that branch tips be collected from all 

sides of the tree. The method is applicable where the uranium-bearing bed is not more than 70 feet beneath the surface.

The sampling interval depends in part upon the objective of the 

project. On a broad flat bench a grid-pattern spacing adequate to 

detect either ore bodies or mineralized halos is desirable. The resulting values may be contoured to show areas favorable for geologic 

exploration. An initial sampling program on a 200- to 250-foot spacing is usually adequate. Later fill-in samples on a 50-foot spacing 

may be collected in anomalous areas. A short interval of 15 to 30 

feet is recommended for sampling across talus-covered outcrop.

In the fluorimetric laboratory procedure, pint samples (about 75 

grams) of material are required for an analysis. Samples are shipped 

to a well-equipped, uncontaminated laboratory for analysis. Two 

fluorimetric methods of analysis for small amounts of uranium in 

plant ash have been developed by the Geological Survey laboratories 

(Grimaldi and others, 1952 and 1954). By the direct fluorimetric 

method the plant ash is mixed with a fluoride-carbonate flux and the
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 407

amount of fluorescence of the bead or button is measured photoelectrically by a transmission fluorimeter. This method is satisfactory 

for samples that contain little or no manganese or other elements that 

may act as a quencher and reduce the amount of fluorescence of the 

uranium bead. When quenching elements are present in quantity, 

the extraction-fluorimetric method is employed. By this method the 

uranium is separated chemically from interfering elements before the 

button is made. The procedure is considerably longer and more expensive than the direct fluorimetric method. Analytical results are 

stated in terms of parts per million of uranium in the plant ash. The 

precision to be expected from the laboratory for values from 0.3 to 

5.0 ppm of uranium is a standard deviation of 0.5 ppm. A chromatographic field test by which many more analyses may be made in a 

day has also been developed in the Survey laboratory.

The detection of radioactivity in plant ash by alpha count has been 

used by Anderson and Kurtz (1955) in prospecting for pitchblende 

vein deposits. It is possible by this method to detect variations in 

uranium content above 10 ppm. Interferences from natural radioactivity due to other elements in the plant ash apparently mask radioactivity due to uranium below this amount. Therefore, the method 

is probably not applicable to prospecting for carnotite-type deposits.

Although the average amount of uranium absorbed by plants rooted 

in ore varies slightly, depending on the type of ore and degree of oxidation and also on the species collected, an average figure of 1 ppm 

in the ash has been used in many areas sampled as an arbitrary cutoff. 

Contents of uranium above this amount are ^considered anomalous 

and indicate favorable and possibly mineralized ground.

In places where grid sampling is used, isograms of the assay data can 

be drawn on base maps. Where rim-sampling is employed, areas of 

favorable rim can be indicated for back-from-rim drilling. The 

anomalies, however, delimit only areas of unusual uranium content in 

the vegetation cover. They do not show a positive correlation between 

the amount absorbed by the plants and the grade of the ore or the depth 

to ore. The interpretation of the data depends on the validity of the 

laboratory analysis, the size of sample interval, and the studies that 

are made of geologic and topographic field relations. Much depends 

on the comprehension by the prospector of the geologic environment. 

Plant analysis is an additional prospecting tool to be used with geologic interpretation in the search for ore.

HOW TO USE INDICATOR PLANTS IN PROSPECTING

The use of a plant as an indicator in prospecting for uranium is 

based on the assumption that its distribution is affected by the avail-
408 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ability of the chemical constituents of the ore. The first step, then, 

in a new area is to study the plants growing in ground known to be 

mineralized. The information on indicator plants included in this 

report was established by marking off 10- by 5-foot areas over known 

ore bodies in a number of districts, and similar areas over unmineralized parts of the same bed with similar exposure and slope. Complete 

lists of plants in each plot were made, and final lists of indicator and 

tolerant plants were derived from them. When any of the plants 

illustrated in this report are observed in a new area, a careful study 

of their distribution should be made to determine whether and how 

they can be used in prospecting.

After such studies have been made, similar plant associations may 

be sought along the outcrop of an ore-bearing bed through reconnaissance prospecting. Caution must be exercised because the plants 

are, of course, all common weeds and may be found in places where 

no uranium occurs. Selenium plants, for example, grow wherever 

there is a small amount of selenium in the soil. Sulfur plants may 

grow w^herever gypsum is present. The plant species described in 

this report, nevertheless, have been noted repeatedly in close association with uranium ore deposits on the Colorado Plateau and have been 

used successfully in uranium prospecting.

Indicator plants are best studied and mapped when in bloom. For 

this reason, the approximate blooming date has been given for plants 

growing at an altitude of 4,500 feet and near the 39th parallel. The 

blooming time for a given plant would be somewhat earlier farther 

south or at lower altitudes, and later farther north or at higher altitudes. In general, ephemeral plants such as the lily family are available for study only in the spring or early summer. Although many 

of the Astragalus species bloom in April, they can be recognized from 

the dead seed pods and stalks and can be used in prospecting throughout most of the year (fig. 74). Stanley a and other mustards bloom 

throughout most of the summer. Many Composites, Plantago, and 

Mentzelia bloom in the late summer and fall.

The plants shown in this report (figs. 76-175) are given in order of 

their importance in prospecting. Those that have aided directly in 

the location of uranium ore have been marked primary indicators; 

those that occur in plant associations known to indicate favorable 

ground are listed as secondary indicators; and common plants known 

to be very tolerant of mineralized ground are included last. It is not 

necessary to identify species of many genera because all species may 

act as indicator plants. Species identification of these genera has not 

been given. Common and scientific names of most species are spelled 

in accordance with Kelsey and Dayton (1942). Descriptions have
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 409

FIGURE 74. Dead plants of Astragalus pattersoni useful in fall and winter in deciding

where to drill.

been written as simply as possible; the technical terms are listed in a 

glossary. All information of interest in the use of these plants has 

been compiled from the references listed. Mining districts (fig. 75) 

in which these plants have been observed are given as a general guide 

to their areal distribution.
410 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

MINING DISTRICTS 

1 Poison Basin 

Uinta Basin 

Meeker

4 Rifle

5 San Rafael

6 Green River

7 Thompson

8 Moab 

Gateway

10 Paradox

11 Uravan

12 Bull Canyon

13 Gypsum Valley

14 Placerville

15 Rico

16 La Plata

17 Cortez

18 Slick Rock

19 Monticello

20 White Canyon

21 Circle Cliffs

22 Henry Mountains

23 Kaiparowits

24 Monument Valley 

Ship Rock

26 Chilchinbito

27 Chuska

28 Defiance

29 Little Colorado

30 Grants

31 La Ventana

FIGURE 75. Index map of part of the Colorado Plateau showing location of mining districts.
SELECTED BIBLIOGRAPHY

Abrams, Le Roy, 1940, Illustrated flora of the Pacific States: 4 v., Stanford Univ.

Press. 

Anderson, R. Y., and Kurtz, E. B., Jr., 1955, Biogeochemical reconnaissance of

the Annie Laurie uranium prospect, Santa Cruz County, Ariz.: Econ. Geology,

v. 50, p. 227-232. 

Benson, L., and Darrow, R. A., 1944, A manual of southwestern desert trees and

shrubs: Ariz. Univ. Bull., v. 15, no. 2, 411 p. 

Cannon, H. L., 1952, The effect of uranium-vanadium deposits on the vegetation

of the Colorado Plateau: Am. Jour. Sci., v. 250, p. 735-770.

 1953, Geobotanical reconnaissance near Grants, N. Mex.: U. S. Geol.

Survey Circ. 264, 8 p. 

Cannon, W. A., 1911, Root habits of desert plants: Carnegie Inst. Washington

Pub. 131, 96 p. 

Dayton, W. A., 1937, Range plant handbook: U. S. Forest Service, U. S. Dept.

Agriculture. 

Grimaldi, F. S., May, Irving, and Fletcher, M. H., 1952, U. S'. Geological Survey

fluorimetric methods of uranium analysis : U. S. Geol. Survey Circ. 199, 20 p. 

Griinaldi, F. S., May, Irving, Fletcher, M. H., and Titcomb, Jane, 1954, Collected

papers on methods of analysis for uranium and thorium: U. S. Geol. Survey

Bull. 1006, 184 p. 

Harrington, H. D., 1954, Manual of the plants of Colorado: Denver, Colo.,

Sage Books. 

Kearney, T. H., and Peebles, R. H., 1951, Arizona flora: Calif. Univ. Press,

1069 p. 

Kelsey, H. P., and Dayton, W. A., 1942, Standardized plant names: Compiled

for American Joint Committee on Horticultural Nomenclature, McFarland

Co., Harrisburg, Pa., 673 p. 

Meinzer, O. E., 1923, Occurrence of ground water in the United States: U. S.

Geol. Survey Water-Supply Paper 489, 320 p.

 1927, Plants as indicators of ground water: U. S. Geol. Survey WaterSupply Paper 577, 95 p.

Muenscher, W. C., 1951, Poisonous plants in the United States: 277 p. New 

York, The Macmillan Co.

Patraw, Pauline M., 1951, Flowers of the Southwest mesas: SW Monuments 

Assoc. Popular Ser. no. 5, U. S. Natl. Park Service, 112 p.

Robinson, T. W., 1957, Phreatophytes: U. S. Geol. Survey Water-Supply Paper 

1423. In press.

Rydberg, P. A., 1917, Flora of the Rocky Mountains and adjacent plains: Published by author, New York, 1110 p.

Shreve, Forrest, 1951, Vegetation of the Sonoran Desert: Carnegie Inst. Washington Pub. 591, v. 1, 192 p.

Trelease, S. F., and Beath, O. A., 1949, Selenium; its geological occurrence and 

its biological effects in relation to botany, chemistry, agriculture, nutrition, 

and medicine. Published by the authors, Box 42, Schermerhorn Hall, 

Columbia Univ., New York.

White, W. N., 1932, A method of estimating ground-water supplies based on 

discharge by plants and evaporation from soil: U. S. Geol. Survey WaterSupply Paper 659-A, p, 1-107.

Wooton, E. O., and Stanley, P. C., 1915, Flora of New Mexico: U. S. Natl. Herbarium Contrib., v. 19, 800 p.

421588 57 2

ILLUSTRATIONS AND DESCRIPTIONS 

OF INDICATOR PLANTS

The plants shown on the facing pages that follow are the same 

species, the scientific name "being given on the left-hand page 

and the common name on the right-hand page.
414 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

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-0

FIGURE 76. Astragalus pattersoni A. Gray.

Family: Pea, Leguminosae.

Subgenus: Jonesiella.

Flowers: Cream-colored irregular flowers with purple dot on keel, growing in

tall clusters which extend beyond the foliage. Blooms in April

and May.

Leaves: Pinnate with numerous oval leaflets. 

Fruit: Fat pods mounted on short stem. Seeds rattle in pod when dry (then

called rattleweed).

Root: Very long taproot, commonly 30 feet or more in length. 

Plant: Perennial, 1-4 feet high. Garliclike odor common to foliage owing

to presence of selenium.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 415 

Primary indicator Control: selenium

FIGTJEE 77. Patterson poisonvetch.

Altitude: 4,500-7,500 feet.

Occurrence: Best selenium-indicator plant in uranium districts of the Colorado Plateau because requirements and absorption of selenium 

are very high. Commonly absorbs several thousand parts per 

million of selenium and several hundred parts per million of 

molybdenum from ore bodies. Plot experiments suggest 

growth stimulated in vicinity of carnotite deposits by increased solubility of selenium and molybdenum but inhibited 

by excesses of calcium sulf ate.

Districts noted : San Rafael, Thompson, Green River, Monticello and Circle Cliffs, 

Utah; Ship Rock, in Arizona; Slick Rock and Gypsum Valley, 

Colo.; Grants and Pojoaque, N. Mex.
416 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r-4

Family: 

Subgenus 

Flowers:

Leaves: 

Fruit: 

Plant:

Dark calyx

FIGURE 78. Astragalus preussi A. Gray.

Pea, Leguminosae.

 Jonesiella.

Purple irregular flowers with darker calyx, arising from creeping

root stalks. Blooms in April and May. 

Smooth pinnate with 11-15 elliptic leaflets. 

Fat smooth oblong pod slightly curved, with short stem. 

Perennial. Many stems less than a foot high arising from a woody

base. Garliclike odor of foliage is due to presence of selenium.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 417 

Primary indicator Control: selenium

FIGURE 79. Preuss poisonvetch.

Altitude: 3,300-6,000 feet.

Occurrence: Common on mine dumps and along outcrops of ore-bearing beds 

where selenium and vanadium are available. Mineralized 

ground under these plants in Yellow Cat area, Utah, at an 

average depth of 41 feet. One of the best selenium indicator 

plants in uranium districts on the Colorado Plateau. Commonly absorbs large amounts of selenium and vanadium from 

the ores.

Districts noted: Ship Rock, in Arizona; Slick Rock, Uravan, and Gypsum Valley, 

Colo.; Thompson, San Rafael, Henry Mountains, Green River, 

and Moab, Utah.
418 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r3

Family: 

Subgenus: 

Flowers:

Leaves:

Fruit:

Plant:

FIGURE 80. Astragalus thompsonae S. Wats.

Pea, Leguminosae.

Euastragalus.

Very showy, pinkish-lavender irregular flowers in clusters on long

stems. Blooms in April and May. 

Leaves all basal, pinnate, with 10 or more pairs of ovate leaflets which

become progressively smaller toward apex. Hairy, but hairs not

alined in any particular direction; spreading. 

Fat, erect, two-celled, slightly curved, hairy pods with thick walls

which become woody. No stem. 

Rosette type of perennial 6-12 inches across, with all leaves basal.

Plant and pods covered with soft, silvery hairs.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 419 

Primary indicator Control: selenium

FIGURE 81. Thompson loco.

Altitude: 4,700-7,500 feet.

Occurrence: On seleniferous sandy soils and rocks. Often grows directly on

rock outcrop, but difficult to distinguish except in bloom. 

Districts noted: Ship Rock, in Arizona; Thompson, San Raf ael, White Canyon,

Monticello, and Uinta Basin, Utah; Gypsum Valley, Bull

Canyon, and Paradox Valley, Colo.
420

FIGURE 82. Astragalus confertifiorus A. Gray.

Family: Pea, Leguminosae.

Subgenus: Cnemidophacos.

Flowers: Cream-colored, irregular flowers in dense inflorescence. Blooms in

May.

Leaves: Pinnate, with 11 to 15 linear leaflets. Silvery hairs. 

Fruit: Erect one-celled pod from stalk, not inflated, and with no individual

stem. Woody. 

Plant: Perennial; about 8 inches; has erect stems and bluish foliage.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 421 

Primary indicator Control: selenium

FIGUEE 83. Blue poisonvetch.

Altitude: 

Occurrence:

5,000-6,000 feet.

Restricted to seleniferous clay which commonly underlies ore

deposits. 

Districts noted: Thompson, Henry Mountains, Monticello, and Uinta Basin,

Utah, Grants, N. Mex.
422 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

-8

Calyx deep purple

Cross section enlarged

FIGURE 84. Astragalus Msulcatus (Hook.) A. Gray.

Family: Pea, Leguminosae.

Subgenus: Diholcos.

Flowers: Deep purple, irregular flowers in dense elongated spikelike inflorescence which extends above the foilage. Blooms in June and July.

Leaves: Smooth pinnate with oval or oblong leaflets.

Fruit: Linear one-celled pod with two deep grooves on the upper side. Pod 

with stem extends from calyx.

Plant: Stout, erect. Perennial.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 423 

Primary indicator Control: selenium

FIGTJRE 85. Two-grooved poisonvetch.

Altitude: 3,500 to 8,000 feet.

Occurrence: Dry meadows and sandy soil. This species absorbs large

amounts of selenium and molybdenum and is very poisonous

to stock. 

Districts noted: Powder River Basin, Wyo.; Huerf ano, Colo.
424 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 86. Astragalus missouriensis Nutt.

Family: Pea, Leguminosae.

Subgenus: Xylophacos.

Flowers: Irregular, large, rose-purple pealike flowers in open cluster. Blooms

in May. 

Leaves: Pinnate, with 9-15 broad leaflets. Hairs oppressed, not spreading,

some pick-shaped or attached below the middle. 

Fruit: Pods 1 inch, 4-angled, 1-celled, beaked, curved slightly upward, and

woody. No stem. 

Plant: Low perennial, with basal resetted leaves and large flowers on many

erect flowering stems.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 425 

Secondary indicator Control: selenium

FIGUKE 87. Missouri milkvetch.

Altitude : 

Occurrence:

3,500-8,000 feet.

Dry sandy soils. Replaced on mesas by closely related A.

shortianus Nutt. with inflated seed pods and deep pink

flowers. 

Districts noted: Thompson and Monticello, Utah; Paradox, Colo. ; Ship Rock,

in Arizona.
426 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

1 6

Family: 

Subgenus: 

Flowers:

Leaves: 

Fruit:

FIGURE 88. Astragalus lonchocarpiis Torr.

Pea, L-eguminosae.

Lonchophaca.

Irregular creamy white, pea-shaped flowers, % to % inch long, in

elongate spreading clusters. Blooms in June. 

Pinnate with three to nine linear or threadlike leaflets. Terminal

leaflet much longer than the others. 

Linear pod with long stem exceeding calyx, tapering at both ends,

1% inches long. Thin, 1-celled, dorsally flattened, with prominent

sutures. Pods pendulous. 

Tall rushlike perennials with 1-2 foot stems arising from woody

base.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 427 

Secondary indicator Control: selenium

FIGURE 89. Long-seeded milkvetch.

Altitude: 4,000-7,500 feet.

Occurrence: Dry, sandy, or clayey soil.

Districts noted: Paradox, Colo.; Cuba, N. Mex.

421588 57-
428 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

-4

FIGURE 90. Astragalus dodgianus Jones.

Family: Pea, L-eguminosae.

Subgenus: Homalobus.

Flowers: Irregular, white, pealike flowers with purple-tipped keel. % inch.

Black hairs on calyx which has triangular teeth. Blooms in May. 

Leaves: Odd pinnate with 9 to 11 linear leaflets % inch long. 

Fruit: Linear pod 1-celled with short stem. Flattened, with both sutures

prominent and lower suture straight. 

Plant: Sparingly hairy perennial with slender lax stems and woody root

stalk.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 429 

Secondary indicator Control: selenium

FIGURE 91. Dodge milkvetch.

Altitude: 4,000-7,500 feet.

