UNITED STATES ATOMIC ENERGY COMMISSION
EQ),IA.kr

RMO- 732
GEOLOGY OF URANIUM DEPOSITS—
A CONDENSED VERSION
By
Donald L. Everhart
With Mineral Tables By
Muriel Mathez

May 1951
Ei- 4 -3
Division of Raw Materials
Exploration Branch

Technical Information Sitrvice, Oak Ridge, T•nn•ss••

METALLURGY AND CERAMICS
Reproduced direct from copy
as submitted to this office.

AEC,Oak Ridge,Tenn.,7-3 -51 - -iloo-W4863
Reprinted,AEC,Oak Ridge,Tenn.,11-8 -51 - -3oo

CCRITENIISPa
INTRODUCTION . OOOOOO ••• OO

OO . . . . . .

1- 2........ . . . . •. . .•

3- 4
4
4,- 6

Shinkolobwe mine, Belgian Cangp . , . . . •Vein deposits in the United States • , , . ▪

6- 8
8-10

Disseminated Deposits in Igneous Rocks . . • . . •10-11. . . . .•111-12(EN AL FEATURES . . . . .

DEPOSITS IN IGNEOUS AND METAMORPHIC ROCES
Hydrothermal Vein Deposits . . . ...

Pegmatites ..... . . . . .

DEPOSITS IN SEDIMENTARY ROCKS . . . • • • • • • • • .

13Carnotite Deposits . . . . . ........ . . ▪

13-14

Copper-uranium Deposits . . ........ • . •14-16

Uranium-bearing Asphalt Deposits . . . . . . . . •16-17

Uranium-bearing Limedtane Deposits . . . ..

17-18

Uranium-bearing Phosphorites . . . . . . . . • . .

18-20

Uranium-bearing Black Shales . . . . . . . . . . . 20-22
Alluvial and Placer Deposits.. . . . . . . . . .

22.23

Lacustrine-saline Deposits. . . . . • • . • • ,23

USF '17 FI7LD INSTRUMENTS FOR RADIATION DETECTION . . . 24.-26
SUGGESTED SAMPLING PROCEDURES AND THE EVALUATION
OF URANIUM ORE BODIES . . . . . . . . . . . . . . . .
TABLE I - CCWON URANIUM MINERALS

iii

26-28

GEOLOGY OF URANIUM DEPOSITS- A Condensed Summary by
Donald L. Everhart
Mineral Tables
byMuriel Mathes

INTRODUCTION
In an effort to stimulate the search for uranium deposits
among professional geologists and mining engineers, the following

pages present a brief summary of some of the pertinent facts and ideas
concerning the geology of uranium deposits evolved by many individuals
who have been actively engaged in uranium exploration. This work has
been done by. members of the U. S. Geological Survey, the U. S. Atomic
Energy Commission, geological surveys of several other countries,
mining companies, and several educational and research institutions.
The writer recommends that the following bibliography beconsulted in conjunction with this paper: Selected Bibliography of

Published References on Uranium Occurrences and Radioactive Ore Deposits,
compiled by. Margaret Cooper, Division of Raw Materials, U. S. Atomic
Energy Commission, New fork, N. Z., March 1951.
Invariable or infallible geologic guides to uranium ore havenot been completely formulated, and the character of even the mostcommon of the uranium minerals in many instances is not fully understood. Furthermore, any system of classification of uranium deposits

must be considered tentative, for varied uranium-bearing mineral,'/'
assemblages continue to be found in igneous, sedimentary, and metamorphic rocks of nearly all ages. The art and science of exploringfor uranium deposits are uniquely aided, however, by the fact that allconcentrations of uranium exhibit abnormal radioactivity. Thus, inaddition to standard geologic and physical techniques used in explore,
tiara, geologists and engimers have at their disposal an additional

tool based upon radioactivity detection.
Incentives for mining uranium ore include not only an assured
market, but guaranteed prices for a specified length of time. Further,
there are negotiated prices that take into account special cost
factors involved in developing new sources of uranium. The by-productvalue of uranium recovered during operations for other metals offers

an additional incentive to the mining industry.
Concepts as to the nature and distribution of uranium ore

deposits are being formulated as exploration and research activities
progress, and now types of uranium deposits are disclosed. Thesepages contain a condensation of the current information on thesesubjects. Some is fact; other is interpretation based upon comparatively
limited experience. As work progresses, ideas on many of these subjects
will undoubtedly change, and this presentatioa is intended only as aninterim summary.

3

GENERAL FEATURES
Perhaps the most striking feature of uranium are deposits
is the wide variety of geologic environments in which uraniun mineral
concentrations have been found, and the range of ore types that are
being studied and developed. Uranium ore deposits are known to occur
in igneous, sedimentary, and metamorphic rocks, and in many different
types of rock within each of these classifications.
In igneous and metamorphic rocks, ranging from pre-Cambrian
to late Tertiary in age, primary uranium-bearing deposits are distributed throughout at least four general major geologic features ofthe earth's crust: the Cordilleran belt of North and South America,
the western marginal areas of the Canadian Shield, the areas of igneous
intrusion in Europe, and the continental "backbone" arm of central
and southern Africa.
Uranium deposits in sedimentary rocks likewise have wide
distribution throughout the world. For example, in the United States,
concentrations of carnotite and copper-uranium mineral assemblages

are distributed widely within sandstones and mudstones of the Colorado
Plateau in adjoining portions of Colorado, Utah, Arizona, and New
Mexico. The host rocks range from Permian to Cretaceous in age.
Miocene and Pliocene phosphate-bearing marine formations, which contain appreciable amounts at uranium, occur throughout a broad area incentral Florida, and uranium-bearing phosphate beds have also beenstudied throughout Permian formations of Idaho, Montana, and Wyoming.

4Jurassic limestone of the Zuni Uplift region in New Mexico contains
some recently discovered uranium deposits. Low-grade concentrationsof uranium exist in several carbonaceous shale formations of Paleozoic
age in the Central and Great Plains regions and in saline-lacustrine
beds in California. Similar deposits in correlative sedimentaryrocks have been described throughout the world.
The general geologic features of some of these major typesof deposits, together with el.amples, are first discussed, followed bybrief comments concerning the radioactivity characteristics, suggested
sampling procedures, and means of evaluating the deposits. Table I,at the end of the discussion, presents current data on the common
uranium minerals.
DEPOSITS IN IGKECUS AND METAKCRPHIC ROCKSUranium deposits within igneous and metamorphic rocks occur
largely in hydrothermal veins, but disseminated bodies of less present
commercial significance are also =own, and scattered amounts ofuranium are found in pegmatites throughout the world.
Hydrothermal Vein Deposits

