GEOLOGICAL SURVEY CIRCULAR 220

SELECTED PAPERS ON 

URANIUM DEPOSITS IN 

THE UNITED STATES
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 220

SELECTED PAPERS ON URANIUM DEPOSITS IN THE UNITED STATES

This report concerns work done on 

behalf of the U. S. Atomic Energy 

Commission and is published with 

the permission of the Commission

Washington, D. C.,1952

Free on application to the Geological Survey, Washington 25, D. C.
PREFACE

The six papers included in this report were prepared in an 

attempt to summarize briefly and make available to the public 

part of the information concerning uranium deposits that is in unpublished reports of work done by the U. S. Geological Survey 

under the auspices, first of the Manhattan Engineer District, and 

later, the U. S. Atomic Energy Commission. They were prepared for oral presentation and were read at the meetings of the 

Rocky Mountain Section of the Geological Society of America at 

Rapid City, S. Dak., on April 13, 1951. They are, consequently, 

of limited scope. It is believed, however, that the publication of 

these speeches in their present form will assist persons currently 

engaged in the search for and study of uranium deposits. Abstracts 

of the papers were published by the Geological Society of America 

in 1951 (Bull., vol. 62, no. 12, pt. 2, pp. 1535, 1537, 1538, 1542, 

1543, and 1544). Much more detailed scientific papers on most of 

these subjects are being prepared and will include a considerable 

quantity of data collected since April 1951.

ii
CONTENTS 

Page Page

Distribution of uranium deposits in the Secondary uranium deposits in the United

United States, by E. P. Kaiser and States, by Frederick Stugard, Jr.,

L. R. Page............................. . 1 Donald G. Wyant, and Arthur J. Gude 3d..... 19

Pitchblende deposits in the United States, Some uranium deposits in sandstones,

by Robert U. King, Frank B. Moore, by Donald G. Wyant, Ernest P. Beroni,

and E. N. Hinrichs ....................... 8 and Harry C. Granger ..................... 26

Uranium in fluorite deposits, by Uranium in black shales, lignites, and

V. R. Wilmarth, H. L. Bauer, Jr., limestones in the United States, by

M. H. Staatz, and Donald G. Garland B. Gott, Donald G. Wyant,

Wyant................................... 13 and Ernest P. Beroni ...................... 31

ILLUSTRATIONS

Page

Figure 1. Distribution of uraniferous deposits in the United States (exclusive of pegmatites and black shales). 2

2. Relation of structurally controlled uranium deposits to pre-Cambrian rocks..................... 4

3. Relation of structurally controlled uranium deposits to post-Triassic intrusives................. 5

4. Relation of structurally controlled uranium deposits to Tertiary volcanic rocks.................. 6

5. Distribution of uraniferous deposits with stratigraphic control................................. . 7

6. Pitchblende deposits in the United States ................................................... . 9

7. Relation of pitchblende deposits to bostonite dikes in the Front Range mineral belt, Colorado...... 11

8. Sections showing depth of pitchblende deposits, Colorado ..................................... 12

9. Distribution of radioactive fluorite deposits in the western part of the United States............. .14

10. Geologic map and section of the Thursday property, Juab County, Utah ......................... 15

11. Geologic map and section of the Burlington mine, Jamestown, Colo. ............................ 16

12. Geologic maps of the Fluorine Queen property, Juab County, Utah............................ .17

13. Chart showing chemical grouping of common secondary uranium minerals....................... 20

14. Diagram showing apparent zonal relationships of secondary and primary uranium minerals

in weathered veins ..................................................................... 22

15. Section along west face of upper cut, East Slope no. 2 uranium prospect, Piute County, Utah...... 23

16. Map showing location of secondary uranium deposits .......................................... 24

17. Vertical section across a vein, Shinkolobowe, Belgian Congo .................................. 25

18. Index map of some uranium deposits in sandstones ........................^.................. 27

19. Section of cliff face, Oyler mine, Wayne County, Utah........................................ 28

20. Cliff face, Shinarump Mesa, Temple Mountain district, Utah .................................. 30

21. Distribution of some uraniferous shales, coals, and limestones ............................... 32

22. Distribution of some uraniferous shales ..................................................... 33

23. Distribution of some uraniferous coals ...................................................... 34

iii
SELECTED PAPERS ON URANIUM DEPOSITS IN THE UNITED STATES

DISTRIBUTION OF URANIUM DEPOSITS IN THE UNITED STATES

By E. P. Kaiser and L. R. Page

ABSTRACT

Uranium deposits in the United States may be grouped as: (1) deposits with structural control, and (2) deposits 

with stratigraphic control. The deposits with structural control include veins, breccias, and pipes; disseminated 

deposits associated with fractures; pyrometasomatic deposits; and pegmatites. The deposits with stratigraphic control include (1) phosphates, carbonaceous shales, and lignites; (2) limestone and dolomite; (3) deposits of the carnotite 

type; and (4) surficial or caliche deposits.

Most of the known uranium deposits are in the western United States. Arizona, Utah, and Colorado contain 

the largest number of deposits.

The deposits with structural control, except the uraniferous pegmatites, are commonly in or related to igneous 

rocks of post-Cretaceous age, and many of them are associated with Tertiary volcanic rocks. Notably few deposits 

are genetically related to pre-Cambrian rocks and to Jurassic intrusives. The pegmatite deposits of the western 

United States are believed to be pre-Cambrian; those of the eastern United States are post-Devonian.

Carbonaceous shales, phosphates, and lignites are restricted, for the most part, to terranes of Paleozoic and 

Tertiary age. Most of the carnotite-type deposits are in sedimentary rocks of Mesozoic age, and the most productive deposits are in rocks of Jurassic age.

Study of the distribution of known deposits indicated that the principal favorable areas for further prospecting 

are those in or near Triassic and Jurassic sedimentary rocks and Tertiary igneous rocks.

The U. S. Geological Survey started an intensive 

study of uranium deposits in 1944. This program was 

carried out at first on behalf of the Manhattan Engineer 

District and later on behalf of the Atomic Energy Commission.

This paper and the five following papers will 

attempt to compile the fragmentary information on 

uranium deposits that has been accumulated during 

the past few years by the Geological Survey. Much 

unpublished information on uranium has been collected 

over a period of years by many members of the Survey, 

and this information has served as the basis for many 

of the more recent, more intensive studies. Particular 

acknowledgment should be made of the early work by 

C. E. Prouty, J. O. Harder, S. E. Clabaugh, A. L. 

Slaughter, J. M. Nelson, C. W. Chester man, and 

F. H. Main, formerly with the Survey, and of A. P. 

Butler, F. W. Stead, and D. G. Wyant, still with the 

Survey.

The uranium deposits of the United States are of 

two broad types--those with structural control and 

those with stratigraphic control. These two types are, 

of course, not mutually exclusive. The deposits with 

structural control can be further subdivided into the 

following groups: (1) veins, breccias, and pipes; (2) 

disseminated deposits; (3) pyrometasomatic deposits; 

and (4) pegmatites. Deposits with stratigraphic control 

include: (1) phosphates, (2) black shales, (3) limestones 

and dolomites, (4) lignites, (5) deposits in sandstones, 

and (6) surficial or caliche deposits.

The distribution of localities where uraniferous 

deposits, except pegmatites and black shales, have 

been studied is shown in figure 1. Deposits of vein 

type, other structurally controlled deposits, and 

deposits with stratigraphic control have been indicated. 

The structurally controlled deposits are most abundant 

in Arizona, Utah, and Colorado.

Of the structurally controlled deposits, the 

vein-type deposits are most numerous and have been 

found in most of the western States. They include 

fissure veins, shear zones and stringer zones, and 

silicified zones or reefs. Most of the domestic production of pitchblende has come from deposits of the 

vein type, but in 1951 pitchblende was produced from 

several deposits with stratigraphic control. At Marysvale, Utah, the recently discovered deposits of the 

secondary minerals--uranophane, autunite, and 

torbernite--occur in the upper part of pitchblendebearing vein structures.

True disseminated deposits of uranium minerals 

are not common; an example is the Red Bluff prospect 

in Arizona (Kaiser, 1951), where uranium is disseminated in pre-Cambrian quartzite. At many places 

secondary minerals occur on fracture surfaces in both 

igneous and sedimentary rocks, with no obvious major 

structural or stratigraphic control. These are generally of little interest, except as possible indicators 

of larger deposits.

Pyrometasomatic uranium deposits occur in the 

Goodsprings district, Nevada (Harder and Wyant,
Figure 1. --Distribution of uraniferous deposits in the United States (exclusive of pegmatites and bla
1944, p. 36), where secondary uranium minerals are 

associated with oxidized lead, zinc, and copper minerals. At the Stalin's Present prospect, Pershing 

County, Nev., a narrow band of lime-silicate rock 

in granite contains uraninite.

Pegmatites that contain uranium minerals have 

been found in all pegmatite districts in the United States, 

but they rarely are more than mineralogical occurrences (Page, 1950).

The stratigraphically controlled deposits are 

widespread. The carnotite deposits in the Morrison 

formation of the Colorado Plateaus have been our 

principal domestic source of uranium (Fischer, 1942; 

1950). The uraniferous phosphates (McKelvey, 1949; 

McKelvey and Nelson, 1950), black shales, and 

lignites are of wide extent and in the aggregate contain a large amount of uranium, but the deposits are 

of very low grade. Less common are the uraniferous 

limestones, dolomites, and caliche-type deposits.

The distribution of structurally controlled uranium deposits in relation to geologic age are shown 

in figures 2, 3, and 4; and the distribution of stratigraphically controlled uranium deposits is shown in 

figure 5.

Figure 2 shows the structurally controlled deposits in the southwestern quarter of the United States 

and the outcrops of pre-Cambrian rocks. It can be 

seen that there is no over-all correlation between the 

distribution of uranium deposits and pre-Cambrian 

rocks in this area. This may explain why we have no 

deposits such as those at Great Bear Lake in Canada, 

which, according to Bain (1950), are related to preCambrian shield areas.

The relation of the uranium deposits in the same 

area to post-Triassic intrusives is indicated in figures. 

No close correlation between the intrusives and deposits 

is apparent; furthermore, there is a relative scarcity 

of deposits in and near the Sierra Nevada batholith. 

