Reconnaissance Study 

of Uranium Deposits 

in the Red Desert 

Sweetwater County 

Wyoming

GEOLOGICAL SURVEY BULLETIN 1030-1

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission 

of the Commission

Reconnaissance Study 

of Uranium Deposits 

in the Red Desert 

Sweetwater County 

Wyoming

By DONALD G. WYANT, WILLIAM N. SHARP, and DOUGLAS M. SHERIDAN

CONTRIBUTIONS TO \ THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-1

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission 

of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington 25, D. C.
CONTENTS

	Page 

Abstract______._________________--______-_____ 237

Introduction __ ______________ __ __________ _ 238

Purpose of the investigation.___ _ _ __ 239

Field work and acknowledgments _ __. ____ _ 239

Previous work._ __._ _____________ _____________ ___ 239

Location and physiography __________ ____________ ______ 240

Accessibility_____________________.___._________ 240

General geology 241

Sedimentary rocks- _ ____________________ __ ___ 241

Igneous rocks______ _________________ _________ ___ 242

Structure______________ _ _ _ _ _. 242

Geologic history 243

Radioactivity.--.-- __ __________________________ ____ 244

Uranium deposits 245

Uraniferous lignite. _________________________________ _ 246

Distribution______________________________ 246

Geology_________________________________ 248

Radioactivity.-- ________________________ _ ______ 250

Origin______.__ ..________.____________-_ 253

Lost Creek schroeckingerite deposit______________________ 254

Location and history _ ______________ ____ 254

Geologic setting. _______ ________ _________ ______ 256

Mineralogy _______ ___ _________ _.__-. 260

Schroeckingerite_______________________________ 260

Other uranium minerals._________________________ 262

Ore bodies___________._____________._____.- 263

Grade_________.._____________________... 264

Auger-testing program of 1950__ __ 265

Sampling and logging procedures__________________-_____ 266

Geologic results.._______________________ 267

Distribution of uranium____________________________ 268

Origin___________________________________ 272

Aids to prospecting______________________________________ 274

Future outlook__________________________________ 275

Literature cited.._______________________________ 276

Stratigraphic sections.. . _________ ___ _ _ 277

Analyses....______________________________________________ 283

Auger-hole data.____________________________________________ 288

Index________________________________________ 307

m
IV CONTENTS 

ILLUSTRATIONS

[All plates In pocket]

PLATE 16. Reconnaissance geology of part of the Red Desert, Wyo.

17. Geology along line of flight.

18. Columnar sections 1-9, Red Desert, Wyo.

19. Geologic map and sections, Lost Creek schroeckingerite 

deposit.

20. Geologic sections in five trenches, Lost Creek schroeckingerite 

deposit.

21. Assays with proposed exploration, Lost Creek schroeckingerite 

deposit.

22. Geologic section C-C' (pi. 21), Lost Creek schroeckingerite 

deposit,

23. Geologic sections with sample assays, Lost Creek schroeckingerite deposit. 

FIGURE 55. Diagrammatic representation of accepted interpretations of

relations of Wasatch, Green River, and Bridger formations Page 

(after Nace)____.._._________.___-_____ 241

56. Section of lignite bed 1, Sourdough Butte, Great Divide

Basin (from Slaughter and Nelson)___________________ 247

57. Records of gamma radiation obtained from carborne and airborne counters (from Stead)_______ -___ 251

TABLES

Page 

TABLE 1. Comparison of radioactivity measurements, Red Desert,Wyo_ 245

2. Summary of paleontologic data, Red Desert, Wyo______ 249

3. Analyses of material other than lignite, carbonaceous shale,

schroeckingerite, or water, Red Desert, Wyo_____________ 283

4. Analyses of water samples (ppm), Red Desert, Wyo__-___._ 283

5. Spectrographic analyses (in percent), of uraniferous lignite,

Red Desert, Wyo____________________________ 284

6. Analyses of radioactive lignite, carbonaceous shale, clinker,

and ash, Red Desert, Wyo_______________----- 284

7. Analyses of rock samples, Lost Creek schroeckingerite deposit. 285

8. Analyses of surface- or ground-water samples, Lost Creek

schroeckingerite deposit_______-___--_---_--_---_------ 287

9. Analyses of plant and soil samples, Lost Creek schroeckingerite deposit __..___-____________________________ 287

10. Lithology of cuttings from shallow auger holes drilled by the 

U. S. Geological Survey, in 1949, Lost Creek schroeckingerite 

deposit______________________________ 288

11. Lithology, content of equivalent uranium and uranium of 

cuttings, and radioactivity of cuttings and wall rocks in 

auger holes ES-1 ES-13 (pi. 21), drilled by the U, S. 

Geological Survey in 1950, Lost Creek schroeckingerite 

deposit______________.___,________-_ 289

12. Comparison of analyses (in percent) of 6 samples prepared by

2 different methods, Lost Creek schroeckingerite deposit. __ 269
CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

RECONNAISSANCE STUDY OF URANIUM DEPOSITS IN 

THE RED DESERT, SWEETWATER COUNTY, WYOMING

By DONALD G. WYANT, WILLIAM N. SHARP, and 

DOUGLAS M. SHERIDAN

ABSTRACT

The largest known deposit of schroeckingerite, a secondary uranium mineral, 

and uraniferous lignite occur in part of the Red Desert, north of Wamsutter, in 

northeastern Sweetwater County, Wyoming. Schroeckingerite was discovered on 

Lost Creek, 38 miles north of Wamsutter in 1936, and lignite between Lost Creek 

and Wamsutter was found to be uraniferous in 1945. It may be possible to produce uranium from the schroeckingerite deposit economically, but the outlook 

for commercial exploitation of the uraniferous lignite is at present uncertain.

An area of 650 square miles in the Red Desert of the Great Divide Basin was 

studied in reconnaissance in 1949 by a'combination of photogeologic and field 

methods, and radioactivity was measured on the ground and from the air. Part of 

the area known to be underlain by uraniferous lignite was mapped in detail, and 

columnar sections were measured to determine, approximately, the stratigraphic 

relation of uraniferous lignite in the southern part of the area to the schroeckingerite-bearing beds in the Lost Creek deposit. The deposit was mapped in detail 

and in 1950 was tested by auger drilling.

The surface rocks in the Red Desert are intertonguing beds of sandstone, claystone, lignite, oil shale, and arkose of the Wasatch, Green River, and Bridger 

formations and the Continental Peak formation of Nace (1939), all of Eocene age, 

and shale, derived from volcanic ash, of the Chadron formation of Oligocene(?) 

age as defined by Nace (1939). Several units of the Green River formation are 

the only Eocene rocks whose formation may be identified readily. The Tertiary 

rocks are covered in part by Pleistocene lake and stream terrace deposits. Most 

of the rocks in the Red Desert are abnormally radioactive.

The topographic feature, Great Divide Basin, is a structural bowl with a few 

subsidiary, broad, gentle folds. In the northern part of the basin the Cyclone 

Rim fault zone trends northwestward and separates nearly horizontal beds to the 

south from folded beds to the north; stratigraphic displacement of beds is 400 to 

700 feet downward pn the southwestern side of the fault zone.

Three main uraniferous lignite beds, each about 10 feet thick and separated by 

45-80 feet of sandstone and claystone, crop out in the southern part of the Red 

Desert. A fourth bed, postulated from drill cuttings, probably underlies the 

three main beds. Unweathered lignite is glossy black, and thin bedded. The 

uranium content of the lignite beds ranges from 0.002 to 0.007 percent. The 

average ash content of the lignite is about 38 percent and the ash contains from

237
238 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

0.004 to 0.022 percent uranium. The uranium in all lignite outcrops is not in 

radioactive equilibrium, probably because some of the uranium originally present 

has been leached from the outcrop. The time and mode of introduction of 

uranium in the lignite, as well as the source of uranium, remain problems. Data 

gathered during this investigation suggest that uranium was present in the 

decaying vegetal matter before it was coalified. More recent studies, in other 

areas, suggest that uranum in coal may^beaepigenetic.

The Lost Creek schroeckingerite deposit is within the Cyclone Rim fault zone 

north of the outcrops of uraniferous lignite. A bed of such lignite, however, 

probably underlies the deposit at a depth of a few hundred feet. Within the fault 

zone, the beds strike northwestward and dip about 20° NE. Schroeckingerite 

is a water-soluble, fluorescent, bright yellow-green uranium salt. Minerals, other 

than detrital quartz and feldspar, that are commonly associated with schroeckingerite are clay, gypsum, aragonite, opal, and efflorescent white salts. Schroeckingerite characteristically occurs in the Lost Creek deposit as round pelletal 

aggregates, as disseminated flakes, or as thin layers. The layers commonly coat 

the ground surface and the flakes are commonly in beds of sandstone. The pellets, 

concentrations of which constitute ore bodies, are distributed irregularly but 

appear to be localized most abundantly in five principal beds of finer-grained 

rocks, shale, claystone, or siltstone (of Eocene age); these beds are separated by 

as much as 100 feet of virtually nonuraniferous sandstone and arkose. Ore 

bodies are about 1 foot thick and extend as much as 35 feet down the dip of the 

beds and a maximum of more than 300 feet along the strike. The uranium content 

ranges from 0.013 to 0.28 percent.

Sandstone adjacent to ore-bearing shale beds, and some of the shale, are commonly stained red, maroon, or orange by iron oxides. Such iron-stained zones 

containing weakly radioactive fluorescent opal and other minerals, as well as nonfluorescent uranium minerals (or uraniferous clay aggregates) were found in auger 

cuttings from beneath the water table. Schroeckingerite, however, has been 

found only above the water table and to a maximum depth of 8 feet beneath the 

ground surface. The water underlying the deposit is slightly alkaline (pH of 

about 8) and contains an abnormal amount of uranium (0.01 to 46.0 parts per 

million).

Schroeckingerite crystallizes near the surface from ascending alkaline ground 

water, preferentially in moist claystone, shale, or in siltstone beds; the process 

differs genetically from deposition of caliche only in the quasi-stratigraphic control. The source of the uranium is not certain. It is possible that uranium, 

transported by ascending ground water circulating within the Cyclone Rim fault 

zone, and derived from uraniferous lignite, may have been deposited above the 

low water table prevailing at times in the Pleistocene epoch; later the rise of the 

water table may have caused the uranium mineral to be dissolved, transported, 

and recrystallized as schroeckingerite. Schroeckingerite may now be forming 

from migrating ground water at about the same rate that it is being dissolved and 

removed by surface water.

Further geologic and exploratory work on the uranium deposits in the Red 

Desert will be done.

INTRODUCTION

PURPOSE OF THE INVESTIGATION

Uranium-bearing sediments at Lost Creek in the Red Desert north 

of Wamsutter, Wyo., were first described by Larsen and Gonyer 

(1937). During subsequent investigations of the deposit, now termed 

the Lost Creek schroeckingerite deposit, A. L. Slaughter and J. M.
URANIUM IN THE RED DESERT, WYOMING 239

Nelson (unpublished report, 1946) found uranium-bearing lignite and 

shale. The U. S. Geological Survey made a reconnaissance study of 

the Ked Desert area hi 1949 to appraise the uranium resources of the 

area, and to accumulate data concerning the geology of uranium and 

the genesis of schroeckingerite and of uraniferous lignite, and to outline further work. It is hoped that this report will provide a framework for the reports of more detailed studies made in the area, and 

will stimulate additional discussion of the genesis of the deposits.

FIELD WORK AND ACKNOWLEDGMENTS

During about 6 weeks in the summer of 1949, a planetable map of 

the Lost Creek schroeckingerite deposit and several detailed sections 

were prepared; a geologic and ground radioactivity map was made of 

a small area to serve as a control for airborne radioactivity measurements; samples and radioactivity data were gathered from a large 

part of the area; nine key stratigraphic sections were measured; 

fossils were collected; and a general geologic reconnaissance was made. 