The major hydrothermal uranium-bearing vein deposits of theworld are typically mesothersal in character, although a few indicate

temperatures of deposition that approach those of epithermal deposits.
In most of them, pitchblende (b, in the mineral table - Table 1) is
the major uranium mineral, accompanied by various secondary alteration

products. Compilation of data and geologic appraisals of a numberof the best-known pitchblende deposits of the world are currently in
preparation (1), and emphasize the following general features,,
The host rocks of the known primary uranium vein deposits
include igneous, sedimentary and metamorphic types, of which the mostfavorable appear to be felsic intrusives and arenaceous metasediments.
Unmetamorphosed sedimentary rocks are apparently relatively poor hosts.
Within the veins themselves, associated miners la containing, indecreasing order of abundance, iron, copper, cobalt, lead, silver,
nickel, and bismuth indicate favorable geologic environments forprimary uranium minerals. Typical associated gangue minerals include
silica in a variety of forms, several types of carbonates, fluorite,
barite, and, in a few places, tourmaline and hydrocarbons. Of these,
crystalline beta quartz, calcite, and dolomite are clearly the mostcommon. In the sequence of deposition •ithin the veins, the uraniumoxides appear to occupy an intermediate to early position although
there are notable exceptions. In several inFtances, pitchblende has
evidently been deposited after the early high-temperature sulphides
and before the later silver and lead minerals. In other places, uraniumoxides were deposited before all of the associated sulphides, underconditions of relatively high temperature. In still others, pitchblende was obviously the latest addition to the vein even following
carbonates. Structurally, pitchblende-bearing veins tend to form
open-space fillings, though replacement of previously existing vein

1. Everhart, Donald L. and Wright, Robert J., Some geologic
characteristics of primary uranium-bearing vein deposits. U. S.
Atomic Energy Commission, New York, N. Y.

quartz has occurred in one notable instance; elsewhere, replacement
has been relatively unimportant, and confined to a few types ofsiliceous host rock. The effect of the pitchblende-depositing solutions on the wall rock is complex and not fully understood. In many
instances the ore-bearing solutions have produced a distinctive redhematitic alteration which, particularly in the Canadian Snield, isa valuable guide to ore. In other places, notably in the granitic
host rocks of the Rocky Mountain areas of the United States, the wallrock has been altered in part to clays with high base-exchange properties, together with kaolinite, and, in addition, it has been affected
locally by chloritization, soricitizations and silicification.

Shinkolobwe mine, Belgian Congo. The primary vein deposits
in the Shinkolobwe mine of the Belgian Congo are by far the largest andrichest known O. present, and a brief description (2) of their geology
may prove helpful in the search for other similar deposits.
The rocks of the area surrounding Shinkolobwe have been

divided into three stratigraphic groups: the basement complex, theKatanga system of pre-Cambrian age, and the overlying Karroo system.
Near the bottom of the Katanga system, a series of five formations,comprising the Wine Aeries," consists of: an upper or "hard" dolomite,
dolomitic shale, cellular quartzite, thin-bedded quartzite, and talcose
dolomite. A series of tight overturned folds, the axial planes of which

2. Merritt, P. L., Pitchblende - the primary source of uranium:
Conference an radioactive ores, Michigan College of Mining and Technology,
Houghton, Michigan, May 6, 1949, pp. 10-11.

dip to the north, and thrust faults of considerable displacement arecharacteristic structures. Thrust plates of the Mine series havebeen moved from the northeast to over-ride the overlying Kundelungu
series, the upper rocks of the Katanga system.
Shinkolobwe mine explores a series of complex fault structures.

One of the principal faults trends westward, transecting the strike of
the Mine series at a low angle. Associated with this main structure

are numerous irregular cross-faults with varying attitudes and strike
lengths. The ore bodies in these cross-faults are .7)calized where
the faults intersect the thin-bedded quartzites, cellular quartzites
and dolomitic shales of the Mine series, and the brecciated zones
adjacent to the principal fault structures.

The veins, varying in width from a few inches to several
feet, pinch and swell both vertically and horizontally and commonly
cannot be traced for more than a few feet along the strike. They may
contain pitchblende with little other filling, or may consist dominantlyof cobalt or copper sulphides with or without associated pitchblende.
Elsewhere, pitchblende, associated with cobalt minerals, occurs in aquarts.-carbc'ciate vein matrix. Open fissures and brecciated zones inthe siliceous rock have favored pitchblende ore deposition. Cobalt
mineralization, on the other hand, has not been confined to thebrecciated zones and cross-faults, but has been disseminated throughthe massive dolomitic wall rocks. In addition to the principal uranium
and cobalt minerals, the Shinkolobwe ores carry significant quantities
of copper, molybdenum and iron sulphides, and gold, platinum, andpalladium.

a

Oxidation of the ore bodies has extended several hundred
feet in depth. In the near-surface deposits there are a host ofcomplex hydrous oxides, phosphates, and silicates such as becquerelite(1), uranophane (x), gummite (y), and torbernite (aa) - (see Table I).
This aupergene torbernite contains more than half of the uranium inthe oxidized zones of the ore body. A typically altered lens of ore
has a central core of pitchblende surrounded by successive zones ofthe yellow, orange, and green secondary minerals. The green phosphates

are generally disseminated extensively through the surrounding rocksof the Mine series.
Vein deposits in the United States. Uranium-bearing vein

deposits of the United States, like most of those in other parts of
the world, are typically mesothermal base-metal veins. The mostfavorable host rocks observed to date are either felaic rocks; such as

granite, quartz monzonite, or syenite, or siliceous metaseamerts suchas quartzite, quartz-biotite schist, or quarts-rich slate. The
characteristic uraniva mineral in the veins is pitchblende, which
occiirs in extremely fine-grained mixtures with iron, copper, lead,and zinc sulfides, and hematite. The major associated minerals of
the deposits include pyrite, chalcopyrite, arsenopyrite, tetrahedrite,
galena, ephalerite, argentite, and proustite, as well as native silver
and hematite. The major gangue minerals are quarts, opal, chalcedony,siderite, calcite, fluorite, and barite.

The known pitchblende-bearing vein deposits of the UnitedStates constitute open-space filling of definite fractures or faults.
splacement of the other vein minerals and the host rock by pitchblende has occurred only on a ve..y small scale (3). The relative ageof the pitchblende with respect to the other minerals is variable.
At some places, it was precipitated early in the mineralisation sequence, while in others, it appears to have been late in the sequence.
Because of the solubility of uranium oxide, it is probably reconstituted
reprecipitated at various stages in the overall mineralization
process, inending secondary action.