Details not shown in this figure that may be of significance are (1) the presence of Tertiary intrusives in 

the Colorado Plateaus; (2) the occurrence of the 

Marysvale deposits of central Utah in and near a small 

Tertiary stock; (3) the intimate relation of the Colorado 

Front Range deposits to small Laramide intrusives; 

and (4) the relationship between uranium veins and the 

rocks of the Boulder batholith of Montana.

The relation of uranium deposits to Tertiary 

volcanic rocks is indicated in figure 4. The outline 

of the Colorado Plateaus of Fenneman (1931), has 

been added. Of particular interest is the grouping of 

uranium deposits in and near areas of Tertiary volcanic rocks in Utah, Arizona, southern California, 

Nevada, and Colorado, and the relative scarcity of 

volcanic extrusive rocks in the Colorado Plateaus, 

where many of the stratigraphically controlled uranium deposits occur.

Figure 5 shows the distribution of terranes, as 

shown on the United States geologic map, that contain 

stratigraphically controlled deposits. Deposits in 

black shales have been omitted.

The uraniferous phosphate deposits of the Permian 

Phosphoria formation in southeast Idaho are believed 

to be syngenetic and contain other metals as well as 

the small amounts of uranium. Phosphate deposits 

in the Bone Valley formation of Pliocene age in Florida

are similar to those in the Phosphoria; however, only 

a small part of the formation is uraniferous, as is 

indicated by the dashed line in figure 5.

Uraniferous black shales are widely distributed 

in age. Samples of the pre-Cambrian Nonesuch shale 

in the Michigan peninsula contain as much as 0.004 percent uranium. Black shales of late Devonian and 

Mississippian age that commonly are uraniferous include the Chattanooga shale of Tennessee and Kentucky, 

the New Albany shale of Indiana, the Antrim shale of 

Michigan, and the Woodford chert in the midcontinent 

region. Black shales .of the Phosphoria formation of . 

Permian age are uraniferous. In contrast, the black 

shales of the Permian basin of Texas and New Mexico 

are not notably uraniferous. No known uraniferous 

shales of Cambrian age occur in the United States, 

although in Sweden, shales of that age are reported to 

be a current source of uranium.

The most extensive uraniferous lignites are those 

of early Tertiary age in North Dakota, South Dakota, 

Wyoming, and Montana. Uraniferous lignite of Tertiary 

age is also found in Nevada. Uraniferous subbituminous 

coals of Cretaceous age occur in western Wyoming, and 

some uraniferous bituminous coals of Paleozoic age occur 

in the midcontinent region.

The most productive uranium deposits in sandstone are in the Jurassic Morrison formation of the 

Colorado Plateaus, but deposits have also been found 

in sandstones ranging in age from Paleozoic to Tertiary.

Uranium is present in the carboniferous Milton 

dolomite of Vermont, in Tertiary limestone in Utah, 

in the Mississippian Spergen limestone in Missouri, 

and in the Jurassic Todilto limestone at Grants, N. Mex.

In the Red Desert area of Wyoming, schroeckingerite (Larsen and Gonyer, 1937) occurs in sands and 

clays of early Tertiary age, in a thin zone above the 

water table, and is probably a caliche-type deposit.

The following papers will describe in more detail 

several aspects.of domestic uranium deposits.

LITERATURE CITED

Bain, G. W., 1950, Geology of the fissionable materials: Econ. Geology, vol. 45, pp. 273-323.

Fenneman, N. M., 1931, Physiography of western United 

States, New York, McGraw-HillBookCo., Inc.

Fischer, R. P., 1942, Vanadium deposits of Colorado and 

Utah, a preliminary report: U.S. Geol. Survey Bull. 

936-P, pp. 363-394.

_________ 1950, Uranium-bearing sandstone deposits 

of the Colorado Plateau: Econ. Geology.vol. 45, pp. 1-11.

Harder, J. O., andWyant, D. G., 1944, Preliminary report on a trace elements reconnaissance in western States: 

U. S. Geol. Survey Trace Elements Inv. Rept. 4, 47pp. 

[ Unpublished. ]

Kaiser, E. P., 1951, Uraniferous quartzite, Red Bluff 

prospect, Gila County, Ariz.: U. S. Geol. Survey 

Circ. 137.

Larsen, E. S., Jr., andGonyer, F.A., 1937, Dakeite, 

a new uranium mineral from Wyoming: Am. Mineralogist, vol. 22, no. 5, pp. 561-563.

McKelvey, V. E., 1949, Geologic studies of the

western phosphate fields: Am. Inst. Min. Met. Eng. 

Trans., vol. 184, pp. 270-279.

McKelvey, V. E., and Nelson, J. M., 1950, Characteristics of marine uranium-bearing sedimentary 

rocks:'Econ. Geology, vol. 45, pp. 35-53.

Page, L. R., 1950, Uranium in pegmatites: Econ. 

Geology, vol. 45, pp. 12-34.
EXPLANATION

A VEIN DEPOSITS

Ji PIPE DEPOSITS

Y OTHER STRUCTURALLY

X CONTROLLED DEPOSITS

i& PRE-CAMBRIAN ROCKS

Figure 2. --Relation of structurally controlled uranium deposits to pre-Cambrian rocks.
iff**.

N '£ V A. D A

UTAH

X A R I.Z 0 N A EXPLANATION

A VEIN DEPOSITS 

 PIPE DEPOSITS

v OTHER STRUCTURALLY 

X CONTROLLED DEPOSITS

POST-TRIASSIC INTRUSIVES

Figure 3. --Relation of struc'i rally controlled uranium deposits to post-Triassic intrusi
EXPLANATIO

VEIN DEPOSITS 

PIPE DEPOSITS

y OTHER STRUCTURALLY 

* CONTROLLED DEPOSITS

TERTIARY VOLCANIC ROCKS

Figure 4. --Relation of structurally controlled uranium deposits to Tertiary volcanic roc
Figure 5. Distribution of uraniferous deposits with stratigraphic control.
PITCHBLENDE DEPOSITS IN THE UNITED STATES

By Robert U. King, Frank B. Moore and E. N. Hinrichs 

ABSTRACT

Pitchblende is found in the United States in (1) veins and breccia zones, (2) pyrometasomatic deposits, (3) pegmatites, and (4) sedimentary rocks. On the basis of past production, the deposits in veins and breccia zones are 

of the greatest commercial significance.

Most of the vein deposits containing pitchblende are in the Front Range mineral belt of Colorado, but a few 

are in Arizona, Idaho, Montana, Nevada, and Utah. The pitchblende deposits in the Front Range mineral belt appear 

to be coextensive with alkali-rich Tertiary intrusive rocks, but a similar relation is not known elsewhere in the

United States.

Pitchblende-bearing vein deposits can be classified on the ;>asis f mineral association as (1) quartz-sulfide 

type, (2) quartz-sulfide-carbonate type, (3) quartz-sulfide-carbonate-hematite type and (4) fluorite-quartz type.

Pitchblende is finely disseminated in deposits of the fluorite-quartz type. In mesothermal veins, pitchblende 

occurs as pods and stringers distributed erratically over relatively narrow vertical limits. In many deposits, pitchblende occurs both as hard botryoidal masses and as powdery films and coatings.

The metallic minerals commonly associated with pitchblende in vein deposits include galena, sphalerite, chalcopyrite, pyrite, silver minerals, and gold. In contrast to well-known deposits in Canada and Africa, cobalt or 

nickel minerals have been'found in only a few of the domestic pitchblende-bearing veins. In a few places, veins 

containing secondary uranium minerals near the surface contain pitchblende at depth.

The relationship of pitchblende-bearing veins to types of wall-rock alteration has not been clearly established.

Pitchblende occurs in many places in the United 

States; however, most of the domestic production has 

come from vein deposits in the Front Range min ral 

belt of Colorado.

Pitchblende was discovered in the United States 

at the Wood mine in the Central City district, Colorado, 

in 1871. Since then it has been found in many mines 

in this distr'ct. More recently, pitchblende deposits 

have been discovered in most of the other western 

States.

Pitchblende is found in vein and breccia deposits, 

in deposits in sedimentary rocks, in pegmatites, and 

in other deposits not readily classified in these groups. 

In vein deposits pitchblende occurs as hard, botryoidal 

masses, as so ty ilms and coatings, and as microscopic granular disseminations. In sedimentary rocks 

it occurs as disseminations in sandstone and limestone. 

In pegmatites, uraninite, rathe, .han pitchblende, is 

the most common uranium mineral but is of little 

economic importance

Vein and breccia deposits of pitchblende are 

found in igneous rocks in Lincoln County, Wash,, near 

Clancey,- Jefferson County, Mont.; at Marysvale, 

Piute County, Utah; in Pima County, Ariz.; and in 

more than 20 deposits in the Front Range mineral belt 

of Colorado (fig. 6). Vein deposits in sedimentary or 

metamorphic rocks occur in the Coeur d'Alene district, Idaho, in Niobrara County, Wyo.; in Baraga

County, Mich.; and in San Miguel County, Colo. 

Pitchblende is disseminated in sedimentary rocks at 

Hack's Canyon, Ariz.; White Canyon, Utah; and at 

Grants, N. Mex. In Pershing County, Nev., pitchblende occurs with contact-metamorphic minerals in 

a thin dark band in granite.

Vein deposits of pitchblende can be classified on 

the basis of mineral association as (1) quartz-sulfide 

type, (2) quartz-sulfide-carbonate type, (3) quartzsulfide-carbonate-hematite type, and (4) fluoritequartz-sulfide type

Massive and sooty pitchblende occurs in veins 

of the quartz-sulfide type, such as the deposits at 

Quartz Hill in the Central City district, Colorado: at 

Prai/ie Divide, Larimer County, Colo.; at Ralston 

Creek, Jefferson County, Colo.; in Lincoln County, 

Wash.: and near Clancey, Mont. Masses or pods of 

pitchblende, sparsely and erratically distributed in 

veins, are as much as 8 inches thick by more than 

10 feet in diameter although such occurrences are 

unusual. These pods contain from 70 to 80 percent 

U30g. Pyrite, galena, and sphaler'te commonly are 

associated with pitchblende in these deposits, and 

chalcopvrite is present \n some but generally is not 

abundant. Fin^ g- ained dense quartz is the most 

common gangue mineral. In Lincoln County, V, ash., 

molybdenite is present in addition to the other base 

metal sulfides. The Colorado quartz-sulfide deposits 

contain gold and minor silver, and were valuable chiefly
EXPL

VEIN 

SEDIMENT

MISCELLAN

Figure 6. --Pitchblende deposits in the United States.
for the gold. The miners in the Central City district 

have learned by experience that an inverse relationship exists between the gold and the pitchblende content where pitchblende was found the gold content 

was low.