Districts noted: Rocky slopes.

Occurrence: Paradox, Colo.
430 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 92. Astragalus tenellus Pursh.

Family: Pea, Leguminosae.

Subgenus: Homalolus.

Flowers: Irregular, ^4-inch cream to pale-lavender flowers with purple tip on

keel generally hidden in the foliage. Blooms in June. 

Leaves: Pinnate with 7 to 21 linear smooth leaflets. 

Fruit: Pods 1-celled, % inch long, laterally flattened with both sutures

prominent. Pods pendulous with short stem exceeding calyx. 

Plant: Perennial with woody root stalk. Stems 8 to 20 inches tall and leafy.

Foliage blackens when dried.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 431 

Secondary indicator Control: selenium

FIGURE 93. Looseflower milkvetch.

Altitude: 5,000-11,000 feet.

Occurrence: Moist alkaline soils.

Districts noted: Poison Basin, Wyo.
432 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 94. Astragalus aculeatus A. Nels.

Family: Pea, Leguminosae.

Subgenus: Kentrophyta.

Flowers: Irregular, small purple pea-shaped flowers about 4 mm long, in axils

of leaves. Blooms in July.

Leaves: Pinnate, with 5 stiff spine-tipped leaflets % inch long. 

Fruit: Pods with 2 prominent sutures 1-celled, ovoid, % inch long. 

Plant: Perennial, with strong taproot, branches sprawling or erect, so

densely covered with prickly leaves as to appear clublike.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 433 

Secondary indicator Control: selenium

FIGURE 95. Spiny rnilkvetch.

Altitude: 4,500-9,000 feet.

Occurrence: Dry mesas.

Districts noted: Pojoaque, and Grants, N. Mex.
434 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

r-6

L 0 

FIGURE 96. Allium acuminatum Hook, and related species.

Family: Lily, Liliaceae.

Flowers: Umbrellalike cluster of small pink flowers at end of long stalk. Each

petal has a middle line of deep pink. Blooms in April and May. 

Leaves: Two linear leaves about 6 inches long from bulb at base. Leaves are

shorter than flower stem. 

Fruit: Three-lobed capsule. 

Plant: Spring ephemeral. Bulb with outer covering. Strong odor of crushed

plant characteristic.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 435 

Primary indicator Control: sulfur, phosphorus

FIGURE 97. Tapertip onion.

Altitude: 4,000-7,500 feet.

Occurrence: Grows in large patches around gypsiferous ore deposits and on 

sulfur-rich shale, but inhibited by highly seleniferous ores. 

Encouraged by increased availability of phosphate in carnotite environment. Roots are shallow, but in Thompson district it is found growing over carnotite deposits lying as much 

as 25 feet below the surface.

Districts noted: Thompson, Moab, and Green River, Utah; Slick Rock, Colo.; 

Chilchinbeto, Ariz.
436 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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FIGURE 98. Calochortus nuttalli Torr. & Gr.

Family: Lily, Liliaceae.

Flowers: Three large white petals marked yellow and purple at base. Gland

with hairs at base of petal. One to five flowers on stalk. Blooms

in April and May. 

Leaves: Several alternate grasslike leaves about 6 inches long, trough-shaped

in cross section. Onionlike bulb. 

Fruit: Three-angled capsule. 

Plant: Spring ephemeral. Grasslike leaves arising from bulb.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 437 

Secondary indicator Control: sulfur, phosphorus

FIGURE 99. Sego lily, mariposa.

Altitude: 5,000-8,000 feet.

Occurrence. Dry sandy soil. A good indicator in early spring.

Districts noted : Thompson, Utah; Slick Rock, Colo.; Poison Basin, Wyo.
438 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

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FIGURE 100. Zigadenus gramineus Rydb.

Family: Lily, Liliaceae.

Flowers: Inconspicuous greenish-white flowers with 6 "petals" which grow in

a raceme on flower stalk about 8 inches high. Gland near the base

of the petal. Blooms in April.

Leaves: Smooth, narrow, grasslike leaves arising from bulb. 

Fruit: Three-celled capsule. 

Plant: Spring ephemeral. Bulb with membranous covering.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 439 

Secondary indicator Control: sulfur, phosphorus

FIGUEE 101. Grassy deathcamas.

Altitude: As high as 12,000 feet.

Occurrence: In sulfur-rich soils, from wet sandy seashore to dry desert 

sandstone. Poisonous to sheep owing to toxic alkaloids.

Districts noted: Thompson, Utah; Slick Rock and Paradox Valley, Colo.; Monument Valley, Ariz.
440 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

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FIGURE 102. Stanley a pinnata (Pursh) Britt.

Family: Mustard, Cruciferae.

Flowers: Golden yellow, with four clawed petals on tall stalk; through the 

summer months the stalks show a progression from buds to flowers 

to seeds. Stamens unequal, with anthers curled at maturity.

Leaves: Pale green, alternate; variable in shape and size, often lyre-shaped 

or entire.

Fruit: Long thin capsule containing many seeds.

Plant: Coarse perennial with thick erect stalk, 1-3 feet high, and woody root.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 441 

Secondary indicator Control: selenium, sulfur

FIGURE 103. Desert princesplume.

Altitude: 2,500-7,000 feet.

Occurrence: Along rims and water courses draining gypsiferous areas. All 

species of this genus require both selenium and sulfur, but 

plot experiments indicate intolerance of highly mineralized 

ground. Therefore useful along drainage courses and in 

prospecting rims.

Districts noted: Ship Rock, Chilchinbeto, in Arizona; Slick Rock, Gypsum 

Valley, and Paradox Valley, Colo.; Thompson, San Rafael, 

Marysvale, White Canyon, Monticello, Green River, Henry 

Mountains, Moab, and Circle Cliffs, Utah; La Ventana, 

N. Mex.
442 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

-4

FIGTJKE 104. Lepidium montanum Nutt.

Family: Mustard, Cruciferae.

Flowers: Dense cluster of white flowers. Four clawed petals one-fourth inch

long which form a cross. Blooms from April to September. 

Leaves: Basal leaves finely divided, several inches long. Upper leaves simple

and smooth edged; do not clasp the stem. 

Fruit: Small round disk-shaped capsules that are not inflated. Narrowly

winged and obscurely notched at the apex. 

Plant: Bushy perennial 1 to 2 feet high. Stems not woody. Several stems

from same root.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 443 

Secondary indicator Control: sulfur, phosphorus

FIGURE 105. Mountain pepperweed.

Altitude: 3,000-7,000 feet.

Occurrence: Common around shallow uranium deposits where sulfur is available in surface soil. Very high absorption of uranium. Common on gypsum dunes of White Sands, N. Mex.

Districts noted: Thompson, White Canyon, and Green River, and Uinta Basin. 

Utah.

421588 57-
444 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 'V> 

r2

Flowers 

(enlarged)

FIGUEE 106. Lepidium lasiocarpum Nutt.

Family: Mustard, Cruciferae.

Flowers: Not conspicuous, may be obsolete. Blooms from January to April. 

Leaves: Small simple rounded leaves. Basal leaves incised. 

Fruit: Notched round disk-shaped capsules.

Plant: Tiny hairy annual, 2 inches high, branched from the base and not 

woody.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 445 

Secondary indicator Control: sulfur, phosphorus

FIGUEE 107. Hairy-pod pepperweed.

Altitude: 3,000-4,500 feet.

Occurrence: Sandy soil where sulfates are present in surface soil.

Districts noted: Thompson and San Rafael, Utah; Ship Rock, in Arizona.
446 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Capsule

FIGURE 108. Sisymbrium altissimum (L.) Britt.

Family: Mustard, Cruciferae.

Flowers: Four creamy, flat, one-fourth inch petals which form a cross. Blooms 

from May to July.

Leaves: Upper leaves threadlike, lower leaves divided and not clasping the 

stem.

Fruit: Thin linear capsules, more than 2 inches long. Divergent.

Root: Tap root, but with fine long laterals ; root system extensive.

Plant: Coarse erect annual 2 to 4 feet high with smooth stems, freely branching. An introduced European adventive weed both tolerant and indicative of soils containing sulf ate.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 447 

Secondary indicator Control: sulfur, phosphorus

FIGUEE 109. Tumblemustard.

Altitude : 

Occurrence:

5,000-7,000 feet.

Around ore deposits on higher mesas. High absorption of

uranium.

Districts noted : Slick Rock, Gypsum VaUey, Paradox Valley, and Rifle, Colo. ; 

White Canyon and San Eafael, Utah.
448 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 110. Cryptantha flava A. Nels. and related species.

Family: Borage, Boraginaceae.

Flowers: Pale-yellow, tubular flowers one-fourth inch long in small congested,

densely hairy heads. Blooms in spring and summer. 

Leaves: Rough, simple, linear, and mostly basal. 

Fruit: Smooth oval nutlet. 

Plant: Stout, pale-green, hairy perennial 4 to 12 inches high, growing from

woody base.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 449 

Secondary indicator Control: calcium

FIGURE 111. Cryptanth.

Altitude: 5,000-7,000 feet.

Occurrence: Prefers dry sandy or limestone soil. Localized around gypsif erous uranium deposits in many districts. The controlling factor is probably available calcium. Common on gypsum dunes 

at White Sands, N. Mex., and on limestone and calcium-rich 

vein deposits in Arizona.

Districts noted: Thompson, Green River, White Canyon, and Circle Cliffs, Utah; 

Grants, N. Mex.; Ship Rock, Defiance, in Arizona; Gypsum 

Valley, Bull Canyon, and Paradox Valley, Colo.; Poison Basin, 

Wyo.
450 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

r4

Seed

-o

FIGURE 112. Oenothera caespitosa Nutt.

Family: Primrose, Onagraceae.

Flowers: Large fragrant white flower with 4 heart-shaped petals on a long

slender calyx tube which rises directly from the ground for about

4 to 5 inches. Flowers open in the evening and turn pink with age.

Fragrant. Blooms in May and June. 

Leaves: Strap leaves in a basal rosette. Smooth-margined or toothed, on

winged stems.

Fruit: Oval capsule with rounded tubercles on the angles. 

Plant: Perennial.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 451 

Primary indicator Control: calcium

FIGUBE 113. Tufted evening-primrose.

Altitude: 3,000-7,500 feet.

Occurrence: Common associate of uranium-indicator plants. The distribution of this plant suggests that it is an indicator of available 

calcium. Listed in flora of White Sands, N. Mex., and common 

on volcanic beds of Arizona.

Districts noted : Grants, N. Mex; Thompson, San Raf ael, Green River, and White 

Canyon, Utah; Ship Rock, in Arizona.
Seed pod

FIGURE 114. Oenothera albicaulis Pursh.

Family: Primrose, Onagraceae.

Flowers: Four large white lobes resembling petals at end of tube 1 inch long.

Blooms from May to July. 

Leaves: Basal leaves, blunt, spatulate, toothed. Stem leaves, 2 to 5 inches

long, deeply divided.

Fruit: Pod, % to 2 inches long, y2 inch thick. 

Plant: Annual or biennial, 4 to 12 inches high, branched at the base.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 453 

Secondary indicator Control: calcium

FIGTJBE 115. Whitestemmed evening-primrose.

Altitude: 2,400-7,500 feet.

Occurrence: Gypsum-bearing sandy soil.

Districts noted: Thompson and San Rafael, Utah.
454 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Flowers

INCHES

4 -,

FIGURE 116. Eriogonum inflatum Torr.

Family: Buckwheat, Polygonaceae.

Flowers: Clusters of 10 to 20 tiny yellow flowers on much-branched mass of

fine stems. Blooms from March to July. 

Leaves: Rounded leaves in rosette at base of plant. 

Seeds: Three-angled dry seed. 

Plant: Bluish-green tubular stems with hollow, inflated, trumpetlike parts

before divisions. Stem divides in threes, 1 to 2 feet high perennial,

with woody base.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 455 

Primary indicator Control: sulfur, phosphorus

FIGTJEE 117. Deserttrumpet eriogonum.

Altitude: 

Occurrence:

As high as 4,500 feet.

Common on sulfur-rich soils and gypsiferous ore deposits. 

Turns Mancos shale yellow when in bloom. High phosphorus 

content.

Districts noted: Ship Rock, in Arizona; Thompson, San Raf ael, Henry Mountains, Green River, Monticello, and Circle Cliffs, Utah.
456 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r-4

Family: 

Flowers:

Leaves: 

Stem: 

Fruit: 

Plant:

Flowers 

(enlarged)

FIGURE 118. Eriogonum fusiforme Small.

Buckwheat, Polygonaceae.

Tiny wrhite or yellowish flowers in diffusely branching inflorescence

Blooms in June and July.

Basal, rounded or kidney-shaped in outline, scattered hairs. 

Inflated part above the middle of stem. 

Dry, small, smooth. 

Annual, writh flower stalk extending from basal rosette.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 457 

Secondary indicator Control: sulfur, phosphorus

FIGURE 119. Deserttrumpet.

Altitude: 4,000-6,000 feet

Occurrence: Dry sandy alluvial soil.

Districts noted: Yellow Cat and Green River, Utah.
458 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

EL,

FIGURE 120. Eriogonum ovalifolium Nutt.

Family: Buckwheat, Polygonaceae.

Flowers: Pale-yellow to pink; in headlike cluster on 4- to 6-inch stalk. Calyx

yellowish with pinkish veins. Blooms from April to June. 

Leaves: Densely wrhite-woolly; oval leaves at base of plant about one-half inch

in size.

Fruit: Dry, small. 

Plant: Hairy perennial with basal cushion of leaves and 10-inch flower

stalks. Woody base.
INDICATOK PLANTS AND METHODS OF BOTANICAL PEOSPECTING 459 

Secondary indicator Control: sulfur, phosphorus

FIGURE 121. Silver plant or cushion eriogonum.

Altitude: 5,000-7,000 feet.

Occurrence: Commonly on sandstone outcrops rooted in cracks and joints.

Phosphate absorber. 

Districts noted : Thompson, Utah ; Ship Rock, in Arizona.

421588 57-
460 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

i' -~'V 

^v^vV JL'*V' Sulfur yellow

INCHES 

-4

FIGURE 322. Eriogonum umbellatum Torr.

Family: Buckwheat, Polygonaceae.

Flowers: Twenty to thirty sulfur-yellow flowers in heads held in simple umbrellalike cluster with leafy bracts at base. Individual flowers tubular 

with reflexed lobes and 9 stamens. Flower stalks stout, woolly, 

and 4 to 12 inches long. Blooms through summer.

Leaves: Thick, oval-to-spatulate, % to 1 inch long, tapering to a stem. Green 

above, white-woolly underneath.

Seeds: Sharply three-angled, dry seeds.

Plant: Perennial with thick taproot. Branched woody base tufted with leaves 

at the nodes from which erect leafless flower stalks extend.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 461 

Secondary indicator Control: sulfur, phosphorus

FIGURE 123. Sulfur eriogonum.

Altitude: 5,000-9,000 feet. 

Occurrence: Dry slopes. Phosphate absorber.

Districts noted: Jefferson County, Colo.; White Canyon, Utah; Phosphoria formation, Wyoming.
462 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 124. Elymus saUna Jones.

Family: Grass, Gramineae.

Flowers: Dense spikes. Spikelets coming off in pairs from jointed axis. No

awns. Blooms through summer. 

Leaves: Broad blades, rolled inward. 

Plant: Perennial grass with harsh foliage. Grows in thick clumps several

feet high.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 463 

Primary indicator Control: Probably phosphorus

FIGURE 125. Salina wildrye.

Altitude: 3,000-7,000 feet.

Occurrence: A grass that formerly covered large areas of the West, now 

present only in relict areas. Common on mine dumps and 

along canyon rims, in the vicinity of uranium ore. Also 

known to occur around base-metal sulfide deposits; this is 

probably due to increased availability of phosphorus.

Districts noted: Ship Rock, in Arizona; Slick Rock, Paradox Valley, and 

Gypsum Valley, Colo.; Thompson, Green River, and Circle 

Cliffs, Utah.
464 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 126. Stipa comata Trin. & Rupr.

Family: Grass, Gramineae.

Flowers: Loose head 5 to 10 inches long with tightly twisted threadlike awns 

4 to 5 inches long resembling tails attached to the seeds. Tight 

twist in lower third only. Blooms in June and July.

Leaves : Harsh, flat, inrolled.

Plant: Deep-rooted perennial 1 to 2 feet high.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 465

Secondary indicator Control: probably phosphorus

FIGURE 127. Needleandthread.

Altitude: 4,500-8,000 feet.

Occurrence: Restriction to mineralized ground in many areas probably owing to increased availability of phosphorus.

Districts noted: Thompson, Utah; Gypsum Valley, Colo.; Grants, N. Mex. 

Closely related species in Ship Rock, in Arizona.
466 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

FIGURE 128. Oryzopsis hymenoides (Roem. & Schult.) Rick.

Family: Grass Gramineae.

Flowers: Small dry flowers in open panicle with branches at right angles in

zigzag pairs. Individual spikelets one-flowered. Blooms in June

and July.

Leaves: Inrolled, narrow. 

Seeds: Small, ricelike; edible. 

Plant: Extensive perennial grass 1 to 2 feet high, with deep fibrous roots.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 467 

Secondary indicator Control: selenium

FIGURE 129. Indian ricegrass.

Altitude: As high as 10,000 feet.

Occurrence: Drought-resistant and alkali-tolerant grass common in any 

western soil which contains a small amount of selenium. 

Capable of absorbing large amounts of selenium and uranium 

although the selenium requirements are very low. Useful 

only in districts where selenium content of the ore is low; 

there the plant may be restricted to ore.

Districts noted: Gypsum Valley, Rifle, Slick Rock, Bull Canyon, and Paradox 

Valley, Colo.; White Canyon, Marysvale, Thompson, San 

Rafael, Henry Mountains, Green River, Moab, Monticello, 

Uinta Basin, and Circle Cliffs, Utah; La Ventana and Grants, 

N. Mex.; Wamsutter and Poison Basin, Wyo.; Ship Rock, 

in Arizona.
408 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

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FIGURE 130. Aster venustus Jones.

Family: Sunflower, Compositae.

Flowers: Composite flowers in 1-inch heads with long white ray flowers resembling daisies. Heads solitary on 8-20-inch flower stalks. Bracts 

nearly equal in length. White "petals" turn lavender on aging. 

Blooms in May and June.

Leaves: Spatula-shaped, with callous point, hairy and alternate. One to two 

inches long.