The solubility of pitchblende in oven slightly acidic groundwaters has generally led to the secondary redistribution of uraniumin oxidized parts of the vein deposits edjacent to the surface, especially in arid or semi-arid regions (4). In these oxidised deposits,
the uranium minerals are largely phosphates, sulfates and tydrous
silicates, &old the grade is oommonly lower than in the unaxidised
veins. As a general rule, these oxidized parts of the depoeits havethe following four characteristics:

1: they are contrclled by persis-

tent tenaional fractures of a type that could :Ave bean favorsale forthe upward passer* :f lay- thermal solutions from below; (2) the
fractures &re filled by secondary met4llic minerals that nay have beec
derived from sulfides or mides of base metals, and gangue minerals
that axe typical of hydrothermal deposits; (3) the uranium mineral_

3. Marlow, Ernest E. and Writ, Robert J., Uraninite in the Coeurd'Alene district, Idaho. Econ. 3eo1. T. 45, 195D, PP. 4c1-402.
. Everhart, Donald L., Some features of the secondary redistributionof uranim in oxidation sones: Paper presented at Geol. Soc. of Ai.
meetings, Washington, D. C., November 17, 1950.

include base metals in their lattices; and (4) the wall rock has

been altered in part to clays with high base-exchange properties aswell as kaolinite, and may have been affected by chloritizatim,
sericitization, or silicification, or by all three processes.
Primary deposits assaying 0.2% or more U;08 are currently
mined commemially. The relatively limited tonnages of these
deposits necessitate grades of this order. In semi-arid or arid
climates, oxidized and impoverished vein outcrops may contain 0.1%
U308 or less.
Disseminated Deposits in 'meow Rocks
Several volcanic flow rocks of the southwestern United States
contain low-grade concentrations of uranium. Some of these deposits

are distributed throughout broad shear zones covering sizeable areas,
and others appear to be structurally controlled by local flexures andcamplimentary fractures in the flow rocks. In at least one shear
zone in silicified rhyolite, pitchblende occurs within fragments ofthe country rock, which is brecciated ana cemented by calcite, fluorite,
galena, sphalerite, and chalcopyrite. In another deposit, secondary
lead and copper minerals, including uranium-bearing pyromorphite, aredistributed over a wide area in the fractures of a sheared zone inflow rock. Commonly, the uranium minerals disseminated through volcanic
rocks at or near the surface include such secondary minerals as autunite) schroeckingerite (r), and uranophane (x) - (see Table I).
To date, none of these disseminated deposits in volcanic

rocks has been a producer of ore. The overall grade of those investigated11

averages less than 0.1% U308, and the uranium is not distributed

widely or uniformly enough to offset the relatively low grade.
Many granite masses contain uranium-bearing accessory
minerals such as monazite (o), zircon, pyrochiore (i), allanite,thorite, and uraninite (a), and some of the more sodic types ofgran" es carry more uranium-bearing accessories than the others.
Albite-riebeckite types of granite are particularly radioactive andmasses of this rock have been sampled in the Witt) Mountains of New
Hampshire, in Vermont, the San Francisco Mountains of Arizona, thePikes Peak region, Colorado, and in Alaska and Nigeria. Even themoat radioactive known granite bodies, however, contain less than

0.015% U 0 and to date have nowhere been a productive source of ore.
38
Pegmatites
Uranium-bearing and rare-earth minerals, including colum-

bates, tantalates, and titanites, are rather common accessories ofmany pegmatite deposits but in general these deposits are not capableof producing uranium on an appreciable scale. They are, however,sources of high-grade specimens, and pegmatite bodily containing
appre;ielle tonnages of uranium minerals may yet be discovered. The

primary uraniumrbearing minerals in this type of deposits include
uraninite and, in special cases, thucholite (d), as well as the12refractory columbo-tantalates such as euxenite (h), smmarskite (g),pyrochlore (i), and fergu9onite (f).
According to L. R. Page (5), potassium-rich pegmatites orzones in them have been found to be the most likely sources ofuranium minerals, whereas sodiumm-rich or lithium-rich pegmatites
or zones are somewhat less favorable.
The "grade" required in pegmatites for possible uranium
production is not ordinarily expressed in the usual percentage U308
figure for the total rock. A few pegmatites have yielded uraniumbearing minerals as by-products of mica or feldspar mining. If
several hundred pounds or tons of such minerals can be effectively
separated, their recovery and sale, of course, becomes economic.

5. Page, Lincoln R., Uranium in pegmatites, Econ. Geol., vol. 45,

1950, pp. 12-34.

13

DEPOSITS IN SEDIMENTARY ROCKSUranium deposits in sandstone, siltatone, shale, and limestone
formations appear to offer the most promise for producing large tonnagesof ore in the United States. Currently, th, carnotitombearing sandstones
and shales of the, Colorado Plateau contribute the major proportion of ourdomestic production, and similar sandstone and shale formations insouthern Utah and northern Arizona, which contain distinctive assemblagesof copper and uranium minerals, promise to become significant producers
in the next few years. At least one belt of recently discovered uranium-•
bearing limestone deposits in the Zuni Uplift area of New Mexico contains

substantial reserves of ore which mill also contribute to domestic pro.
duction.
Carnotite 'Deposits

Concentrations of carnotitea and related minerals in sandstoneand shale have been found principally throughout the Colorado Plateau in
the thick series of sedimentary rocks that underlies about 130,000 square

miles of -eastern Utah, northeastern Arizona, northwestern New Mexico, andColorado west of the Rocky Mbuntainso Smaller carnotite deposits havebeen studied in the Mojave Desert area of southern California, in partsof the Mauch Chunk formation of Pennrylvania, and in rocks bordering the
Front Range in Colorado.
In the Colorado Plateau area, carnotite deposits occur in the
Coconino formation (Permian) and upwards through the stratigraphic column
to include the Mesa Verde formation (Upper Cretaceous), but the important
producing horizons have been in the Morrison and Entrada formations(Jurassic) and the Shinarump formation (Triassic). Most of the oredeposits are irregular but roughly tabular in shape, with the greater
dimensions in planes essentially parallel to the generally horizontal
bedding of the enclosing sandstone and mudatone. Despite this general
conformity to the bedding, the ore bodies tend in part to cut acrossthe stratification, and in places they thicken to form concretion-likemasses known as "rolls.a The ore deposits ommmonly are associated withfossilised tree trunks, branches, or leaves, and some of the richestores oonsist of logs partly replaced by uranium and vanadium minerals.
All of the above features are generally associated with ancient stream

channels, which seem to represent the dominant structural control of
the ore bodies. There is yet considerable question as to whether theminerals were precipitated from ground water solutions after Lhecents had accumulated but before deformation and fracturing of therocks (6), or whether the major uranium-bearing solutions formed thedeposits in post...Cretaceous time. In either event, the old stream channelways are considered the most important controlling structures.
The ore-forming minerals, which include mainly carnotite,
vanoxite (2V204,V205,8H20), and hewettite (Ca0,317205, H20), aredeposited as coatings on grains of sandstone or along the parting planesof shale, and most of the ore contains 0.2 to 0.4% 11308 and 1.5% to 2%
V205.
Copper-uranium Deposits
Distinctive assemblages of copper and uranium minerals occur
at many localities in conglomerate, sandstone, and shale formations of

6. Tischer, Richard p., Uranium-bearing sandstone deposits of theColorado Plateau, Eoone Geol" vol. 45, 1950, pp. 1-'l1.

15

Triassic age in the western and southern parts of the Colorado Plateau.
Most of these localities are in southern Utah and northern Arizona, inthe Moenkopi, Shinarump, or Chinle formations of Triassic age. Copper..
uranium mineralis4tion appears to have occurred in a somewhat restricted
stratigraphic horizon at the base of the Shinarump formation and in theupper few feet of the Moenkopi formation immediately beneath it. However,
several notable copper-' ant:ma deposits have been localised at several
other stratigraphic horizons in the Triassic sedimentary rocks ofsouthern Utah and northern Arizona. For example, in the *hits Canyon.
Red Canyon district of San Juan County, Utah, a persistent sandstone orconglomerate, averaging 10 to 20 feet in thickness, near the middle of the
Moenkopi strata, forms the locus for copperunranium mineral concentrations.