Pitchblende vein deposits of the quartz-sulfidecarbonate type are typified by those in the Lawson 

district and in the Caribou mine, Colorado. These 

pitchblende ore bodies are generally smaller than 

those in the quartz-sulfide veins of the Front Range; 

however, isolated pods may contain as much as 70 percent uranium. Silver is the most common precious 

metal, and the sulfide minerals include pyrite, galena, 

sphalerite, and minor amounts of chalcopyrite and 

tetrahedrite. Quartz, dolomite, and calcite are the 

common gangue minerals, and at the Caribou mine 

carbonates locally comprise the entire vein filling.

Pitchblende in veins of the quartz-sulfidecarbonate-hematite type occurs as microscopic grains 

or aggregates disseminated in dense quartz-hematite 

or jasperoid and as fine-grained streaks at the edges 

of carbonate veinlets; for example, the deposits in 

the Coeur d'Alene district, Idaho. Typical veins of 

this type contain silver minerals, galena, sphalerite, 

gersdorffite, chalcopyrite, and a siderite-quartz 

gangue. Reddish hematite-stained quartz veinlets 

also are present at Caribou.

The fluorite-sulfide-quartz type of pitchblende 

veins are represented by deposits in the Jamestown 

district, Colorado, and the Marysvale district, Utah. 

At Jamestown uraninite occurs as microscopic grains 

disseminated in fluorite veins and also in a quartzmonzonite breccia that has a fluorite matrix. Pyrite, 

galena, sphalerite, and rarely chalcopyrite are sparsely 

disseminated through the deposits. At Marysvale 

pitchblende occurs as small hard nodules and as sooty 

streaks and masses with pyrite and fluorite.

The pitchblende-bearing veins in the United 

States cut rocks ranging in age from pre-Cambrian 

to Tertiary, but most of the known deposits are in 

pre-Cambrian granitic and metamorphic rocks. The 

pitchblende deposits at the Caribou mine, Colorado; 

Clancey, Mont.; Pershing County, Nev.; and Marysvale, 

Utah, are in or near granite, monzonite, or quartz 

monzonite intrusives of late Cretaceous or Tertiary 

age.

With few exceptions, the pitchblende-bearing 

veins in Colorado are confined to the northeastern 

half of the Front Range mineral belt, an area 

characterized by the occurrence of numerous bostonite 

dikes (fig. 7). The dikes are two to five times as 

radioactive as the enclosing pre-Cambrian granitegneiss and schist, in places containing as much as 

0.01 percent uranium. Some of the pitchblendebearing veins cut the dikes.

Sericite and clay minerals seem to be the more 

common alteration products associated with pitchblendebearing veins in the Front Range of Colorado. The 

wall rock of the pitchblende veins at the Caribou mine 

has been intensely altered. Pyroxene has been converted to chlorite, feldspars to clay minerals, and 

feldspars and biotite to sericite. Calcite and siderite 

cut and replace feldspars, and quartz replaces earlier 

minerals.

In the Colorado pitchblende deposits, secondary 

minerals have been noted in a few places. In the 

Lawson district torbernite and autunite occur near the 

surface and pitchblende occurs at depth in nearby veins, 

but primary and secondary minerals have not yet been 

found in the same veins. Johannite and zippeite are 

the only secondary minerals that have been found in 

the Central City district.

Torbernite has been identified at Jamestown in 

a pitchblende-bearing fluorite deposit. Oxidized 

pyrometasomatic lead-zinc-copper deposits at Goods.prings, Nev., contain the secondary uranium silicate, 

kasolite, and the phosphate, dumontite, which may 

have developed from the weathering of pitchblende.

Pitchblende is associated with copper sulfides 

and secondary uranium minerals in sandstone in the 

basal part of the Shinarump conglomerate at White 

Canyon, Utah. Pitchblende has also been identified 

from deposits in the Coconino sandstone at Hack's 

Canyon, Ariz., and in the Todilto limestone at Grants, 

N. Mex. At Grants,uranophane, carnotite-tyuyamunite, 

fluorite, and calcite are also present.

In the United States the metals commonly associated with pitchblende are lead, zinc, copper, silver, 

and gold. Analyses of samples from the 1,040-foot 

level in the Caribou vein, Colorado, indicate that 

pitchblende is most abundant in the parts of the vein 

richest in copper, lead, and silver, and is less abundant in those parts rich in zinc. This relationship 

has not been established in other deposits in the United 

States.

In contrast to foreign deposits, cobalt, nickel, 

and bismuth generally are not closely associated with 

pitchblende deposits in the United States. In the 

Coeur d'Alene district, Idaho, cobalt occurs near but 

not within the pitchblende-bear ing veins. Small quantities of cobalt are present in the deposits of White 

Canyon, Utah, and at Caribou, Colo.

Pitchblende veins have been considered by some 

writers as shallow deposits, but recent work indicates 

that they may have a greater vertical range than has 

hitherto been suspected. Figure 8 shows that the range 

of these veins in the Front Range, Colo., is at least 

1,000 feet. At Kirk mine in the Central City district 

of Colorado, pitchblende is known from the surface to 

a maximum depth of 400 feet where the ore shoot may 

bottom. In the Caribou mine and in the mines of the 

Lawson district, Colorado, pitchblende occurs at 

depths of about 1, 000 feet below the surface; at the 

Sunshine mine, Idaho, it occurs on the 3J.OO- and 

3,700-foot levels. The vertical range in which the 

pitchblende occurs in each place, however, appears 

to be rather short--about 200 to 400 feet.

In summary, by far the greatest number of the 

pitchblende deposits found in the United States to date 

have been in the Front Range mineral belt of Colorado. 

Pitchblende is most common in deposits containing 

copper, lead, and silver; although, in foreign deposits, 

cobalt, nickel, and bismuth are considered favorable 

associations. Recently discovered deposits indicate that pitchblende may be found in veins that 

have a greater vertical range than has hitherto been 

suspected.

10
N

CARIBOU

o

LAWSON

JAMESTOWN

EXPLANATION

Pitchblende deposit

Bostonite dike

23456 MILES

Geology after Layering and Goddard, 1939

Figure 7. --Relation of pitchblende deposits to bostonite dikes in the Front Range mineral belt, Colorado.

11
CARIB

CENTRAL CITY

EX

Known 

Reporte

Figure 8. --Sections showing depth of pitchblende deposits, Colorado.
URANIUM IN FLUORITE DEPOSITS

By V. R. Wilmarth, H. L. Bauer, Jr., M. H. Staatz, and Donald G. Wyant

ABSTRACT

The association of small quantities of fluorite with uranium minerals in veins has been reported for many 

localities. Recent studies in Colorado, Utah, Wyoming, and New Mexico further indicate that uranium is a common 

constituent of many fluorite deposits.

Fluorite deposits known to contain uranium occur in breccia zones, veins, pipes, and bedded replacement 

deposits. These deposits can be grouped on the basis of essential minerals as (1) fluorite, (2) fluorite-quartz-sulfide, and (3) fluorite-sulfide deposits. The deposits contain pitchblende or other primary uranium minerals, together with such secondary uranium minerals as schroeckingerite, torbernite, autunite, uranophane, carnotite, and 

sklodowskite.

In some deposits the uranium occurs as fine-grained primary minerals disseminated through the fluorite ore 

body; in others the uranium is in the fluorite itself in a form not yet identified. Secondary uranium minerals coat 

fracture surfaces and vugs in both the ore bodies and adjacent wall rocks.

Purple fluorite is commonly associated with radioactive deposits, but because of the many exceptions to this 

rule it is of limited value.

Uranium minerals are associated with fluorite 

in fluorite deposits and in polymetallic Veins in the 

United States and other countries. The fluorite veins 

at Wolsendorf, Bavaria, are the only ones that have 

furnished appreciable quantities of uranium ore. Uranium has been found in 18 fluorite deposits (fig. 9) in 

the western States, and although no uranium has been 

produced as a byproduct of fluorite mining, recent 

studies by the U. S. Geological Survey on behalf of 

the Atomic Energy Commission have shown that some 

of these deposits may yield significant quantities of 

uranium.

The fluorite deposits known to contain radioactive minerals occur as veins, breccia zones, pipes, 

and tabular to irregular replacement bodies, and most, 

if not all, of these deposits are related to Tertiary 

igneous activity. The deposits, however, are in preCambrian granites, Middle Paleozoic to Tertiary 

sedimentary rocks, and Tertiary igneous rocks. "

The uranium-bearing fluorite veins in all deposits are similar in that they have irregularly mineralized margins. Typical fluorite veins such as 

those at the Thursday property (fig. 10)--are from 

6 inches to 25 feet thick and from 5 to 1,000 feet long. 

In some veins discontinuous tabular shoots of fluorite 

are common; in others, pockets, seams, and small 

rodlike bodies are abundant. The average fluorite 

content in these deposits is as much as 80 percent 

and the uranium content ranges from 0.003 to 0. 45 percent.

Uraniferous fluorite breccia zones in the Jamestown district, Colorado, and in southwestern New 

Mexico, are from 5 to 50 feet thick and from 40 to 

350 feet long. The Burlington mine (fig. 11) is

typical of mines in the district that have been worked 

to depths of more than 600 feet. Fluorite forms the 

matrix of the breccia, and the content of each deposit 

varies widely. The amounts of fluorite and uranium 

in the breccia zones studied to date are, in general, 

less than those in vein deposits.