Seeds: Small silky seeds remain in dried heads through summer months.

Plant: Woody perennial base and naked flower stalks ; long taproot. Plant 6 

to 18 inches high.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 469 

Secondary indicator Control: selenium

FIGUBE 131. Woody aster.

Altitude: 

Occurrence

3,000-5,000 feet.

Restricted to low altitudes. Common on clay soils of Mancos 

shale and alluvium of uranium districts in Utah. Although 

species absorbs large amounts of selenium when available, restriction to clay soils limits its usefulness to alluvium and 

drainage prospecting. 

Districts noted : Thompson, Moab, Henry Mountains, and Green River, Utah.
470 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 132. Toicnsendia incana Nutt.

Family: Sunflower, Compositae.

Flowers: Daisy-like composite with yellow disk flowers and one-half-inch white

to pink ray flowers. Blooms in April and May. 

Leaves: Spatula-shaped, blunt hairy leaves 1 inch long arising from basal woody

crown.

Seeds: Small flattened dry seeds. 

Plant: Hairy perennial with woody crown and flower stems less than 4 inches

high. Taproot.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 471 

Secondary indicator Control: selenium

FIGURE 133. Hoary townsendia.

Altitude: 5,000-6,500 feet.

Occurrence: On selenium-bearing sands. Conspicuous only when in bloom.

Districts noted: Thompsons, Green River, Monticello and White Canyon, Utah.
472 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

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Linear leaves

FIGURE 134. Aplopappus armeriodes A. Gray.

Family: Sunflower, Compositae.

Flowers: Heads clustered at top of stem with yellow tubular disk and one-halfinch long ray flowers. Blooms in June and July.

Leaves: Smooth, 3-nerved, linear leaves, 1 to 3 inches long.

Plant: Perennial herb with leafless flower stems 2 to 6 inches long arising from 

bunched leaves at woody base.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 473 

Secondary indicator Control: selenium (?)

FIGURE 135. Goldenweed.

Altitude: 4,000-6,000 feet.

Occurrence: Dry sandstone mesas.

Districts noted: Thompson, San Raf ael, Henry Mountains, Green River, and

White Canyon, Utah; Bull Canyon, Colo.; Ship Rock, Defiance

uplift, Ariz.
474 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r3

Bract

FIGURE 136. Grindelia sqiiarrosa (Pursh) Dunal, and closely related species.

Family: Sunflower, Compositae.

Flowers: Yellow radiate heads in flat-topped clusters. Green bracts of heads

strongly graduated in 4 to 8 rows with recurved tips and

mucilaginous. Blooms in fall.

Leaves: Undivided, alternate leaves clasping the stem; resinous and stiff. 

Seeds: Dry, small, and short. 

Plant: Biennial or perennial, 8 to 40 inches high; mucilaginous plant with

long taproot. Balsamlike odor from exuded gum.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 475 

Secondary indicator Control: unknown

FIGUEE 137. Curlycup gumweed.

Altitude: 

Occurrence

As high as 9,000 feet.

Common in drainage and seeps from mines of high selenium content or rooted in ore deposits of low content. Plot studies indicate very high absorption of uranium and a marked increase 

in absorption in carnotite environment with development of 

anomalous growth habits. Intolerant of highly seleniferous 

soils. Calcium absorber. 

Districts noted: Thompson, Utah; and others.

421588 57-
476 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

o-1

^ ty Base leaf 

FIGURE 138. Senecio longilobus Benth.

Family: Sunflower, Compositae.

Flowers: Yellow composite with %-inch disk and long yellow ray flowers. Heads

in flat-topped clusters. Blooms through summer months. 

Leaves: Pinnate leaves with linear, threadlike, hairy leaflets. 

Seeds : Small dry seeds. 

Plant: Ill-scented perennial 1 to 2 feet high covered with white-woolly hairs

and having a long taproot The plant is very poisonous to cattle.

Poison, alkaloid.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 477 

Secondary indicator Control: calcium

Altitude : 

Occurrence

FIGURE 139. Threadleaf groundsel.

4,000-7,500 feet.

Along roadsides and in dry, alkaline country. Various species

of Senecio are known to act as indicators around many types of

heavy-metal deposits. The control may be phosphorus or calcium. Useful secondary indicator. 

Districts noted : Thompson, Utah, Ship Rock, Defiance uplift, Ariz. ; Slick Rock

and Gypsum Valley, Colo.
478 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

/Gland 

Involucre

INCH

FIGTJKE 140. EtiphorMa fendleri Torr. & Gr., and related prostrate species.

Family: Spurge, Euphorbiaceae.

Flowers: Minute flowers in peculiar "petaled" involucre from which stalked 

glands extend. Flowers occur in axils of leaves. Bloom from April 

to October.

Leaves : Oval, opposite, entire, pale-green leaves % inch long.

Fruit: Quadrangular seeds in lobed smooth capsule.

Plant: Prostrate, pale-green annual with forking stems radially branched at 

the base. Milky acrid sap which is poisonous and may cause dermatitis upon contact.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 479 

Secondary indicator Control: calcium or sulfur

FIGURE 141. Sandmat or Fendler euphorbia.

Altitude: 4,000-7,000 feet.

Occurrence: Common on gypsum-bearing soils. Of importance only where 

soluble salts from ore deposits have migrated into the surface 

soils. Experimental plot studies show stems of this plant 

tend to be erect on high-sulfate soils and completely prostrate on low-sulf ate soils.

Districts noted: Thompson, San Rafael, and Henry Mountains, Uinta Basin, 

Utah; Grants, N. Mex.; Ship Rock, in Arizona.
480 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

-3

L0

FIGURE 142. Mentzelia multiflora (Nutt.) A. Gray.

similar in appearance.

Several other species are

Family: Loasa, Loasaceae.

Flowers: Light-yellow, star-shaped flowers with 10 petals and many stamens.

Stamens in outer row are petallike. Opens in afternoon. Blooms

from May to August.

Leaves: Light green, sticky, alternate, and toothed. 

Fruit: Three- to five-valved capsule. 

Plant: Stems freely branching; plant 1 to 3 feet high. Barbed stinging hairs.

Perennial. Stout taproot.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 481 

Secondary indicator Control: calcium

FIGURE 143. Desert blazingstar.

Altitude: As high as 7,000 feet.

Occurrence: A common weed of roadsides and disturbed ground. This 

genus is found around many uranium deposits and on the 

pure gypsum sands of White Sands, N. Mex. It absorbs 

large amounts of calcium. As the growth is favored by 

the presence of carnotite ore, several species may be used 

under certain circumstances as an ore indicator.

Districts noted: Lost Creek, Wyo.; La Ventana and Penasco Hot Springs, 

Grants, N. Mex.; Gypsum Valley, Colo.; Ship Rock, in 

Arizona; and San Raf ael, Utah.
482 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

FIGURE 144. Solidago petradoria Blake.

Family: Sunflower, Compositae.

Flowers: Five to eight small yellow flowers in heads in dense flat-topped clusters.

Blooms in July and August. 

Linear-oblong, three-nerved, rigid alternate leaves, 2 to 4 inches long

and resinous. 

Dry, flat, five-nerved.

Low, tufted, perrenial herbs with short branched woody base. Smooth, 

4 to 6 inches long, erect flower stems from cushion of basal leaves 

Extensive root system.

Seeds 

Plant
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 483

Tolerant

FIGURE 145. Rock goldenrod.

Altitude: 5,500-7,500 feet. 

Occurrence: Rock ledges and dry sandy soils.

Districts noted: Thompson and White Canyon, Utah; Paradox Valley and Bull 

Canyon, Colo; Defiance uplift, Ariz.
484 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Pappus

INCHES

Recurved spines

FIGURE 146. Tetradymia spinosa Hook. & Arn.

Family: Sunflower, Compositae.

Flowers: Fleshy smooth heads of four yellow flowers % to % inch long arising 

from axils of the leaves. Bracts at base of heads woolly. Blooms 

from May to July.

Leaves: Primary leaves converted to woolly recurved spines % to y2 inch long. 

Secondary leaves linear, 14 to % inch long, fleshy and in clusters.

Plant: Divaricately branched xerophytic shrub 2 to 4 feet high with white 

woolly branches and characteristic recurved woolly spines which 

are soft and pliant when first produced. High potassium content 

in leaves and buds. Organic compound in plant poisonous to sheep.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 485

Tolerant

FIGURE 147. Cottonthorn horsebrush.

Altitude: 4,000-7,000 feet.

Occurrence: Dry sandy plains and sandstone mesas.

Districts noted: Thompson, San Raf ael Swell, Unita Basin, Utah, Gypsum 

Valley, Colo.
486 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

FIGURE 148. Cowania stansburiana Torr.

Family: Rose, Rosaceae.

Flowers : Creamy yellow solitary flowers with 5 oval petals, 5 sepals, and many

stamens. Fragrant; resembles the wild rose. Flowers through

spring and summer whenever water is plentiful. 

Leaves : Alternate gland-dotted, evergreen leaves with 3 to 5 lobes and curledunder margins. White fuzz underneath. 

Seeds : Dry, attached to several long plumes which appear from each flower

before the petals have dropped. 

Plant: Twisted shrub, 3 to 12 feet high with shaggy gray bark and reddish

twigs. Plant has a bitter taste and very acid cell sap.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 487

Tolerant

FIGURE 149. Stansbury cliffrose.

Altitude: 

Occurrence

3,500-8,000 feet.

Phreatophyte, occurring with juniper and pinyon on rock mesas 

and along sandy washes. Called "vanadium-bush" and used 

as indicator by early prospectors although probably indicating water commonly trapped in ore rolls. Able to grow in 

highly mineralized ground and to absorb large amounts of 

uranium. Type locality: Stansbury Island, Great Salt Lake. 

Districts noted: Ship Rock, Chilchinbeto, Chuska, and Defiance uplift, in 

Arizona; Thompson, San Rafael, White Canyon, Henry Mountains, and Circle Cliffs, La Ventana, and Grants, N. Mex.
488 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Seed pod

FIGURE 150. Purshia tridentata (Pursh) DC.

Family: Rose, Rosaceae.

Flowers: Solitary at the ends of branches. Tube-shaped, hairy, flve-lobed calyx,

five yellow petals. Many stamens in single series. Blooms from

April to July. 

Leaves: Alternate but crowded into fascicles. Three-cleft, 0.2 to 1 inch long,

wedge-shaped with rolled margins. White fuzz beneath. 

Seeds: Spindle-shaped, % inch long, exserted from calyx tube with persistent

break. 

Plant: Intricately branched shrubs 1^ to 9 feet high with brown to gray

bark. Drought resistant. Foliage has bitter taste.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 489

Tolerant

FIGURE 151. Antelope bitterbrush.

Altitude: 4,000-9,000 feet

Occurrence: Arid plains and foothills. Common on volcanic flows.

Districts noted: MonticeUo, Utah; Slick Rock, Colo.; Henry Mountains, Utah.
490 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r4

Leaflet

i-o

FIGURE 152. Hedysarum fioreale Nutt.

Family: Pea, Leguminosae.

Flowers: Showy rose-purple irregular flowers in loose racemes which grow from 

the axils of leaves. Stamens 9 and 1. Blooms in June and July.

Leaves: Odd-pinnate with many oblong leaflets. Finely punctate, smooth on 

upper surface and sparingly hairy beneath.

Fruit: Compressed, several-jointed pod divided into 2 to 4 separable rounded 

segments.

Plant: Perennial herb with 1 to 3 foot erect, leafy stems with scattered hairs. 

Resembles the Astragalus genus closely in general appearance except for seeds and hairy roughness.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 491

Tolerant

FIGURE 153. Northern sweetvetch.

Altitude: 4,000-7,000 feet.

Occurrence: Phreatophyte, tolerant of mineralized ground. 

Districts noted: Thompson, White Canyon, Circle Cliffs and San Rafael, Utah; 

Paradox Valley, Colo.; Defiance uplift and Chuska, Ariz."

421588 57-
492 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

r2

Family: 

Flowers:

Leaves: 

Fruit: 

Plant:

FIGUEE 154. Castilleja Integra Gray.

Figwort, Scrophulariaceae.

Spikes of flowers consisting of three-cleft, brilliant scarlet bracts

surrounding yellowish fused calyx and narrow yellow petals. Four

stamens. Blooms throughout summer. 

Alternate, sessile, linear leaves, 2 to 4 inches long. 

Two-celled capsule containing many seeds. 

Erect perennial herb with simple leafy stem and spike of red or yellow

bracted flowers. Roots fibrous, partly parasitic on other plants.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 493

Tolerant

FIGURE 155. Indian paintbrush or paintedcup.

Altitude: 

Occurrence

3,000-7,500 feet.

In sandy soils. Capable of absorbing considerable selenium

although not believed to be an indicator plant.

Districts noted: Thompson and White Canyon, Utah; Grants, N. Mex.; Chilchinbeto and Chuska, Ariz.
494 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 156. Plantago purshi Roem. & Schult.

Family: Plantain, Plantaginaceae.

Flowers: Tiny dry flowers in dense cylindrical spike resembling wheat. Spike

y2 to iy2 inches long on 2-inch woolly stem. Individual flower parts

in fours. Blooms throughout summer. 

Leaves: Woolly, linear, 3-ribbed leaves 1 to 2 inches long on a short stem from

the base of the plant. 

Fruit: Oblong, 2-seeded pod which divides in middle so that top half falls

off like a lid.

Root: Long taproot; most deeply placed roots of any annual. 

Plant: Tiny, drought-resistant, winter annual consisting of several leaves

and single flower spike which arise from the base. Seeds become

mucilaginous when wet.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 495

Tolerant

FIGURE 157. Woolly indianwheat.

Altitude: 1,000-7,000 feet.

Occurrence: Full sunlight and dry sandy soil. Commonly associated with

sulfur-indicator plants. 

Districts noted : Thompson, Utah; Grants, N. Mex.
L-0

FIGURE 158. Atriplea confertifolia (Torr.) S. Wats.

Family: Goosefoot, Chenopodiaceae.

Flowers: Small dense clusters. Blooms in late summer.

Leaves: Thickened, ovate, scurfy leaves; resembling a shad scale. Leaves

have short stem. 

Fruit: Fruit in large conspicuous yellowish-green to pinkish bracts at ends

of the branches. Bracts never with wings. 

Plant: Grayish-green xerophyte shrub 1-4 feet high; woody and branched.

Branches ending in spines. Seeds not produced on same plants

with pollen.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 497

FIGUBE 159. Shadscale saltbush.

Altitude: 4,200-6,000 feet.

Occurrence: Drought-resistant and alkali-tolerant plant commonly the dominant species of uranium districts. Plant has ash content of 

about 25 percent consisting mostly of sodium. Absorbs uranium and selenium readily although not restricted in distribution to mineralized ground. Type locality: Great Salt Lake.

Districts noted: Wamsutter, Poison Basin, and Lost Creek, Wyo.; La Ventana, 

N. Mex.; Slick Rock, Colo.; Thompson, San Rafael, White 

Canyon, Moab, and Uinta Basin, Utah.
498 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 160. Atriplex canescens (Pursh) Nutt.

Family: Goosefoot, Chenopodiaceae.

Flowers: Staminate flowers small glomerules in dense spikes. Pistillate flowers

enclosed in bracts with no calyx or petals. Blooms in June and

August.

Leaves: Linear, thick, grayish, scurfy. 2 inches long. No leaf stem. 

Fruits: Fruits one seeded with four prominent wings. Fruiting bracts

stalked, thick, fleshy and ovoid. 

Plant: Woody perennial 2-8 feet with male and female flowers on separate

plants. Branches circular in cross sections, white scurfy. Bark

peels from old stems in thin layers. Roots reach 20 feet in length.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 499

Tolerant

FIGURE 161. Fourwing saltbush.

Altitude: 4,000-8,000 feet.

Occurrence: Dry sandy plains and hills. Alkaline soil. High ash content 

largely sodium. Replaced by A. confertifolia in extremely saline areas.

Districts noted: Yellow Cat and Green River, Utah; Ship Rock, Grants, and 

Nambe, N. Mex.; Uravan, Colo.
500 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES

r-10

-0

Staminate

Pistillate

FIGURE 162. Sarcobatus vermiculatus (Hook.) Torr.

Family: Goosef oot, Chenopodiaceae.

Flowers: Pollen and seeds not produced on same plant. Seed-producing flowers 

axillary and with cup-shaped enlarged calyx. Pollen-producing 

flowers small, in terminal spikes. Blooms from June to September.

Leaves: Alternate, linear, and fleshy leaves, %-!% inches long. Sessile.

Seed: Nutlet attached to expanded, membranous calyx.

Plant: Erect shrub 4-8 feet high, much branched and thorny with gray bark 

and fleshy linear leaves.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 501

FIGURE 163. Black greasewood.

Altitude: 1,000-7,000 feet.

Occurrence: A phreatophyte or ground-water plant tolerant of alkaline and 

saline soils. An indicator of "black alkali," or sodium carbonate. Poisonous to sheep in spring, owing to salate of sodium 

and potassium in sap. Absorption of uranium very high.

Districts noted: Thompson and Henry Mountains, Utah; Lost Creek, and Poison 

Basin, Wyo.
502 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Male Female 

(enlarged)

FIGURE 164. Ephedra sp.

Family: Jointfir, Gnetaceae.

Flowers: Small male and female yellow flowers in short catkins with persistent 

bracts. Stamens united, 2-lobed flower tube. Blooms in spring.

Leaves: Scalelike in pairs or threes at stem joints.

Seeds: Hard nutlets.

Plant: Shrubs 6-25 inches high with rigid jointed striated branches resembling Equisetum and reduced leaves. Twigs opposite or clustered 

at stem joints.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 503

Tolerant

FIGURE 165. Jointfir, or mormon tea.

Altitude: 4,500-9,000 feet.

Occurrence: Dry desert areas.

Districts noted: Yellow Cat and Henry Mountains, Utah; Ship Rock, N. Mex.
504 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 166. Opuntia engelmanni Salm-Dyck and other species.

Family: Cactus, Cactaceae.

Flowers: Many waxy colored petals, numerous sensitive stamens, and short 

green calyx supported on cup-shaped tube. Diurnal flowers normally several inches across arise from same growing centers as 

spines. Blooms in May and June.

Leaves: Small, awl-shaped deciduous, as much as % inch long.

Roots: Extensive fibrous roots.

Fruit: Fleshy edible berry as much as 2 inches long with many bony seeds.