In the Silver Reef district of Washington County, the oopperianranium
deposits appear to be confined to the Silver Reef sandstone Bomber of the
Chinle formation.
All of the host sandstones of the copper...uranium deposits are
typically lenticular in character, thinning and thickening markedly along
the strike of the bedding. This Character is interpreted as indicating

fluviatile deposition in and adjacent to stream channels. As in the
carnotite deposits, the mineral oonoentrations appear to be in or near the
thickest and lowest parts of the sandstone or conglomerate beds — that is,along the ancient channelways. Characteristically the deposits are spotty
and erratic in distribution. Although in general the uranium and copper
minerals occur together, the visibly identifiable copper minerals are nota reliable guide to uranium ore, for copiously copper-stained beds may
exhibt little or no radioactivity and beds with negligible copper oonm.
tent may contain appreciable amounts of uranium.

-16One of the characteristic features of the copper-uranium
deposits is the mineralogic difference between the relatively
unoxidised and the oxidised portions of the deposits. Although they

have been studied and mined in only a few edits, the prtmary minerals
induct() pitchblende, pyrite, chalcopyrite, oovellite, boruites galena,
and gersdorffite. Chalcocite is also present in unoxidised wanes, but
may be secondary after the other copper sulfides. At the oxidiued rim
outcrops the primary minerals are typically altered to hydrous sulfates,
phosphates, silicates, carbonates, and arsenates including johannite (p),torbernite, uranophane, schoepite (m) -becquerelite (1), and sippeite (s),with malachite, antlerite, chalcanthite, brochantite, cyanotrichite, anderythrite (7). From the few deposits thus far studied, it appears thatoxidised rim outcrops are depleted in uranium, and thus an improvementin grade may be expected with advancing development.
Currently, copper-uranium deposits that Appear to containseveral thousands of tons are considered potential ore producers if theoxidised rim outcrops assvf more than 0.05% U308. It is believed thatunoxidised portions of such mineralised bodies may contain ore averaging
several tenths of one percent U308.

Uranium-bearing Asphalt Deposits
Uranium-bearing asphalt (8) or asphaltite occurs in lenses,
globules, and irregular masses in certain sandstone beds of Triassic age
in southern Utah. Structurally and lithologically, these deposits are

7. Mineral determinations are largely by J. W. Gruner and Lynn Gardiner,
University of Minnesota.
8. Asphalt is defined here in the broad sense - as natural, or native,
brown to black bitumen.

- 17 similar to the carnotite and copper-nranium deposits in the same formations. In many other asphalt deposits of the world, however, noeconomically significant amounts of uranium are present.
The uranium-bearing asphalt deposits in the San Rafael Swell
area of Emery County, Utah, contain uranium in a variety of forms, In
the Temple Mountain deposits on the east flank of the Swell, uraniumand vanadium-bearing asphalt, intimately associated with pyrite, partly

in the form of black powdery corvusite and rauvite (e), cements thegrains of the sandstone and forms replacement masses, In other parts of
the Swells uranium is present in relatively spuren asphalt, althoughsmall amounts of mpper minerals, incluuing seunerite (bb) are associated(9) • The latter is an oxidation product of the uranium-bearing asphalt.
Gypsum is almost universally associated with these deposits,
Uranium-bearing asphaltic sandstone deposits that contain atleast an average of 0.2% U308 have been, and are currently, worked as
economic producers of ore.
traniva-bearing Limestone Deposits
Limestone formations containing commercial ooncentrations ofuranium are relatively rare; however, certain limey phosphatic beds

throughout the world, described in the following section, have been known
for some tine to contain appreciable quantities of uranium.
Uranium-bearing limestone deposits having commercial importanceoccur along the northeast flank of the Zuni Uplift in northeastern
New Mexico. Uranium minerals here are concentrated in irregularly shaped

9• Mineral determinations by J. I. Groner and Lynn Gardiner, Universityof Minnesota.

18

tabular -es, largely in the upper two or three feet of the Todilto
formation of Jurassic age although uranium mineral concentrations
extend downward into lower beds along joints and bedding planes. The
upper beds of this formation, which varies fro* 2 to 20 feet in thickness,consist of massive, compact, coarsely crystalline limestone, and theformation as a whole generally caps benches underlain by the Entrada,
Wingate, and Chinle formations of Jurassic and Triassic age.

Uranophane, carnotite, and tyuyarunite (t) are the mostabundant uranium minerals; sklodowskite (w) and pitchblende occur in local
concentrations. Associated minerals are fluorite, calcite, hematite,goethite, various manganese oxides, and carbonaceous matter (10). PitOhblende„ hematite, and fluorite appear to form small replacement masses in
the limestone, and the pitchblende occurs in ublebs,” as much as 3 mm. ingreatest dimension. intergrown with calcite. Haloes of amorphous
secondary yellow uranium minerals in general . and carnotite and tyqyamunite in particular - appear to be confined to bedding planes, joints,
and other smaller fractures in the rock, and it is these minerals that
contain most of the uranium in the known deposits. The ore in these
deposits, in which there is believed to be promise of considerable tonnage,
averages about 0.2% U308 and 0.]5% V205.
Uranium-bearing Phosphorites

Uranium in significant quantities has been reported in phosphate
deposits of Russia, Morocco, Algeria, Tunisia, and Egypt, in the Phosphoric

10i Mineral determinations by J. W. Gruner and Lynn Gardiner, Universityof Minnesota.

- 19 -

(Permian) formation of Idaho, Montana, and Wyoming, and in the Hawthorne(Miocene) and Bone Valley (Pliocene) formations of central Florida (11).
Becaus6 of this associations the U. S. Geological Survey has been
engaged for some time in investigating all known marine phosphate formations in the United States and an excellent summary of the salient conclusions derived from this work has been presented by McKelvey and
Nelson (12). Some of their significant observations are repeated here.
All marine phosphate formations tested for radioactivity havebeen found to contain significant amounts of uranium. These uraniumbearing phosphates, which range in age from Paleozoic to Cenozoic,

generally contain uranium in proportion to the phosphate contents althoughcertain high-grade phosphate beds are relatively low in uranium and themost uraniferous beds known are not the most phosphatic. The phosphates

are characteristically thin formations, and many are associated with uncon,
formities.
The Phosphoria formations which averages 200 to 500 feet in thickness, contains various mnounts of intermixed phosphate, fine-grained elastic

material, organic matter, carbonates, and chest, even the most *pure"phosphate beds being contaminated with these other materials. An inverse
proportion appears to exist between uranium and carbonate, all samples

assaying 0.01% U308, or more, containing less than 2% CO2.
In Florida, according to Cathcart (13), three types of phosphate

11. Maelvwy, V.F. and Nelson, J.M., Characteristics of marine uraniumbearing sedimentary rocks: Economic Geology, Vol. 45, No. 1, January-

February 1950, p. 40.
12. McKelvey, 14E., and Nelson, J V

en-.E.-. cit., pp. 40-52.