Aerial photographs were used hi the field. In the office, uncontrolled 

planimetric base maps were made from the aerial photographs, and 

the geology was compiled on the maps from field notes and from 

office study of the photographs. From October to December 1950, 

preliminary auger testing was carried out at the schroeckingerite 

deposit by the Geological Survey, the results of which, although 

preliminary to more thorough testing, are incorporated in this report.

The work was done on behalf of the Division of Raw Materials of 

the U. S. Atomic Energy Commission. Samples were analyzed by 

the U. S. Geological Survey. The writers are indebted to Walter 

Byron, president of Uranium Inc., the lease holders; the late Mrs. 

Minnie McCormick, who discovered the schroeckingerite deposit; 

Kleber Hadsell, and Gasper Meyer, residents of the area; L. T. Hart, 

Carter Oil Co.; and R. L. Kretz, Bell Petroleum Co., for their courtesy 

and cooperation.

PREVIOUS WORE

No general account of the geology of the area described in this 

report has been published. The geology of some parts of the area, 

and of bordering areas, has been described by many workers, some 

of whose publications are cited hi the list of references (Blackwelder, 

1915; Bradley, 1926, 1928, and 1945; Dobbin and others, 1927; Fath 

and Moulton, 1924; Kemp andfKnight, 1903; Nace, 1939; Schultz, 

1909; Sears and Bradley, 1923; Smith, 1909; Westgate and Branson, 

1913).

LOCATION AND PHYSIOGRAPHY

The Red Desert, hi northeastern Sweetwater County, is hi the 

central part of the Great Divide Basin, a topographic basin of interior
240 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

drainage that occupies about 4,000 square miles on the divide between 

the Colorado and Missouri River watersheds. The basin is bounded 

on the north by the Green Mountains, the Granite Mountains, and 

the Antelope Hills; on the east by the Rawlins Uplift; on the south by 

the Laney Rim and the Sierra Madre Range; and on the west by the 

Rock Springs uplift. The basin is on the eastern margin of the 

larger Green River Basin. About 650 square miles hi the northcentral part of the Great Divide Basin, a part of the Red Desert, 

was mapped during the investigation by reconnaissance methods. 

The Red Desert is an area of low relief where the altitude ranges 

between 6,000 and 6,600 feet. Its name refers to the red soil that 

mantles its southwestern part (Fenneman, p. 143, 1931). The 

principal topographic features are the low hills between Wamsutter 

and Chain Lakes; the broad depressions occupied by Chain Lakes 

and Lost Creek Dry Lake; the bluffs northwest of Lost Creek DryLake; and the escarpment of Cyclone Rim (pis. 1 and 2).

The climate is semiarid, and the vegetation accordingly consists 

largely of low-growing greasewood (Sarcobatus sp.), sagebrush (Artemisia tridentata), saltbush (Atriplex sp.), and some prairie grasses and 

herbs. The Red Desert is in the heart of Wyoming's sheep country; 

consequently the natural water supply, consisting of a few springs 

and permanent streams, has been augmented by several wells.

ACCESSIBILITY

Many trails or roads crisscross the Red Desert. The main-traveled 

road heads north from Wamsutter to the Sweetwater River through 

Crook's Gap in the Green Mountains. In places it is graded. From 

the Lost Creek schroeckingerite deposit fair roads lead east to Bairoil 

and northwest to Atlantic City. Ordinary vehicles may be used on 

all the roads, but they should be driven with caution hi the sand-dune 

country near Lost Creek Dry Lake, and throughout the area after 

rains. The nearest supply point is Wamsutter, at the southern edge 

of the Red Desert, 40 miles west of Rawlins and 68 miles east of Rock 

Springs on U. S. Highway 30 and the Union Pacific Railroad.

GENERAL, GEOLOGY 

SEDIMENTARY BOCKS

The Red Desert is underlain largely by Tertiary sedimentary rocks 

(pi. 16). Most are Eocene rocks, of the same general type as those 

in the Green River Basin, which are more readily separated and are 

better known. In the Red Desert these rocks are predominantly 

fluviatile conglomerate, sandstone, siltstone, and claystone, with subordinate beds of lignite, all typical of the Wasatch and Bridger formations, and lacustrine shale, typical of the Green River formation.
URANIUM IN THE RED DESERT, WYOMING 241

Cropping out in a smaller area are younger fluviatile conglomerate and 

tuffaceous sandstone and claystone typical of parts of the Continental 

Peak formation of Nace (1939).

The Eocene rock units are all lenticular and interfinger with one 

another (Bradley, 1926, 1945; Nace, 1939). Figure 55 illustrates 

diagrammatically their relationships. Although these formations and 

members can be readily distinguished northwest of the Red Desert, 

they can be traced only with difficulty into this area, because the 

rocks are similar and the exposures are poor. Accordingly, and 

because of lack of time, the units were not mapped. Shale of Green 

River type, however, is so characteristic of the formation that such 

rock was mapped as lenses of the Green River formation. The area 

includes the eastern limits of several lenses of these shale-strata of the 

Green River formation. The gradation between Green River-type 

shale, and green claystone and sandstone characteristic of the Wasatch 

formation may be seen along the bluffs west of Lost Creek, and about 

2 miles northeast of Eagles Nest (center of the mapped area on pi. 16). 

In the excavation for the sump at the site of the California-Wyoming 

Development Co. oil well (4% miles north of Eagles nest, pi. 16), 8 feet 

or more of shale of the Green River formation is well exposed. Farther 

north, at the schroeckingerite deposit, several thin shale beds ranging 

in thickness from 0.2 to 5 feet are exposed in trenches.

Although formations were not delineated and stratigraphic correlations with formations outside of the area mapped in reconnaissance 

have not been attempted in this report, Bradley has traced from the 

west the Tipton tongue of the Green River formation and the overlying Cathedral Bluffs tongue of the Wasatch formation to within 

about 12 miles west of the exposures of the Green River shown on 

plate 16 north and west of Lost Creek Dry Lake (Bradley, W. H., 

written communication). Also, Nace (1939, p. 25) observed exposures 

of his Continental Peak formation within the Cyclone Rim at Lost 

Creek.

Hiawatha member 

Main body of Wasatch formation, cool bearing

FIGUEE 55. Diagrammatic representation of accepted interpretations of relations ofWasatch, Green River,

and Bridger formations (after Nace). 

388177 57 2
242 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Tentative geologic correlations of the Eocene rocks within the 

Red Desert are shown on plate 18 and are described under the heading 

Stratigraphic sections. As shown on plate 18, an attempt was made 

to correlate the beds in the vicinity of the schroeckingerite deposit, 

on the northeast side of the Cyclone Rim fault zone, with the lignite 

beds south of Chain Lakes. A detailed correlation was not possible, 

owing both to the distances between the measured sections and to poor 

exposures, but the approximate relations of the rocks throughout the 

area are shown.

The youngest Tertiary rocks are light-colored shale containing 

volcanic ash, sandstone, conglomerate, and limestone of the Chadron 

formation of Oligocene(?) age of Nace's usage (Nace 1939). These 

rocks crop out in the northwestern part of the area. They have been 

mapped by Nace to the west of the area shown on plate 16.1 The 

Chadron formation unconformably overlies undifferentiated rocks of 

the Continental Peak formation of Nace (1939) and the Bridger, 

Green River, and Wasatch formations, all of Eocene age.

The thickness of the Tertiary section is probably about 2,000 feet. 

The Eocene rocks west and east of the mapped area rest conformably 

on the Paleocene Tongue River member of the Fort Union formation, 

which in turn rests unconformably on folded Cretaceous and Paleozoic 

rocks. North and northwest of the Red Desert the Tertiary rocks 

rest directly upon the Precambrian and Paleozoic "basement complex" of the Granite and Sweetwater Mountains.

Overlying the Tertiary rocks are Pleistocene and Recent fluviatile, 

lacustrine, eolian, colluvial, and alluvial sediments, which portray a 

complex physiographic history. Conspicuous features of the area 

are the broad depressions formerly occupied by Pleistocene lakes and,, 

the terrace deposits bordering Recent and Pleistocene streams.

IGNEOUS BOCKS

Igneous rocks are not exposed within the Red Desert but the 

volcanic ash content of some beds of the Bridger, Continental Peak 

of Nace (1939), and Chadron formations indicate considerable volcanic activity during their deposition. The well-known lava flows 

and associated intrusive alkalic igneous rocks of the Leucite Hills 

are about 30 miles northwest of Lost Creek Dry Lake.

STRUCTURE

Structurally, most of the area is a relatively simple basin, the 

approximate center of which is Lost Creek Dry Lake. Broad, shallow

> Subsequent to the present work, more detailed mapping in the area was done, 1951-1954 by Harold 

Masursky and Q. N. Pipiringos. Their work indicates that the Chadron formation of Nace's usage (Nace, 

1939) and as shown on plate 16 may include the Brown's Park(?) formation of late Miocene or early Pliocene 

age. If so, the beds labeled Chadron ( Toe) on plate 16 may be a part of the Brown's Park, and true Chadron 

may either be missing, or be present in the Cyclone Rim but included in the strata mapped under the symbol 

Ten as undifferentiated formations of Tertiary age.
URANIUM IN THE RED DESERT, WYOMING 243

folds modify this simple structure; some faults displace the beds in 

Monument Dry Lake.

Relatively intense folding is restricted to the area north of the 

Cyclone Rim. The Rim marks a zone of en-echelon faulting, the 

Cyclone Rim fault zone, a major structural feature of the Red Desert, 

that extends at least 10 miles northwestward, and perhaps farther, both 

to the northwest and the southeast. Apparent stratigraphic displacement along the fault zone is about 400 feet downward on the 

southwest side and may be as much as 700 feet. The fault zone may 

be a high-angle thrust with movement upward on the northeast side, 

but more exploratory work at the schroeckingerite deposit will undoubtedly contribute more detailed information about the faulting. 

Some of the anticlines north of the Cyclone Rim were drilled by oil 

companies, but no records show production of oil or gas in the mapped 

area.

GEOLOGIC HISTORY

Throughout the early part of the Eocene epoch, sediments were 

carried into the area by streams from the surrounding lands to form 

the Wasatch formation. During the first stage of deposition of the 

formation, plant material accumulated in some swamps or bogs to 

form thick lignite beds. Later, intermittent fresh-water lakes were 

formed. The eastern margins of some were approximately along a 

line extending northward from Chain Lakes to a point about 2 miles 

east of the Lost Creek schroeckingerite deposit (pi. 16). In the lakes 

fine-grained sediments rich hi organic matter accumulated to form 

the oil-rich shale and fresh-water limestone of the Green River formation that are interlayered with the fluviatile sediments of the Wasatch 

formation. In middle Eocene time, streams deposited grit, sand, and 

clay to form the Bridger formation. These fluviatile sediments were 

eroded, then streams deposited a sequence of tuff and tuffaceous 

sands, the Continental Peak formation of Nace (Nace, 1939). The 

strata formed by consolidation of all these sediments were tilted, 

faulted, eroded, and hi Oligocene(?) time covered by the conglomerate, 

ash, and fresh-water limestone of the Chadron formation of Nace's 

usage (Nace, 1939). Before deposition of the Chadron, the Cyclone 

Rim fault zone was formed.2 The Miocene and Pliocene epochs, 

although possibly represented by part of the Chadron formation as 

used by Nace (Nace, 1939) were probably largely epochs of erosion 

and nondeposition in the area of the Red Desert.

In Pleistocene .time, a large amount of water flowed south from 

Lost Creek, past the site of Wamsutter and out of the Great Divide 

Basin, through a former stream channel that extends to the southwest

* More recent work of Masursky and Pipiringos suggests that faulting along the Cyclone Rim fault zone 

may have taken place before deposition of sediments of the Brown's Park(?) formation (of Miocene or Pliocene age) that are included with the Chadron fonnatlon in this report, and, possibly, after deposition of the 

tow Chadron formation of Oligoeene age (if missing in the area) Jn adjacent areas.
244 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

from the vicinity of the schroeckingerite deposit. The main channel 

of this Pleistocene stream is just beyond the west edge of the area 

shown on plate 16 and is easily recognized along U. S. Highway 30 

about 7 miles west of Wamsutter. Either because of a decrease in the 

amount of water in late Pleistocene time, or because of local structural 

warping, or due to both causes, drainage out of the area ceased and 

large lakes were formed in the basins, whose centers are now occupied 

by small lakes or playas. These former lakes are called, in this 

report, Pleistocene Lost Lake, Pleistocene Chain Lakes (lower and 

upper), and Pleistocene Monument Lake. Stream terraces were cut 

along Lost Creek; the highest terrace above the creek probably was 

cut at the time of the largest expansion of Pleistocene Lost Lake. 