Plant: Succulent shrubs as much as 5 feet high with fleshy, jointed, flattened 

stems. Areoles, or growing centers, bear minute leaves, spines, and 

bristles. Water content 80 percent in stems. Acid cell sap.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 505

Tolerant

FIGURE 167. Engelmann pricklypear.

Altitude: 1,000-8,000 feet. 

Occurrence: Sandy plains and sandstone mesas.

Districts noted: Thompson, Henry Mountains, and Green River, Utah ; Defiance 

uplift, and Ship Rock, in Arizona.
506 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

FIGURE 168. Mirabilis multiflora A. Gray.

Family: Four o'clock, Nyctaginaceae.

Flowers: Clusters of 6 rose-colored, funnel-shaped flowers 2 inches across enclosed in a large funnel-shaped bract. Three-five unequal stamens. 

Flowers open toward sunset. Blooms in July and August.

Leaves: Thick, opposite, entire leaves, oval or heart-shaped and 2-3 inches 

long.

Seeds: Oval black seeds, 10-f urrovved toward base.

Roots: Large and fleshy.

Plant: Perennial herbs with thick root stalk and stout stems, spreading or 

ascending, 2-3 feet long.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 507

Tolerant

FIGURE 169. Colorado four-o'clock.

Altitude: 2,500-7,500 feet. 

Occurrence: Hillsides and rocky mesas.

Districts noted: Thompson and White Canyon, Utah; Ship Rock and Grants, 

N. Mex.; Uravan, Colo.

421588 57 8
508 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

INCHES 

r4

L0

-Winged fruits

FIGURE 170. Frawinus anomalaTorr.

Family: Olive, Oleaceae.

Flowers: Four-toothed, bell-shaped flowers. Blooms in April and May. 

Leaves: Simple, smooth, rounded leaves 1-2 inches long occurring in threes. 

Fruits: Dry, winged, oblong one-seeded fruits % to 1 inch long. 

Plant: Small tree 5 to 15 feet high, with 4-angled twigs and thick simple 

leaves. Extensive root system.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 509

Tolerant

FIGURE 171. Singleleaf ash.

Altitude: 2,000-7,000 feet.

Occurrence: Dry sandstone mesas and sandy washes in full sun. 

Districts noted: Ship Rock, N. Mex.; Thompson, San Rafael, and Green River, 

Utah.
510

INCHES 8-

FIGURE 172. Hymenopappus filifolius Hook.

Family: Sunflower, Compositae.

Flowers: Several heads of tubular yellow flowers with tubes longer than lobes.

No ray flowers. Blooms in July and August. Bracts at base of head

with yellowish tips.

Leaves: Woolly basal leaves twice-divided into threadlike segments. 

Seeds: Small dry seeds with long silky hairs. 

Plant: Woolly perennial plants with leaves crowded at branching woody base

and 10 to 20-inch stalks.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 511

FIGURE 173. Mneleaf hymenopappus.

Altitude: 3,500-8,000 feet.

Occurrence: Semiarid hills and mesas, commonly on sandstone.

Districts noted: Thompson, Utah ; Pojoaque, N. Mex.
512 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Ray flower 

(enlarged)

FIGURE 174. Actinea acaulis (Pursh) Spreng.

Family: Sunflower, Compositae.

Flowers: Single composite head of yellow flowers on 8-inch leafless scape or 

flower stalk. Single series of ray flowers, 3-toothed, with orange 

veins. Bracts at base of flower in 2 or 3 rows, not united and 

densely hairy. Blooms from June to September.

Leaves: Basal rosette of linear leaves, % to 2 inches with entire margins, silky. 

Glands prominent.

Seeds: Dry, angled, hairy seeds crowned with 6 papery scales.

Plant: Perennials with woody base and strong taproot. Single leafless flower 

stalk with leaf rosette. Bitter, aromatic taste.
INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING 513

Tolerant

FIGURE 175. Stemless actinea.

Altitude: 3,500-12,000 feet. 

Occurrence: Dry rocky slopes. 

Districts noted: Thompson and San Raf ael, Utah ; Grants, N. Mex.
514 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GLOSSARY

Awn_________ A slender bristlelike appendage on grasses.

Axil_________. The angle formed by a leaf or branch with the stem.

Bract_________ A modified leaf subtending a flower or flower cluster.

Calyx_________ The outer series of parts in a flower immediately surrounding the petals.

Corolla_______. The inner series of parts in a flower. Composed of petallike parts which may be brightly colored.

Deciduous______ Falling away at the end of the growing period; not persistent. Commonly said of plants with such leaves.

Disk-flowers____ Tubular flowers of a composite head as distinct from the 

peripheral ray flowers.

Diurnal_______ Daily; new flowers opening each day.

Irregular______ A flower in which one or more of the petals are unlike the 

rest.

Keel__________. The two anterior petals of a legume flower joined in such a 

way as to resemble the keel of a boat.

Pinnate_______. Compound (leaf) with leaflets arranged on eaoh side of a 

common stem. Featherlike.

Punctate______. Dotted with depressions or with translucent glands.

Raceme_______. A simple cluster of stalked flowers upon a common elongated 

stem.

Ray-flowers_____ Straplike marginal flowers of a composite.

Sepal_________. Division of the calyx corresponding to petals in the corolla.

Sessile- Attached directly at the base; without a stalk.

Stamen_______. One of the pollen-bearing organs of a flower.
PLANT INDEX

Actinea acaulis..... _._.____ _--_-_._-

Allium acuminatum.......__.............

Antelope bitterbrush.----._..............

Aplopappus armeriodes. ....._._-_ -_._

Aster venustus...... ___..--..--..-.-...-

Astragalus aculeatus.....---.-----..-.-.--..

bisulcatus -..... ...__..._..___

confertiflorus.... .___.._-..-----.

dodgianus........ ._......_..._.....

lonchocarpus- --..... .__._..__.

missouriensis.-.. ... ...._____.___

pattersoni. ........_____.__._ 409.

lenellus-... ...

thomptonae.--.

Atripl&c cdtiescefis.

confertifolia....

Page 

512, 513 

434,435 

488,489 

472,473 

468,469 

432,433 

422,423 

420,421 

428,429 

426,427 

424,423 

414,415 

416,417 

430,431 

418,419

Black greasewood-_.............__._. 500,501

Bluepoisonvetch..__.............. _.. 420,421

0 

Calochortus nuttalli ...............-....... 436,437

CattiUeja Integra............................ 492,493

Colorado four-o'clock____......._..... 506,507

Cottonthornhorsebrush_......_.__ ..... 484,485

Cowania stansburiana........................ 486,487

Cryptanth.-.._-.---_.-_-_-.-_-_-_--_----- 448,449

Cryptanthaflava.................. __________ 448,449

Curlycupgumweed.............._....... 474,475

Cushion eriogonum......_.________.______._ 458,459

D 

Desert blazingstar_.......________._._ 480,481

princesplume.---._._......_________ 440,441

Deserttrumpet.--.___._._______... 456,457

eriogonum...--_.___.__________.__.. 454,455

Dodgemllkvetch_______________... 428,429

E 

Elymus salina.................... .___.... 462,463

Englemann prlcklypear...-.--..-...-.-.-.. 504,505 

Ephedrasp. __...____.........___. 502,503

Eriogonumfusiforme........................ 456,457

inflatum.... ___....................... 454,455

ovalifolium.........._.........__.. 458,459

umbellatum_________________.. 460,461 

Euphorbiafendleri.......................... 478,479

F 

Fendler euphorbia.......... . --.. 478,479

Fineleaf hymenopappus________._.. 510,511 

Four-o'clock, Colorado.....__.__________ 507

Fourwing saltbush__________. ___ 498,499 

Fraxinus anomala........................... 508,509

Q 

Goldenweed----.--.-.----.---_------- 472,473

Grassy deathcamas._______ ______ 438,439 

Greasewood____________. _____ 500, 501 

Grindelia sguarrosa.......................... 474,475

421588 57 9

H

Hairy-pod pepperweed. ___________ 444,445 

Hedysarum boreale.......................... 490,491

Hoary townsendia_--__---_._---_------ 470,471

Hymenopappus filifolius.................... 510,511

Indian paintbrush....---------------------- 492,493

Indian ricegrass..____..._____... 466,467

Jointflr. -.-- __-.--.--.__ 502,503

Lepidium lasiocarpum...................... 444,445

montanum...__________...... 442,443

Long-seeded milkvetch____....... __ _. 426,427

Looseflower milkvetch____._.___.. 430,431

M 

Marlposa... .- . -.-- - 436,437

Mentzelia multiflora........................ 480,481

Mirabilis multiflora............ ._.____ 506,507

Missouri milkvetch_________ _____ 424,425 

Mormon tea_____._ __________ 502,503 

Mountain pepperweed--...___.--.-._ 442,443

N

Needleandthread_______________ 464,465 

Northern sweetvetch.._______-... 490,491

O

Oenothera albicaulis. __..._...___-... 452,453

caespitosa_________...____._.. 450,451

Opuntia engelmanni........................ 504,505

Oryzopsis hymenoides...... _________ _.... 466,467

Paintedcup______ ____________.. 492,493 

Patterson poisonvetch ________ __ __ 414,415 

Plantagopurshi............................. 494,495

Preuss poisonvetch_-------_____________ 416,417

Purshiatridentata. ....................... 488,489

R

Rock goldenrod.-..----------------------- 482,483

Sandmat- --. -- - 478,479 

Salinawildrye ---------- ---. - 462,463

Sarcobatusvermiculatus-------...__..__ 500,501

Segolily .- 436,437

Senedolongilobus........................... 476,477

Shadscale salt bush---__-___................ 496,497

Silverplant. -- - _ - 458,459 

Singleleaf ash-___.._______...__ 508,509 

Sisymbriumaltissimum.--.................. 446,447

Solidagopetradoria.......................... 482,483

SpringmUkvetch......----.----.---.-.-.-.- 432,433

Starileya pinnata............................ 440,441

Stansbury cllflrose.._._____.____ 486.487 

Stemless actinea_.__ ..____ .... 512,513

515
516 INDEX

Stipa comata_. _____. __. _ _. ____ 464,465 

Sulfureriogonum __--------_.- 460,461

Tapertlp onion_____________._.-.- 434,435

Tetradymia spinosa,. ________ ___ 484,485

Threadleaf groundsel- --------.- 476,477

Thompson loco.____ .___..___.-_._ 418,419

Townsendia incana. __._----__...__ 470,471

Tuftedevening-prlnirose_.________.- 450,451

Tumblemustard -----------.----- 446,447

Two-grooved poisonvetch------___ _ _.__ 422,423

W

Whitestemmedevening-primrose.___._._- 452,453 

Wild onion, tapertip.--------------- 434,435

Woodyaster.. - -- 468,469

Woolly indianwheat_______-_....- 494,495

Z 

gramineus.-.----- ....__-.--. 438,439

o


Geology and Uranium 

Deposits of the Caribou 

Area, Boulder County 

Colorado

By F. B. MOORE, W. S. CAVENDER, and E. P. KAISfiR

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-N

This report concerns work done partly on 

behalf of the U. S. Atomic Energy Commission and is published with the permission of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing-Office 

Washington25, IX C. - PriceiJ1.2S (paper cover)
CONTENTS

Page

Abstract -..-___ _________ _ ________ ___ 517

Introduction-_________________________ ____ . _._ 517

Location and general features_________________________________ 518

History and production_ __ ___________________ _ _____ 521

Geology- _ _ _ 522

Rock units______________________'___________ 522

Idaho Springs formation__-__-__________-___-___________> 523

Boulder Creek granite____.._____________.________ 523

Caribou stock_________________________________________ 523

Structure ---- -- 524

Ore deposits________ __________________________________ 526

Gold veins__________________________ 527

Lead-silver veins_____________________________________ 528

Uranium-bearing lead-silver veins____________________ 536

Mine descriptions. -____ ________ _ 540

Silver mines__..______________ _____________ 541

Caribou mine__ _ ____ ________ ____ _ ___ 541

No Name mine___ _____________________________ __ 541

Poorman mine________________________________ _ ____ 541

Sherman mine________ ______ _________ _ _ __ 544

Columbia, Spencer, and Socorro mines_____ ____ _____ 544

Radium, Elmer, and Nelson veins__ _ __________ 545

Belcher mine_____ __ _ _ ____ 545

Comstock mine.__ _ __ _ _ 546

Native Silver mine.- _ _____________ __ 546

Seven-Thirty mine._________________ _ _ _ __ 546

Isabel mine_____ ________________ __ __ _ __ 547

Wigwam mine 547

Potosi and Cross mines____________________________ 547

Great Northern mine. 547

Gold-silver mines. _ 548

Silver Point mine -- ___ __ 548

Idaho mine_____ ______ 548

Gold mine 548

Literature cited_ _ ____ 549

Index.____...__________._________________ _ ... 551

nz
IV CONTENTS

ILLUSTRATIONS

[All plates are in pocket]

Plate 35. Geologic map of the Caribou area, Boulder County, Colo.

36* Composite map of the Caribou mine, showing vertical section through 

the Caribou and Poorman veins.

37. Geologic maps .of the 360, 920, 1040, and 1140 levels, Caribou mine!

38. Geologic map of the 500 level, Caribou mine and the Idaho tunnel.

39. Geologic map of the 300 level, Caribou mine.

40. Geologic maps of the 380,470, 530, 600, 740, 800, and 860 levels, Caribou

mine.

FIGURE 176. Maps showing location of the Caribou area, Boulder County, Paw 

Colo.......__________... __ 519

177. Geologic map of the Grand Island-Caribou mining district 520

178. Generalized structure of the Caribou group vein system. 525

179. Generalized section of Caribou Hill_____ ____. 530

180. Diagrammatic cross section of vein, showing alteration 531

181. Vertical longitudinal projection of the Radium and Elmer 

veins workings, showing location of pitchblende-bearing ore 

shoots ____._. __ 537

182. Vertical longitudinal projection of the Caribou vein, Caribou

mine________._________.______ 542

TABLE

Analyses of samples from the Radium vein, Caribou mine __-__. 536
CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

GEOLOGY AND URANIUM DEPOSITS OF THE CARIBOU 

AREA, BOULDER COUNTY, COLORADO

By F. B. MOORE, W. S. CAVENBEB, and E. P. KAISER

ABSTRACT

The Caribou silver-mining area is underlain by schists and gneisses of the 

Idaho Springs formation and the Boulder Creek granite, both units of Preeambrian 

age, and monzonite of Tertiary (?) age. Most of the uranium occurs in mesothermal lead-silver veins which cut the monzonite in an area less than a half 

mile square; a few lead-silver veins and a few gold veins occur ia the Idaho Springs 

formation but are relatively unimportant. The total value «f metals produced 

from the area is estimated to be about $6,000,000.

The lead-silver deposits occur in two sets of interconnecting fractures: (1) a 

northeast-striking series of shear fractures which parallel the regional trend, and 

(2) a west-striking series of tension fractures. The deposits occur in shoots 

localized chiefly at junctions of veins occupying the fractures bat to a lesser extent 

where strike and dip of the fractures change. Few of the veins have been worked 

to depths of more than 300 feet.

In the Caribou area pitchblende in quantities of more than trace amounts has 

been found only in the Radium vein in two ore shoots at depths between 900 and 

1,140 feet. The larger shoot has a horizontal dimension of 75 feet along the vein 

and extends from the 920 level to the 1140 level; the smaller shoot has a horizontal 

dimension of 35 feet along the vein and extends upwards 70 feet from the 1040 

level. In both shoots pitchblende occurs in a % to 6-inch-wide streak along the 

footwall side of the vein. Most of the pitchblende is soft and sooty, but in 

places sooty pitchblende encloses small quantities of a hard botryoidal pitchblende. 

Silver, lead, zinc, and carbonate minerals are in contact with but are not intermixed with the pitchblende. There is no apparent difference in mineralogy, 

other than the presence of pitchblende, between the uranium-bearing veins and 

other lead-silver veins at Caribou.

INTRODUCTION

Pitchblende was discovered in the Caribou mine of the Consolidated 

Caribou Silver Mines, Inc., in Boulder County, Colo., during the 

reopening of the 1040 level in 1948. Since then a small quantity of 

pitchblende has been produced from the Radium vein in this mine 

during exploratory work that was done under contract with the U. S. 

Atomic Energy Commission. The underground workings of the 

present Caribou mine, primarily a silver mine, expose five veins, the 

Caribou, No Name, Poorman, Sherman, and Silver Dollar, that 

formerly were worked through separate shafts. Three other veins, 

the Radium, Elmer, and Nelson, are exposed only in the Caribou 

mine at and below the 020 level.

517
518 CONTRIBUTION TO THE GEQIXJST OF UBANTOM

The general geology of the Caribou area has been discussed by Bastin 

(1917) and more recently by Lovering and Goddard (1950). In 1937, 

a detailed study of the petrography of the Caribou stock was made by 

Smith (1938). In 1948 and 1949, R. U. King (1952) of the U. S. 

Geological Survey examined the Caribou mine to evaluate the uranium 

occurrence. In 1951 the U. S. Geological Survey began a detailed 

investigation of the Caribou area on behalf of the Division of Raw 

Materials of the U. S. Atomic Energy Commission, the principal purpose of which was to evaluate the uranium occurrences in the area. 

The study was begun by E. P. Kaiser and W. S. Cavender, who 

established a triangulation net, using a base line in Caribou Park for 

horizontal control and a U. S. Geological Survey bench mark on the 

top of Caribou Hill for vertical control. Kaiser left the pro j ect in August 

1951, and the investigation was continued until November 1951 by 

F. B. Moore and W. S. Cavender. During the study of the district, 

a geologic map was prepared at a scale of 1:1,200 of an area covering 

about one square mile. The mapped area includes most of the mines 

in the Caribou district and embraces the eastern half of Caribou Hill 

and adjacent areas to the east and north. In addition, all accessible 

underground workings were mapped at a scale of 1:480. Surface 

mapping was done by planetable methods. For underground mapping, a compass and tape were used in conjunction with base maps furnished by the Consolidated Caribou Silver Mines, Inc.

The writers wish to acknowledge the cooperation of the staff of the 

Consolidated Caribou Silver Mines, Inc., who made the Caribou mine 

available for examination at all times and who furnished maps and 

suggestions that were of great assistance. Mr. A. E. Blakesley, 

owner of the Comstock mine, was also most cooperative in making 

possible the examination of his mine. Thanks are due Dr. E. E. 