13. Cathcart, James B. Uranium-bearing sedimentary rocks in the land peblie
phosphate deposits of Florida: U. S. Geological Survey Trace Elements

Investigations Report 79 (Confidential), January 1950, 16 pp.

20

deposits are found: the so-called land pebble, hardrock, and river
pebble phosphates. Of these, only the "land pebble" type is marine inorigin and is the only one known to contain significant amounts ofuranium. Phosphate occurs in both the Hawthorne formation (lower middle
Miocene) and the overlying Bone Valley formation (Pliocene) but it is
the latter that includes most of the "land pebble" deposits. Uranium inthe formation is restricted to the high-grade phosphate districts.
Further, the thickest, high-grade, and most uraniferous phosphate deposits
occur in depressions on the old erosional surface of the Hawthorne forma.

tion. Concentration of uranium is greatest in the upper or "leached"sone of the Bone Valley formation and much less in the underlying "matrix"
phosphate, which is the principal source of commercial phosphate. Concentration of uranium in the "leached" sons was partly effected by removalof more soluble material following its apparently syngenetic deposition
from marine waters.
Most of the uranium in known phosphate deposits appears to be in

the minerals fluorapatite or cellophane in which uranium probably replaces
calcium in part. Uranium also undoubtedly is contained in some of theclay minerals of TA4e phosphate deposits and is absorbed in some of theorganic matter. Small amounts of minerals in the torbernite and autunitegroup have bef i identified in some of the phosphate deposits.
Uranium-bearing phosphates that are currently consideredsignificant for possible production of uranium gangs betwee_ ).01 and
0.03% U308 in grade.
Uranium-bearing Black Shales
Comparatively low concentrations of uranium in vast tlnnages ofcarbonaceous and bituminous ahales have been known in many parts of the-21.

world for several decades. According to McKelvey and Nelson (14)uranium in black shale yes first discovered in the alum shale, ofCambrian age, in Sweden in 1893. Since that time, uranium has been discovered a. a progrestively increasiag rate in certain black shales in
Russia, 'Bstonia, Alaska, and throughout broad areas in the central partof continental United States. Many bituminous or carbonaceous rocks are
not uraniferous, however, which suggests that special characteristics
are required in rocks of this type if they are to offer favorable chances
for disccvery of appreciable uranium. The significant uranium-bearing

marine shales are all black or vary dark in color, have a high content
of organic matter and sulfide, are low in carbonate, are relatively thinand thinly bedded, and, so far as known, are mostly pre-Mesozoic in aged
L. C. Conant, R. H. Stewart, and A. B. Keller (15) characterise
the radioactive black shales of the United States as being comparatively

uniform in thickness and composition, but locally containing abnormally
radioactive lenses. The most common constituents are silica, organic
matter or carbon, and clay minerals, with associated pyrite, marcasite,and phosphate. In the United States, the Cht„anooga formation of upper
Devonian-lower Mississippian age is a radioactive black shale leAch is

distributed over wide areas in Tennessee, Kentucky, and adjacent, states,
but is only 5 to 100 feet thick throughout most of its extent. Its mosturaniferous parts are in central Tennessee and southern Kentucky, whore

114. McKelvey, Va., and Nelson, Ja., op. cit., pp. 37-53.
15. Staff Report, Characteristics of radioactive carbonaceous and bituminous
shales: U. S. Geological Survey Trace Elements Investigations Report 78(Confidential), January 1950, 21 pp.

22
thousands of square stiles of the uppermost part of the formation containfrom 0.002 to 0.013% u308 and average 0,008% U308. Formations correlative to the Chattanooga, extending throughout Indiana, Kentucky,
Ohio, Michigan, and New York are less radioactive, but the uranium con.
tent of the rolIghly equivalent Woodford formation of Oklahoma and Kansas
is comparable. Certain black shales of Pennsylvanian age in Alabama,Kansas, and Oklahoma also range from 0,003 to 0.013% in U308 content,
but the average is somewhat less than that of the Chattanooga *ha?:. andthey are not so widely exposed nor so mineable,
The mineralogy of the uraniferous black Shales has not been

completely solved as yet, and no definite uranium minerals are identifiable
in Rost cases. Uranium occurs in the finer grained portions of the rock,and is soluble in acid; it nay be incorporated into the crystal latticesof clay minerals and organic compounds. The exact structural types of clay
minerals and organic compounds favorable to the adsorption of uranium ions
are subjects of continuing research and, when fully deernined, areexpected to constitute valuable guides to uraniferous shale bodies.
The grade of even the most uraniferoum shales described in theforegoing paragraphs is, of course, too law for economic recovery underpresent conditions, Ways and means of utilising the available vast tonnagesof shale are under constant consideration, however, and further explorationof such shales seems warranted, All thin black shale formations of
Paleozoic, and probably pre-Cambrian age, representing periods of stable,
slow sedimentation in shallow seas, are worthy of investigation if theyafford large tonnages and may be mined at low costs.
Alluvial and Placer Deposits
Concentrations of uranium-bearing minerals in alluvial and placer

.23.

deposits are, in general, considered negligible sources of production.
One notable exception to this generality must be pointed out, however, if
one accepts an alluvial origin for the gold (and associated uranium) oresof the Witwatersrand in South Africa. Here, uraninite has been reported
in many parts of the gold reefs, and Bain (16) has indicated that thegrade of large tonnages of these ores is probably on the order of 0.01% 103084)

Elsewhere, however, attempts to recover uranium from minerals
concentrated in alluvial and placer deposits have not, with few exceptions,proved successful. Most uraniferous minerals are not resistant and notamenable, therefore, to concentration by alluvial action. Those that are
amenable--largely the "refractory" radioactive minerals originating in peg.
matites and granitic rocks--are not very high in uranium content and concentrations of them are generally uneconomic.
Lacustrine saline Deposits
A few weak concentrations of secondary uranium minerals occur withsaline minerals in the clays, silts, sands, and ahaley limestoras of former
lake beds. Several such deposits have been described, for example, in thevicinity of Barstow, California. A similar origin has been postulated for
schroeckingerite (r) deposits in the Lost Creek district, near lamsutter,
Sweetwater County, Wyoming. Current studies in this area by the U. S.
Geological Survey, however, indicate that the uranium in the young sedimentsof the Wsmsutter area may have migrated upward from below, along a major
fault, and thus were not originally deposited by lacustrine action. In any
case, uranium deposits of the lacustrine-saline type have not been ore producers and do not appear to offer any significant degree of promise at this time.