The abrupt change in width of the terrace deposit along Lost Creek 

at its junction with the Cyclone Rim fault zone suggests there may 

have been renewed faulting in the area in late Pleistocene tune, but the 

widening may be the result of other causes. The Pleistocene lake 

basins gradually are being filled with debris washed in from the 

surrounding highlands and from the Tertiary sediments traversed by 

the streams. This debris is being modified by wind action.

RADIOACTIVITY

Uraniferous sediments are widespread within the Red Desert. 

The average radioactivity of rocks in the area is greater than is 

common for sediments. . As an example, sample DW-102 (S:295), 

(mud and silt) from the center of Lost Creek Dry Lake, contains 0.003 

percent equivalent uranium 3 and 0.002 percent uranium. Evans 

and Goodman (1941) give for terrestrial sediments other than limestone, a uranium content of 1.3 gm per ton (0.00013 percent).

Radioactivity data were obtained with (a) hand-carried GeigerMueller counters and (b) an instrument composed of two 40-inch 

gamma-probes coupled to a car-mounted circuit, or from (c) analyses 

in the laboratory of the samples collected at the outcrop.

Radioactivity measured at several outcrops with both the handcarried and the car-mounted Geiger-Mueller counters was compared 

with the equivalent-uranium content, determined in the laboratory, 

of samples taken from the same outcrops. The comparison established an approximate correlation among the different instruments 

used, and allowed the transformation of field radioactivity measurements to estimated percent equivalent uranium. Although the 

figures for estimated percent equivalent uranium plotted on the maps 

are not quantitatively accurate, they do indicate correctly, orders of

* Equivalent uranium is a measure of the total amount of radioactivity emitted by the sample, and is 

expressed as if all the radioactivity were due solely to uranium in equilibrium with the products in its disintegration series. The radioactivity of all radioactive substances, such as thorium, potassium (K<»), or 

uranium would, therefore, be included as the percent equivalent uranium, if they were present. The 

equivalent-uranium content of these samples was determined by Geiger-Mueller counters in the laboratory.
URANIUM IN THE RED DESERT, WYOMING 245

magnitude. It was not feasible during reconnaissance work to collect samples at every station. The correlation among methods used 

in measuring radioactivity is summarized in table 1. More than 150 

observations were made in the area either with the car-mounted 

instrument or with the hand-carried meters. Forty-three samples 

were taken for analysis. Tables 3 and 4 include the laboratory 

analyses of materials other than lignite, carbonaceous shale, or 

schroeckingerite ore.

TABLE 1. Comparison of radioactivity measurements, Red Desert, Wyo.

Laboratory 

analysis 

equivalent 

uranium 

(percent)

0.014 

0.013 

0.012 

0.010 

0.009 

0.008 

0.007 

0.006 

0.005

Average readings on carborne 

Geiger-Mueller 

counter 

(meter units)

15.5 

15.0 

14.0 

13.0 

12.0 

11.0 

10.0 

9.0 

9.0

Average readings on handcarried counter 

(meter units)

17 

14 

11 

10 

9 

8 

7 

5 

5

Most of the material sampled in addition to lignite and schroeckingerite-bearing rock is abnormally radioactive but contains little 

uranium (tables 3 and 4). Pebbles of fluorescent chert collected 

from a wide area northwest of the Lost Creek schroeckingerite deposit, contain as much as 0.010 percent equivalent uranium and 0.006 

percent uranium. A. L. Slaughter and J. M. Nelson (unpublished 

report, 1946) also collected from the general area pebbles of fluorescent chert that contain 0.030 percent equivalent uranium. They 

examined the Leucite Hills, 30 miles to the west of the area shown on 

plate 17, and reported that some of the pumice beneath one flow of 

leucite-rich lava contained an estimated 0.007 percent equivalent 

 uranium.

Gypsiferous sandstone and sandy claystone collected at Arapahoe 

Creek contained as much as 0.006 percent equivalent uranium, and 

a maximum of 0.003 percent uranium,

A large quantity of the material in the immediate vicinity of the 

shroeckingerite deposit contains as much as 0.010 percent uranium.

On the road about 3 miles northeast of Eagles Nest the carborne 

Geiger-Mueller counter indicated a slight increase in radioactivity 

above the green claystone and red sandstone that grade laterally 

into shale lentils of the Green River formation.

URANIUM DEPOSITS

Most of the beds in the area mapped'in the Red Desert are more 

than normally radioactive but contain too little uranium to be of
246 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

economic significance. The beds of radioactive lignite and the 

schroeckingerite-bearing sediments, which contain the most uranium, 

may, however, be of economic significance.

UBANIFEROUS LIGNITE

In 1945, during a reconnaissance examination, A. L. Slaughter and 

J. M. Nelson found that some beds of lignite and carbonaceous shale 

in the Red Desert were abnormally radioactive. They took samples 

for analysis and measured one exposure of lignite (unpublished report, 

1946). They observed that radioactivity was greater hi the interbedded carbonaceous shales than hi the adjacent lignite, and chemical 

analyses showed that the equivalent-uranium content was greater 

than the uranium content. Samples taken by them of the more 

radioactive lignite and shale beds contained from 0.010 to 0.015 percent equivalent uranium and from 0.002 to 0.004 percent uranium. 

A columnar section made by them on the west end of Sourdough 

Butte (see pis. 16 and 17) is given in figure 56.

DISTRIBUTION

The area examined in reconnaissance in 1949 in which radioactive 

lignites crop out is shown on plate 17. It extends northward from a 

point about 9 miles north of Wamsutter to the ridge of High Point, 

south of Chain Lakes a distance of 11 miles. The maximum width 

of the area mapped containing radioactive lignites is about 7 miles, 

although the beds extend beyond the limits of this area. Thin beds 

of lignite are present between Wamsutter and the area studied, but 

they are not appreciably radioactive. They may be stratigraphically 

higher than the more radioactive beds.

Lignite also is exposed along U. S. Highway 30 between Rawlins 

and Wamsutter. Many of the exposures were examined by Slaughter 

and Nelson who found only one bed of appreciably radioactive clinker; 

their sample of this bed contained 0.012 percent equivalent uranium 

and 0.004 percent uranium. Smith's map (1909, pi. 12) shows about 

200 square miles of the Red Desert underlain by lignite. This 

area extends well beyond that shown on plates 16 and 17.

Radioactive lignite also was observed (1) in the bluffs west of Lost 

Creek Dry Lake, (2) in cuttings from the sludge pit of a water well 

drilled at the site of the California-Wyoming Development Co. oil 

well, and (3) at Coal Bank dam about 7 miles north of the Lost Creek 

schroeckingerite deposit. Although the maximum extent of the radioactive lignite is unknown, such lignite probably underlies most of the 

area shown on plates 16 and 17, and some beds certainly extend 

beyond it to the east and to the west.
URANIUM IN THE EED DESERT, WYOMING 247

Radioactivity and 

uranium content

25 20 15 10 5

Description

-4,

Sandstone, yellow to buff, very fine-grained

Shale, brown to gray, fissile

0-8 ps^ 7 Shale, gray to dark-gray, hackly to fissile

8

Coal, fissile; brown shale in part 

Shale, gray, hackly to fissile 

Coal, fissile

Shale, gray, hackly, fissile in part, yellow-brown stains; separated into 

lenticular parts by thin coal seams

Coal, shaly, fissile

10

Shale, dark-gray to black, fissile; thin coaly layers; gypsum in thin 

layers in bedding

Coal

Shale, dark-gray to black

Coal, shaly, fissile

Shale, gray to black, partly fissile; gypsum

Coal, shaly, fissile

Shale, dark-gray to light-gray, clayey, hackly

Coal, shaly, fissile

Shale, gray, hackly, jointed, yellow stains on joints, darker and more 

fissile in part, soft, clayey; gypsum

12

M 13

Coal, fissile and shaly in part; yellow stains and coatings along bedding; 

gypsum, selenite

Shale, black, fissile

14 Shale, dark-brown, clayey

Base of section not exposed

EXPLANATION

Radioactivity determined by outcrop test

Approximate radioactivity, determined by testing (in field) 

crushed rock, expressed in thousandths of percent 

equivalent uranium; not determined for all samples

Uranium content, determined by chemical analysis 

expressed in thousandths of percent

4 Feet Measured and sampled by A. L. Slaughter 

and John M. Nelson, 1946

FIQUBB 56. Section of lignite bed 1, Sourdough Butte, Great Divide Basin, Sweetwater County, Wyo.
248 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGY

Three prominent zones containing alternating layers of lignite and 

carbonaceous shale have been mapped (pi. 17). These zones are 

designated as lignite beds in this report, and are referred to as lignite 

beds 1, 2, and 3, numbered in ascending stratigraphic order. Cuttings of radioactive lignite from shotholes drilled for seismic surveys 

indicate that another bed underlies bed 1 on the east edge of Pleistocene Monument Lake (pi. 17), but outcrops of this lower bed were 

not observed in the map area.

The radioactive lignite beds are probably early Eocene in age and 

may be correlated with part of the Wasatch formation. Plant fossils 

were collected from partly baked claystone underlying lignite bed 1 

at the south side of Sourdough Butte. They were examined by R. 

W. Brown, who determined their age to be early or middle Eocene 

and tentatively correlated the rocks with the Eocene of Yellowstone 

Park. Gastropod and pelecypod fossils were collected at a point 

about 1% miles southeast of No Name well (pi. 16) from a bed of 

calcareous sandstone about 55 feet stratigraphically above lignite bed 

3 and shown^as fossilliferous zone F-9 on columnar section 5 of plate 

18 (see also stratigraphic section 5, p. 280). They were examined by 

T. C. Yen, who determined their age as early Eocene and correlated 

the sandstone with a part of the Wasatch formation. Fossils of 

similar types were collected from other beds of calcareous sandstone 

about 60 feet higher stratigraphically than the bed in which zone F 

9 occurs and at a point 0.8 of a^mile^northeast of No^Name well 

(fossiliferous zone F-6 and F-7 on columnar section 4 of plate 18 

and stratigraphic section 4, p. 279). Mr. Yen determined their age as 

late early Eocene and tentatively correlated these sandstone beds 

with the upper part of the Wasatch formation. These paleontologic 

data are summarized in table 2.

As shown in columnar sections 1, 2, and 3 of plate 18 and stratigraphic sections 1-3, (p. 277) the stratigraphic interval between lignite 

beds 1 and 2 is about 80 feet, and that between beds 2 and 3 is about 

45 feet. The stratigraphic interval between bed 1 and the bed that 

is assumed to underly it is not definitely known, but is estimated to 

be about 100 feet. The total stratigraphic interval that contains the 

principal beds of known radioactive lignite is, therefore, about 225 feet.

The lignite beds are interbedded with gray, buff, drab, or white, 

micaceous arkosic sands tone, silty sandstone, and calcareous sandstone; 

brown, gray, or green plastic claystone; and platy carbonaceous shale. 

Details of lithology of the rocks are shown in the columnar sections 

(pi. 18 and fig. 56) and detailed descriptions are given under the heading Stratigraphic sections.

The lignite beds themselves are composed of black vitreous lignite 

seams from about one-sixteenth to one-half inch thick, interbedded
URANIUM IN THE RED DESERT, WYOMING 249

with dark-brown or gray fissile carbonaceous shale layers of similar 

thickness. The thickness of lignite beds 1 and 2 ranges from^about 

2.5 to 20 feet; the average in each is about 10 feet. Bed 3 ranges in 

thickness from about 1 to 6 feet and^averages about 2 feet in^thickness.