Uraniferous fluorite pipes have been found only 

in the Thomas Range, Utah, where they are important 

sources of fluorspar. Some of the pipes are circular; 

others such as the Fluorine Queen shown in figure 12-- 

are elliptical or irregular in plan, and all pipes plunge 

at steep angles. The circular pipes are as much as 

15 feet in diameter and have a smooth sharply defined 

contact with the enclosing dolomite. The elliptical or 

irregular pipes, in plan view, range in size from 

10 feet by 25 feet to 25 feet by 145 feet. The contacts 

are ragged and indefinite in outline, and many small 

fluorite veinlets extend outward from the main body 

into the country rock. One of the fluorite pipes has 

been mined through a vertical distance of more than 

220 feet. The fluorspar that has been recovered contains from 65 to 95 percent CaF£ and from 0. 005 to 

0. 33 percent uranium.

Near Sundance, WTIO. , tabular and irregular 

replacement deposits occur along fractures and bedding planes in limestones. They vary in size from a 

few widely spaced crystals of fluorite to discontinuous 

masses 3 feet wide and 50 feet long. At the Poison 

Lake lode, Beaverhead County, Mont., a series of 

small fissure fillings and replacement bodies form a 

zone 75 feet wide and 200 feet long. Both the Sundance 

and the Beaverhead County deposits are highly radioactive, but most of the radioactivity is caused by 

thorium.

13
EXPLANAT

O FLUORITE

X FLUORITE-SU

A FLUORITE-QU

Figure 9. --Distribution of radioactive fluorite deposits in the western part of the United States
EXPLANATION

Altered rhyolite porphry

Dolomite

Strike and dip of beds

Open cut

O 

Prospect pit Fluorite ore body

Approximote contact Underground workings

-off %'^ 

Fault-showing dip,dashed Dump 

where approximate

SECTION A-A'

UNDERGROUND WORKINGS 

Geology by V.R Wilmarth and H.L.Bauer.Jr,September 1950

Figure 10.--Geologic map and section of the Thursday property, Juab County, Utah.

Uraniferous fluorite deposits are similar in 

mineralogy and can be grouped according to their 

essential mineral constituents as fluorite, fluoritequartz-sulfide, or fluorite-sulfide deposits.

Uraniferous deposits (fig. 9) essentially composed of fluorite contain as much as 0. 33 percent 

uranium, but primary uranium minerals have not 

been identified. Either the uranium mineral is exceedingly fine-grained, or the uranium may substitute for 

calcium in the calcium fluorite molecule. In some 

of the deposits small quantities of secondary uranium 

minerals coat fracture surfaces in both the ore bodies 

and adjacent wall rocks. Carnotite has been found in 

the Thomas Range deposits, Utah; autunite and uranophane at the Staats mine, Beaver County, Utah; 

uranophane at the Terry property, Sierra County, 

N. Mex.; and autunite from the Hines property, Grant 

County, N. Mex. The fluorite in this type of deposit 

varies from a fine-grained pulverulent earthy variety 

in pipes to a coarsely crystalline variety common in 

breccia zones, veins, and irregular replacement deposits. Except for the white earthy highly uraniferous 

fluorite of the Thomas Range deposits, all radioactive 

fluorite so far as known is dark purple to black. Common gangue minerals are clay minerals, barite, chert, 

carbonates, and wad.

The fluorite-quartz-sulfide-deposits typically 

occur as fissure veins either near the contact of acid 

igneous rocks or within the igneous rocks. Deposits 

of this type have been found in Utah, Colorado, Wyoming,

and Montana. The deposits in Utah and Colorado contain secondary uranium minerals, which commonly 

coat fractures in the dark-purple fluorite. In the 

Honeycomb Hills, Utah, the uranium minerals 

sklodowskite, uranocircite, and soddyite coat crystal 

faces of pale-green fluorite. Kasolite, a lead-uranium 

silicate, has been identified in the Saint Peters dome 

area of Colorado; autunite at Indian Creek, Utah; 

uranophane in the eastern part of the Thomas Range, 

Utah; and autunite and other uranium minerals in the 

Marysvale district, Utah. No uranium minerals have 

been identified with the dark radioactive fluorite at the 

Poison Lake lode, Montana, and the Sheeprock Mountains, Utah. Nonradioactive, pale-green fluorite predominates in the more siliceous parts of the fluoritequartz-sulfide deposits. In all deposits the fluorite is 

erratically distributed as small irregular masses and 

narrow veinlets that are associated with massive and 

finely crystalline white quartz. The primary sulfide 

minerals--galena, sphalerite, chalcopyrite, and pyritecommonly are in blebs, pockets, or narrow veinlets 

that cut quartz and fluorite. The accessory secondary 

minerals--azurite, malachite, limonite, opal, clay 

minerals, and hematite--are locally abundant.

Uraniferous deposits of fluorite and metallic 

sulfides without quartz occur as veins and breccia 

zones in pre-Cambrian to Tertiary igneous rocks in 

Colorado and Arizona. Pitchblende, uraninite, 

autunite, and torbernite are associated with finelycrystalline to massive dark-violet or black fluorite. 

In the Jamestown district, Colorado, uraninite has 

been identified as discrete grains disseminated through

15
Breccia 

less than 30% Ca F,

A1

7300' 

7200' 

Fluorspar br

D-60% C

50 200 Feet 

_I

Geology b

Figure 11. --Geologic map and section of the Burlington mine, Jamestown, Colo.
WEST PIPE

20 FEET

40 FEET

EAST PIPE

EXPLANATION

Geology by M.H. Staatz and 

H.L. Bauer, Jr.,September 1950

Figure 12. --Geologic maps of the Fluorine Queen property, Juab County, Utah.

17
the fluorite of the deposits, and torbernite occurs 

on fractures in fluorite and altered granodiorite in the 

Nations Treasure mine in this district. Pitchblende 

occurs in narrow veinlets in the fluorite veins on the 

Black Dike claims, Pima County, Ariz. Autunite is 

found along fractures in schist at the Sure Fire property in the same county. No uranium minerals have 

been identified at the Red Hills deposit, Yuma County, 

Ariz., but abnormal radioactivity was noted in close 

association with lavender fluorite. In the fluoritequartz-sulfide deposits various sulfide minerals 

occur as small irregular masses, lenses, and finegrained aggregates. The predominant sulfide minerals are galena, sphalerite, pyrite, chalcopyrite, 

but minor quantities of enargite and tennantite are 

present locally. Clay minerals, carbonates, quartz, 

and opal are common gangue minerals.

In summary, uraniferous fluorite is found 

in many geologic environments in the western 

States. Pitchblende or uraninite has been reported only from the fluorite-sulfide deposits at 

Jamestown, Colo., and the -Black Dike claims, 

Yuma, Ariz. In both localities dark-purple 

fluorite is associated with the uranium minerals. 

At 10 of the 18 known radioactive fluorite deposits, 

secondary uranium minerals are associated with 

dark-purple to black fluorite. At 6 of these 

localities the form in which the uranium occurs 

is unknown. In general it would appear that 

dark-purple to black fluorite is a favorable 

indication of the presence of radioactivity, and 

wherever dark fluorite is discovered radiometric 

studies and sampling for uranium should be 

undertaken.

18
SECONDARY URANIUM DEPOSITS IN THE UNITED STATES 

By Frederick Stugard, Jr., Donald G. Wyant, and Arthur J. Gude 3d

ABSTRACT

Reconstituted, or secondary, uranium minerals found in domestic deposits include oxides, phosphates, silicates, vanadates, arsenates, sulfates, and carbonates. Next to the vanadates carnotite and tyuyamunite, the most 

abundant are the phosphates autunite and torbernite and the silicate uranophane. Less common secondary uranium 

minerals are the oxides "gummite" and pitchblende; the phosphates dumontite and uranocircite; the silicates kasolite, 

skodowskite, and soddeite; the arsenates zeunerite and uranospinite; the sulfates zippeite, uraconite, and johannite; 

and the carbonate schroeckingerite. Other secondary minerals, in general, are only of mineralogic interest.

Many secondary uranium mineral deposits.show no obvious relation to known primary uranium minerals. The 

deposits now being mined at Marysvale, Utah, however, are surface expressions of pitchblende-bearing deposits. 

Recent studies indicate that formation of secondary minerals has in some places resulted in concentration and elsewhere in dispersion of uranium. Concentrations from ground water have formed extensive deposits of schroeckingerite 

in Sweetwater County, Wyo.

Many uranium compounds appear to be highly soluble and mobile. Successful distinction between secondary 

deposits resulting from concentration and those resulting from dispersion of primary deposits has not generally 

been made to date. Some sooty pitchblende is secondary.

Investigations by the Geological Survey on behalf 

of the Atomic Energy Commission have brought together 

considerable information on the mineralogy, distribution, and occurrence of secondary uranium deposits 

in the United States. Nevertheless, comparatively 

little is known on these subjects. Use of genetic 

designations such as "hypogene" and "supergene" does 

not yet seem practicable. We have designated as 

secondary minerals those derived from previously 

deposited uranium minerals. Under this definition, 

minerals formed as a part of original vein fillings 

are considered primary minerals.

Secondary uranium minerals occur in small 

quantity in many metallic veins, pyrometasomatic 

deposits, altered zones of volcanic rocks, sedimentary 

rocks, and pegmatites. In rare instances, secondary 

uranium minerals are sufficiently abundant to be 

economic sources of uranium, but elsewhere one of 

their main values is as possible indicators of associated primary ore.

More than 60 uranium minerals commonly of 

secondary origin have been listed (George, 1949; 

Frondel and Fleischer, 1950). If varietal names 

and uranium-proxy minerals be included, the list 

grows to more than 300. Species previously recorded 

only from foreign localities are being discovered in 

almost every new deposit studied. Mineralogic work 

on this group is often difficult because of the intimate 

mixtures and variable water content that characterize 

these assemblages, and because of similarities among 

species of physical, optical, and chemical properties. 

Definite field identification of individual minerals is 

commonly impossible; often it must be changed after 

laboratory study.

Secondary deposits include uranium chemically 

combined as vanadates, phosphates, silicates, arsenates, 

sulfates, carbonates, and oxides. Almost every deposit includes several of these groups. Figure 13 shows 

some of the minerals that are known and their chemical 

grouping.