Wahlstrom of the University of Colorado and to the Boulder Daily 

Camera for the use of their files, which contain information on the 

Caribou mine.

LOCATION AND GENERAL, FEATURES

The Caribou area is in sec. 8, T. 1 S., R. 73 W., sixth principal 

meridian, in the Grand Island mining district, in the southwest part 

of Boulder County, Colo. (fig. 176). The now almost completely 

abandoned town of Caribou, 17 miles west of Boulder and 4 miles 

northwest of Nederland, is readily accessible by means of an improved 

gravel road from Nederland.

The Caribou lead-silver mines are at an altitude of about 10,200 feet 

on the northeast side of Caribou Hill. Klondike Mountain is on the 

west and Boulder County Hill on the east (fig. 177). Although the 

relief in the area mapped is nearly 1,000 feet, both Caribou and
GEOLOGY OF THE CARIBOU AREA, COLORADO 519

108° |06°

BOULDER COUNT'1

COL

10 0

' L ' 

0

104° I

 Denver

R A

50

V, B 0 U 

j CO

\ CARIBOU AREA 

) * 

} Nederland

1 O

L 

U N

-\

9

D 0

z°

40°

"38°

100 Miles

D E R 

T Y

H^ Boulder

IO Miles

FIGUEB 176. Index maps showing location of Caribou area, Boulder County, Colo.
520 CONTfclBtJTIONS TO THE GEOl/OGY OF URANIUM

' / IPOMEROY MTN _' ',; > J.'s i VV.f' V '

a3P5Pea ^V< I tr^-G/?E-fl T NORTHERN MINE .jJ

VV \ x BOULDER COUNTY HILL. \-,.'%','

Datum is mean sea level

EXPLANATION

-! ° Boulder Creek granite

Granite and, quartz monzonite

Dikes of alkali syenite, diorite, 

monzonite or sodic granite

Quartz monzonite,

Diorite, diabase, and gabbro

S Quartz monzonite gneiss 

g and gneissic pegmatite

Idaho Springs formation

Ctittfy iiiotite schist

Laramide fault

< Dashed where approximately locate

Strike and dip of platy structure 

or schistosity

Veins of gold, silver, lead or zinc

Contact

lashed where approximately located

Pegmatite

FIGUBE 177. Qeologic map of the Grand Island-Oariboa mining district, Botdder County, Oolo.
GEOLOGY OF THE CARIBOU AREA, COLORADO 521

Boulder County Hills are well rounded, with moderate slopes. 

North and south of Caribou Hill are broad, flat, mountain meadows.

HISTORY AND PRODUCTION

The ores of the Caribou Hill "silver-belt" were discovered in 1869 

by a party of prospectors led by Samuel Conger, who had prospected 

Caribou Hill several years earlier without realizing the value of the 

minerals he found. Claims on the Caribou and the Poorman lodes, 

two of the richest in the area, were located in 1869 and in the following 

year the No Name, Native Silver, and Seven-Thirty claims were 

staked. By the end of 1871, most of the richer lodes on the hill had 

been found and in 1874, $330,000 worth of ore was shipped from the 

Caribou, No Name, Poorman, Sherman, Seven-Thirty, and Native 

Silver mines (Raymond, 1875).

The ore in the upper levels of many of the mines on Caribou Hill 

was exceedingly rich, as shown by reports in issues of the Rocky 

Mountain News for the period 1871-1872 and the Mining Review for 

1873-1874. Assays of more than 1,000 ounces of silver per ton were 

not uncommon. The ores mined at that time were divided into four 

classes: first-class ore, more than $300 per ton; second-class ore, 

$100-$300 per ton; third-class ore, $50-$100 per ton; and fourth-class 

ore, less than $50 per ton, which was either discarded or stockpiled 

to await construction of a millThe high value of much of the near-surface ore apparently resulted 

from supergene enrichment. Native silver and horn silver (cerargyrite), both secondary minerals, are frequently mentioned in early 

newspaper reports. Gold content was low in the lead-silver veins, 

and Henderson (1926) records no lead production for Boulder County 

until 1887, when 593 pounds were produced. Raymond (1875) noted 

a decrease by 1874 in the grade of the ore from the Caribou mine at 

a depth of 430 feet. The value of ore from the mine that year totaled 

$130,000, with an average value of $72 a ton. Many of the mines, 

from which ore valued at $300 to $1,000 per ton was reported early 

in the camp's history, failed to yield a large production. This apparent inconsistency could be the result, in part, of the over-enthusiastic reports of individual owners and, in part, to the inability 

of the owners to work the narrower veins profitably below the oxidized 

zone. Scattered reports in issues of the Mining Review and the 

Rocky Mountain News, for the 70's, and Corbett (1879), Fossett 

(1876), Burchard (1882), and Raymond (1872, 1873, 1874, 1875), 

when integrated show there was a definite, gradual decline in grade 

of ore as the mines became deeper.

Ore was produced from the Caribou area until 1893, when a drop 

in the price of silver forced most of the mines to close. Some of

427373 57 2
522 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

the richer of the gold mines, whose initial production had been completely over-shadowed during the early silver boom, resumed pror 

duction in 1898. However, from 1900 to 1948, activity in the area 

was limited to sporadic attempts by individual operators to reactivate 

certain mines or to mill the material from some of the larger dumps. 

The production for this period is believed to have been small. In 

1948, after the discovery of pitchblende on the dump, the Caribou 

mine was reopened by the Consolidated Caribou Silver Mines, Inc. 

This mine, which has workings also intersecting the No Name, 

Poorman, Sherman, and Silver Dollar veins, was the only one operating in the Caribou Hill area at the time of the investigation in 1951.

The total value of lead and silver produced from the Caribou area 

before 1924 is estimated, based in part on figures compiled by 

Henderson (1926) for production from Boulder County, to have been 

approximately $6,000,000. Of this total, the larger part was furnished 

by five mines: the Caribou, No Name, Poorman, Native Silver, and 

Seven-Thirty. No figures are available from which to estimate the 

value of gold produced, but it is believed to have been small.

The ore currently produced from the Caribou mine is concentrated 

at the company mill at Lakewood, about five miles east of the mine. 

From the mill the concentrate is sent by truck to a smelter at Leadville.

GEOLOGY

The Caribou area, which is part of the Front Range mineral belt, 

is underlain by Precambrian igneous and metamorphic rocks and, 

with the exception of unconsolidated Quaternary glacial and stream 

deposits, is devoid of sedimentary rocks. The Precambrian rocks in 

the Caribou area and in the adjoining areas to the north and south 

are intruded by Tertiary(?) igneous rocks which form several small 

stocks (Lovering and Goddard, 1950, plate 2). The dominant structural feature of the Front Range mineral belt, a series of northeasttrending folds and faults, is reflected in the Caribou area chiefly by 

northeast-trending mineralized shear fractures, several of which were 

quite productive of lead and silver. The lead-silver deposits at Caribou, with the exception of one mineral, are similar to many other 

lead-silver deposits throughout the Front Range mineral belt; the 

presence of pitchblende in some of the lead-silver ores at Caribou 

distinguishes these deposits from all but a few in the Front Range.

ROCK UNITS

The three principal rock units in the Caribou area are the Idaho 

Springs formation and the Boulder Creek granite, both of Precambrian 

age, and the monzonite of the Caribou stock (fig. 177), of Tertiary (?) 

age. The Caribou stock also contains small bodies of diorite, gabbro, 

and ultrabasic rocks.
GEOLOGY OF THE CARIBOU AREA, COLORADO 523

Minor units include Precambrian quartz monzonite gneiss and 

pegmatite (fig. 177). All the Precambrian rocks are cut by Eocene(?) 

dikes of diorite and andesite in the area southeast of Caribou. Because 

none of the minor rock units occur in the area mapped (pi. 35), they 

are not described below. Most of the lead-silver veins of the area 

are in the Tertiary (?) monzonite of the Caribou stock but all the gold 

veins are in Precambrian rocks.

IDAHO SPRINGS FORMATION

Schists and gneisses of the Idaho Springs formation occupy a large 

area in the Front Range and are described by Bastin and Hill (1917, 

p. 26) as follows:

The predominant rocks of the Idaho Springs formation are light- to dark-grey 

quartz-biotite schists, in places carrying some hornblende or muscovite. With 

these are associated lesser amounts of biotite-sillimanite schist, quartzitic gneiss, 

dark-green hornblende schist and gneiss, and lime-silicate rocks that represent 

metamorphosed limestones.

In the Caribou area the Idaho Springs formation occupies a narrow 

belt, about a half mile wide, along the eastern edge of the area mapped 

(pi. 35); it is bordered on the west by monzonite and on the east by 

granite. Within this belt, the Idaho Springs formation consists mostly 

of quartz-biotite schist and injection gneiss and, near its contact with 

monzonite on Idaho Hill, includes a large amount of pegmatitic rock. 

This formation is the host rock for most of the known gold veins in 

the area.

BOUIJ>ER CREEK GRANITE

The Precambrian Boulder Creek granite does not crop out in the 

mapped area, but is mentioned here because it occupies an area of 

several square miles adjoining the mapped area to the north and east 

(fig. 177). According to Levering and Goddard (1950, p. 25): "the 

Boulder Creek is commonly a dark-gray faintly banded rock that 

ranges in composition from a quartz monzonite to a sodic granite." 

In the area near Caribou it contains but few ore-bearing veins.

CARIBOU STOCK

The Caribou stock underlies most of the area mapped (pi. 35). 

It is not uniform in composition and is described by Smith (1938, 

p. 161-196) as: "a composite Tertiary(?) intrusive mass composed 

chiefly of monzonite but with masses of titaniferous magnetite and 

bodies of ultramafic and gabbroic rocks." Lovering and Goddard 

(1950) mapped bodies of quartz monzonite, gabbro, and ultramafic 

rocks within it as part of the stock.

The monzonite, which constitutes about 90 percent of the stock, 

is a bluish-gray, medium-grained rock composed essentially of biotite,
524 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

augite, orthoclase, and andesine; locally, fine-grained and porphyritic 

facies are common. At many places, hornblende forms thin seams 

along joint planes; in a few places the fresh monzonite shows faint 

layering which is not apparent on weathered outcrops. Outcrops of 

monzonite are few, but fresh rock can be found in many prospect pits 

and on the mine dumps.

Bodies of ultramafic and gabbroic rocks, as much as several hundred 

feet hi diameter, occur at many places hi the stock, but Smith (1938, 

p. 171) points out that "the distribution of the ultramafic and gabbroic 

bodies is irregular." The ultramafic bodies are chiefly pyroxenite and 

contain masses of titaniferous magnetite hi interlacing veins as much 

as 5 inches thick. One of the larger ultramafic bodies, known locally 

as the "Iron Dike," forms the eastern margin of the Caribou Hill 

lead-silver belt (pi. 35).

STRUCTURE

The dominant structure of the Caribou region is a large northnortheast-trending anticline of Precambrian age which appears to 

have controlled the intrusion of the Caribou and other nearby stocks. 

Lovering and Goddard (1950, p. 54) describe this anticline as extending 

south-southwest from Caribou to Empire, a distance of 12 miles. 

The Caribou stock and a monzonite stock two miles to the south form 

an elongate, discontinuous body that coincides with the axis of the 

anticline.

In the area mapped (pi. 35) the foliation in the Idaho Springs 

formation wraps around the north end of the anticline and, therefore, 

in many places the contact with the monzonite is discordant locally. 

The general distribution of the monzonite bodies in the region, however, is nearly concordant with the regional trend of the Precambrian 

structures. Such preexisting structures hi the Precambrian rocks may 

have controlled the localization of the stocks in two ways: (1) directly, 

by forming zones of weakness or layers along which ease-of-access of 

intruding magmas would be greater than normal, and (2) indirectly, by 

influencing the trend of later (Laramide) structures, which in turn 

would control localization of the stocks. No evidence was found 

during mapping with which to determine which type of control was 

dominant.

Jointing in the monzonite is common but is not conspicuous. The 

most prominent set of joints ranges in strike from N. 40° to 60° 

E. and hi dip from 70° to 90° NW., with an average strike of N. 506 

E. and an average dip of 85° NW. Much less prominent are sets of 

steeply dipping north-trending and east-trending joints.

To the east of Caribou, in Boulder County, are a series of northwesttrending major faults (Lovering and Goddard, 1950, pi. 2), and to the
GEOLOGY OF THE CARIBOU AREA, COLOBADO 525

south, in the northern parts of Clear Creek and Gilpin Counties are 

several large northeast-trending faults. Although these faults are not 

apparent in the Caribou area, they can be traced to within a few miles 

of Caribou and, if projected along their strikes, would intersect in the 

Caribou district. These faults may be present at depth, even though 

no surface indication of the faults exist. Lovering (1932) believes 

that the northwest-trending faults of Boulder County localized most 

of the ore deposits in Boulder County.

Three sets of steeply dipping veins northeast-trending, easttrending, and northwest-trending occur in the Caribou area. All the 

veins dip north at angles of 70° or more. The northeast and easttrending veins on Caribou Hill are chiefly in monzonite of the Caribou 

stock and form an interconnecting vein system (fig. 178 and pi. 36); 

the east-trending veins are at an angle of about 40° to the more persistent northeast veins. To the east, on Idaho and Boulder County 

Hills, a few west- and northwest-trending veins, which contain chiefly 

pyrite, gold, and quartz, form a separate system in the Idaho Springs 

formation. These veins may be older than the Caribou stock.

The northeast-trending veins on Caribou Hill are interpreted as 

occupying shear zones and the east- and west-trending veins are interpreted as occupying tension fractures branching from the shear zones. 

Although such features as offset geologic contacts were not in evidence 

to furnish conclusive proof, this interpretation is compatible with most 

of the geologic data. A northeast-trending shear fracture could be 

produced either by a compressional force acting nearly in an east or 

west direction or by a northeast-southwest shearing couple. The

FIGURE 178. Generalized structure of the Caribou group vein system, Boulder County, Colo.
526 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

regional forces producing fracturing in the Front Range mineral belt 

of Colorado are interpreted by Levering and Goddard (1950, fig. 81) 

to have acted in a northeast-southwest direction. If the component 

of a couple on the northwest side of such a shear fracture moved 

northeast with respect to the southeast side, any tension fractures 

produced should trend about east-west, as do the Caribou, Poorman, 

and Radium veins (fig. 178).

The direction of relative movement of the vein walls is difficult to 

determine by underground examination. Slickensides are nearly 

horizontal as seen in the mine workings but the evidence presented 

by chatter marks is inconclusive. Horizontal movement along the 

veins was small. There is no apparent displacement of the ultrabasic 

body lodally called the "Iron Dike" that is only 100 feet beyond 

the northernmost workings on the No Name vein (along the strike). 

What appears to be a displacement of the Radium-Elmer vein (fig. 

178) is the fortuitous branching of two separate veins from the No 

Name vein at nearly the same place. The Radium vein leaves the 

No Name vein in a smooth curve and is not cut off sharply, as would 

be true were it displaced by later faulting. Van Diest (1875) stated 

that the Caribou vein was cut and offset by the No Name vein, with 

the eastern extension of the Caribou vein being displaced about 10 

feet to the southwest. This interpretation seems unlikely, for no ore 

has been found along such eastern extensions of the Caribou vein, 

even on the levels where it contained good ore a few feet west of the 

No Name vein.

Although movement along the No Name vein may have been small, 

the brecciation and fracturing both of the vein walls and the vein filling 

show that movement did take place, some of it after the fractures were 

mineralized. If the walls along the No Name vein moved as indicated 

in figure 178, ore bodies would be expected in places where the strike 

changes to a more easterly direction. As intersections with the Caribou 

vein probably had an equal or greater effect in localizing ore bodies 

than did changes in strike along the veins, the effects of changes in 

strike alone will be most noticeable on the levels below the 860-level. 

On the 920-level and less obviously, on the 1040-level, ore bodies are 

found along the No Name vein in places where the strike changes to a 

more easterly direction. The movement along the northeast-trending 

Nelson vein apparently is in the opposite direction, because the vein 

widens where the strike is more northerly.

ORE DEPOSITS

Two types of ore deposits lead-silver veins and gold veins are 

present in the Caribou mining district. The lead-silver deposits have
GEOLOGY OF TEE CARIBOU AREA, COLORADO 527

been the most important economically, with silver being the most 

valuable metal recovered. Since 1948 small quantities of uranium 

have been produced from the lead-silver-bearing Radium vein.

Most of the lead-silver veins are within an area of about one-half 

square mile on Caribou Hill (pi. 35); a few are on Boulder County 

and Idaho Hills, half a mile to the east. Almost all are in the 

Tertiary (?) monzonite but a few occur in the Precambrian rocks. 

The gold veins occur predominantly in gneisses of the Idaho Springs 

formation, and none are known in the monzonite, which suggests that 

the gold veins may have been formed before the fracturing of the Caribou monzonite stock or even before its emplacement, whereas the 

lead-silver veins were formed after its consolidation. This interpretation is in harmony with Bastin and Hill's (1917) conclusion that in 

the Central City district the gold mineralization was earlier than the 

lead-silver mineralization.

QCMLD VEINS

The gold veins of the Caribou area are relatively unimportant, both 

quantitatively and economically. A few were worked in the 1890's 

(as reported in issues of Rocky Mountain News for 1890-1900), after 

the silver mines were closed, but their total production is believed to 

be small. A small group of veins, including the Silver Point, Idaho, 

Elephant, and Windy Point (pi. 35), which contained both gold and 

silver minerals (Lovering and Goddard, 1950, p. 202) are discussed in 

this report with the gold veins, but perhaps these should be classed as 

composite veins. None of the gold mines were accessible at the time 

of this survey.

The gold veins are on the west side of Idaho Hill, less than half a 

mile east of the Caribou mine (pi. 35). Although the shafts of several 

of these mines are only a few hundred feet east of the monzonite stock, 

and the veins if extended westward would cut the monzonite, no 

monzonite was seen on the dumps. Therefore, these veins probably 

do not extend into the monzonite. The country rock cut by the gold 

veins is mostly schist and gneiss of the Idaho Springs formation; 

however, near the contact with the monzonite, large amounts of 

pegmatitic rock are present.

Although none of the gold veins could be examined, the character 

of the ore can be determined from a study of the dump material. 

Samples from the dump of the largest gold mine in the area, the St. 