TABLE 2. Summary of paleontologic data, Red Desert, Wyo. 

[Identification, age, and correlation of mollusks by T...C.!Yen and of plants by R. W. Brown]]

Fossiliferous 

zone 

(reference 

no. on pis. 

16 and 21)

F-6._ -

F-8. _____

F-8-. __ . 

F-9. _ . _ -

F 1A

F-11... - -

JBR-1... 

JBR-2.......

JBR-3. ..

JBR-4... .

JBR-5. 

JBR-6,. ._

JBR-7. .

Columnar 

section 

(PL 18)

4

4

4

5

6

7

(2)

7

9

9

9

(0

(6)

Fossils

Vivlparus paludinaeformis

(Hall).

Viviparus paludinaeformis 

(Hall).

Physa cf. P. pleuromatis White. . 

Viviparus cf. V. paludinaeformis 

(Hall).

Viviparus cf. V. paludinaeformis 

(Hall).

(Meek).

Unioct. U. wasatchmsis CockerelL

Goniobasis cf. G. carterii (Conrad).

identifiable. 

Equisetumsp ..... ...............

Asplenium magnum Knowlton.. 

Smilax lamarensis Knowlton _

leaves.

Pisidlum sp. undet. ] 

Viviparus sp. undet. 1 (poorly 

Goniobasis sp. undet. (preserved)

Menetus sp. undet. J 

Goniobasis cf. G. nodulifera 

(Meek).

Lymnaea cf. L. stmilis Meek ....

Goniobasis cf. G. nodulifera 

(Meek).

Australorbis cf. A. spectabilis 

(Meek).

determinable.)

Australorb is sp. undet. _. .....

Hayden).

Probable age

Early Eocene.

.... do.... ..

Late early EoEarly EoceneEarly to mid

Possibly EoEocene -- 

.... do.........

Middle Eocene.

Probable correlation

Upper part of the Wasatch

formation.

Do.

Do.

Part of the Wasatch formaUpper part of the Wasatch 

or lower part of the Bridger

is possibly equivalent to 

JBE-4 below).

Eocene of Yellowstone NaNone (habitat area was 

probably shallow and still

water).

Upper part of the Wasatch 

or lower part of the Bridger

formation. 

Upper part of the Wasatch

or lower part of the Bridger 

formation (the collection is

above).

1 Qoniobasis arcta (Meek) was originally described from the Bridger formation in southwest Wyoming. 

8 No columnar section measured, Sourdough Butte, lignite bed 1.

* This would be lower Bridger of Nace.

4 No columnar section measured, on Lost Creek at Chalk Banks.

 No columnar section measured, Bridger formation of Nace, from north side of Continental Peak, Sweetwater County.

388177 57 3
250 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The proportion of shale to lignite varies from place to place in each 

lignite bed, but in general the lignite is of poor quality for use as fuel. 

Locally, as in bed 1 on Hign Point Ridge (southeast corner of the 

mapped area on pi. 16) and in bed 3 west of the mouth of Sourdough 

Creek (sample WNS-13 (S:18)), the lignite is free from clay. As 

noted in table 6, sample WNS-13 (S:18) contains only 9.1 percent 

ash. Considerable but variable amounts of gypsum occur in the lignite beds. No marcasite was observed. An appreciable amount of 

silicon and iron, and small amounts of magnesium, boron, titanium, 

zinc, calcium, barium, cerium, and lanthanum were found by spectrographic*analysis of some of the lignite samples (table 5).

Some of the lignite beds have been burned at the outcrop. The 

burning has converted the shale and lignite to clinker and to ash, 

respectively, and has baked the sediments above and below for a few 

inches or a few feet. As observed by the senior author in North 

Dakota, this burning takes place only if the lignite is relatively close 

to the surface and about 5 feet or more thick. In the Red Desert 

many of the outcrops of lignite have been burned back for a short 

distance. These beds of clinker and ash are not delineated on the 

maps because they occupy only local areas (pi. 17), but some of these 

areas are listed below:

(1) Bed 2(?) east of the road on the north side of anticline at Monument 

Lake.

(2) Bed 1 along the north side of Pleistocene Monument Lake.

(3) Bed 1 northwest of Sourdough Butte.

(4) Bed 3 for a short distance east of the mouth of Sourdough Canyon.

RADIOACTIVITY

The amount of radioactivity of the lignite beds is indicated on 

plates 16 and 17. A. L. Slaughter and J. M. Nelson (unpublished report, 1946) found that radioactivity is not confined to the lignite 

seams; the interbedded layers of carbonaceous shale are also radioactive. For this reason, evaluation of the radioactivity of only the 

lignite seams, requires additional samples. Composite samples of 

the entire lignite bed were generally taken, in order to obtain a measure 

of the total radioactivity information required in the experimental 

airborne survey. Treated as units, the lignite beds provide radioactivity meter-readings at their best outcrop (pi. 17) that range from 

a fraction to more than six times the local background. When using 

the car-mounted Geiger-Mueller counter an increase in counting rate 

is easily discernible in crossing radioactive lignite beds, or the ash and 

clinker formed by the natural burning of the lignite beds. For example, in driving over the small outlier of lignite bed 2, half a mile 

east of the road intersections on High Point Ridge (pis. 16 and 17), 

the meter readings increase from about 9.5 scale divisions over the
URANIUM IN THE RED DESERT, WYOMING 251

sandstone on either side, to about 11.5 scale divisions directly over 

the small area of lignite.

Airborne equipment was successful in detecting the radioactive 

lignite beds. The test flights, methods, equipment, and results are 

given by F. W. Stead (unpublished report, 1949) and Nelson and 

others (1951) and will not be given here. Radioactivity measurements obtained by carborne and airborne Geiger-Mueller traverses 

and the geology are shown on figure 57. The intensity of the radioactivity varies from bed to bed, and over long distances along the 

strike, but in general is remarkably constant in all beds.

10

Note: Arrow indicates 

direction of flight

ACTIVITY AT 250 FEET

ACTIVITY AT GROUND LEVEL

GEOLOGY ALONG FLIGHT LINE 

10 3 Miles

FIGURE 57. Records of gamma radiation obtained from carborne and airborne counters.
252 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Analyses of samples of lignite, carbonaceous shale, clinker, and ash 

from the flight-strip area over which the airborne equipment was used 

are shown in table 6.

Samples of lignite contain from 0.002 to 0.015 percent equivalent 

uranium and from 0.002 to 0.007 percent uranium. Most of these 

samples are composite samples of an entire bed and therefore include 

clay from interbedded carbonaceous shale. The combustion of lignite 

to an ash is a possible approach to the commercial production of 

uranium. Sample WNS-13 (S:18), representing 6 feet of highquality lignite with very little interbedded shale, produced ash containing 0.015 percent uranium, as compared to the 0.002 percent 

uranium contained in the original material.

Isolated outcrops of radioactive lignite and paper-thin shale, in 

part burned to clinker, were found about 1% miles north of the northwest corner of Lost Creek Dry Lake. Radioactivity measurements 

at the outcrop suggest that the partly burned material contains about 

0.006 percent equivalent uranium. This bed of radioactive lignite was 

mapped by Smith (1909, pi. 12).

Equilibrium status. A sample of uraniferous rock in which radioactive equilibrium exists should contain as much uranium as equivalent 

uranium, unless elements of other radioactive series such as the thorium 

series are also present. Judged by the radioactivity of some samples 

not in radioactive equilibrium (table 6 and pi. 17), some of the lignites 

once contained more uranium than is indicated by the equivalenturanium (eU) content, or else disintegration products (principally 

radium) have concentrated in the lignite. Analytical work by the 

Geological Survey has demonstrated that radioactive equilibrium 

noted in analyses of the samples is caused by an abnormal radium-touranium ratio; there is about 60 percent more radium than needed for 

the equilibrium ratio (John Rosholt, written communication).

The measured radioactivity of sample WNS-4 (S :5) is equivalent to 

a uranium content of 0.015 percent, on the assumption that uranium is 

in equilibrium with its disintegration products. Chemical analysis, 

however, shows that it contains only 0.003 percent uranium. Because 

in this arid environment uranium salts are relatively soluble in comparison to radium salts (sulfate, chloride, and carbonate), it may be 

presumed that much of the uranium and its preradium disintegration 

products have been leached out. If this is true, material of the sample, 

before leaching, would have contained more uranium than the 0.015 

percent suggested by the equivalent-uranium content. Specifically, 

a uranium content of 0.026 percent would be required to give the 

observed radioactivity, if uranium and all its disintegration products 

were present and in equilibrium.

The simple calculations as evidence for this statement are shown 

below:
URANIUM IN THE RED DESERT, WYOMING 253

0.003X0.40=0.0012 Percent equivalent'uranium due to uranium 

and its preradium disintegration products

0.015 0.0012=0.0138 Percent equivalent uranium due to radium 

and its disintegration products

0.0138-5-0.60=0.023 Percent uranium necessary for equilibrium 

with 0.0138 percent radium, and its disintegration products

0.023+0.003=0.026 Total percent uranium necessary for equilibrium

Sample WNS-17 (S:23), consisting of fragments of lignite, carbonaceous shale, and admixed surface debris, was picked from the sludge 

and cuttings of other rocks that accumulated in the sump during the 

drilling of a water well at the site of the California-Wyoming Development Co. oil well. This sample contained 0.011 percent equivalent 

uranium and 0.012 percent uranium. After burning in the laboratory, 

it contained 73.7 percent ash and 0.014 percent uranium in the ash. 

The sample, although small and impure, demonstrates that beneath 

the surface at this locality radioactive lignite contains uranium 

essentially in equilibrium with its daughter elements. The high ash 

content, due largely to extraneous surface debris, suggests that 

samples of the lignite free from such diluting material may contain 

appreciably more uranium.

ORIGIN

The process by whiqh uranium accumulated in uraniferous lignite 

is not known, but two alternative suggestions have been made: (1) 

uranium is syngenetic, that is, it was carried by ground and surface 

water into the swamps in which plants and plant debris were accumulating, and was fixed before coalification either by absorption in 

the tissues of live plants or by absorption or adsorption, or by chemical 

reaction with, the carbon and organic material of plant debris; or, (2) 

uranium is epigenetic, that is, it was leached from overlying source 

rocks, such as beds of volcanic ash, by ground or surface water and 

carried down to be precipitated in or be adsorbed by lignite (Tolmachev, 1943).

In support of the epigenetic origin ofjuranium in coal, N. M. 

Densen, G. O. Bachman, and H. D. Zeller (unpublished report, 1950) 

have observed that (1) beds of uraniferous lignite in North and South 

Dakota occur in several formations, but only in those underlying 

Oligocene rocks and only those beds of lignite nearest the unconformity at the base of the Oligocene rocks are uraniferous; (2) uranium 

is concentrated near certain fractures and near the tops of the lignite 

beds; and (3) lignite beneath relatively impermeable strata generally 

contains less uranium than lignite beneath relatively permeable 

strata. They believe the source of the uranium to be volcanic ash in 

the White River formation of Oligocene age.

In the Red Desert and surrounding region in Wyoming there are 

rocks derived from volcanic ash (parts of the Bridger, Continental
254 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Peak of Nace (1939), Chadron, and Brown's Park(?) formations of 

Eocene, Oligocene(?), and Miocene or Pliocene age), and also slightly 

radioactive igneous rocks (the rocks of the Leucite Hills).

The theory of epigenetic origin of the uranium in the lignite beds of 

the Red Desert is, on the other hand, difficult to accept for the following reasons:

1. At the outcrop some of the lignite apparently has been subject 

to leaching (see analyses of samples, table 6), and has lost part of its 

uranium content. If we assume an epigenetic origin for the uranium, 

as outlined above, it is difficult to understand how the leaching could 

have taken place; the lignite of the outcrops should be enriched, 

rather than impoverished, in uranium.