16. Bain, George W., Geology of the fissionable materials: Econ. Geol,vol. 45, no. 4, June-July 1950, D. 322.

-

USE OF FIELD INSTRUMENTS FOR RADIATION DETECTION

The simple techniques necessary for the operation ofradiation detection instruments in the field are described in publications by the U. S. Government (17) and (18) and the Halross Instrument
Corporation (19) and (20).
It is necessary, in addition, to consider careftlly the
specific application of radiomet:ic instruments to evaluating theindividual types of uranium deposits described in the foregoing para-graphs. The tendency of many prospectors is to place too much emphasison the reaction of a radiation detecting instrument and to attemptquantitative interpretations of the recorded radioactivity. In general,these instruments are valuable only as qualitative indicators, andgreat care must be used to interpret the dial readings or impulse rates
in the light of the physical environment.
In the examination of vein deposits, radiometric traverses
are commonly required both over surface outcrops and in underground workings, either by Geiger4fueller counters or by scintillation-type instruments.

17. Prospecting for uranium: U. S. Atomic Energy Commission and theU. S. Geological Survey, Washington, 1949, pp. 28-35.
18. Use of the Geiger-Mueller counter for prospecting, U. S. Atomic
Energy Commission, Raw Materials Operations, New York office,May 16, 1950.
19. Operating Instructions - Model 939 Scintillometer, Halross
Instruments Corp., Ltd., Winnipeg, Manitoba.
20. Procedures of Geologic Surveys - Preliminary, Halross Instruments
Corp., Ltd., Winnipeg, Manitoba.

-25The fact that veins generally have steep attitudes, of course, causes
the anomalous areas, where intersected by nearly horizontal planes of
erosion, to be very narrow (on the order of 2 or 3 feet) and linear
in dimension. In addition, the spotty distribution of pitchblendecreates a highly discontinuous anomaly pattern along the strike of avein. Moreover, on the surface, a few feet of overburden mask theradioactivity. All of these factors tend to localize markedly the radioactivity detectable from uranium-bearing veins. Underground traverses
with detection instruments away from the radioactive veins yield somewhat lower background readings than on the surface, but in drifts along
the veins, the readings are generally higher and more uniform due toredistribution of the uranium by ground waters and the precipitationof secondary uranium minerals on the mine walls. As a general rule,
when the probe of the instriu►pnt is held adjacent to pitchblendebearing vein material, counts on the order of at least 30 times background are to be expected.
The use of radiation detecting instruments in examining .nd
evaluating carnotite deposits is perhaps somewhat less important thanin most other types, because of the distinctive yellow color of the ore.
Here the visual identification of the uranium-bearing mineral is a relatively reliable guide although other yellowish minerals, such as jarosite$
mar be confused with it. Most carnotite deposits are in relatively flatlying sandstone beds exposed on the rims of plateau cliffs. Although
the ore bodies as a whole are erratic in size and dimension, the distribution of the carnotite within the mineralized beds is relatively
uniform, and counts an the order of at least 20 times background arerecorded consistently along the truncations of the ore beds when the probe- 26 -

is held within an inch or two of the outcrop. The behavior of radiation
detection instruments in the examination of uranium-bearing asphalt
deposits is very similar to that observed at carnotite deposits, andtypical are beds 2 or 3 feet thick generally give counts of 5 to 20
times background.
The erratic distribution of uranium in the copper-uranium
deposits and common departures from radioactive equilibrium createa special problem in evaluating this type of deposit in the field by
the use of counters or scintillometers. Any quantitative interpretationmust rely on chemical analyses of carefully collected channel samples
and no conclusions as to the grade of a copper-uranium deposit canreliably be based on results obtained with a field radiation detecting
instrument.
In the field examination of sedimentary formations such as
phosphates, black shales, or lacustrine deposits, in which low-grade concentrations of uranium are relatively evenly distributed, counters andscintillometers are fairly reliable. Only the ordinary precautions ofconsidering background counts and the geometry of the scanning operations
need to be taken, and by standardizing the radiometric surveying procedures employed,even rough quantitative approximations can be achieved.
SUGGESTED SAMPLING PROCEDURES AND THE
EVALUATION OF URANIUM ORE BODIESThe mineralogic and structural nature of the various types ofuranium ore bodies described in the foregoing paragraphs has a definite

bearing, of course, on the most reliable sampling procedures and otherimportant factors in the proper evaluation of the deposits. Experience27
to date has shown that certain general procedures should be strongly

recommended in each of the various types of uranium deposits.
Uranium concentrations in primary vein deposits are soerratic and variable that, to obtain even an approximation of thegrade of an ore body, careful channel sampling across mineable widths atleast every three or four feet is essential. In complex vein systems,

especially where the pitchblende is very fine-grained and intimately
associated with sulfides, it is necessary in many properties to obtainbulk samples of several hundred pounds to get a true grade figure.
The tonnages of ores must be calculated as increments in smiaJl blocks

along the closely sampled segments of the veins. In general the orebodies are relatively small and closely controlled by the structure of
the veins, and their shape can be rather sharply defined. Thus, meaningful
estimates of tonnage and grade are especially difficult to obtain inprimary vein deposits without prior geologic mapping and close sampling.

Carnotite deposits, characterized by erratic distribution
and irregular shtpel offer special problems in the estimation of tonnage.

Experience on the Colorado Plateau has shown that close-spaced drillingis commonly the only reliable method of obtaining the three-dimensional
shape of ore bodies, and hence their tonnage. Grade figures are, in
general, less erratic than in the vein-type and the copper-uranium deposits,
and in many instances p.verage grade figures, obtained by channel sampling,hold rather uniformly for large ore bodies. Special studies of the relationships between the ore bodies and the lithology of the sediments

and structure of ancient channelways are most helpful in outlining carnotite

- 28 -

ore bodies. The problems of sampling and evaluation in uraniferous
asphaltic sandstone bodies are generally similar to those in carnotit9
ore bodies.
It has been pointed out that the general geologic environmentof the typical copper-uranium deposits is also similar to that ofcarnotite deposits. Their mineraloeic character, however, leads tospecial problems in sampling ane evaluation. In many of the de?osits,
oxidation and repeated solution and redistribution of uranium cause
disequilibrium of radioactivity as well as highly erratic distribution.
In addition, leaching action near the oxidized rim outcrops tends to indicate deceptively low grade for the ore body as a whole. Thus bulk
sampling and chemical assays of mineralized rock, not only at the surface
but also in relatively unoxidized portions of the ore bodies, are essential.
Erratic distribution of uranium is also characteristic in thephosphorite deposits, particularly in the "leached zone" of the Bone
'Paley formation in Florida. Hence, close channel sampling is also necessary in the evaluation of deposits of this type. In general, however,a satisfactory correlation between radiometric and chemical assays canbe established and rapid radiometric assaying is adequate for the bulkof the samples.
In lacustrine deposits, the typical uranium minerals are perhaps
more soluble, in general, than in any other type of deposit and hence theirsampling and evaluation is proportionately difficult. The action of surface and ground waters may even alter the loci of uranium concentrations
and the percentage of uranium content from year to year. This migrationof "ore bodies" constitutes a significant factor in the evaluation of these
deposits in general, and partly because of their unreliable behavior, they
have not yet been considered economic sources of uranium.