Louis, contained quartz, pyrite, chalcopyrite, covellite(?), and minor 

amounts of galena and sphalerite. Some carbonates (mostly dolomite) and quartz are found in vugs and presumably were deposited 

later than the ore minerals.
528 CONTBIBTJTIONS TO THE GEOLOGY OP URANIUM

Production figures for the Idaho Hill gold mines are not available 

and no estimate of the average value of the ore can be made. Bastin 

and Hill (1917, p. 181), in describing the St. Louis mine, state:

The ore treated was free milling and the value was mainly in gold. Sixteen 

tons shipped in 1905 are said to have shown an average content of gold, 3.28 

ounces; silver, 9 ounces; and silica, 17 percent. Two tons shipped in 1904 are 

said to have assayed gold, 5.81 ounces; silver 8.5 ounces; silica, 41.7 percent.

LEAD-SILVER VEINS

In all the veins in the Caribou monzonite stock, silver is the most 

valuable metal and lead the most abundant. The Radium vein also 

contains pitchblende and therefore is discussed separately. A small 

quantity of pitchblende was found on the dump of the Great Northern 

mine, but as this mine now is inaccessible, the vein could not be 

examined. The vein systems exposed in the Caribou mine and the 

Comstock mine were the only ones accessible for study in the Caribou 

area in 1951.

The lead-silver veins of the Caribou area are concentrated in an 

area about half a mile square, on the east and northeast slope of Caribou Hill (pi. 35); a few veins are present about one mile away to the 

east, north, and northwest of Caribou Hill. Only the Boulder 

County vein to the east is believed to have produced more than a 

small amount of ore and none of these outlying veins is included in 

the area mapped.

The description of mineralogy and paragenesis of the Caribou leadsilver ores is based largely on the study of samples from the Caribou 

mine, although samples from the dumps of most of the larger mines 

in the area also were examined. Listed in approximate sequence of 

deposition, the primary minerals in the lead-silver ores are quartz, 

pyrite, sphalerite, galena, chalcopyrite, argentite, ruby silver (pyrargyrite), and carbonates. Secondary minerals include native silver, 

azurite, malachite, and limonite. Reports by early workers (Mining 

Review, 1873, Endlich, 1874, Raymond, 1875) indicate that tetrahedrite, cerussite, "brittle silver" (stephanite(?)), "horn silver" 

(cerargyrite), and barite were present in small amounts in the upper 

workings.

Quartz, although one of the earliest minerals deposited, was deposited also in minor amounts as a late mineral. It formed either 

during several stages of mineralization or throughout the entire 

period of mineralization. The early quartz is massive white "vein 

quartz," commonly with small amounts of pyrite. Late quartz, in 

the form of clear crystals, fills vugs and forms veinlets cutting all 

other vein minerals except the carbonates. Cryptocrystalline quartz 

with fine-grained pyrite replaces the wall rock near the veins. Finegrained pyrite is common in all the lead-silver ores but is not abundant.
GEOLOGY OF THE CARIBOU AREA, COLORADO 529

Galena and sphalerite are closely associated, although sphalerite is 

sparse at shallow depths, either because of zonal deposition or leaching 

by ground waters. Both dark sphalerite, "black jack," and yellowishgreen sphalerite, "rosin jack," are present in the Caribou mine. 

Except in one place along the Radium vein at the 1040 level, chalcopyrite occurs only in small amounts. For the most part it appears to 

be contemporaneous with sphalerite and galena. Carbonates (dolomite and calcite) were the last minerals formed, and carbonate veinlets 

cut all other minerals.

Distribution of the minerals along the veins shows some variation. 

Quartz is more abundant in the Caribou vein than in other veins of 

the Caribou mine. The highly silicified Caribou-vein material formed 

what was known to the miners as a "hard ore." Sphalerite appears 

to increase with depth. Chalcopyrite is plentiful only on the 1040 

level of the Radium vein. Carbonates are present in all the veins 

but are more abundant than average along the No Name vein and 

less so along the Caribou vein. Massive pink carbonate more than 

a foot in width occurs along the No Name vein on the 500 level.

The upper parts of the veins at the Caribou mine have been greatly 

enriched in silver in the highly oxidized zone above the 300 level. 

The workings are inaccessible, but Endlich (1874) reported cerussite, 

malachite, and native silver from the 210 level and Raymond (1875) 

reports "horn silver" from the 200 level. The writers found abundant 

native silver in a veinlet on the 300 level and saw small amounts on 

the 360 level. The operators of the mine report that some native 

silver was found in a stope on the 920 level. Raymond (1875) noted 

a decrease in the silver content of the Caribou ore at a depth of 420 

feet.

The presence of the secondary minerals cerussite and "horn silver" 

in only the oxidized parts of veins, at depths of 300 feet or less; the 

abundance of native silver at depths of less than 300 feet; and the 

rapid decreases in grade of ore between 300 and 420 feet indicate that 

the oxidized zone of secondary enrichment did not extend much below 

300 feet. In the oxidized zone, the enrichment was from 3 to 10 

fold. Below the oxidized zone, in the zone of secondary sulfides, 

enrichment is much less pronounced. From the few production 

figures available, it is estimated that the enrichment in the secondary 

sulfide zone may have increased the grade of the ore values by as 

much as 50 percent. The base of the zone of secondary sulfides is 

believed to be at about 740 feet, where there is a noticeable decrease 

in iron oxide.

The lower limits of the oxidized and the secondary-sulfide zones are 

related to position of the water table, which is controlled primarily by 

the topography (fig. 179). The water table is normally somewhat

427373 57 3
530 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

o

o.,

o

oo-1
V V V

V V

v v \

-«-Silica decreases - -Silica decreases

I_f~Width of zone ranges from a few inches to several I 

feet, is proportional to thickness of vein I

EXPLANATION

Fresh rock, Chloritic zone; texture Silicified sericitized zone, 

unaltered preserved; slightly altered hard, bleached; texture

not preserved; carbonates, 

highly altered

Vein 

FIGURE 180. Diagrammatic cross section of vein, showing alteration, Caribo
532 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

higher than indicated in figure 179 and only during excessively dry 

periods would be at the level shown. The lowest position of the 

fluctuating water table marks the base of the oxidized zone and of the 

highly enriched ore. In the oxidized zone, ground water would move 

relatively rapidly downward, but in the secondary-sulfide zone it 

would move much more slowly, because the hydraulic gradient would 

be controlled by Coon Trail Creek at the same altitude as the 740 

level in the Caribou mine. Below the 740 level, in the zone of primary ore, the ground water is nearly static and therefore the ore has 

not been altered. The boundaries of the oxidized, secondary-sulfide, 

and primary-ore zones are gradational. The absence or scarcity of 

pyrrhotite, chalcocite, and similar very active precipitants of silver 

in the mine make possible the easy transportation of the silver by the 

ground water.

The effects of supergene enrichment on ore minerals other than those 

of silver are not well known at the Caribou district but appear to be 

of minor importance. Because zinc sulfide, a relatively soluble ore 

mineral, is rarely mentioned in the early accounts of the district, 

presumably it was leached from the near-surface parts of the veins. 

The Mining Review (1873, v. 1, no. 6, p. 11) states that the ores of the 

Caribou mine then exposed to a depth of 320 feet contained "but 

little zinc, arsenic or antimony." Zinc is fairly abundant on the 1040 

level but there is no evidence of secondary deposition either here or 

on the upper levels. Galena is plentiful throughout the veins and, 

being only moderately soluble, was apparently little affected by 

ground-water action. The pitchblende in the Radium vein occurs 

below the oxidized zone and probably was not exposed to secondary 

processes. If it was present in the oxidized part of the vein, it probably was removed for it is readily soluble in acid solutions.

Most of the wall rock of the Caribou lead-silver veins is mediumgrained, gray to dark-gray monzonite. Small masses of diorite, 

gabbro, pyroxenite, and biotite pyroxenite are exposed in the Caribou 

mine, but no comparative study of the alteration products of the monzonite and those of the more mafic rocks was made.

The wall rock of the lead-silver veins of the Caribou area has been 

progressively silicified, argillized, and chloritized for as much as 3 feet 

outward from the vein. Silica and chlorite occur along all veins. 

The products of argillization, possibly once extensive, have been 

partly obliterated by later sericitic alteration; they form a distinct 

zone at only a few places. The monzonite adjacent to the veins is 

intensely altered to form an inner zone of hard, bleached, silicified 

rock in which the original texture has been destroyed. The zone 

ranges from a few inches to 2 feet in thickness and is characterized 

by disseminated cryptocrystalline quartz, sericite or illite, or both,
GEOLOGY OF THE CARIBOU AREA, COLORADO 533

and carbonate minerals, as well as by numerous veinlets of finegrained quartz and carbonate minerals. In most places this intensely 

altered zone grades into a zone of slightly altered rock characterized 

by chlorite. This outer, or chloritic, zone ranges from about 6 inches 

to 2 feet in thickness, grading outward into fresh rock. A middle, or 

argillized, zone occurs in a few places between the chloritic and silicified zone (fig. 180). Composed of a green-gray, friable rock, the 

argillized zone contains abundant minerals of the montmorillonite 

group. This argillized, or montmorillonite, zone is only 6-12 inches 

thick along the Radium vein, but is several feet thick along the No 

Name vein on the 500 level. The contacts between the montmorillonite and adjacent zones are sharp.

Assignment of alteration minerals to definite zones is not meant 

to imply that these minerals are found only in a particular zone or 

that other alteration minerals are absent from this zone. The zones 

are named for the most abundant or characteristic alteration minerals, 

which were originally identified in thin section under a microscope. 

Recent X-ray studies by E. W. Tooker of the U. S. Geological Survey 

on the clay minerals of the inner and middle zones have largely confirmed the original identifications. Altered material in the inner or 

silicified zone believed to be sericite was shown by its X-ray pattern 

to be a mixture of sericite and illite. Although no determination of 

the relative distribution of sericite and illite within the zone could 

be made with the samples available, Tooker (1953, oral communication) states that, in general, the ratio of sericite to illite decreases 

with an increase in distance from the vein. The distribution of 

alteration minerals in the three zones are given below, listed according 

to means of identification:

SUicified (inner) zone Montmorillonite (middle) zone CMoritic (outer) zone

Microscope Quartz, sericite, car- Montmorillonite, some Chlorite.

bonate, some kaoli- kaolinite, beidellite,

nite. and illite. 

X-ray Mostly serieite-illite, Montmorillonite, Not deter10-15 percent kaoli- 10-15 percent kaoli- mined.

nite, 5-10 percent nite, some illitemontmorillonite, sericite.

5-10 percent halloysite.

H. D. Wright (1950, written communication) in studying the major 

pitchblende ore shoot in the Radium vein, recognized four zones of 

alteration which he numbered in order outward from the vein as (1) 

a 2- to 6-inch hard, compact bleached zone containing sericite, carbonate, and fine-grained quartz, (2) a 2- to 3-inch dark green-gray, 

friable zone containing iron-stained montmorillonite, some kaolinite, 

and a little sericite, (3) a discontinuous zone resembling zone 1, but
534 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

with little silica and containing abundant sericite and small amounts 

of kaolinite and montmorillonite, which mark the outer limit of 

argillic alteration; (4) a zone of propylitized rock in which the pyroxenes have altered to chlorite, calcite, and a little epidote. Zones 

1 and 3 of Wright correspond to the inner zone of this report. Except 

where separated by a montmorillonite layer (zone 2 of Wright), they 

form a single gradational zone.

The most persistent vein in the Caribou area the No Name vein 

(pi. 36 and fig. 178) strikes northeast and has been worked for a 

horizontal distance of at least 1,000 feet and to a depth of 1,100 feet. 

This vein marks the eastern boundary of the main productive area 

on Caribou Hill (pi. 35). Most of the other veins are short 300-400 

feet in length and few have been worked to depths of more than 300 

feet. The Caribou vein, which can be traced for 300 feet on the 

300 level of the Caribou mine, appears to become shorter as the depth 

increases. Below the 860 level, it cannot be recognized. Several 

veins which are known only on the deeper levels the Elmer, Radium, 

and Nelson may actually be deeper parts of outcropping veins that 

were worked only to shallow depths.

The lead-silver ore bodies of the Caribou mine are vertical or 

steeply-plunging ore shoots. The larger shoots extend more than 

200 feet along the vein and have been followed to depths of more than 

700 feet. The veins are as much as 7 feet thick in places but the "pay 

streak" is rarely more than 18 inches wide.

The veins are mostly fissure fillings, but in places the wait rock has 

been replaced. Some veins have one well-defined wall; the other is 

gradational. The ore bodies are almost entirely in monzonite; and 

where the veins cut mafic rocks, they are weakly mineralized. There 

are no mines in the mafic rocks.

The ore shoots of Caribou Hill are localized by changes in dip or 

strike of the vein and by vein junctions. A series of tension fractures 

that trend west from the No Name vein contain ore shoots near 

their junction with the No Name vein. The concentration of ore 

minerals in the tension fractures such as the Caribou vein was in 

many places greater than in the stronger shear fractures, such as 

the No Name vein, that trend northeast. Prior to mineralization 

highly fractured rock partly filled the openings along the No Name 

vein and locally was cemented by vein minerals. Such brecciation 

is absent along the subsidiary west-trending tension fractures. Postmineral movement, indicated by crushed vein minerals, is apparent 

along the northeast-trending shear fractures. No postmineral movement is apparent in vein minerals of the west-trending tension fractures.
GEOLOGY OF THE CAEIBOtJ AREA, COLORADO 535

The ore shoots in the Caribou vein are thicker in the less steeply 

dipping parts of the vein. This is especially evident on the 360- 

level where the vein decreases in dip from about 80° to 50° and 

increases to 10 feet in thickness (pi. 37, section A Af). The Caribou 

vein steepens at the 800-level and here is too thin to be worth mining; 

it was not explored below the 860-level. Although the other veins 

in the Caribou group are not sufficiently well exposed to determine 

the structure of their ore shoots, it is believed that a similar structural 

relationship may also control, in part, the localization of ore in other 

shoots in the Caribou area.

Changes in strike, especially along the northeasterly-striking shear 

fracture veins, apparently helped influence the localization of ore. 

The best ore exposed in the Nelson vein is along that portion of the 

vein in which the strike is more northerly. Along the No Name vein, 

the junction of that vein with the Caribou vein was the dominant 

influence in localization of ore, but on the 1040- and 920-levels (pi. 37), 

the Caribou vein is absent and slight changes in strike to a more 

easterly direction coincide with the stoped areas. In general, veins 

occupying the westerly trending tension fractures are straight because 

the wall rock is homogeneous and the horizontal movement, relative 

to that of the shear fractures, is small. Accordingly, changes in strike 

were not important factors in the control of the ore deposition in the 

tension-fracture veins. The ore shoot localized by a change in strike 

along the Radium vein (tension-fracture) is small.

Silver is by far the most valuable metal in the lead-silver ores of 

Caribou Hill area. Gold rarely exceeds 0.1 or 0.2 ounce per ton and 

gold was not reported present in the lead-silver veins by early newspaper accounts or by Fossett (1879) or Raymond (1872, 1873, 1874, 

1875). Lead, which currently is being produced from the Caribou 

mine, is believed to account for only a small percentage of the total 

production from the mining district. The earliest recorded production 

of lead from Boulder County, as reported by Henderson (1926), was 

in 1887, a time at which the production of ore from the Caribou area 

was declining rapidly.

The ore, especially in the oxidized zone, was exceedingly rich; assay 

values of 200 to 300 ounces of silver per ton were not uncommon. 

However, the bulk of the production came from ore of much lower 

grade. The Caribou vein, the richest and most productive in the area 

(about $1,500,000 to 1883), yielded $334,000 worth of ore of an average 

grade of $70 per ton during 1874 and 1875.

Since the Caribou mine was reopened in 1947, a total of $519,642.19 

worth of lead-silver ore has been produced. 1 Most of the ore came

1 Data furnished by Consolidated Caribou Silver Mines, Inc. Published with permission of the company.
536 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

from the 920- and 1040-levels but a small amount came from the 

500-level. The largest ore bodies were found along the Nelson vein 

but the Elmer, No Name, and Radium veins also yielded ore. Some 

of the ore contains as much as 100 ounces of silver and 10 percent lead. 

Zinc is less abundant than lead. Analyses of 17 samples taken from 

the uranium-bearing areas of the Radium vein are shown below.

Analyses of samples from the Radium vein, Caribou mine, Boulder County, Colo.

[Analysts: W. D. Goss and D. L. Skinner for samples CAA-1 to -10; E. C. Mallory and D. L. Skinner for

samples FM-5-48 to -56.]

Sample No.

Location, 

distance 

from No 

Name 

vein (feet)

Length 

ofsample 

(inches)

U Pb Zn Cu

Percent

Ag Au

Ounces per ton

920 level

CCA- !...._

2.....

5.__._

6 __ 

8.__._

9_____

10 __

75

80

111

116 

121

126

131

8

8

9

2^ 

9

10

9

0 08

22

79

18 

23

1 85

11

5.85

2. 29

4. 28

8.29 

3.01

5. 20

3. 96

3.94

3.78

5.27

407 

3.07

2.77

2.82

0 02

04

02

11 

36

39

24

72.07

10. 14

15. 12

76.77 

75.84

217. 64

38.28

0 03

03

04

10 

Tr.

14

08

1040 level

CCA- 3.....

FM5-48.._._

49.....

50...._

51.....

52... ._

53.....

54.....

55... ._

56...._

51

271tf

276

280}£

285

285

293#

302

309)4

315

3

6

7

12

13

12

13

12

8

8

36

49

04

36

08

01

15

19

28

02

22. 99

3. 73

1. 96

10. 13

15. 82

11. 84

7. 74

12. 23

6. 16

.46

16. 73

5. 33

1. 46

4.80

7.68

17. 06

3.98

2. 78

6. 61

. 22

01

04

02

01

02

03

05

16

02

< 01

3.20

22.31

2. 76

8. 87

1. 64

4. 30

14.05

108. 40

7.84

.72

Tr.

.05

None

.03

None

.04

.02

.07

. 02

None

URANIUM-BEARING LEAD-SILVER VEINS

Except for the presence of pitchblende, the uranium-bearing veins 

in the Caribou area do not differ in mineralogy from other lead-silver 

veins of the area; the two types of veins form one interconnecting vein 

system. However, the uranium-bearing veins are discussed separately 

in this section, not because they are considered a separate type of vein, 

but because they warrant special attention, in view of the strategic 

importance of uranium.