2. Lignite buried about 100 feet beneath impervious shale in 

Monument Dry Lake, and beneath as much as 300-500 feet of 

impermeable shale and other Eocene rocks at the site of the CaliforniaWyoming Development Co. oil well, is uraniferous. If the uranium 

is epigenetic in origin, the lignite at these localities should not be 

uraniferous, because water carrying uranium could not percolate 

down through the shale. The lignite at the site of the oil well has 

apparently not been leached of its uranium content, as is indicated 

by the equilibrium relationship.

3. The radioactivity of the lignite beds is remarkably uniform along 

strike; no marked change in radioactivity was observed for 10 miles 

or more from High Point Ridge to Monument Dry Lake (pi. 17); the 

uranium content, however, is not uniform, a fact which could be 

attributed to differential leaching.

4. The evidence listed in support of an epigenetic mode of origin 

may be interpreted in several other ways; for example, in other types 

of uranium deposits secondary uranium minerals are commonly 

concentrated along fractures.

5. Autoradiographs of hard vitreous coal indicate a uniform 

distribution of radioactive material, a distribution difficult to explain 

by processes other than syngenetie processes.

It is the writers' opinion, therefore, that available evidence supports 

a syngenetie or at least pre-coalification origin for the uraniferous 

lignite beds hi the Red Desert. However, a more thorough study of 

the region and of the physical chemistry of uranium and carbonaceous 

material is required before any theory of origin may be considered 

as demonstrated.

LOST CREEK SCHROECKINQERITE DEPOSIT 

LOCATION AND HISTORY

The Lost Creek schroeckingerite deposit (pis. 19 and 21) is 38 miles 

north of Wamsutter (index map, pi. 16) on the east side of Lost Creek, 

near the Kleber Hadsell shearing pens and cabin. The deposit is in
URANIUM IN THE RED DESERT, WYOMING 255

sees. 30 and 31, T. 26 N., R. 94 W., sixth principal meridian, and 

may be reached from Wamsutter, the nearest railroad station, by 

traveling 43 miles on a graded desert road.

The country surrounding the deposit, which occupies a broad open 

valley, is relatively flat but slopes gently southward. A mile north 

of the deposit a series of northwest-trending ridges rises a hundred 

feet or more above the general land surface. Farther west, these 

ridges are as much as 500 feet above the general land surface and form 

the Cyclone Rim escarpment. About 13 miles north of the deposit 

the Green Mountains and Antelope Hills form the northern rim of 

the Great Divide Basin.

Lost Creek rises in the Green Mountains, but a few intermittent 

streams from the east are tributary to it. It drains into Lost Creek 

Dry Lake when in flood, but is seasonally intermittent below the 

schroeckingerite deposit.

The schroeckingerite deposit was discovered in 1936 by the late 

Mrs. Minnie McCormick. The deposit is covered by the placer mining 

claims, Golden Arrow Nos. 1 to 9, filed by the late Mrs. Minnie 

McCormick and her associates, Louis A. McCormick, Mrs. Mabel 

A. McVae, Mrs. Emma J. Eversole, Mrs. Laura E. A. McCargar, 

Kleber H. Hadsell, and Tom W. Whelan. Since the time of filing, 

C. A. Brimmer has been added to the list of owners. The property 

was leased with option to buy in January 1948 to Uranium Inc., 

Denver Colo., whose president is Walter Byron, and whose members 

include K. W. Robinson, R. D. Charlton, and Robert Swanson, also 

of Denver.

Many geologic examinations of the deposit have been made: (Knight 

and Gilbert, 1937 4 ; Dake, 1938; Harder and Wyant, unpublished 

report, 1944; Guillotte, G. B., unpublished report, 1945; Slaughter 

and Nelson, unpublished report, 1946; C. C. Towle, unpublished 

report, 1948; and D. G. Wyant, unpublished report, 1949).

The exploration work at the deposit carried out for Uranium Inc., 

hy the Minerals Engineering Co. in 1948 consisted of about 3,900 

feet of trenches, 13 pits, a few bulldozer cuts, and many auger holes. 

The average maximum depth reached in this exploration was about 

5 feet beneath the surface, but most of the excavations were caved 

or filled by surface wash before the summer of 1949.

The field work in 1949 was done by D. G. Wyant, W. N. Sharp, 

and H. L. Bauer, Jr.; in 1950, D. M. Sheridan carried out the prelimary deeper auger testing. During about 2% weeks in 1949, a 

planetable map and geologic sections of some of the trenches were 

made, and 39 shallow auger holes were bored. During about 8 weeks 

in 1950, 13 deeper auger holes, totaling 397 feet, were bored and 208 

samples were taken for analysis.

* The geologic occurrence, chemical composition, and optical properties of a new uranium mineral: unpublished paper presentedjbefore[the'chemistry section of the Am. Assoc. Adv. Sci, at Denver. Oolo.j
256 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGIC SETTINO

The Lost Creek deposit, the largest deposit of schroeckingerite 

now known, is located within the Cyclone Rim fault zone, in an area 

predominantly of Wasatch-type green claystone, arkosic sandstone, 

and grit, and subordinately of thin interbeds of Green River-type 

platy shale. The Bridger formation and the Continental Peak formation of Nace (1939) are also possibly represented. The deposit is 

made up of several thin, irregular tabular mineralized bodies either 

in beds of platy shale of the Green River formation at their contact 

with beds of sandstone of Wasatch type, or in gray-green silty claystone of Wasatch type. These beds have been folded, faulted, eroded, 

and covered by successive terrace deposits of Pleistocene to Recent 

gravel, silt, alluvium, and colluvium. The Pleistocene terrace deposits 

shown on plate 19 indicate at least two periods of terrace formation. 

The older, or upper terrace surface, is probably continuous along 

Lost Creek to a point where it leads into the delta-fan of Pleistocene 

Lost Lake in the vicinity of Eagles Nest.

About 1% miles north of the deposit, near Soda Lake (pi. 16), the 

northeast-dipping Eocene strata are overlain unconformably by the 

Oligocene(?) Chadron formation of Nace's usage (Nace, 1939, 

pp. 31-35).

Lithology. The deposit is very near the eastern margin of several 

thin tongues or lentils of the Green River formation and presumably, 

therefore, near the former fluctuating margin of one of the Eocene 

Green River lakes. Shale of the Green River formation ranging in 

thickness from 0.1 foot to about 30 feet, is exposed in units d and h of 

outcrop A (pi. 19), in the principal mineralized bodies (for example, in 

pit 8 and trench L), and in the bluff of Lost Creek. Plate 20 illustrates 

the repetition of the shale strata of the Green River at different 

stratigraphic positions in the trenches. Many of these thin beds are 

contorted, and weather to curved plates. In these beds ostracods 

were observed 60 feet east of the northeast corner of the Hadsell 

shearing pen (outcrop (a), pi. 19), and from them fragments of 

vertebrate fossils were collected (unit h, outcrop A, pi. 19).

Outcrops are sparse. The lithology of most outcrops is summarized in the following paragraphs. In outcrop A, west of the road 

fork in the south-central part of the mapped area, nine lithologic 

units are exposed: unit a is brown claystone containing some white 

sandstone; unit b is gray-green platy shale; unit c is white coarsegrained arkosic sandstone that is in fault contact with units d and e, 

which are respectively shale of the Green River and blocky gray 

shale (the sandstone is stained orange brown along the fault); unit/ is 

white coarse-grained sandstone, stained orange brown by iron oxides 

along its upper contact with unit g, a dark-brown claystone; unit h 

is brown shale of the Green River containing a few vertebrate fossils;
URANIUM IN THE RED DESERT, WYOMING 257

and unit i is gray-green claystone and gypsiferous sandstone, partly 

obscured by colluvium.

Outcrop B, shown near the center of the north edge of the mapped 

area, includes six stratigraphic units: unit a is light-green clayey 

sandstone; unit b is green gypsiferous claystone containing schroeckingerite; unit c is white-weathering brown conglomerate; unit d is 

green claystone and some sandstone, containing schroeckingerite 

pellets and gypsum; unit e is gray-green silty gypsiferous claystone; 

and unit/ is arkosic conglomerate and green silty gypsiferous claystone 

that contains large pellets of schroeckingerite.

Outcrop C, west of outcrop B, is composed of 2 units: a, whiteweathering brown sandstone, and 6, medium-grained green sandstone 

and some claystone. Outcrop D, north of the HadseU shearing shed, 

exposes brown claystone but may also include some shale of Green 

River type.

In addition to these outcrops, 8 outcrops too small to delineate as 

areas but plotted as points on plate 4 are as follows:

Outcrop (a), near the Hadsell shearing shed, contains platy brown 

shale of the Green River; in outcrop (6), near outcrop (a), green 

sandstone is exposed; outcrop (c), at the creek bank by the bridge, 

consists of green claystone in which pellets and flakes of schroeckingerite are concentrated in an irregular zone 2 inches*thick adjacent 

to an overlying iron-stained solution zone in sandstone; outcrop (d), 

about 400 feet northeast of the bridge, exposes green-gray claystone 

containing schroeckingerite pellets; outcrop (e), north of Osborne 

Draw, exposes gray- and maroon-mottled claystone; outcrop (/), near 

outcrop (e), contains green, chocolate, or maroon sandy claystone; in 

outcrop (g), south of trench K in the west-central part of the mapped 

area, pellets of schroeckingerite are in gray-green platy shale above 

iron-stained sandstone; and in outcrop (h), 50 feet east of outcrop (g), 

schroeckingerite pellets are in green claystone.

The lithology as seen in, or as deduced from the material on dumps 

of shallow auger holes, pits, and bulldozer cuts is listed below:

Pits and bulldozer cuts

Reference no.

(pi. 19) Lithologic description

!______________ Claystone, green, silty; contains schroeckingerite pellets.

2______________ Claystone, gray-green; contains schroeckingerite pellets and

flakes; overlies iron-stained solution zone in green, clayey

sandstone. 

3______________ Silt (terrace deposit).

4______________ Shale, gray-green, platy; contains schroeckingerite pellets and

gypsum. 

5______________ Gravel, white to brown (terrace deposit).

6______________ Gravel (terrace deposit).

7__________ _ Sand, white, and brown clayey sand and gravel (terrace

deposit). 

388177 57 4
258 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM 

Pits and bulldozer cuts Continued

Reference no.

(pi. Iff) Lithologic description

8_.____________ Shale, gray, platy, weathering to curved plates; contains

schroeckingerite pellets; overlies iron-stained solution zone 

in white sandstone.

9_________----_ Siltstone, green, sandy; contains schroeckingerite pellets;

underlies basal boulder-gravel bed of terrace deposit.

10_ ____________ Sandstone, white to brown, clayey, and colluvium.

11_________ Gravel, brownish white, clayey (terrace deposit).

12_____________ Gravel (terrace deposit).

13_____________ Claystone, gray; contains schroeckingerite pellets and white

efflorescent salt.

14_____________ Claystone, gray-green; contains schroeckingerite pellets, and

sandy siltstone. (Pit contains water.)

15___________ Gravel of subrounded frosted quartz and feldspar grains (terrace deposit).

16___________ Siltstone, green; contains schroeckingerite (dump material

from filled pit).

17_____________ Gravel, white to buff, and green sand (terrace deposit).

18__________-_- Shale, gray-green and purple, platy; contains schroeckingerite

pellets; overlies brown-stained solution zone in white sandstone.

19__-___-__--_- Siltstone, green, clayey; contains schroeckingerite pellets; 

overlies iron-stained solution zone in white micaceous sandstone.

20___________ Shale, gray-green, platy; contains flakes of schroeckingerite;

overlies iron-stained solution zone in white sandstone and 

conglomerate (faulted).

21 _____________ Claystone, gray-green, overlying orange-stained white sandstone; contains no schroeckingerite.

22_____________ Siltstone, green; contains schroeckingerite pellets, and overlies

iron-stained sandstone on west and north sides of pit; platy 

grey-green shale with no schroeckingerite, overlies siltstone on 

south and east sides of pit (faulted).

23_____________ Sand, green, clayey (terrace deposit); overlies gray-green

gypsiferous claystone.