In the United States the production of most of the 

uranium--and formerly that of the radium--has come 

from carnotite (the hydrous potassium-uranium vanadate) deposits in sandstone. Tyuyamunite is the calcium analogue of carnotite. The most ubiquitous of 

all uranium minerals probably are the phosphates 

autunite and torbernite, and their "meta" forms. 

Dumontite and uranocircite are less abundant phosphates. The most common uranium silicate is uranophane, which usually occurs as fracture coatings in 

igneous and sedimentary rocks. Less common silicates include kasolite, sklodowskite, and soddyite.

Uranium arsenates have been found in very few 

localities in the United States. Zeunerite has been 

collected from Majuba Hill, Nev., and the Clancey 

area, Montana. Uranospinite, the calcium-uranium 

arsenate, has been tentatively identified from the 

Honeycomb Hills of Utah.

Efflorescent uranium sulfates and carbonates 

occur in semiarid environments. Zippeite characteristically occurs as coatings on mine walls, carbonized 

wood, and gypsum, as in the Oyler mine near Fruita, 

Utah. Uraconite is possibly only a lower hydrate of 

zippeite and has been found on mine faces in Gilpin 

County, Colo., and in the Hillside mine, Arizona. 

Johannite, a hydrous copper-uranium sulfate, is 

associated with a large suite of secondary minerals

19
GROUP

V ANADATES

P HOSPHATES

S 1 I ICATES

A RSENATES

S ULFATES

C AR80NATES

OX IDES

Ml NERAL

CARNOTITE 

TYUYAMUNITE

AUTUNITE 

TORBERNITE 

DUMONTITE 

URANOCIRCITE

URANOPHANE 

KASOLITE 

SKLODOWSKITE 

SODDYITE

ZEUNERITE 

URANQSPINITE

ZIPPEITE 

URACONITE 

JOHANNITE

 \ SCHROECKINGERITE-

* RUTHERFORD INE"

"6UMMITE" 

BECOUERELITE 

SOOTY PITCHBLENDE

PROBABLE FORMULA

K20.2U03 .V205 .nH20 

Ca0.2U03.V205.nH20

CaO.U03 .P205 .H20 

Cu0.2U03 .P205 .l2H20

2Pb0.3U03 .P205 .5 H20 

Ba0.2U03 .P205 .l2 H20

Ca0.2U03 .2SI02 .6 H 20 

P bO.U03 .S!02 .H20 

Mg0.2U03 .2S!02 .6 H20 

5U03 .2SI02 .6 H20

Cu0.2U03 .As205 .l2 H 20 

Ca0.2U03 .As205 .l2 H20

2U03 .S03 .nH20 

2U03 .S03 .nH20 

Cu0.2U03 .2S03 .7 H20

-Ca3Na.U02 .C03 .SOi|.F.IO H20 

Ca.C03 plus uranium silicate mineral

U6 ,Pb, H20 In variable proportions 

2U03 .3.H20 

U02 plus U03

MEGASCOPIC APPEARANCE

Yellow, powdery. 

Greenish yellow. Powdery.

Lemon yellow to apple green. Fluoresces brig

Green platey crystals. 

Yellow. 

Yellow to yellow green. Vivid greenish-yello

Straw yellow to orange yellow. Aclcular cry

Yel low, slightly brownish. 

Yellow. 

Greenish yei low.

Green platey crystals. 

Yellow to green. Fluoresces bright greenish 

Yellow to orange. Fluoresces yellowish gree

Yellow, green, or black.

Yellow.

Bright orange. 

Amber. 

% Black unless colored by Impurities such as f

Figure 13. Chart showing chemical grouping of common secondary uranium minerals.
in the Happy Jack mine, San Juan County, Utah, and 

is also reported from Gilpin County, Colo. Schroeckingerite, the fluoro-sulfate and carbonate, occurs 

both in sedimentary rocks, as at Wamsutter, Wyo., 

and above vein structures, as at Marysvale, Utah, 

and the Hillside mine, Yavapai County, Ariz. 

"Rutherfordine" is intimately mixed with pitchblende 

and uranophane in veins of cryptocrystalHne silica 

near Clancey, Mont.; much material previously called 

rutherfordine is now being reidentified as other uranium minerals with carbonate impurities. Three new 

carbonate minerals have recently been described by 

Axelrod and others (1951), and new discoveries are 

to be expected. As is evident from figure 13, numerous 

minerals appear very much alike to the naked eye.

The three most common secondary oxides of 

uranium are "gummite, " becquerelite, and sooty 

pitchblende. Gummite is a common alteration product 

of uraninites in pegmatites and is easily recognized 

by its orange color; it does not have a valid formula. 

Some becquerelite and sooty pitchblende are redeposited forms of primary hard pitchblende.

An understanding of the distribution of secondary 

minerals in uranium deposits is essential to evaluation of the economic possibilities for most mines 

and prospects. Fragmentary information indicates 

that during the weathering and alteration of primary 

uranium deposits, different secondary uranium minerals form in different zones. The minerals formed 

vary with the composition of the vein and country rock, 

and the solutions formed by weathering. Figure 14 

shows the general zonation of secondary uranium minerals in weathered veins. The diagram is a composite 

of available data from numerous deposits in sedimentary 

and igneous rocks.

As shown in the right-hand column, a vein containing primary uranium oxides, with the necessary 

accessory metals, would be altered under favorable 

conditions of weathering to yield a secondary deposit 

capped by a zone of efflorescent uranium sulfates and 

carbonates. This zone may be expected to grade downward into a zone containing uranium silicates, phosphates, arsenates, or vanadates; the assemblage that 

is developed depends upon the composition of the 

solutions causing the alteration. This assemblage 

grades' downward into a zone of secondary uranium 

oxides, accompanied by relict primary uranium oxides. 

Below this is the zone of unaltered primary oxides.

The deposit of secondary minerals is shown in 

figure 14 as widening upward, spreading laterally 

along fractures. This lateral migration may result 

in an over-all dispersion of the uranium from the 

vein. In places,such as Marysvale, Utah, these deposits are sufficiently rich to form a minable ore 

body.

Marysvale is the best-known domestic area to 

date that has economic deposits of both primary and 

secondary minerals in the same altered vein structures. 

Investigations of operating mines in the district, 

currently in progress by the Atomic Energy Commission, are expected to yield much information on 

the relationships of primary to secondary minerals.

Weathering of veins containing pitchblende, 

quartz, fluorite, pyrite, and other sulfides at Marysvale has produced the typical zonation of uranium 

minerals, as shown in figure 14. At the surface, 

schroeckingerite Is associated with uranophane, 

autunite, and torb.ernite; this assemblage grades 

downward into a zone in which uranophane is the 

dominant mineral. Autunite and torbernite become 

relatively abundant in the lower parts of this zone and 

grade into a zone containing sooty pitchblende and 

relict masses of primary pitchblende.

The diagram showing zonation of secondary minerals in veins may be considered a mnemonic device. 

If figure 14 be turned on its side so that the surface 

represents a vertical cliff face, it will represent 

essentially the sequence of minerals found in sedimentary deposits inward frbm a leached outcrop, as 

for example at the Happy Jack mine, San Juan County, 

Utah. The surface exposure of this ore body contains 

efflorescent salts, such as johannite and chalcanthite. 

Uranophane and torbernite appear within a short distance and increase in abundance inward toward a deposit containing pitchblende, pyrite, chalcopyrite, 

chalco.cite, and gersdorffite.

In contrast to the example just given, some 

actual vein-type deposits do not appear" in the field to 

look much like the idealized diagram. In the Marysvale area, at East Slope no. 2 deposit (fig. 15), 

secondary uranium minerals are associated with 

alunitic and clay alteration zones in a veinlike structure within hornfels. Autunite, metatorbernite, 

schroeckingerite, and uranophane are distributed 

along the face of the open-cut in two main zones, 

roughly symmetrical about a core of hematite-alunitequartz-kaolinite rock. The uranium minerals coat 

fractures and joints in the altered hornfels. It is 

not known whether this deposit is transitional downward into other depth zones of the typical vein structure.

Secondary uranium vanadates and arsenates 

occur in vein structures at several places. For 

example, tyuyamunite is found in fractured quartzite at the Yellow Canary claims, Daggett County, 

Utah, and carnotite in the fluorite deposits of the 

Thomas Range district, Utah. Zeunerite is associated with torbernite at Majuba Hill, Nev., and 

Clancey, Mont. These localities, together with the 

others mentioned in this report, are shown in figure 16.

Many pegmatites contain gummite, autunite, 

and other minerals as halos around primary uranium 

minerals. Pegmatite localities are not shown on 

figure 16.

Lignites in North and South Dakota, Montana, 

and Wyoming, contain a hydrous uranium oxide, probably becquerelite. Some uranium oxides associated 

with organic minerals found in stratigraphically controlled deposits have secondary characteristics.

Interesting comparisons might be made between 

the secondary uranium minerals found in the United States 

that may lead to primary ore as the deposits are developed, 

and the secondary uranium minerals accompanying the 

great deposits being mined in Canada and the Belgian Congo. 

Many descriptions of these foreign localities, however, 

make little mention of the secondary minerals. One of 

the few good illustrations of secondary minerals accompaning primary uranium oxide is that given by Thoreau 

and Terdonck (1933), adapted here as-figure 17.

21
Essential uranium minerals 

at Marysvale, Utah

Typical vertical zonation in weathered veins

Schroeckingerite

Uranophane with 

autunite and torbernite

Autunite and torbernite 

with uranophane

Sooty pitchblende with 

autunite and torbernite

Pitchblende

Figure 14. --Diagram showing apparent zonal relationships of secondary and primary uranium minerals in w
-Uraniferous zones

EXPLANATION zone

Visible uranium minerals

H emat it e-alunite-quartzkaolinite rock

+ * + * « 

^ + + + + 

+ + + + 4

Montmori llonite-bearing 

rock

Limonite- quartz rock

10

. Contact

^^/~ 

Gradational contact

Fault 

o 10

Hornfels

Figure 15. --Section along west face of upper cut, East Slope no. 2 uranium prospect, Piute County, Utah.
EXPLANATION

t Secondary uranium deposits 

{") Uroniferous lignites

Figure 16. Map showing location of secondary uranium deposits.