The only known pitchblende deposits in the Caribou area are in the 

Caribou mine, but pitchblende is believed to occur in the Great 

Northern mine. The pitchblende occurs in the Caribou mine along
GEOLOGY OF THE CARIBOU AREA, COLORADO 537

EXPLANATION

Monzonite

Gobbro 

Contact, doshed where projected

Diomond-dnll hole, where drill 

hole intersects vein. Assay

Pitchblende'ore shoot

8!

t

JT1O-LEVEL 

'I'lilo'Nmte Orillt

ELMER VEIN ; V. . <RAb«iM-XVE1N ,-fli'P"

obi boo/

"0 001 °

FIGURE 181. Vertical longitudinal projection of the Kadium and Elmer vein workings, showing locations 

of pitchblende ore shoots, Caribou mine, Boulder County, Colo.

the Radium vein at depths between 900 and 1,140 feet (pi. 37 and 

fig. 181) and along an unnamed vein, possibly the Nelson vein, on the 

500 level (pi. 38). Pitchblende was found on the dump of the Great 

Northern mine, but because the mine is inaccessible and there is no 

record of pitchblende having been found in the mine, this occurrence 

cannot be evaluated.

In the Caribou mine, pitchblende occurs beside galena, sphalerite, 

and silver minerals along the footwall of the Radium vein. Some of 

the pitchblende is hard, but most is soft and sooty and coats vugs and 

fractures. The hard pitchblende occurs as a band, generally less than 

an inch thick, between sulfides and gouge along the footwall of the vein. 

In a few places the band is as much as 6 inches thick and locally splits 

into stringers that form a braided network.

The paragenesis of the minerals constituting the Radium vein was 

determined by a study of polished sections. Quartz and pyrite (a 

minor amount) were the earliest minerals. Most of the quartz is white 

and massive; however, some occurs in vugs as crystals. Sphalerite
538 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

and galena, apparently contemporaneous, fill vugs and fractures in 

the quartz. Chalcopyrite, in part contemporaneous with the sphalerite and galena, is also probably younger in part. One specimen shows 

a chalcopyrite veinlet cutting sphalerite but not galena. A younger 

age for part of the chalcopyrite is indicated by its occurrence along 

cleavages in galena and as crystals growing along a sphalerite-galena 

contact.

The position of the pitchblende in the paragenetic sequence is not 

definitely known because only small amounts of the hard, lustrous 

pitchblende are present along the veins, and because the samples that 

were collected did not show definite age relationships with other 

minerals. One specimen contains an irregular veinlet of hard pitchblende that cuts pyrite. On the basis of negative evidence, it is 

believed that the hard pitchblende also is younger than the sphalerite 

and galena. If the pitchblende were earlier than the galena, evidence 

that galena cuts pitchblende should be present, owing to the relative 

abundance of galena in the pitchblende zone. If the pitchblende were 

contemporaneous with the galena and sphalerite, some of the pitchblende should be intergrown with those minerals. None of the pitchblende contains any appreciable quantity of sulfides nor do the adjacent 

sulfides contain any visible pitchblende. Autoradiographs of two 

specimens of sooty pitchblende show that the sooty variety is confined 

to vugs and fractures and is not intermixed with the sulfides.

H. D. Wright (1950, written communication) in discussing the 

mineralogy of the Radium vein states:

The ore minerals recognized in the polished surface are uraninite, 2 pyrite, 

chalcopyrite, sphalerite, galena, argentite, ruby silver, and native silver. Gangue 

minerals represented are quartz, carbonate and barite. The existence of two 

characteristic assemblages of ore minerals suggests two stages of vein formation. 

In Stage A, which is thought to be earlier, quartz, sphalerite and galena were 

deposited. Uraninite was deposited early in Stage B. The other minerals of this 

stage are chalcedony, chalcopyrite, sphalerite, argentite, ruby silver, and native 

silver.

The hard pitchblende at Caribou occurs as "inclusions" in the soft, 

sooty variety, suggesting that the sooty pitchblende was deposited by 

hypogene solutions after the hard pitchblende or that it resulted from 

the supergene alteration of it. Sooty pitchblende deposited in vugs 

after deposition of colloform quartz and fine oolitic pyrite in the vugs 

indicates a late and probably low-temperature stage of deposition.

Although age determinations for the comparison of the relative 

ages of the soft and hard pitchblende are not available, the field relations show that the soft variety is the younger. Kerr and Kulp

8 Pitchblende is generally considered to be a noncrystalline form of uraninite.
GEOLOGY OF THE CARIBOU AREA, COLORADO 539

(1952) give an age of 23 million years (±10 million) for the pitchblende at the Caribou mine. This age determination was probably 

ma,de on pitchblende of the hard variety and was not corrected for 

common lead. Phair (1952) recalculated the age of the Caribou 

pitchblende and determined a possible maximum age of 44 million 

years. The pitchblende from the nearby Central City district, 

Colorado, which contains a much higher ratio of hard to soft material 

and which Bastin (1917, p. 124) believed was contemporaneous with 

the gold ores, was determined by Nier, Thompson, and Murphey 

(1941) to be from 57 to 59 million years old.

Kerr (1951, p. 91-92), after studying samples of "uraninite" from 

Colorado, Canada, and the Belgian Congo, states: "A number of 

observations indicate that the sooty uraninite may be a later form 

high in UO3 that has originated at the expense of earlier hard uraninite, 

high in UO2". It is possible that the soft pitchblende is a first step 

in the chemical alteration of pitchblende to secondary minerals. The 

absence of any of the typical alteration products (gummite, torbernite, 

etc.) at Caribou may be due to the limiting factors of the environment. 

Kerr adds that "although the sooty mineral is later, it is found at such 

depths that it apparently does not represent a typical surface-weathering product." Two separate stages of primary uranium deposition 

seem unlikely because, were this true, in some places only hard pitchblende should occur and in others only soft pitchblende. However, 

the two varieties appear to be coextensive.

Pitchblende has been exposed along the Radium vein on the 920, 

1040, and 1140 levels, the only levels that have explored the Radium 

vein (pi. 37). Two ore shoots containing pitchblende occur about 170 

feet apart in the Radium vein on the 1040 level. The larger shoot 

extends from the 920 level downward to the 1140 level and is more 

than 70 feet long (fig. 181). The smaller ore shoot extends for 35 feet 

along the drift and vertically for 70 feet in a raise from the 1040 level. 

The larger ore shoot plunges steeply to the west; although the smaller 

one appears to be vertical, it also may plunge steeply to the west.

Within the ore shoots the pitchblende is erratically distributed. 

Assays vary by as much as 100 to 1 in a distance of 2% feet. At 

places where pitchblende occurs, minerals typical of the lead-silver 

veins are invariably present, commonly in considerable abundance. 

Some of the pitchblende-bearing ore is worth mining for lead and 

silver. The uranium ore, a part containing as much as 7 percent 

uranium, has been separated from the lead-silver ore and from the 

gangue by hand sorting. Except for a small shipment for metallurgical purposes, all the uranium ore from the Caribou mine has been 

stockpiled by the company.
540 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

MINE DESCRIPTIONS

The Boulder County claim map for sec. 8, T. 1 S., R. 73 W., shows 

100 patented claims in the area mapped; 46 of these claims have been 

identified with surface workings, and names also have been assigned 

to an additional 38 unpatented properties. The names of mines and 

veins shown on plate 35 were determined in large part from a map 

published in the Engineering and Mining Journal (1877) and in part 

from information given by Mr. Elmer Hetzer of Boulder, Colo. 

Many of the smaller mines or prospects could not be identified. 

About 30 mines were worked to a depth of 100 feet or more, but production figures are available for only a few of the larger properties. 

The mines described below are believed to be significant because of 

their production, size of workings, location, or mineralogy. One, 

the Great Northern, is a few hundred feet beyond the area mapped 

but its location is shown on figure 177. The Caribou and the Cornstock mines were the only ones accessible during this study.

SILVER MINES

Of the silver deposits in the Caribou area, those worked by the 

Caribou group of mines are the most important; only one other mine 

is accessible and only one other deposit yields evidence of pitchblende.

The Caribou group consists of eight mines, the Caribou, No Name, 

Poorman, Silver Dollar, Sherman, Columbia, Spencer, and the 

Socorro. The Caribou, No Name, Poorman, Silver Dollar, and 

Sherman veins can be identified on the Caribou mine's 300 level and 

form an interconnecting vein system. The Columbia and Spencer 

veins, which parallel the No Name vein, were incorporated in the 

holdings of the Caribou company as early as 1883. The Socorro 

vein is parallel to the Caribou vein on the south and may be identical 

with the South Caribou vein of this report. Recently three more 

veins, the Radium, Elmer, and Nelson, have been exposed on the 

920- and 1040-levels of the Caribou mine but have not been definitely 

correlated with any of the veins exposed at the surface.

The Caribou group is owned by the Consolidated Caribou Silver 

Mines, Inc., who reopened the mines in 1948 by means of an adit, the 

Idaho tunnel, 3,700 feet long (pi. 38) that intersects the Caribou 

shaft at a depth of 500 feet. In 1951 the ore was being exploited 

from the No Name, Nelson, Elmer, and Radium veins on the 920 

and 1040 levels.

CARIBOU MINE

The Caribou vein, discovered in 1869, is the richest silver vein hi 

the Caribou area. The value of silver ore shipped from the mine 

before 1880 totaled more than $1,000,000 (Fossett, 1879). Corregan 

and Lingane (1883) gave the total production of the Caribou and No
GEOLOGY OF THE CARIBOU AREA, COLORADO 541

Name veins as $2,500,000. Since 1883, the Caribou mine has been 

operated intermittently. Some of the ore was very rich; assay values 

of $300 to $500 a ton were common.

A shaft 1,040 feet deep gives access to levels at 50, 100, 200, 300, 

360, 500, 530, 600, 670, 740, 800, and 860 feet below the collar (pis. 

37, 38, 39, 40, and fig. 182). Shafts 100 feet apart along the vein, 

1 east of the main shaft and 5 to the west are now covered by the 

mam dump.

The Caribou vein strikes approximately west and has an average 

dip of 75° to the north. The vein is nearly 300 feet long on the 

300 level (pi. 39) but shortens at depth and feathers out 860 feet 

below the collar (pi. 36). The width of the vein averages about 2 

feet, increasing to a maximum of 10 feet on the less steeply dipping 

parts (flats) of the vein. The silver ore is localized in well-defined 

shoots, mostly in the eastern part of the vein near its junction with 

the No Name vein (fig. 182). The ore is highly siliceous and shows 

no evidence of postmineral crushing. Carbonate minerals are sparse 

in the Caribou vein, probably owing to nearly complete filling of 

openings by earlier vein material.

Ore minerals are galena, sphalerite, argentite, pyrargyrite, and 

native silver. Finely disseminated pyrite replaces the wall rock near 

the vein, but only a small amount of pyrite is present in the ore. 

Some of the ore contains a minor amount of chalcopyrite.

The main Caribou vein has been stoped to a depth of nearly 800 

feet and westward from its junction with the No Name vein for 

distances ranging from 300 feet on the 300-level to 150 feet on the 

740-level. Because the main Caribou vein feathers out a short 

distance below and to the west of the stoped areas and because no 

ore-bearing extension of the Caribou vein has been found east of the 

No Name vein, it is doubtful that the vein still contains workable ore.

NO NAME! MINK

The No Name vein is the most persistent vein in the Caribou area, 

having been worked for more than 1,000 feet both horizontally and 

vertically. According to Raymond (1875, p. 370), the total value of 

ore produced before 1875 was estimated by the owner to be $400,000. 

Total production from the vein to date is believed to be about 

$1,000,000.

The No Name vein is developed by a shaft more than 500 feet deep; 

the levels correspond to those of the Caribou mine to a depth of 860 

feet. In addition there are three deeper levels at 920-, 1040-, and 1140 

feet (pi. 37). The vein was not being worked in 1951.

The No Name vein is not a single fissure filling like the Caribou 

vein but rather a mineralized shear zone, as much as 7 feet wide, that
542 CONTRIBUTIONS TO THE GEOLOGY OF tTEANTtlM

CARIBOU SHAFT

EAST 

CARIBOU SHAFT

EAST

Stopes

Dashed sfopes after 

Fossett, 1879

 

Drift

By Moore ond Covendei;l95l

200 FEET

FIGUEB 182. Vertical longitudinal projection of Caribou vein, Caribou mine, Boulder County, ColO
GEOLOGY OT1 THE CARIBOU AREA, COLORADO 543

strikes N. 55° E. and dips an average of 70° NW. (pi. 37). The ore is 

disseminated in stringers through the shear zone, cutting and surrounding brecciated fragments of country rock. The ore minerals are similar 

to those of the Caribou vein: galena, sphalerite, argentite, pyrargyrite, 

and native silver. Postmineral movement fractured the early vein 

minerals and formed openings in which late carbonates were deposited. 

The carbonate minerals, mostly dolomite and calcite, occur as veinlets 

and as tabular masses as much as one foot thick along the vein.

The shape and distribution of ore shoots along the No Name vein 

cannot be accurately determined because large parts of the No Name 

workings are inaccessible. One ore shoot extends from the 600 to the 

920 level at and near the junction of the No Name and Caribou veins 

and plunges steeply to the northeast. The lateral and upward limits 

of this shoot are not known, but it is believed to be a downward continuation of the main No Name ore shoot. A large stope to the 

southwest on the 600 level (pi. 40) indicates the presence of a second 

ore shoot in that direction.

Reserves of lead-silver ore in the No Name vein are believed to be 

small.

POORMAN MINE

The Poorman shaft is 190 feet north-northeast of the main Caribou 

shaft (pi. 35). The mine worked the Poorman and probably the Silver 

Dollar veins, both of which were owned by the Poorman Mining 

Company. Although the Poorman vein was one of the first to be 

discovered in the area (1869), the mine was not one of the early producers. In 1879, when the shaft was 220 feet deep, the production to 

that time was estimated to be only $35,000 (Corbett, 1879). A 

prospectus written by the Poorman Mining Company about 1885 

states that mill certificates show a total production (Poorman and 

Silver Dollar veins) of nearly $200,000. The mine was operated until 

1893, and consists of the Poorman shaft, 600 feet deep, with acccessible levels corresponding to the 300,500, and 670 levels of the Caribou 

mine.

The Poorman vein strikes N. 78° W. and dips steeply to the north. 

On the 500 level, stope outlines indicate that the ore bodies were 

localized along the Poorman vein near its junctions with the No Name 

vein on the east and with an unnamed vein (possibly the Nelson) on 

the west (pi. 38). The eastern ore body extends for more than 120 

feet along the vein. The vertical dimensions of the ore bodies are not 

known.

The Poorman vein contains highly siliceous ore resembling the ore 

in the Caribou vein, although not as rich. A sample from the 670 level 

contains sphalerite, galena, pyrite, and chalcopyrite in silicified 

monzonite. The sulfides occur in interwoven veinlets and dissemi-
544 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

nations with sphalerite the most abundant. No silver minerals are 

visible.

The nearly vertical Silver Dollar vein strikes northeast and crosses 

the Poorman vein without displacement (pi. 39). Where exposed on 

the 300 level of the Caribou mine, it is a 1-foot-wide brecciated, ironstained shear fracture with no visible sulfides. The absence of stopes 

on this vein indicates that the production was probably small.

SEBBRMAN MINE

The Sherman mine, about 100 feet north of the Caribou mine, is 

developed by a shaft 265 feet deep. The workings are cut by the 

Caribou tunnel at a depth of 210 feet (pi. 39). The mine is on the 

Sherman vein which strikes east and dips 85° to the north. Where 

cut by the Caribou tunnel the vein is timbered and could not be 

examined. The ore apparently did not extend to depth and no evidence of the vein can be found on the 500 level of the Caribou mine.

According to Raymond (1875), $40,000 worth of silver was produced 

in 1874 from ore valued at $180 per ton. Fossett (1879) states that 

300 tons of ore produced in 1896 had an average value of $270 per ton.

COLUMBIA, SPENCER, AND SOCORRO MINES

The Columbia, Spencer, and Socorro mines are on veins closely 

related to the Caribou-No Name vein system. About 1881, the 

Columbia and Spencer mines were incorporated with the Caribou and 

No Name mines, largely in order to avoid litigation. The Columbia 

is apparently on a southwestern extension of the No Name vein. The 

Columbia workings are undercut by the No Name workings. The 

mine produced little ore. The Spencer vein is adjacent and parallel 

to the No Name vein on the southeast. Developed by a shaft 420 

feet deep, it is credited with a total production of $10,000 before 1879 

(Corbett, 1879). The Socorro claim adjoins the Caribou claim on 

the south. No evidence remains of the Socorro mine but its reported 

location suggests that it probably was on the South Caribou vein 

which is exposed in the Caribou mine workings. No production is 

recorded from the Socorro mine.

RADIUM, ELMER, AND NELSON VEINS

The Radium, Elmer, and Nelson veins are exposed on the 920 and 

1040 levels of the Caribou mine (pi. 37), but have not been correlated 

with veins visible at the surface. The Radium vein branches to the 

east from the No Name vein near the point where the Elmer vein 

joins the No Name from the west. The Radium vein strikes east and 

the Elmer vein slightly north of west; both dip about 85° north on the 

1040 level but the dip of the Elmer vein decreases to about 60° above 

the 920 level. The Nelson vein strikes northeast and is nearly vertical.
GEOLOGtY OF THE CARIBOU ABEA, COLORADO 545

Lead-silver ore averaging at least $40 a ton has been produced 

recently from both the Elmer and the Nelson veins. The Radium 

vein also contains pitchblende, and mining of the vein has been confined to the uranium-bearing ore shoots. Except for pitchblende, the 

mineral suites of the Radium, Elmer, and Nelson veins generally are 

similar. Galena, sphalerite, argentite, and ruby silver are the ore 

minerals, with galena as the most abundant. Sphalerite, both dark 

and rosin colored, is intermixed with the galena. The gangue consists of quartz, carbonates, chalcopyrite and pyrite, with quartz as 

the chief gangue mineral, although, locally, carbonates and chalcopyrite are abundant. On the 1040 level, near the northeast face of 

the Nelson vein, more than half the vein filling is carbonate (calcite 

and dolomite). Chalcopyrite is the most abundant sulfide at a point 

30 feet east of the winze along the Radium vein on the 1040 level. In 

general, however, carbonates, chalcopyrite, and pyrite are present in 

only minor amounts. Pitchblende occurs with the lead-silver ore on 

the 920 and the 1040 levels of the Radium vein (pi. 37). The pitchblende forms a streak %-6 inches wide on the footwall side of the vein 

and is not intermixed with the sulfides.