24 _____________ Shale, gray, platy, weathers to curved plates; contains schroeckingerite pellets; overlies iron-stained solution zone in white 

sandstone; claystone seams 10 and 17 inches below contact 

also contain schroeckingerite.

25_____________ Sand, gray-green, and clayey sand (terrace deposit).

26___________ Sand, greenish white, and gravel (terrace deposit).

27_________ Shale, gray-green, platy; contains schroeckingerite pellets;

overlies iron-stained solution zone in white sandstone.

28_____________ Shale, gray-green, platy; contains schroeckingerite pellets;

overlies iron-stained solution zone in white sandstone.

29_________ Gravel (terrace deposit) fills pit.

30_____________ Sand, white-weathering, brown (terrace deposit); fills pit.

Shallow anger holes

H-3________ Claystone, maroon, sandy. .

H-4_________ Claystone, green, gravelly.

H-5__. Gravel (terrace deposit).

H-6_______ Gravel, white-weathering, brown-(terrace deposit).
URANIUM IN THE BED DESERT, WYOMING 259

Shallow auger holes Continued 

Reference no.

(pi. 19) Lithologic description

H-7___________( Gravel, white-weathering, brown, and some white clay (terrace

deposit?).

H-8_________ Claystone, light-green, silty.

H-9.__________ Sand, white-weathering, buff and green, and gravel; gravel

contains fluorescent chalcedony (terrace deposit?).

H-10__________ Sand, green (terrace deposit).

H-ll__________ Clay, green, and gravel (terrace deposit).

H-12__________ Claystone, green.

H-13__________ Claystone, green.

H-14______ Gravel, green (terrace deposit).

H-15________ Gravel (terrace deposit); hole is filled.

H-16__________ Gravel (terrace deposit); hole is filled.

H-17__________ Sand and gravel (terrace deposit); overlies green sandy siltstone; hole is filled.

H-18________ Sand and gravel (terrace deposit); overlies green sandy siltstone; hole is filled.

H-19__________ Shale, gray-green, platy; contains schroeckingerite pellets,

and brown sandstone; hole is filled.

H-20_______ Silt, buff (terrace deposit).

H-21__________ Sand, white (colluvium).!

H-22__________ Sand, white, coarse (colluvium and terrace deposit).

H-23_________ Gravel (terrace deposit); hole is filled.

H-24__________ Shale, gray-brown, platy; schroeckingerite?; hole is filled.

H-25__________ Gravel (terrace deposit, colluvium); hole is filled.

H-29__________ Claystone, brown.

H-31 __________ Sandstone, green, silty.

H 33__________ Claystone, gray, silty; contains schroeckingerite.

H-34__________ Claystone, gray, silty; contains schroeckingerite.

H-35__________ Sand and gravel (terrace deposit).

H-36______ __ Clay, green, sandy (terrace deposit?).

H-37__________ Claystone and sandstone, iron-stained.

Trenches F, G, H, /, and P (pi. 19) were filled or caved in the summer of 1949, although some information concerning lithology and ore 

zones was gathered by inspecting the dump material. Trenches Ii, J, 

Ji, MI were not deep enough to expose bedrock below the Pleistocene 

terrace deposit. Vertical sections were prepared of trenches C, E, EI, 

L, and N. The other trenches were open but were not mapped 

because the time was too short. The general relations between the 

various type of sediments and schroeckingerite in these five trenches 

are shown on plate 20.

Additional lithologic data obtained from cuttings of shallow auger 

holes drilled in 1949, and from deeper auger holes drilled in 1950 

are tabulated in the section Auger-hole data (tables 10 and 11).

Structure. The deposit is within the Cyclone Rim fault zone 

that separates folded beds to the northeast from nearly horizontal 

beds to the southwest. (See cross sections A-A' and B-B', pi. 19.) 

Faults within the Cyclone Rim fault zone were first observed while 

measuring columnar section 9, about r 8% miles northwest of the
260 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

deposit (pi. 16). These faults strike N. 50°-70° W., dip vertically or 

steeply to the south, and individual faults displace the beds on the 

southwest side downward as much as 33 feet. Within the schroeckingerit deposit, minor faults, ranging in strike from N. 70° to 85° 

E., and in dip from 25° to 53° SE., were mapped in trench C, trench 

A, pit 21, and outcrop A. Offsets on these faults appear to be small 

but were not positively demonstrated.

In general, the sediments within the deposit strike northwestward 

and dip northeastward. Their strikes, as determined in trenches and 

pits, range from N. 89° W. to N. 72° E. but average about N. 65° W.; 

dips range from 4° to 42° NE., and average about 20° NE. In 

trench L, pit 8, and in the bluffs of Lost Creek below the bridge, the 

beds strike northeastward and appear to be continuous between 

exposures, which suggests that they have been folded rather than 

faulted. The nearly east direction of strikes in pit 2, trench 0, pit 

4, and trench N, may also reflect the attitude of such a postulated 

fold rather than the effects of local faulting or "surface creep."

It is possible that most 'of the ore bodies are along fault surfaces 

that parallel bedding surfaces. Natural exposures are too few and 

exploration too shallow to afford adequate observation of this 

relationship.

MINERALOGY

The principal uranium mineral in the deposit is schroeckingerite, 

but fluorescent uraniferous opal, and undetermined minerals of 

uranium also occur.

SCHROECKINGERITE

Schroeckingerite, NaCasCUOaXCOsMSO^F-lOHaO, is a bright yellowish-green mineral that contains about 27 percent uranium. Under 

ultraviolet light the mineral fluoresces an even brighter yellowishgreen than it appears in white light. Schroeckingerite, hand-picked 

from Lost Creek ore, and estimated to contain only 1 percent of 

impurities (sand, clay, etc.) contains 11.0 percent equivalent uranium 

and 24.5 percent uranium; the discrepancy between the analytical 

and theoretical uranium content may mean that the Lost Creek material analyzed contained nearly 4 percent impurities. The smaller 

equivalent uranium content reflects a relative deficiency in radium 

and indicates that the schroeckingerite formed so recently that the 

uranium and its disintegration products have not yet attained radioactive equilibrium. The optical properties determined by Joseph 

Berman correspond closely to those reported by Jaffe, Sherwood, and 

Peterson (1948). Other work concerning the mineralogy of this mineral has been done by Schrauf (1873), Larsen and Gonyer (1937), 

Knight and Gilbert (see footnote 4, p. 255) (1937), Dake (1938), and 

NovaSek (1939).
URANIUM IN THE RED DESERT, WYOMING 261

Some loose pellets of schroeckingerite, observed in the rock debris 

at the base of the bluff below the bridge and in the dumps of the 

trenches, appear to differ from normal schroeckingerite. These pellets 

are harder, slightly more yellow than the normal yellowish green, and 

are commonly encased by a reddish-brown shell; they may possibly 

be dehydration forms of the mineral or may be schroeckingerite 

slightly modified by the addition to or loss from the molecule of some 

components other than water.

In the Lost Creek deposit, schreockingerite has 3 characteristic 

modes of occurrence: 1, as round aggregates or pellets, as much as 

three-fourths of an inch in diameter, made up of platy crystals; 2, as 

individual, small flaky crystals; and 3, as 1 millimeter-thin layers made 

up of numerous small crystals that coat grains of quartz, calcite or 

other sandstone components or the surface of efflorescent salts. The 

mineral also occurs, rarely, in microscopic fibrous masses in silica and 

calcium carbonate.

The pellets, concentrations of which constitute the ore bodies, 

seem to occur preferentially within brown, gray, or varicolored shale 

of the Green River formation or in massive gray-green silty claystone 

or clayey siltstone of Wasatch type. Some pellets fill shrinkage 

cracks in the claystone. The commonly associated minerals, other 

than the predominant clay minerals of the montmorillonite group and 

quartz of silt-size, as determined by Joseph Berman in hand specimens 

of typical pelletal schroeckingerite ore, are gypsum, aragonite, calcite, 

and iron-oxides.

The individual thin flaky crystals of schroeckingerite that are 

commonly disseminated in loose sand or sandy clay, as well as the 

thin layers coating other minerals at the ground surface attest to the 

ready solubility and mobility of schroeckingerite in cold water. The 

mineral is periodically dissolved by rain and melting snow and carried 

down the slopes, where it recrystallizes upon drying as a surface 

incrustation. During the winter season of 1948-49, the individual 

crystals and pellets exposed on the dumps of the trenches dissolved 

and, during the, dry season of 1949, recrystallized as thin efflorescent 

coatings of the ground below the dumps; these coatings cover areas as 

much as 20 feet square. Schroeckingerite is also readily dissolved 

and transported by near-surface ground water from which the mineral 

reforms on evaporation, so that a blanketlike thin layer of disseminated 

schroeckingerite flakes commonly coats shale beds or claystone that 

immediately underlie porous terrace sand and gravel, or colluvium. 

A specimen representative of this type of occurrence from the older 

terrace deposit (Qt2) at pit 18, overlying an ore body that was examined by Berman, consists of a friable, porous arkose composed 

predominantly of subrounded grains of microcline and a moderate 

amount of quartz; the grains are loosely bonded by small amounts of
262 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

clay and calcium carbonate. Small specks of fluorescent material 

are probably schroeckingerite. Such widespread dispersion of the 

mineral, although an aid in prospecting, hampers the finding of ore 

bodies; the thin coatings, although a spectacular sight under ultraviolet light, are not ore.

OTHER URANIUM MINERALS

Unknown uranium-bearing minerals or substances are present in 

the deposit and in the adjacent rocks, as was first noted by Slaughter 

and Nelson (unpublished report, 1946), who took samples of claystone 

that was radioactive but contained no visible schroeckingerite. One 

of these samples contained 0.018 percent equivalent uranium and 

0.004 percent uranium; another contained 0.019 percent equivalent 

uranium and 0.039 percent uranium. The presence in the first sample 

of a probable excess of radium (analogous to some of the radioactive 

lignite), and in the second of a probable excess of uranium, certainly 

indicates the presence of other uranium minerals or uranium-bearing 

substances. Sample WNS-5-233, of a 3-inch bed of white ashy 

material from trench K2 (pi. 21), contains 0.025 percent equivalent 

uranium, 0.011 percent uranium; the sample is composed of dolomitic 

calcite containing minor amounts of subrounded particles of partly 

devitrified volcanic glass (?) and quartz silt, Joseph Berman (written 

communication). A sample, DW-108-305, of gypsiferous sandstone 

from Arapahoe Creek contains 0.005 percent equivalent uranium and 

0.003 percent uranium (table 3). The sample, according to Berman, 

is composed of albite, gypsum, calcium carbonate, clay, some oligoclase and rose quartz, and small amount of microcline, altered rhyolite, and biotite. The oligoclase is largely altered to sericite. Fluorescent, radioactive agate pebbles occur at the Lost Creek deposit. 

In 1948 C. C. Towle and the senior author took samples of terrace 

deposits and of green clay in which no schroeckingerite was observed 

but which contained as much as 0.011 percent equivalent uranium 

and 0.006 percent uranium (sample TW-13, table 7).

Schroekingerite is associated with small amounts of fluorescent 

uraniferous opal, carbonate, and gypsum, and with nonfluorescent 

uranium minerals (or adsorptions on clay). During the program of 

auger-testing in the fall of 1950, material having fluorescent characteristics similar to those of schroeckingerite was found in all the holes 

bored. The fluorescent material was first thought to be schroeckingerite, but analyses show it does not contain as much uranium as 

schroeckingerite. M. E. Thompson determined the material to be, 

in part, opal; in part fluorescent calcite; and in part, an unidentified 

constituent. Examination of samples under ultraviolet light with 

a binocular microscope indicated that many fluorescent clots, which 

megascopically appeared to be small clots of schroeckingerite, are in 

reality grains and aggregates of other minerals with thin, irregular
URANIUM IN THE RED DESERT, WYOMING 263

coatings of schroeckingerite. Some of these other minerals, notably 

opal, calcite, and gypsum are also fluorescent.