24
GREEN ORE 

(TORBERNITE AND PARSONSITE)

(After Thoreau and Terdanck, plate 17, 1933)

Figure 17. Vertical section across a vein, Shinkolobwe, Belgian Congo

Around the pitchblende is a halo of becquerelite. 

This in turn is surrounded by an orange zone composed 

of curite (a uraniferous hydrate of lead), mixed with 

kasolite, soddyite, and uranophane. The yellow ore 

beyond that is schoepite (a hydrated oxide of uranium), 

together with the silicates soddyite or uranophane. The 

outside part of the vein is composed of torbernite and 

parsonite (hydrated phosphates). Thus, from the inside to outside the mineral assemblage is: oxides, 

hydrates of lead and uranium, silicates, phosphates. 

All the secondary minerals have been derived apparently 

from the primary vein pitchblende. The small-scale 

zoning apparent here may be represented on a large 

scale by zones of secondary uranium minerals above 

primary deposits in the United States.

In conclusion, secondary uranium minerals 

form under a great variety of conditions. It is clear 

that uranium possesses great mobility in some form 

at surface temperatures. The of ten-observed presence of fluorite suggests that, in some deposits at 

least, dilute hydrofluoric acid solutions from the 

fluorite may form complex uranium fluorides that are 

readily soluble in cold water and adsorbed in silica 

gel. Abundant iron staining in most deposits 

suggests that uranium is distributed in much the same

manner as ferrous or ferric iron during the weathering 

cycle. It is also known (Rankama and Bahama, 1950, p. 636) 

that uranium compounds are adsorbed on iron hydroxide 

gel and silica gel. The size and mineralogy of secondary 

deposits are systematically related to the original bulk 

chemical composition and the erosional environment.

LITERATURE CITED

Axelrod, J. M., Grimaldi, F. S., Milton, Charles, 

and Murata, K. J., 1951, The uranium minerals 

from the Hillside mine, Yavapai County, Ariz.: 

Am. Mineralogist, vol. 36, pp. 1-22.

Frondel, J. W., and Fleischer, Michael, 1950, A 

glossary of uranium- and thorium-bearing minerals: 

U. S. Geol. Survey Circ. 74.

George,d'Arcy, 1949, Mineralogy of uranium and,, 

thorium bearing minerals: U. S. Atomic Energy 

Comm., RMO-563, rev. ed., Tech. Inf. Service, 

Oak Ridge, Term.

Rankama, Kalvero, and Sahama, T. G., 1950, Geochemistry [Chicago], Univ. Chicago Press.

Thoreau, J., and du Trieu de Terdonck, R., 1933, 

Le gite d'uranium de Shinkolobwe-Kasolo (Katanga): 

Inst. royal colonial beige, Sec. Sci. nat. et m£d., 

Mem., tome 2, fasc. 1, pi. 17.

25
SOME URANIUM DEPOSITS IN SANDSTONES

By Donald G. Wyant, Ernest P. Beroni, and Harry C. Granger 

ABSTRACT

The uranium deposits in sandstone of the Jurassic Morrison and Entrada formations of the Colorado Plateaus 

are relatively well known and have long been the principal sources of domestic uranium and vanadium. Not so well 

known are uranium deposits in other sandstones that range in age from Paleozoic to Recent.

Of the uranium deposits in sandstone, some are of the type common to the Colorado Plateaus, but many others 

differ from this type in mineralogy, host rock, localization, and possible origin. The deposits may be grouped on 

the basis of mineral or metal assemblage into (1) uranium-vanadium deposits; (2) copper-uranium-vanadium-car - 

bonized wood deposits; (3) uraniferous asphalt deposits; and (4) miscellaneous deposits including carbonate deposits.

In general these deposits occur in lenses'of argillaceous sandstone or conglomerate interbedded with shales. 

Common associated materials are iron oxide, carbon, and copper compounds. The localization of some of these 

deposits appears to be controlled by initial sedimentary features of the enclosing rock, that of others by porosity, 

fractures, and proximity to the surface. Some of the uranium minerals may have been deposited from ground water, 

some may have formed by weathering and oxidation of other minerals, and some may be hydrothermal in origin.

The carnotite and roscoelite deposits in sandstones of the Morrison and Entrada formations of 

Jurassic age have long been the principal domestic 

sources of uranium and vanadium. Descriptions of 

many of these deposits on the Colorado Plateaus have 

been published, and the deposits are relatively well 

known. Not so well known are uranium deposits in 

other sandstones that range in age from Paleozoic to 

Recent.

It is the purpose of this paper to point out the 

geographic and geolagic distribution of uranium deposits in sandstones, some of their characteristics, 

similarities, and differences. Much of the data on 

which this paper is based has been collected during 

work on uranium deposits by the U. S. Geological 

Survey on behalf of the Atomic Energy Commission.

Uranium minerals found in lenses of porous 

terrestial sandstones containing shale fragments or 

pellets, or in conglomerates interbedded with shales, 

are commonly associated with vanadium, carbon, 

copper, and iron oxide.

On the basis of these associations the uranium 

deposits in sandstones may be grouped into four main 

types: (1) uranium-vanadium deposits; (2) copperuranium-vanadium-carbonized wood deposits; (3) uraniferous asphalt deposits; and (4) miscellaneous deposits, 

including the caliche-type carbonates and deposits in 

tuffs. Nearly all these deposits have resulted probably 

from epigenetic processes, although their geologic 

history is incompletely known; in any event, the 

uranium appears to have been redistributed by ground 

water in many of them.

The best-known uranium-vanadium deposits are 

the stratigraphically controlled carnotite deposits in 

the Salt Wash sandstone member of the Morrison formation in the Colorado Plateaus. Similar deposits include those in the Morrison formation northeast of 

Meeker, Colo. (fig. 18), and the roscoelite deposits 

in the Entrada formation near Rifle and Placerville, 

Colo. These deposits have been adequately described 

by Fischer (1942) and others. According to McKeown 

(1949) and Butler and Bush (1951), uranium-vanadium 

deposits also occur near Mauch Chui.k, Pa. (fig. 18), 

with thin stratigraphic units in sandstones of the 

Pottsville formation of Pennsylvanian age and in 

Willards Cherry Ridge red beds of Upper Devonian 

age. Here the uranium has been redistributed byground water.

Fractures and related faults control the localization of the uranium minerals in sandstone of the 

Morrison formation at the Mike Doy'e prospect (Beroni 

and King, 1950), in sandstone of the Kaibab limestone 

of Permian age at Goodsprings, Nev. (Hewett, 1923), 

and in limestone of the Laramie formation of Cretaceous 

age at the Leyden coal mine (Gott, 1950; McKeown and 

Gude, 1951).

A second type of uraniferous deposit found in 

sandstone includes those deposits containing copper, 

uranium, vanadium, and carbonized wood. They are 

found in sandstones of Permian to Eocene age. Other 

elements commonly present in these deposits include 

silver, cobalt, iron, sulphur, selenium, and carbon. 

In some, carnotite is the principal mineral, but in 

others, uraniferous carbonized wood or copper minerals predominate. Uranium oxide, probably pitchblende, has been found in a few.

Several deposits of this type resemble the 

carnotite deposits of the Colorado Plateaus in apparent 

lack of structural control and in vanadium content. 

Examples are the Silver Reef deposits, Utah (fig. 18), 

and the deposits at Skull Creek and Garo, Colo.

26
INDEX OF DEPOSITS

1 Meeker, Colo.

2 Rifle deposits

3 Placerville deposits

4 Mauch Chunk deposits

5 Mike Doyle claim

6 Goodsprings, Nev.

7 Leyden coal mine

8 Silver Reef deposits

9 Skull Creek deposits

10 Garo carnotite deposit

11 Copper Globe deposit

12 Oyler mine

13 Spotted Dog claim

14 Oak Creek deposit

15 Circle Cliffs deposits

16 White Canyon deposits 

33 Virgin

17 Uinto Basin deposit

18 Hack's mine

19 Mclntire deposit

20 Bulloch claims

21 Stockton deposit

22 Jesus lode

23 Snaw claims

24 RAJ deposit

25 Staneart property

26 Temple Mountain deposit

27 Lone Tree deposit

28 Red Canyon deposit

29 Lost Creek deposits

30 Ray claims

31 Wooley property

32 Rosamond Hills deposits 

Valley deposits

EXPLANATION 

TYPES OF DEPOSITS

A 

URANIUM-VANADIUM DEPOSITS

A COPPER-URANIUM-VANADIUM 

D COPPER-URANIUM

X URANIUM-VANADIUM-CARBONIZED woqo 

COPPER-URANIUM-VANADIUM-CARBONIZED WOOD DEPOSITS

 

URANIFEROUS ASPHALT DEPOSITS

T 

MISCELLANEOUS DEPOSITS (CARBONATES AND TUFFS)

Figure 18. --Index map of some uranium deposits in sandstones.

27
(fig. 18), reported by Gott, 1951. In the Silver Reef 

deposits, carnotite, volborthite (a basic copper vanadate), and an unidentified uranium mineral are associated with cerargyrite (silver chloride), carbonized 

plant remains, and copper carbonates. In addition 

selenium is uncommonly abundant. The deposits are 

in irregular lenses of sandstone containing clay pellets. These lenses are part of the Chinle formation 

of Triassic age. Carnotite and volborthite are found 

associated with uraniferous carbonaceous shale and 

carbonized plant fossils at Skull Creek and Garo, Colo. 

These deposits are in shale and sandstone in the upper 

part of the Jurassic Navajo sandstone, and in sandstones of the Permian and Pennsylvanian Maroon 

formation.

The most economically important subdivision 

of the second general type is the copper-uranium 

deposits, which contain little or no vanadium. These 

deposits have been found in sandstones from Permian 

and Pennsylvanian to Eocene age, but are particularly 

abundant in the Triassic Shinarump conglomerate on 

the Colorado Plateaus. The known deposits of this 

subdivision are in southwestern Utah (fig. 18) (Wyant 

and others, 1950; Granger and Beroni, 1950; Granger 

and Bauer, 1950); in Hack's Canyon, Ariz. (fig. 18), 

according to Dunning (1948); and in the Mclntire prospect in Huerfano Park, Colo.