The Radium and Elmer veins occupy tension fractures produced by 

the No Name shear fracture (pi. 37). Ore bodies occur along both the 

Radium and Elmer veins near their intersections with the No Name 

vein (pi. 37). The eastern ore body of the Radium vein and the ore 

body in the Nelson vein were localized apparently by changes in 

strike. The ore body west of the crosscut to the Elmer vein at and 

above the 920 level was controlled by a decrease in dip.

BELCHER MINE

The Belcher mine, 350 feet west of the Poorman mine, is on a 

northeast-striking vein. Corbett (1879) reports that the vein is 4 feet 

thick with a 6- to 18-inch "pay vein" that averages 50 ounces of silver 

per ton. The shaft was 110 feet deep in 1879 and 120 feet deep in 

1883. Most of the ore from this mine is believed to have been produced in the late 1890's, when most of the camp was closed. Seeley 

(1906) reports that the shaft was 300 feet deep and the total production was $75,000.

COMSTOCK MINE

The Comstock mine (pi. 37) is the only mine, other than the Caribou 

Group, that was accessible in 1951. Although not in operation, the 

mine is being maintained in a working condition. The workings 

consist of a shaft 450 feet deep, accessible levels at 200 and 450 feet, 

and an inaccessible level at 45 feet.

The Comstock vein strikes nearly east and dips 88° to the north. 

The vein cuts gabbroic rocks about 50 feet east of the shaft but con-
546 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

tains few ore minerals. On the 200 level west of the shaft, the vein 

consists of heavily iron-stained quartz and carbonate. One hundred 

and fifty feet west of the shaft on the 450 level, the vein splits; the 

south branch strikes S. 67° W., and is almost certainly the No Name 

vein. The Comstock workings on this level apparently joined with 

the 600 level of the No Name mine; but the workings are caved about 

35 feet, horizontally and vertically, from the presumed junction. 

The ore along the south (No Name) branch of the Comstock vein is 

similar to the ore in the No Name mine. Galena, sphalerite, quartz, 

and massive carbonates are abundant as in the No Name vein. 

Bastin and Hill (1917) report that the owners of the Comstock mine 

recognized the No Name vein on the 45 level, 80 feet west of the shaft.

NATIVE SILVER MINE

The Native Silver mine is 700 feet west of the Caribou shaft and 

nearly on strike with the Caribou vein. Although the Rocky Mountain News for July 21, 1877, states that the Native Silver vein is 

really a western extension of the Caribou lode, recent workings on the 

500 level in the Caribou mine indicate that the two veins are not 

continuous.

The Native Silver vein strikes nearly east and dips steeply to the 

north. Minerals reported (Corregan and Lingane, 1883) as present 

in the mine are galena, gray copper (tetrahedrite?), yellow copper 

sulphurets (chalcopyrite?), and quartz.

The vein reportedly averages 5^ feet in width, with a pay streak 

as much as 4 feet wide (Corbett, 1879). Workings consist of a shaft, 

at least 580 feet deep, and levels aggregating 1,700 feet hi length. 

The total production from the mine to 1883, the last year for which 

figures are available, is estimated to be $1,000,000 (Corregan and 

Lingane, 1883). __ __

SEVEN-THIRTY MINE

The Seven-Thirty mine is 100 feet north of the Native Silver mine 

and like the latter was considered a westward extension of the 

Caribou lode. However, there is no evidence in the present Caribou 

mine workings to indicate a westward extension of the Caribou vein.

The Seven-Thirty vein strikes nearly east and dips about 80° to 

the north. Corbett (1879) reports a "pay vein" as much as 22 inches 

wide with ore averaging $143 per ton in silver. Unlike most of the 

mines on Caribou Hill, the near-surface ore was very low grade. The 

Rocky Mountain News (October 19, 1880) reports that the mine 

"having passed through 200 feet of 'Cap' it opens up with a rich pay 

streak." The main shaft was 185 feet deep in 1879, but the size of 

the dump indicates further development. Production of the mine 

before 1879 was $25,000 (Corbett, 1879).
GEOLOGY OF THE CARIBOU AREA, COLORADO 547

Samples of vein material found on the dump contain quartz, galena, 

sphalerite, chalcopyrite, and carbonate. In one sample from the 

dump only pyrite and quartz are visible; this sample bears much 

more resemblance to the ore from the gold mines than to the typical 

lead-silver ore of the Caribou Hill mines.

ISABEL MINE

The Isabel mine is 400 feet southeast of the Native [Silver shaft, 

Corbett (1879) stated that the main shaft was 60 feet deep and production from the mine totalled $10,000. The size of the dump indicates that the mine is considerably deeper than 60 feet.

The Isabel vein appears to strike S. 78° E. and to have a vertical 

dip. The relationship of the vein to the southwest extension of the 

No Name vein is similar to that of the Caribou vein to the central 

part of the No Name vein.

WIGWAM MINE

The Wigwam mine is on the south side of the Caribou area and 

marks the southeastern limit of the mineralized area in the Caribou 

stock (pi. 35). The mine consists of a shaft 215 feet deep and levels 

at 75, 125, and 200 feet (Bastin and Hill, 1917). Production from 

the mine in 1874 was valued at $40,000 (Lovering and Goddard, 

1950).

The Wigwam vein strikes about N. 75° E. and changes in dip from 

steeply north at the surface to steeply south at depth. Primary 

minerals reported by Bastin and Hill (1917) are galena, sphalerite 

(in part resinous), very minor amounts of chalcopyrite and pyrite, 

quartz, calcite and barite.

POTOSI AND CROSS MINES

Both the Potosi and Cross are fairly large mines on the south side 

of Idaho Hill near the contact of the Caribou stock. The material of 

the dump of the Potosi mine is mostly monzonite and that of the 

Cross mostly gneiss. Vein material on the dumps is too sparse to 

determine the average nature of the ore. It is believed that the 

Cross mine was worked for gold and silver during the late 1890's. 

[They are only briefly mentioned by the Rocky Mountain News 

(1895-1900) and the Mining Reporter (1898).] The Engineering 

and Mining Journal (1877) states that the Potosi vein is similar to 

the Caribou and is credited with a production of $18,000 to that time.

GREAT NORTHERN MINE

The Great Northern mine (fig. 177) is on the east side of Caribou Park, 

3,000 feet northeast of the Caribou mine. Although it is on the 

contact of the Caribou stock, most of the dump material is monzonite.
548 CONTRIBUTIONS TO THE GEOLOCtY OF URANIUM

The vein is believed to strike east, and on the basis of the size of the 

dump, to have been developed to a depth of at least 200 feet. Bastin 

and Hill (1917, p. 182), describe the ore as consisting of quartz, 

pyrite, and chalcopyrite with subordinate, possibly younger, sphalerite 

and galena. A small amount of pitchblende, not associated with any 

sulfide minerals, was found on the dump. Other than the veins in 

the Caribou mine, this is the only known evidence of pitchblende in 

the Caribou area.

GOLD-SILVER MINES

A small group of mines on Idaho Hill, 2,500 feet east of the Caribou 

shaft (pi. 35) was worked for both gold and silver. These mines are 

in the gneissic and pegmatitic rocks east of the contact with the 

Caribou stock.

SILVER POINT MINE

The Silver Point mine, about 800 feet east-northeast of Caribou, is 

on a vein that strikes east and dips about 80° north. Levering and 

Goddard (1950) state that the vein has been worked to a depth of 

250 feet and that in the oxidized zone the ore averaged about 2 ounces 

of gold and 100 to 200 ounces of silver per ton. Some of the pegmatitic 

material on prospect pits just east of the dump is slightly radioactive.

IDAHO MINE)

The Idaho mine is 400 feet east-southeast of the Silver Point mine. 

The Idaho vein strikes N. 75° E. and is vertical. In a crosscut at a 

depth of about 300 feet in the Idaho Tunnel, it is a 2- to 3-inch ironand copper-stained shear zone containing no visible sulfides. Corregan and Lingane (1883) report that the vein contained galena and 

"sulphuret" ore which, when sorted, was valued at from $50 to $500 

per ton. The Idaho shaft in 1883 was 180 feet deep and total production was estimated at $7,000. Because this mine was operated hi 

1898, when most of the silver mines were closed as a result of the low 

price of silver, it is believed that ore from the vein contained considerably more gold than most mia^s on Caribou Hill.

GOLD MINE

The St. Louis mine on the west side of Idaho Hill, 1,800 feet east of 

the Idaho mine (pi. 37), is the only large mine in the area which was 

worked primarily for gold. Although no figures are available, production apparently was large enough to warrant the erection of a mill 

and an aerial tram to it. Bastin and Hill (1917) report the shaft to 

be 335 feet deep.

The vein strikes N. 63° W. and dips 78° NE. Ore found on the 

dump contained quartz, pyrite, chalcopyrite, and minor amounts of 

sphalerite and galena. Some crystals of late carbonate minerals and 

quartz line vugs.
GE©LOGT'-OF THE CAKIBC«J^AIIEA, COLORADO 549

UETEBATUBE CITED

Bastin, E. S., and Hill, J. M., 1917, Economic geology of Gilpin County and 

adjacent parts of Clear Creek and Boulder Counties, Colo.: U. S. Geol. 

. .Survey Prof. Paper 94, 37q p.

fiurchard, H. G., 1882, Report of the Director of the Mint, on the production of 

precious metals in the United States during the calendar year1 1882, p. 

397-398.

Corbett, T. B., 1879, Colorado Directory of Mines, containing a description of 

the mines and mills, and the mining and milling corporations of Colorado, 

arranged alphabetically by counties, and a history of Colorado from its 

early settlement to the present time; Denver Colo., Rocky Mountain News 

Printing Co.

Corregan, R. A., and Lingane, D. F., 1883, Colorado Mining Directory: containing an accurate description of the mines, mining properties and mills, 

and the mining, milling, smelting, reducing and refining companies and 

corporations of Colorado, arranged alphabetically by counties; Denver, 

Colo., The Colorado Mining Directory Co.

Endlich, F. M., 1874, Report of F. M. Endlich, in F. V. Hayden, Annual Report 

of the United States Geological and Geographical Survey of the territories 

embracing Colorado, being a report of progress of the exploration for the 

year 1873, p. 300-301.

Eng. and Min. Jour., 1877, v. 24, no. 6, p. 105-107.

Fossett, Frank, 1876, Colorado; a historical, descriptive, and statistical work on 

the Rocky Mountain gold and silver region: Denver, Colo. Daily Tribune 

Steam Printing House.

 1879, Colorado; its gold and silver mines, farms and stock ranges, and 

health and pleasure resorts. Also 2d ed., Tourists' guide to the Rocky Mountains: New York, C. G. Crawford.

Henderson, C. W., 1926, Mining in Colorado, a history of discovery, development, 

and production: U. S. Geol. Survey Prof. Paper 138.

Kerr, P. F., 1951, Natural black uranium powder: Science, v. 114, no. 2952, p. 

91-92.

Kerr, P. F., and Kulp, J. L., 1952, Precambrian uraninite, Sunshine mine, Idaho: 

Science, v. 115, no. 2978, p. 86-87.

Lovering, T. S., 1932, Preliminary map showing the relations of ore deposits to 

geologic structure in Boulder County, Colo.: Colo. Sci. Soc. Proc., v. 13, 

no. 3, p. 77-88.

Lovering, T. S., and Goddard, E. N., 1950, Geology and ore deposits of the Front 

Range, Colo.: U. S. Geol. Survey Prof. Paper 223.

Min. Rev., 1873, 1874, January, February, March, April, May, 1873. February, 

May, July, August, December, 1874.

Nier, A. D., Thompson, R. W., and Murphey, B. F., 1941, The isotopic constitution of lead and the measurement of geological time, pt. Ill: Phys. 

Rev., v. 60, no. 2, p. 113.

Phair, George, 1952, Radioactive Tertiary porphyries in the Central City district, 

Colorado, and then* bearing on pitchblende deposition: U. S. Geol. Survey 

TEI-274, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

Raymond, R. W., 1872, 1873, 1874, 1875, Statistics of mines and mining in the 

States and Territories west of the Rocky Mountains: 3rd Ann. Rept., 566 p., 

(1872); 4th Ann. Rept., 550 p. (1873); 5th Ann. Rept., 585 p. (1874); 6th 

Ann. Rept., 540 p. (1875).

Rocky Mountain News, 1871, 1872, 1874, 1877, 1880, 1890-1900, Denver, Colo.
§50 coNTBmunoiis ^BO SHE GiibljOGT O

Seeley, W. L., 1906, Report of mines and minerals of Boulder County, on line of

the Colorado and Northwestern Railroad. 

Smith, Ward C., 1938, Geology of the Caribou stock in the Front Range, Colo.:

Am. Jour. Sci., v. 36, no. 213, p. 161-196. 

Van Diest, P. H., 1875, The crossing of the No Name and Caribou veins: Min.

Rev., v. 6, p. 5.
INDEX

Page

Acknowledgments_____._______ 518 

Alteration_______._________ 532-534 

Analyses__________________ 536 

Argentite.__________________ 528 

Argillite zone ... ....... ____ 533

Bastin, E. S., and Hill, J. M., cited___ 527,528 

Belcher mine________________ 545 

Boulder Creek granite________ 520,522,523 

Brecciation ._ ... 526,534,541,543

Carbonate minerals___ 527,528,529,541,543,545 

Caribou area, location.... 518,519

relief .__._____.________ 518 

Caribou stock..._______ 522,523-524,527,528 

Cerargyrite. ________..._______ 528

Cerussite ......... 529

Chalcopyrlte_________._ 529,538,541,545 

Cblorite. _____ _..__.. 532,533 

Cblorite zone.._______________ 533 

Crushing, postmineral__._______ 541,543

Displacement of veins___________ 526

Faults.._______...__________ 524-525 

Foliation..__________________ 524 

Front Range mineral belt__________ 522

Oabbroic rocks ..... 524

Galena....................... 529,532,537,538,545

Gneiss.....________________ 523,527

Goddard, E. N., and Levering, T. S., cited. 523,

526 

Gold .____. ...._ 522,535

Gold mines....... ___ _._ 522,527,548

Gold veins.____.______ 523,525,527,528 

Granite. .......___ _______ 523

Great Northern mine.________ 636,547-548

Hill, J. M., and Bastin, E. S., cited___ 527,528 

Horn silver ___ ....__ 528,529

Idaho Springs formation... _ 522,523,527 

Elite -___.____..____.__. 532,533 

Intrusive rocks........__........___ 524-525

Iron dike..__...____.....______ 526

Joints...___________________ 524

Page

Levering, T. S., cited..

Zerr, P. F., quoted____........

Zerr, P. F., and Kulp, J. L., cited.

- 539 

.. 539

Lead ... _____ _...._ 521,535 

Lead-silver deposits____.- 522,526-^527,528-536 

uranium-bearing..__ . ___ 536-539 

Localization of ore bodies_....._____ 534 

Levering, T. S., and Goddard, E. N., cited. 523,

526

Malachite..__............................ 529

Mine dumps, as indicators of vein material. 527,

537,547,548

Mineral assemblages, altered zones 533 

gold veins.... 527

lead-silver veins......... 533,543,545,546,547

Mines, Caribou mine__________ 517,521,

528,532,534,535-536,537-538,540-641

Columbia mine_____________ 5

Comstock mine. _ 528,645-546

Cross mine.___-_...___-_.... 547

Idaho mine. 548 

Isabel mine_______________ 547 

Native Silver mine-_........._.. 521,546

Potosimine_ 547 

St. Louis gold mine_._-_.... .. 548

Seven-thirty mine_________ 546-547 

Sherman mine. 544 

Silver Dollar mine ... ... . 540 

Silver Point mine_............. 548

Spence mine. 544

Socorro mine. 540,544

Wigwam mine . 547

Mining, history______._______ 521

Montmorillonite. 533-534

Monzonite. ... - 522,523,524,527,532,548

Movement along veins 526

postmineral 534

Ore, enriched__.__________ 521,529,532 

high-grade...____________ - 521,535 

silicified___._____________ 529 

value_______________ 521,535,545

Ore shoots .... - 534,535,541

Paragenesis, Caribou lead-silver deposits. 528-529,

537-538

Radium vein. ___._ - 537 

Pegmatite 523,527

Pitchblende.. __....__- 517,532,536-38

age_____.. _____________ 538-539 

distribution in Radium vein_____ 539,545 

hard.. ..................... 537,538,539

paragenesis_ . 538

soft, sooty___________ 537,538,538,539

Precambrian rocks. -_______.... . 522,523

Production___________ 522,535,540,645,546 

Pyrargyrite...__ 528 

Pyrite ...... ....._- 528-529,537

Quartz. 528,529,632,537

551
552 INDEX

Page 

Raymond, E. W.f cited..._._. ......... 521,529

Schist..............._____. ........ 523,527

Sericitizatlon________________ 532 

Shear zones.___............ 525,641

Shear fractures__________ 522,525,534,535

Siliciflcation_________________ J32

SUver__________________ 522,532,535

minerals._____________ 521,528,529

native.____._.__ .... 629

Sphalerite._____________ 629,537-538,545 

Strike, changes and localization of ore shoots. 635 

Structure, regional____............ 522,524-525

'Veins, Caribou vein.. ..... 526,829,634,635,541

east-trending.._.... . >......... 52S

Elephant veto_____.._._...... 627

Elmer vein. __.-. _-.-.-.-- 640^64*-646 

fissure filling______________ 634 

Idaho vein 527 

lead-silver.__.____.... 629-635,644,645

uranium-bearing ......._...... 636-539

Nelson vein_____________ 640,^44-645

No-Name vein. ___________ '526,

529, 633,534,53S, 541,643, 646

Page

Veins Continued

northeast-trending. 5?s 

northwest-trending__________.. 52, 

Poorman vein 643-544 

Badium vein 529, 

533,634, 535, 536-537, 538, 539, 541, 544-545 

replacement . 634 

Seven-Thirty vein..__ _____.. 546 

Silver Dollar vein 644 

Silver Point vein 527 

Spencer vein 540,544 

wall rock - 532-533

Windy Point vein 527 

Veto systems 526 

Wag filling _______________ 627,637,538

Wrigni, H. D., quoted 

Zine 

Zone, of oxidation _______ .___ 829,632,636

of secondary aalfides 529,532

of supergene enrichment ... .. 529

Zones, of alteration... . 631-634

o