Sample WNS-20 (S:28), of dull-yellow-fluorescent gypsiferous 

claystone from the west side of Lost Creek about 1% miles northwest 

of the Hadsell shearing sheds, contains 0.004 percent equivalent 

uranium, 0.002 percent uranium (table 3). The sample, as examined 

by Berman, is an argillaceous siltstone containing substantial amounts 

of gypsum. The clay is a physical mixture of an illite-type clay 

mineral and kaolinite. The silt particles are principally feldspar and 

quartz.

Some samples containing as much as 0.019 percent uranium contain 

only a relatively small amount of schroeckingerite. It is possible 

that uranium may be adsorbed in clay aggregates in some of these 

samples.

Semiquantitative spectrographic analyses of some of the augerhole samples have been made by Paul R. Barnett. Major constituents 

other than silicon and iron are calcium, barium, magnesium, and 

titanium. It is likely that barium and radium occur together. As 

much as O.OX percent vanadium, manganese, lanthanum, and cerium 

were found in some samples.

ORE BODIES

The schroeckingerite ore bodies at the Lost Creek deposit are shown 

on plate 19. The examination of the rock exposed in open trenches 

and pits and of the rock fragments in the dumps of auger holes and 

filled trenches and pits suggests that the more continuous ore bodies 

occur-either in platy shale overlying sandstone or in gray-green 

massive silty claystone. The shale-sandstone type of ore body, 

which appears to predominate, is in detail, as follows: white friable 

sandstone of Wasatch type is overlain sharply by gray platy (commonly contorted) shale of Green River type. A thin zone, 1-8 

inches thick, largely but not entirely in the sandstone, at the contact 

of shale and sandstone is invariably stained brown, orange, or purple 

by iron and manganese (?) oxides. Pellets of schroeckingerite are 

commonly disseminated in the shale parallel to the iron oxide-stained 

zone and only occasionally within the zone, although flakes of schroeckingerite may be sparsely disseminated in it.

A typical ore body of the shale-sandstone type (pi. 20) is from 6 to 

15 inches thick, the average is 1 foot in thickness, and extends 5 feet 

or more vertically beneath the surface (pi. 19, trench A; pi. 20, 

trench Z). The maximum vertical depth to which schroeckingerite 

has been found is 8 feet, in pit 18 and in trench C, and was a distance 

of 37 feet down the dip of the ore body.

The length of individual ore bodies is unknown. The longest 

distance explored along the strike of a bed is 150 feet in trench D\.
264 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

The schroeckingerite ore body in this trench extends, with a gap of 

about 100 feet, into pit 18 and is exposed by trench C. There is no 

apparent diminution in grade throughout the length explored. 

Therefore, it is reasonable to assume this body is continuous between 

exposures and that it is at least 270 feet long.

Schroeckingerite in shale overlying iron-stained sandstone (the 

shale-sandstone type of ore body) is found in nearly all trenches that 

are deep enough to expose bedrock. This shale-sandstone sequence 

of beds seems to be the most favored association for schroeckingerite, 

but this sequence is not invariably schroeckingerite bearing. In 

trench (7, about 62 feet from the southeast end, and in pit 21 this 

characteristic favorable sequence of beds is barren of schroeckingerite.

The schroeckingerite body of the shale-sandstone type exposed in the 

bluff of Lost Creek west of trenches K and L projects directly into 

the exposure of the body in trench Z, thence into pit 8, and if the 

interpretation of structure is correct from pit 8 around a sharp fold 

into trench K. An auger hole, H-19, about 110 feet southeast of this 

shale-sandstone body hi trench K, intersected the same deposit. 

From this point southeastward to trench / there are no exposures. 

The platy shale and schroeckingerite pellets in the dump at the southwest end of trench / are approximately on the trend of the schroeckingerite body and are assumed to be its southern extension. Two 

shale-sandstone ore bodies at the northeast end of trench A may be 

projected through trench E, possibly as far as trench F.

The continental sedimentary rocks in this area are characteristically 

nonpersistent, lenticular, and their contacts may be in part fault 

contacts; thus, the projection of shale-sandstone contacts and associated schroeckingerite bodies is somewhat questionable. In addition, 

the ore bodies are in the Cyclone Rim fault zone where the beds 

should be expected to be displaced by faults.

Schroeckingerite in gray-green silty claystone or clayey siltstone 

is exposed in trench L, pits 13 and 14, trench KZ, the southwest end 

of trench F, trench C, pit 1, and outcrop (d).

Thin stringers or mantles of schroeckingerite pellets and flakes 

that are too thin and irregular to constitute potential ore occur along 

the bluff of Lost Creek below the bridge, and near the edge of the colluvium in outcrop A;m a, similar position in outcrop B; and in trench 

P. These occurrences are probably the result of the re-formation 

of schroeckingerite from ground and surface water that has passed 

over or through schroeckingerite-bearing material elsewhere.

GRADE

The grade of samples of schroeckingerite-bearing material that have 

been taken from the Lost Creek deposit since 1948 ranges from 0.013 

to 0.28 percent uranium.
URANIUM IN THE RED DESERT, WYOMING 265

The analyses of samples of schroeckingerite-bearing material, water, 

plants, and soil taken by the Minerals Engineering Co. and by the 

Geological Survey are given in tables 7, 8, and 9. The analyses of 

rock samples (table 7) disclose discrepancies between equivalenturanium and uranium contents, and differences in the uranium content 

of samples taken by the Minerals Engineering Co. and those taken 

by Towle and Wyant. Some of the discrepancies may be attributable 

to sampling procedures. The report by George Petretic, Geological 

Survey, accompanying the analyses of the samples taken by Towle 

and Wyant (table 7) stated:

. . . the correspondence between the percent ell [equivalent uranium in table 

7] determined by reference to a standard in which uranium is in equilibrium with 

UXi and UX2 only and percent uranium is good except for samples 5828 (TW-17), 

5836 (TW-25), and 5837 (TW-26). Although this agreement is not good, it 

can be attributed to the non-homogeneity of the samples. The schroeckingerite 

is dispersed throughout the matrix of feldspar, etc., and observation of the samples 

under an ultra-violet lamp clearly shows that a non-representative sample can 

easily be obtained, particularly if less than a gram is used for analysis.

The difference in analyses may be attributed in part to differences in 

the sampling procedure, and in part to the fact that schroeckingerite 

is erratically distributed in the ore bodies and that this soluble mineral 

is in process of being redistributed by ground and surface water. 

Bulk sampling probably is the only way to obtain representative 

samples.

The analyses of water samples (table 8) show an abnormal uranium 

content in the ground water underlying the deposit (as much as 0.88 

parts per million). The spring at the mouth of Osborne Draw (northwest part of map, pi. 19) is probably a seep of near-surface water, 

possibly localized by fracturing or faulting. It is of interest to note 

that there is a seasonal fluctuation of the uranium content of the 

spring water. Sample WNS-9-13 of water from pit 14 contains much 

more uranium (46 parts per million) than do many other water 

samples. This is not surprising, inasmuch as the schroeckingeritebearing material in this pit was exceptionaUy high grade, and as the 

water (in direct contact with this ore) had been stagnant in the pit for 

at least four months. The ground water is mildly alkaline (pH of 

7.8-8.3).

The plant and soil samples also show abnormally high uranium 

contents (table 8). A sample of greasewood roots (P 4) contains 7,400 

parts per million in the ash, according to Helen Cannon (written 

communication), who'states ". . . so far as I know, this is the highest 

value for uranium ever reported in a plant." The greasewood plant 

was growing on a schroeckingerite body (exposure d, pi. 19).

AUGER-TESTING PROGRAM OF 1950

A program of auger drilling was begun at the Lost Creek schroeckingerite deposit on October 23,1950, and was recessed on December 20,

388177 5T 5
266 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

1950. The drilling was done with a jeep-mounted auger-drill rig 

equipped with augers 4% inches in diameter.

The objectives of the auger-drilling program were (1) to determine 

the maximum depth at which schroeckingerite occurs, (2) to obtain 

preliminary data about the lateral distribution of schroeckingerite, 

and (3) to determine more accurately the relations of schroeckingerite 

to beds of different lithology and to the Cyclone Rim fault zone.

Because of contamination inherent in the auger-drilling method, 

assays of auger-samples were not expected to give representative 

grades of schroeckingerite ore bodies; it was hoped, however, that 

such bodies could be delineated by means of these assays.

SAMPLING AND LOGGING PROCEDURES

Thirteen auger holes, totaling 397 feet, were drilled to depths ranging from 9 to 51 feet. The location of these holes is shown on plate 21. 

Eleven (holes ES-1 to ES-3 and ES-5 to ES-12), are along line of 

section C-C' shown on plate 22 and are oriented approximately perpendicular to the average strike of the ore bodies. These holes were 

spaced at intervals of 2-23 feet apart near known ore bodies in the 

trenched area, and at intervals of 163-1,000 feet apart, where remote 

from known ore bodies. Hole ES-13 was collared at a point 2,000 

feet S. 60° E. from the northernmost end of section C-C' and hole ES-4, 

at a point 2,200 feet N. 45° W. from the southernmost end of section 

C-C'.

Samples were taken from top to bottom of the hole at 2-foot intervals except where changes in lithology made a different sample interval preferable or where drilling difficulties required special sampling 

intervals. For example, drilling below the water table required large 

sample intervals, in order to save time and insure better recovery. 

Each sample for analysis consisted of all the rock recovered from the 

interval being drilled, except for small samples removed for lithologic collections. Whenever the sample was obviously contaminated, 

such information was noted. A total of 198 rock samples for analysis 

was taken from the 13 auger holes.

Samples of the dry rock above the water table were collected by 

spinning the auger without lowering or raising the position of the bit, 

so that the rock traveled up the spiral auger and accumulated on a 

flat steel plate. This procedure was fairly satisfactory, but contamination by wall rock of the hole was unavoidable. For example, 

a 2-foot auger sample may consist entirely of clay mixed with sand and 

may assay 0.050 percent uranium. These data cannot be interpreted 

to mean that the sample represents an ore body 2 feet thick consisting 

of sandy claystone because the schroeckingerite may have been concentrated in any fraction of the 2-foot interval with a correspondingly 

higher grade in that fraction, and may all occur in the claystone and
URANIUM IN THE BED DESERT, WYOMING 267

not in the sandstone. By the time the sample reaches the surface it 

has undergone considerable mixing and the ore minerals may be 

scattered through the entire sample; caving may also add the ore 

minerals to succeeding samples.

In the drilling of holes below the water-table, sampling required 

the removal of rods after each sampling-run so that they could be 

stripped clean of adhering mud and ice.

Sample logs of each hole were made during the drilling and small 

representative samples of individual lithologic units were collected to 

preserve a record of each hole. A sample was taken of water in 

each of the 10 holes in which the water table was reached (all holes 

except ES-1, ES-11, and ES-13), and gamma-ray logs of each hole 

were made with a Geiger-Mueller counter to which a 2-foot gamma 

probe was connected by 50 feet of cable. In several holes caving 

prevented probing the total depth of a hole and the total footage of 

radiometric logging is only 326.5 feet, as compared to 397 feet of 

hole drilled.

Dry auger-samples were examined at night with an ultraviolet 

lamp having its highest efficiency at a wave length <rf 2540 angstrom 

units. The schroeckingerite content of each sample was estimated 

on the basis of yellowish-green to greenish-yellow fluorescence. 

Radioactivity examination of these dry samples was made with a 

Geiger-Mueller counter, using a small probe with the -beta shield 

open. The lithology, depth of sample, the radioactivity of samples 

determined in the field, the laboratory analyses of samples, and the 

gamma-logs of the bore holes are given in table 11.

In summary, the auger-drilling program allowed tbe determination of the general sequence of subsurface lithology and the determination of approximate locations, but not specific dimensions of 

schroeckingerite ore bodies. The grade figures calculated from the 

analyses are, at best, of value only in determining the uranium content 

of large intervals of rock.