-29 -TABLE I. COMMON URANIUM MINERALSBLACK MINERALS

Name

ChemicalComposition

Lustera) Uraninite(also grayish,
greenish, brownish)

Mixture UO2 and UO3 Glassy, dull,with varying percen- submetallic
tages of lead, combined rare-.earths
and thorium.

b) PitchblendeSame as uraninite.
Less than 1.5%
combined rareearths and thorium.

of Brannerite(usually altered
to brawn)

Fluores«
hard- Specificcence ness gravity

Fracture
andCleavage

None

5e6

Pitehlike,
dull

None

5-6
(Variable)

Oxide of uranium
and titanium withminor calcium, rareearths, thorium, andiron. (40-90% u308).

Vitreous

None

4-5

4-5i
(variable)

Conchoidald) Thucholite(also brownish
blank)

Hydrocarbon anduranium.

Dull, pitchy

None

3-4

2

Conchoidale)Rauvite(also purple)

Hydrous calciumuranium vanadate;(up to 3l U306).

Dull

None

Soft

Davidite

See Brown Minerals

Samarskite

See Brown Minerals

Euxenite-colycraae

Seo Brown Minerals

Pyrochlore-miorolite See Brown Minerals

Uneven, subconchoidal

6-8

CrystalSystem

Habit

Isometric

Octahedral, clabic, massive

Pegmatites
veins

In thin slivers or powdered, always black or
greenish-black, almost
new brownish cr reddish as are the rareearth columbo-tantalates.
Also =re radioactive
than rare-earth columbotantalates. Isomerphole with thorianite.

Botryoidal surfaces, banded, massive; as blebs insulphides and quarts; as
extremely fine-grained powder intimately associatedwith other minerals especially copper sulphides
and hydrocarbons.

In veins withsulphides; insedimentaryrocks.

The term pitchblendeis applied to lcwthorium vein material
assooiated with basemetal sulphides.

Prismatic crystals;
rounded grains.

In placers, withcobalt and nickel
sulphides; inpegmatites.

Coal-like; irregularnodules.

In pegmatites,
veins, and asphaltic sedimentary rocks.

Possibly a mixture ofuraninite and hydrocarbon. Will tern.

Powdery masses; botryoidel; massive.

Cementing material in sandstone.

Possibly a mixture oftwo minerals.

Uneven. subconchoidal

BrittleMonoclinic

Colloidal

Mode ofOccurrence

Remarks

BROWN MINERALS

Name

ChemicalComposition

LusterFluoresoonce

Hardnese

Specific
gravity

Fracture andCleavage

CrystalSystem4-6(variable)

Conchoidal touneven.

Tetragonal

Rough prismatic crystals;
radiating groups.

In pegmatites;
lees commonlyin plaoers.

In thin slivers or powdered, brownish or reddish, not black or green
like pitchblende. Usual.
ly coated with buff topinkish earthy clay-likematerial.

Conchoidal

Orthorhombic

Massive; rough prismatic
crystals.

Pegmatites;
less commonlyin placers.

In thin slivers or powdered, brownish or reddish, not black or green
like pitohblende. Resembles euxenite,

Conchoidal

Ortnorhombic

Massive; less commonly
stout prismatic crystals.

Pegmatitea;
less commonlyin placers.

In thin slivers or powdered, brownish or reddish, not black or green
like pitchblende. Resembles samarekite.

Hal--itMode ofOccurrence

Remarksf)Fergusoniteformanite(Dark brown to
black with reddish
cast, "liver brawn")

Oxides and columbates
and tantalates of yttrium group withvariable amounts ofuranium, thorium, calcium, iron, titanium
and water (up to S
U308).

GlassyNone5-6g)Samarakite(Dark brown to bleckwith reddish cast,"liver brawn").

Oxides and columbates
and tantalates of theyttrium group withvariable amounts ofuranium, thorium, calcium and iron (up to
2C1 U306.

Glassy
when
fresh

None

5-6

h)Euxenite-polyorase(Dark brawn to blackwith reddish cast,"liver brawn").

Oxide, and columbates,
Glassytantalates and titanwhen
atea of the yttrium
fresh
group with variable
amounts of uranium,
thorium and rare-earthsof the cerium group (upto l7% U308).

Nonei)Pyrochlore-miorolite(colorless, yellow,
red, green, black).

Complex oxides of columbium, tantalum, sodium and calcium withhydroxyl and fluorine(up to l5% U308).

Glassyorresinous

None

5-6

4-6
(variable)

Conchoidal, uneven, splintery,brittle.

Isometric

Octahedral crystals; small
grains; irregular masses
imbedded in otherminerals.

In pegmatites,
syenites, limestones. Often
associated withlithium or fluorine minerals.

Darker shades characteristic of pyrcchlore.

j)Davidite(also black)Fe0.3TiOp. (Theoretical rormula, up
to 10% U30e).

Glassy,.
submetallic

None

5-6

41
(variable)

Subconchoidal
to uneven.

Hexagonal(?)

Massive, irregular clusters; large crystals.

Pegmatites andin mafic rocks
associated withlater felsic
mineralization.

Usually moderately magnetic with the band
magnet.

k) Uvanite

Hydrous uranium vanedate (up to 40% 0308).

PearlyNone

Two cleavage
directions.

Orthorhombic

Granular earthy masses or
crystals showing two pineooidal cleavages.

In sandstone
with asphalt.

GummiteSee Orange Minerals

Uraninite

See

Brannerite

See Black Minerals

MonaziteSee Yellow Minerals

Black Minerals

5-7

4-6
(variable)

4-6(variable)

YELLOW MIMENALS
FluoresHard- Specific Fraoture andCleavagecone. nese gravity

Luster1) Beoquerelite(also brownish
yellow)2005.3H20(questionable)

Adamantine
to resinous

None(?)

2-3

4.96-5.68 (001) perfect(101) distinct

Orthorhombic Minute tabular crystals;
polysynthetic twinning

An alteration
A rare also:el.
product of uraninite. ocaurringwith secondary
uranium minerals.

m) Sohoepite

4UO3.9020(H20 variable)

Adamantine

Yellow..
green(?)

2-3

4.83-4.96 (001) perfect

Orthorhombic Tabular cr short prismatic crystals oommonly
containing inclusions.

An alteration
product of urani.
nits, occurringwith secondary
uranium minerals.

n)Autunite(lemon-yellow toapple-green)

Hydrated osicium
uranium phosphate.
Theoretical formula'
Ca0.2CO3.P205.12B20(meta variety carries
8H20).

2-3
Pearly, sub- Always
adamantine
brilliantyellow or
green onfresh surfaces.