In the Huerfano Park district, and in some of 

the deposits in the Circle Cliffs area (fig. 18), carnotite, 

carbonized wood, and radioactive iron oxide are the 

dominant uranium-bearing materials, but at the Copper 

Globe, Spotted Dog, Oak Creek, and Uinta Basin deposits (fig. 18) torbernite and uraniferous carbonized 

plant fragments are the common uranium-bearing materials. In the Oyler mine, in White Canyon, Utah, and

in the Hack's mine, Arizona, several hydrous uranium oxides, phosphates, and sulfates are abundant 

near the surface. In the Happy Jack mine in the White 

Canyon area (fig. 18) the deposit grades laterally from 

secondary carbonates and sulfates at the exposed cliff 

face to sulfides and pitchblende in the mine workings 

about 75 feet underground.

At the Oyler mine near Fruita, Utah (figs. 18 

and 19), zippeite, torbernite, and other secondary 

uranium minerals, together with highly uraniferous 

carbonized wood and hydrocarbons, are associated 

with copper sulfates and carbonates in podlike lenses 

at the base of the Shinarump conglomerate. Samples 

from the mine workings contain from 1. 50 to 4.00 percent equivalent uranium and from 0. 33 to 1. 22 percent 

uranium. The excess radioactivity is caused by radium, 

and calculations suggest that the fresh, unweathered 

ore might have contained as much as 6. 8 percent uranium. These high-grade ore bodies are at the base of 

the Shinarump conglomerate in zones that represent 

local irregularities of ancient stream channels. Within these channels, individual ore bodies are localized 

by small primary sedimentary structures that resemble 

monoclinal folds or synclines. Below the ore zones, 

the gray-green altered Moenkopi shale is highly calcareous.

Deposits of this subdivision probably represent 

the weathered part of primary bodies.

Another subdivision of the copper-uranium-vanadium-carbonized wood deposits is that in which the 

deposits contain little or no copper. Deposits of this 

type are found in Triassic, Jurassic, and Eocene sandstones in New Jersey, Colorado, and Utah. At the 

Bulloch claims near Orderville, Utah (fig. 18), Beroni 

and others (1951) report that carnotite, autunite,

Horizontal and vertical scale 

10 30 Feet

EXPLANATION

Gray-green shale Gray-green calcareous 

Reworked shale of the Moenkopi formation shale and sandstone

Red-maroon shole 

and sandstone

Figure 19. --Section of cliff face, Oyler mine, Wayne County, Utah

28
torbernite, and uraniferous carbonized wood are 

disseminated or coat pebbles and fracture eurfaces 

in the sandstones of the Cretaceous Dakota and Jurassic 

Summerville formations. In New Jersey (fig. 18) 

torbernite occurs in arkoses of the Triassic Stockton 

formation. Torbernite, or autunite, and uraniferous 

carbonized wood are present in Cretaceous Dakota 

sandstone at the Jesus lode (fig. 18), in Cretaceous 

Mesa Verde sandstone on the Snow claims (fig. 18), 

and in the Eocene Green River formation at the RAJ 

prospect (fig. 18).

The uraniferous asphalt deposits are a third 

major type of uranium deposits in sandstone. They 

have been found in Permian sandstone at the Staneart 

property in Oklahoma (fig. 18) and in Triassic sandstones and conglomerates of the Shinarump and Chinle 

formations at the Temple Mountain, Lone Tree, and 

Red Canyon deposits in the San Rafael Swell, Utah 

(fig. 18).

In the Temple Mountain district, Utah (figs. 18 

and 20), uraniferous asphaltite occurs as void fillings,' 

rounded pellets, veinlike fillings, and as detrital grains 

in friable sandstone lenses of the Shinarump conglomerate. Carnotite, zippeite, and other secondary uranium and vanadium minerals coat asphaltite grains. 

Carnotite also occurs in "rolls" in sandstone that 

resemble the rolls described in the Morrison carnotite 

bodies. The asphaltite ore bodies are localized in 

sandstones that fill ancient stream channels. The 

carnotite in this district appears to have been derived 

from the asphalt. The asphalt in all these deposits 

may be the mineraloid thucholite. Similar highly 

radioactive pellets have been found in the Oyler mine, 

the Oak Creek prospect, and at the Four Aces mine 

in the White Canyon area, Utah (fig. 18).

A fourth general type of uranium deposits in 

sandstone includes caliche-type carbonate deposits, 

uranium deposits in waterlaid tuffs and placers, and 

other miscellaneous deposits. Schroeckingerite at 

Lost Creek, Wyo. (fig. 18), is in rounded pellets in 

Eocene Green River shale or in flakes in the enclosing 

Eocene silts and arkoses (Page, 1950; Wyant and 

Sheridan, 1951). Schroeckingerite has been found to 

depths of 8 feet beneath the surface, but always above 

the ground-water table. The mineral has been deposited 

as an evaporite. So far as known, it is limited to a 

zone of faulting and overlies uraniferous lignite.

Uranium minerals have been described from 

samples of Tertiary tuff s near Aquila, Ariz. (Hewett, 

1925), and from the Wooley prospect in Utah, from 

Rosamond Hills, Calif. (Chace, 1950), andfrom 

Virgin Valley (StaatzandBauer, 1951). (Seefig. 18.) 

Carnotite, autunite, uraniferous opal, and probably 

Schroeckingerite are the uranium minerals.

Resistant rare-earth thorium minerals containing 

a little uranium are found in some placer deposits. We 

know of no deposits containing placer pitchblende.

The origin and genesis of the uranium deposits in 

sandstones is still an open question. Ground water has 

played an important role in all of them, either by redistributing uranium from the primary concealed deposits, 

or by introducing uranium from outside sources. The 

localization of some of the deposits is controlled by fractures, that of others by porous sandstone. In some, a 

rotation to petroleum seems evident. Many may have 

haa a hydrothermal origin. More must be known about

uranium deposits in sandstones before a comprehensive 

explanation of their origin and distribution canbe made.

LITERATURE CITED

Beroni, E. P., and King, R. U., 1950, The Mike 

Doyle carnotite deposit, El Paso County, Colo.: 

U. S. Geol. Survey Trace Elements Mem. Rept. 133. 

[Open files. ]

Beroni, E. P., McKeown, F. A., Stugard, Frederick, 

Jr., and Gott, G. B., 1951, Uranium deposits on 

the Bulloch group of claims, Kane County, Utah: 

U. S. Geol. Survey Trace Elements Mem. Rept. 213. 

[ Unpublished. ]

Butler, A. P., Jr., and Bush, A. L., 1951, Inspection of carnotite deposits near Mauch Chunk, Carbon 

County, Pa.: U. S. Geol. Survey Trace Elements 

Mem. Rept. 241. [Unpublished.]

Chace, F. M., 1950, An autunite deposit in the Rosamond Hills, Kern County, Calif.: U. S. Geol. Survey Trace Elements Mem. Rept. 136. [ Unpublished. ]

Dunning, C. H., 1948, Report on Hack's Canyon uranium mine: Arizona Dept. Mineral Resources. 

[ Unpublished report. ]

Fischer, R. P., 1942, Vanadium deposits of Colorado 

and Utah, a preliminary report: U. S. Geol. Survey Bull. 936-P, pp. 363-394.

Gott, G. B., 1950, The Leyden uranium prospect, 

Jefferson County, Colo.: U. S. Geol. Survey Trace 

Elements Mem. Rept. 132. [ Unpublished. ]

________1951, Garo uranium deposits, Park County, 

Colo.: U. S. Geol. Survey Trace Elements Mem. 

Rept. 222. [Unpublished.]

Granger, H. C., and Bauer, H. L., Jr., 1950, The 

Eureka and Happy Landing groups of claims, Uintah 

County, Utah: U. S. Geol. Survey Trace Elements 

Mem. Rept. 32. [ Unpublished. ]

Granger, H. Ct, and Beroni, E. P., 1950, Uranium 

occurrences in the White Canyon area, San Juan 

County, Utah: U. S. Geol. Survey Trace Elements 

Mem. Rept. 7. [ Unpublished. ]

Hewett, D. F., 1923, Carnotite in southern Nevada: 

Eng. and Min. Jour.-Press, vol. 115, no. 5, pp. 232- 

235.

_________1925, Carnotite discovered near Aguila, 

Ariz.: Eng. and Min. Jour-Press, vol. 120, no. 1, 

p. 19.

McKeown, F. A., 1949, Preliminary report of uranium deposits near Mauch Chunk, Pa.: U. S. Geol. 

Survey Trace Elements Mem. Rept. 19. [ Unpublished.

McKeown, F. A., and Gude, A. J. 3d, 1951, Preliminary report on the carnotite deposits of the 

old Leyden coal mine, Jefferson County, Colo.: 

U. S. Geol. Survey Trace Elements Mem. Rept. 308. 

[ Unpublished. ]

Page, L. R., 1950, Interim report of geologic investigation, Lost Creek schroekingerite deposits, 

Sweetwater County, Wyo.: U. S. Geol. Survey Trace 

Elements Mem. Rept. 183. [Open file.]

Staatz, M. H., and Bauer, H. L., Jr., 1951, Virgin 

Valley opal district, Humboldt County, Nev.: U. S. 

Geol. Survey Circ. 142.

Wyant, D. G.; Stugard, Frederick, Jr.; and Kaiser, 

E. P., 1950, Uranium resources in the Marysvale 

region, Utah, and interim report: U. S. Geol. Survey 

Trace Elements Mem. Rept. 169. [Unpublished.]

Wyant, D. F., and Sheridan, D. M., 1951, Interim 

report, Lost Creek schroekingerite deposit, Sweetwater County, Wyo.: U. S. Geol. Survey Trace 

Elements Mem. Rept. 244. [ Unpublished. ]

29
 _ o o n « x .r- -s- ooooo

Horizontal and vertical scale 

0 40 

I i I_________.

120 Feet

EXPLANATION

Lime-pellet conglomerate

Chert-pebble conglomerate

Uranium ore 

Asphaltite grains in sandstone

Q.*- 

C O

wg

o

o

CO f<

a: hH 

11

Mudstone and mudstone-gravel

Figure 20.--Cliff face, Shinarump Mesa, Temple Mountain district, Utah.