3.05-3.19 (001) perfect

Orthorhombic Basal tablets or micaceous(pseudotetren- masses with rectangularoutline, foliated.
onal)

Associated with
A common uranium mineraluraninite, gum- always of secondary ori•
mite. uranophene. gin. isomorphous withand uraniferous
uranaspinite in which
oolumhatess inarsenic subetitutes foroxidised sone of phosphorus*. the meta
most uranium
variety is more a moon.
deposits.

o)Monazite(also brown)(Ce.La,3d,POPO4 (upto 269 Th02 and 0.4%

Resinousp)Johannite(also green)(Cu.Peptia2)0.UO3.
SC5.4820

Vitreousq)Troegerite

31103.As205.12B20(H20 variable)

Pearly Weak(?) 2-3

Theoretical Formulas
3CaO.NaF.UO3.3CO2.

PearlyNone

4.6-5.3

2-3

3.3-3.9 (001) and (oil)r)Sohroeokingerite

sopluo.

s) Carnotite

Theoretical Formulas.2003.V205.1-3
H2°

3.3

Usuallyearthy.
crystalsarepearlyBright yel2-3
lowish
green

None

2-3

2.51

ikenarta.110•10110

Flattened crystals;
rounded grains.

Placers; an somisery constituent in !skinigneous rooks.

Triennia

Minute lath-like crystals;
polysynthetic twinning almost invariably present;in druses and reniform
masses.

Occurs withseoondary uranium minerals.

Two cleavages atright angles.

Monoclinic(?) Thin tabular crystals re(Pseudotetrasr sembling gypsum.
onal)With secondary
minerals including erythrite.

A rare aineral.

Perfect basal
cleavage.

Crthorhombic Small, rounded masses con
posed of aggregates offlaky crystals; pseudohexagonal micaceous plates.

Rounded masses
distributed in
gypsum-bearing
sandy clay; as
coatings in decomposed igneousrooks.

M., •••••10,

Orthorhombic Earthy, thin coatings,
oryptoorystalline masses.

Cementing agent
in sandstones,
associated withfossil logs andbones in Colorado Plateau ores.

distinct(variable

Habit

Monoclinic(100) distinct,
conohoidal

u308)

None

(001) perfect

5-5i

CrystalSystemMode of
Deourrenoe

ChemicalComposition

Name(001) perfect4(variable) cleavage

Not a commercial sourceof uranium.

.160. 4000

Color sometimes dulled
or oonosaled by organicand iron staining; insuch oases, pole greenish or brownish tinge.

-32 -YELLOW MINERALS - cont'd

Name
t)

Tyuyamunite

ChemicalComposition
Theoretical formulas
Ca0.2UO3.V205.n1120

LusterUsuallyearthy,c”ystela are
pearly andadamantine

Fluorescanoe

Hardnests

None,rarelyweak

2-3

Specific
gravity
3-4(variable)

Fracture andCleavage

CrystalSystemHabit

Mode of
Oocurrenceaemarks(001) perfect(010)(100)distinct

Orthorhombic

Earthy, cryptocrystalline masses, scales

Cementing agent insandstones, associated with fossil logs
and hones in Colorado
Plateau ores.

Analogous to carnotite
with calcium substitutin; for potassium.
Difficult to distinguishfrom carnotite.

u) Beta uranotil(also orange,
yellow, green)

Ca0.21302.2Si02.6H20

Pearly2-3

3.95(010) perfect(100) distinct

Monoclinic

Velvety radial aggregates,prismatic andacicular crystals.
Zonal growth and twinning common.

An alteration productof uraninite and gum.
mite.

A rare mineral. Limorphoomwith uranophane.

v)

5UO3.2.02.6820

Dull,
pearly3-4

1!.63

Two directions (?)

Orthorhombic

Minute prismatic andpyramidal crystals.

Intimately associatedwith secondary uranium
minerals.

A rare mineral.

w) Sklodawakite

Mg0.2'J01.2Si02.7H20.
ig sometimes partially replaced by Cu toform cuprosklodowskite.

Vitreous,
pearly2-3

3.54-3.74(130) and (110)perfect

Orthorhombic

Minute prismatic toacicular crystals
grouped in radial aggregates; also feltlike coatings.

Occurs with secondary
uranium minerals.

x) Uranophane(also pale green
and pale orange)

cao.2u03.2si02 .6112o

Pearly,greasy2-3

3.81-3.90(100) good

Orthorhomic

Minute acicular prisms
in radial or stellate
aggregates; less commonly massive and fibrous.

In veins, pegmatites
and granites.

Soddyite

GummiteSee Orange Minerals

Zippeite

See Orange Minerals

Pyrcohlore-micr,lite

See Brown Minerals

Uvanit,,See Brawn Minerals

Fergusoniteformanite

See Brown Minerals

None or
very
faint
green

A oommon uranium mineral.
An alteration rroduct of
gu:maite, uraninite or otheruranium minerals. Commonly associated with othersecondary uranium minerals.
Dimorphous witt betauranotil.

- 33 -

ORANGE MINERALS
ChemicalComposition

Lustery) Gummite(also red andyellow)

1303.nH20; contains
Pb, Ca, Ba, Si, P, Mn,
Fe (up to about 7C
D3Ce and 20% Th02)

Waxy, dull, Nonegreasy, cm..
oasionally
vitreouss) Zippeite

2UO3.S03.BE20(?)

Earthy,vitreous

Name

Beta uranotil

FluoresHard. Specificcane nese gravity
Variable

Brilliant 2-3
green

3*
Variable

Fracture andCleavage
Conehoidal tounevenCrystalSystemHabit

Mode ofOccurrence

Remarks

Dense and massive, some- An alteration product Common. Gummite is some•times pseudomorphs.
of uraninite and pitch. times consideree a genericblends.
ter% fcr many alteration
prolucts of urtninite.

(010) perfect Monoolinio(?) Earthy or powdery, inminute lath-shaped
crystals.

An alteration productof pitchblende and asa ooating in asphaltic
sandstones.

•••••••••See Yellow Minerals

GREEN MINERALS
aa)
Torbernite

Cu0.2UO3.P205.12520(meta variety carries
8/120)

Pearly, sub- None or 2-21
&clementine. veryfaint3.2-3.6

Square tablets, basal(001) perfect Orthorhombic(100) distinct (pseudotetrag- plates, micaceous
onal)masses.

With other uranium
minerals, especiallythose associated with
ooppar minerals.

Zeunerite

Cu0.21703.A.205.121120(meta variety carries
HBO)

Pearly,vitreous

2-3

3.2-3.3(001) perfect(100) good

Tabular (001) crystals
Orthorhombic(pseudotetrag- resembling torbernite,square tablets, mional)
caceous masses.

A secondary mineralwith other uranium
minerals, especiallyassociated with arsenic minerals.

AutuniteSee Yellow Minerals

Johannite

See Yellow Mineralsbb)

1D OF DOCUMENT

None orvery
faint

A oommon supergene
mineral. Meta variety
is more common.