30
URANIUM IN BLACK SHALES, LIGNITES, AND LIMESTONES IN THE UNITED STATES 

By Garland B. Gott, Donald G. Wyant, and Ernest P. Beroni 

ABSTRACT

Small quantities of uranium occur in carbonaceous deposits at a great many localities in the United States, 

but the amount rarely exceeds 0.1 percent. The most common uranium-bearing carbonaceous deposits are in the 

black marine shales, principally of Paleozoic age, exposed in the eastern and central parts of the United States. 

The uranium content of most of these shales ranges from a few thousandths to a little more than 0.01 percent.

Another type of low-grade uranium-bear ing carbonaceous deposit is represented by some of the lignite deposits of Tertiary age in Montana, Nevada, North Dakota, South Dakota, and Wyoming. The uranium content of 

these uraniferous lignites is comparable to that of the black shales. The concentration of uranium in the lignite 

ash, however, is considerably greater than in the black shales.

Several widely distributed uranium deposits in limestone, most of which are low grade, have been discovered 

recently in Missouri, New Mexico, New Jersey, Utah, and Vermont. The limestones range in age from pre-Cambrian to Tertiary. In some of these deposits the uranium is associated with phosphatic, carbonaceous, or argillaceous 

material. In others, secondary uranium minerals occur as fillings in fractures and vugs.

Uraniferous black marine shales have been 

described by many investigators, but reference to 

uraniferous terrestrial shales, coals, and carbonate 

rocks are not common. Recent investigations by the 

U. S. Geological Survey, made on behalf of the Atomic 

Energy Commission, have indicated that such deposits 

are widespread in the United States.

Figure 21 shows the distribution of some of the 

uraniferous black shales, coals, and limestones in the 

UnitedStates. Figure 22 shows, in more detail, the 

distribution of some of the better-known uraniferous 

marine carbonaceous shales. This type of shale is best 

represented by the Chattanooga shale of Devonian and 

Carboniferous age. It is best exposed in Tennessee and 

Kentucky, but its equivalents underlie much of the area 

between the Appalachian and Rocky Mountains.

The uranium content of the Chattanooga shale 

ranges between 0.001 and 0.03 percent. In general, 

the uranium content is greater in the more organic 

facies, although no direct ratio of uranium to organic 

material has been established. A few samples, consisting almost entirely of bitumen, contain more uranium than the enclosing shale. Analytical data suggest that there is a general correspondence between 

the uranium and the iron sulfide and vanadium content of the shale. The uranium is evenly distributed 

throughout the shale and apparently is inversely proportional to the carbonate and phosphate content.

Gamma-ray logs of oil wells in Kansas, Oklahoma, west Texas, and New Mexico indicate that 

the radioactivity of the Chattanooga shale, and its 

equivalent, the Woodford chert, is comparable to 

that exposed in the eastern United States.

Uranium content of the black Pennsylvanian 

shales in Kansas and Oklahoma is similar to that of 

the Chattanooga shale. Phosphatic nodules in these 

Pennsylvanian shales have a much higher uranium 

content than the clastic parts of the bed. Small 

quantities of thorium also are present in both the 

shale and the nodules. The blacker and more fissile 

phosphatic carbon-rich shales in this area contain 

the greater amounts of uranium.

Samples of carbonaceous marine shale of 

Pennsylvanian age from an oil well in east-central 

Wyoming contain from 0.005 to 0.02 percent uranium, 

which is comparable in grade to the Pennsylvanian 

carbonaceous shales of Kansas and Oklahoma and 

the Chattanooga shale in Tennessee and Kentucky. 

The oil content of the samples ranges from about 

1 to 5i percent.

The marine carbonaceous shales briefly discussed above are only some of many such shales 

in the United States. Other shales may be as radioactive or more radioactive than the Chattanooga and 

Pennsylvanian shales.

Uraniferous coals of Paleozoic, Mesozoic, 

and Tertiary ages are known in the United States. 

The greatest concentrations of uranium occur 

in Paleocene and Eocene lignites in the Dakotas, 

Montana, and Wyoming (fig. 23) and in a highash lignite in Nevada. A few bituminous Pennsylvanian coals in the midcontinent region and subbituminous Cretaceous coal in southwestern Wyoming 

contain as much as 0.004 percent uranium, but hundreds of others have been tested radiometrically and 

chemically with negative results.

31
EXPLANATION 

 SHALE

A COAL

x LIMESTONE

Figure 21. Distribution of some uraniferous shales, coals, and limestones.
KANSAS

-- \

MISSOURI

PENNSYLVANIAN ROCKS

V

OKLAHOMA

<WOODFORDj

^ CHERT i

CHATTANOOGA 

SHALE

ARKANSAS

) TENNESSEE

x. .---~-

TEXAS

i- .-

! ..-._.._.j MISSISSIPPI

LOUISIANA

«£

r

GEORGIA

Figure 22. --Distribution of some uraniferous shales.
Figure 23. Distribution of some uraniferous coals.

In the Dakotas, Montana, and part of Wyoming, 

the greatest concentrations of uranium occur in the 

first group of lignite beds below the Pal eocene-Eocene 

unconformity. 'The uranium content of the lignite beds 

is variable, but some contain slightly more than0.01 percent. The apparent relationship between these lignites 

and the unconformity between the Paleocene and the 

Eocene rocks suggest that the uranium may have been 

leached from volcanic ash in the White River formation and introduced into the lignite by surface waters 

during post-Paleocene time. The even distribution, 

however, of the uranium in the lignite, as indicated 

by an autoradiograph of one sample from North Dakota, 

and the absence of any apparent concentration of uranium on fracture planes in this area, suggest that the 

uranium was present before coalification.

In the Red Desert area of Wyoming uraniferous 

lignites in the Wasatch formation of Eocene age contain from about 0. 002 to 0. 007 percent uranium. The 

presence of about 60 percent more radium than that 

required for equilibrium with uranium indicates that 

uranium in the exposed lignite has recently been 

leached and suggests that fresh lignite contains more 

uranium.

A high-ash lignite of Tertiary age in Churchill 

County, Nev., contains as much as 0.05 percent uranium. The extremely high-ash content of this lignite, 

however, seems to preclude a significant concentration 

of uranium by burning such as can be effected with the 

other lignites mentioned.

The distribution of most of the uranium deposits 

that have been found in limestone or dolomite is shown 

in figure 21. Most of them are low in grade.

Uranium, possibly of syngenetic origin, has been 

found in a fresh-water limestone in the Uintah formation of Tertiary age in northeastern Utah, and in the 

Milton dolomite of Cambrian age in northwestern 

Vermont. The uranium in the Milton dolomite occurs 

in slightly petroliferous and phosphatic clay galls.

At Bussen's Quarry in Ste. Genevieve County, 

Mo., the Spergen limestone of Mississippian age contains finely disseminated detrital carbonaceous material and purple fluorite. Both the carbonaceous material and the fluorite contain uranium. The limestone 

encloses thin black shale beds that have been molded 

into stylolitic structures. The shale contains about 

0. 6 percent uranium, more than 100 times greater 

than in the average shales of the Chattanooga and 

Pennsylvanian type. Carnotite is sparsely distributed 

in the limestone adjacent to the black shale, and it is 

thought that the uranium in this mineral was leached 

from the black shale and transported by ground water.

The deposits near Grants, N. Mex., are in the 

Todilto limestone of Jurassic age. Uranium minerals 

are associated with hydrocarbon products and are 

localized by minor folds and fractures that may have 

been caused by intraformational slumping. Pitchblende, 

carnotite, tyuyamunite, and uranophane are associated 

with hematite, limonite, pyrite, and fluorite.

34
Radium- and hydrocarbon-bear ing dolomite and 

limestone of Ordovician and Pennsylvanian age are 

present in the subsurface of the North Augusta oil 

field in southeastern Kansas.

The concentration of uranium in organic marine 

shales has been the subjec.t of considerable speculation, 

but the processes responsible for the accumulation 

have never been demonstrated. It has been variously 

suggested that the uranium was extracted from sea 

water by living organisms, that it was concentrated 

by colloidal adsorption, or that it was precipitated 

in the presence of a reducing agent. There seems 

to be supporting evidence for each of these hypotheses, 

but the common association of uranium with carbonaceous material suggests that the uranium was most 

probably concentrated originally by biochemical processes. The association of uranium with bituminous 

shales, asphaltic sandstones, and petroliferous limestones suggests that some crude oils may also serve 

as distributing agents during the process of dissemination and concentration of uranium. If greater concentrations of uranium occur in the bitumen than in the 

enclosing shales, as the limited data suggest, it is 

entirely reasonable that uranium is carried along with 

crude oil as it migrates to points of accumulation in 

the reservoir rocks. Tomkeieff (1946)* quotes data 

to show that petroleum, on an average, contains 100 

grams of uranium per ton, and that oil waters contain

1Tomkeieff, S. I., The geochemistry of uranium: Sci. Progress, 

vol. 34, no. 136, pp. 696-712, 1946.

10 grams per ton. Highly uraniferous asphaltic sandstones are present in some breached anticlinal struc - 

tures, as for example the San Rafael Swell and the 

Waterpocket fold in Utah. Evidently hydrocarbons 

migrated into the closed structures, and, after removal of the cap rock by erosion, all the petroleum 

except the residual asphalt escaped. The presence 

of such highly uraniferous asphalts in former structural traps raises several questions. Was the uranium picked up in the path of the migrating hydrocarbons? Was it removed from organic shales from 

which the petroleum was presumably derived, or were 

small quantities of uranium inherent in the liquid 

hydrocarbons concentrated by some process of fractionation of the oil ?

The presence of relatively large quantities of 

radium and radon in some oil and gas fields indicates 

a possible genetic relationship between the products 

or uranium and hydrocarbons.

Some of the many problems that are deserving 

of further investigations, therefore, are (1) the 

possible migration of uranium in hydrocarbon solutions 

derived from carbonaceous shales; (2) the possibility 

of precipitation of uranium compounds from oil solutions; and (3) the effect of polymerization of the hydrocarbons by alpha radiation.

In conclusion, uranium is associated with some 

coals and carbonaceous marine shales, phosphatic 

rocks, petroleum products, and disseminated carbonized wood fragments throughout the world.

35

IHT.-DUP. SEC., WASH., D.C. 32111