GEOLOGIC RESULTS

The subsurface lithology determined during the auger-testing program and tabulated in the sample logs (table 11) has been plotted 

on geologic cross sections at scales of 1 inch to 200 feet (holes ES-2, and 

3, and ES-5-ES-12, pi. 22) and 1 inch to 20 feet (all holes except ES-1, 

pi. 23). The locations of all auger holes are shown on plate 21. 

Hole ES-1, abandoned at a depth of 9 feet, is only 2 feet from hole 

ES-2, and no section of it was prepared.

Holes ES-2, ES-3, ES-5, and ES-6 are near enough to each other 

to permit a general correlation of beds, aided in part by data from 

previous geologic mapping in the trenches. In the vicinity of these 

holes the lenticular beds of sandstone, siltstone, and claystone (trench
268 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

C, pi. 20, and pi. 23) show on a small scale the interfingering relationship that the Wasatch-type sandstone and claystone have to shale of 

the Green River formation elsewhere near Eagles Nest (pi. 16) on a 

larger scale. Faults, if present, were not recognized. The other 

auger holes were spaced too far apart to permit intercorrelation of 

the beds.

Hole ES-11, located just south of the southeastern limit of the 

Cyclone Run fault zone, is mainly in brown, hard, platy shale and 

small amounts of interbedded sandstone. Holes ES-1 to ES-6, all in 

the trenched area, and holes ES-7, ES-8, and ES-10 are in a series 

of interbedded sandstone, siltstone, and claystone with scattered 

iron-stained zones at the contacts of sandstone and claystone beds, 

but hole ES-9, 29 feet in depth, is almost entirely in pebbly sandstone 

with only minor amounts of siltstone and no claystone. Hole ES-12 

cut beds of siltstone and claystone with only minor amounts of sandstone. Hole ES-13 penetrated sandstone and subordinate amounts 

of interbedded siltstone and claystone beds.

The most notable features of the general lithology described above 

are the thick sections of sandstone in holes ES-9 and -13, as compared 

with the sequence of siltstone and claystone in hole 12 and the sequences of sandstone, siltstone, and claystone in the other holes. 

Hole ES-9 is on the south flank of a ridge trending northwest (pi. 16), 

whereas hole ES-13 is on the north flank of the same ridge; hole 

ES-12 is at the foot of this ridge on its northeastern side.

Aerial photographs suggest that this ridge is formed of sandstone, 

and this is corroborated by the sandy character of the beds cut in 

holes ES-9 and ES-13. The shale penetrated in hole ES-12 suggests 

that a claystone sequence begins immediately north of the sandstone 

ridge. The data obtained by drilling indicate that the stratigraphic 

interval between the beds seen at the southwestern limit of the Cyclone Rim fault zone (pis. 16 and 19) and those cut in hole ES-9 

(pi. 21) is occupied by relatively thin sandstone beds with a high 

proportion of claystone, shale, and siltstone beds, whereas the stratigraphic interval between the beds of hole ES-9 and those of hole 

ES-12 (pi. 21) is occupied by relatively thick sandstone beds with a 

low proportion of claystone and siltstone beds. Another sequence 

predominantly of shale and siltstone beds extends for an unknown 

distance northeast of hole ES-12.

DISTRIBUTION OF URANIUM

Visual estimates of the schroeckingerite content of each auger sample 

were made on the basis of fluorescence and auger samples were then 

analyzed by the Geological Survey (table 11). A comparison of 

uranium content determined by chemical analysis with the preliminary estimates of schroeckingerite content made in the field disclosed
URANIUM IN THE RED DESERT, WYOMING 269

several discrepancies: (1) in some samples the uranium content estimated from the amount of fluorescent material was much greater 

than that determined by chemical analysis, and (2) in some other 

samples opposite relationship was true.

For example, the average of estimates made by three observers of 

the schroeckingerite content of sample DS-2-10 (hole ES-=2, table 11) 

is about 1 percent. Schroeckingerite contains about 27 percent 

uranium; therefore, this sample should have contained about 0.27 

percent uranium. Actually, it contained only 0.049 percent uranium. 

Three sources of error may account for this type of discrepancy: 

(1) errors in preparation or analysis, (2) errors in estimation of 

schroeckingerite content, and (3) the errors caused by the presence 

of fluorescent material other than schroeckingerite. Accordingly, an 

effort was made to check these possible sources of error. To check 

the methods of preparation, 6 representative samples were prepared 

by hand pulverized on a buckboard, ground in an agate mortar, 

mixed in a sampling cloth, and a representative split taken and were 

then analyzed. The results are shown in table 12. With one exception (sample DS-5-80), probably the result of an uneven original 

split, the resulting assays agree very closely with the original assays 

and the assays of the laboratory-prepared split, and indicate that 

neither the method of preparation nor the method of analysis (unless 

part of the uranium is consistently lost in the chemical procedure) 

are the sources of error. Though visual estimates of the schroeckingerite content based on fluorescence are admittedly subject to error, 

it is believed that the discrepancies between estimates and assays are 

caused in part by the presence of fluorescent material other than 

schroeckingerite. (See under section headed Other uranium minerals.)

TABLE 12. Comparison of analyses (in percent) of six samples prepared by two 

different methods, Lost Creek schroeckingerite deposit, Red Desert, Wyo.

Original analyses

No. of sample

DS-2-9-. .......... ...........

DS-2-10- _____ ___ ..

DS-2-11.. ....................

DS-5-80. ____ . __ . __ ..

DS-7-111 ________ .......

DS^3-39 .......... ......

Equivalent 

uranium

0.006 

.021 

.005 

.036 

.003 

.007

Uranium

0.007 

.049 

.007 

.063 

.001 

.007

Check test

Hand-prepared split

Equivalent 

uranium

0.006 

.023 

.005 

.037 

.004 

.007

Uranium

0.004 

.047 

.004 

.081 

.000 

.006

Laboratory-prepared 

split

Equivalent 

uranium

0.007 

.021 

.005 

.037 

.003 

.006

Uranium

0.004 

.044 

.006 

.080 

.000 

.005

Schroeckingerite was identified under the petrographic microscope 

in sample DS-2-10. In some other samples, however, containing 

little or no uranium and from 0.1 to 5 percent of fluorescent material, 

little or no schroeckingerite was observed. For example, on the
270 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

basis of fluorescence, sample DS-10-157 from hole ES-10 was estimated to contain from 1 to 2 percent schroeckingerite. Therefore, 

theoretically, it should have contained from 0.27 percent to 0.54 

percent uranium, but actually it assayed only 0.001 percent uranium. 

The fluorescent material in this and other similar samples, examined 

under the binocular microscope, fluoresces a slightly duller and more 

yellow color than does schroeckingerite (megascopic examination of 

the fine-grained material does not permit such fine color distinctions 

to be made) and is a very fine-grained aggregate with an index of 

refraction of less than 1.49; it is possibly allophane or opal. Some 

samples of this type contain very fine grains that are believed to have 

the true color of schroeckingerite in addition to the unknown material 

of lower refractive index.

Traces of fluorescent material which may be in part schroeckingerite 

were found at a maximum depth of about 34 feet in hole ES-13 and 

at various depths above the water table in all 13 auger holes. In 

trenches and pits schroeckingerite extends to a depth of at least 5 feet. 

The evidence obtained from the program of preliminary auger testing 

in 1950 suggests that schroeckingerite does not occur below the water 

table, and that schroeckingerite concentration in bodies of potential 

ore grade may not extend below a depth of about 8 feet.

Preliminary field mapping has indicated that rich concentrations 

of schroeckingerite in the shale are localized along some of the contacts between the shale and iron-stained sandstone. Iron-stained 

material was found as much as 35 feet beneath the water table. Data 

obtained from the auger drilling (table 11) and from investigations of 

the trenches suggest that the richest concentrations of schroeckingerite 

in the trenched area near holes ES-1, -2, -3, -5, and -6 are within 7.5 

feet of the surface. It cannot be concluded from assays, however, 

that rich concentrations do not persist to greater depths, because 

schroeckingerite pellets are erratically distributed within beds both 

horizontally and down dip. This has been shown by surface mapping 

and also suggested by some of the auger-testing data. Hole ES-7 

was drilled at a point determined by projection of an ore body from 

trench <73 so that the ore would be intersected at a depth of about 10 

feet. Samples in this hole, from depths of 5 to 12 feet, contain only 

0.001 percent uranium (Auger hole ES-7, table 11). In the field 

about 5 percent of the samples of damp rock directly above the 

water table (12 feet) fluoresced, but when this material was dried, no 

fluorescent material was observed; apparently the fluorescence was 

caused by efflorescent salts that contain little or no uranium and which 

lost their ability to fluoresce upon drying. Hole ES-4 was so located 

that an ore body projected from trench L and pit 8 would be intersected at a depth between 10 and 15 feet. Samples from this hole
URANIUM IN THE BED DESERT, WYOMING 271

(table 11) contain 0.007 percent uranium in the interval between 

depths of 10 to 12 feet and 0.005 percent uranium in that between

12 to 14 feet, compared to a general content of 0.002 percent uranium 

in samples from the rest of the hole. A very thin concentration of 

schroeckingerite diluted by wall rock during drilling may cause the 

abnormal uranium content in the interval 10-12 feet.

The lack of significant amounts of schroeckingerite at depths which 

are above the water table and along projections of ore bodies may be 

attributed to (1) its sporadic distribution in each ore body both 

horizontally and down dip, (2) the possibility that it does not occur 

below depths of 8 feet, (3) the possibility that favorable host beds 

either lens out or have been offset by faults, and (4) the possibility 

that schroeckingerite may be present in thin bodies that are insignificant in relation to the length of the sampled interval.

Radioactivity anomalies obtained from the gamma-ray logs of the 

auger holes (table 11), that do not correspond with the sample assays, 

such as the high radioactivity of the wall rock throughout hole ES-5, 

are not explained by existing data. It is possible that radon may 

cause some of the anomalies, or that imperfections of the instrument 

are to blame.

The uranium content of water samples (table 8) from 10 of the

13 auger holes ranged from 0.004 to 0.88 ppm. The analyses of 

water from holes ES-2, -3, -4, -5, and -6 indicate a fairly uniform 

abnormal uranium content in the ground water in the area near the 

trenches. Water from holes ES-7 and -10 contain, respectively, 0.50 

and 0.88 ppm, but rock samples from neither of these holes contained 

more than 0.006 percent uranium much less than the maximum 

uranium content of rock samples from holes ES-2, -3, and -5. The 

analyses of water from holes ES-8, -9, and -12 indicate that the 

ground water north of the fault zone contains relatively little uranium.

The limits of this near-surface uranium deposit are not known and 

will remain unknown until additional exploration is done. The gentle 

fold assumed to be in the vicinity of trench L and K (pi. 4) and the 

obscuring alluvial material along Lost Creek make it difficult to 

project positions of the beds which are the loci of ore bodies to the 

west side of Lost Creek.

Hole ES-7 cuts a sequence of interbedded sandstone, siltstone, and 

claystone and reached the water table at a depth of 12 feet. Although 

only one claystone bed was cut above the water table in this hole, 

many claystone beds were cut below the water table. These can be 

projected updip to positions above the water table in the area between 

holes 6 and 7, where it is possible that some may be schroeckingerite 

bearing. Additional auger-drilling or trenching, outlined on pi. 21, 

will be required to predict the total number of such loci for ore 

bodies in the deposit.
272 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

ORIGIN

A thorough understanding of the source of uranium and the processes involved in the formation of the Lost Creek deposit the largest 

deposit of schroeckingerite now known in the world would have wide 

application in the continuing study of other deposits of secondary 

uranium minerals. Although the final stages in the formation of 

schroeckingerite are reasonably clear, data available are insufficient 

to do more than indicate several possible sources for the uranium.

The final stage in the formation of schroeckingerite appears to be 

crystallization from alkaline ground- or surface-water solutions during evaporation of the water. The mineral must thus be deposited 

above the water table, near the surface. An arid or semiarid climate 

would thus seem to be a requirement for its accumulation, for under 

wet climatic conditions the mineral would tend to be flushed out of 

the area. The process of schroeckingerite deposition is thus conceived to differ from that of caliche deposition only in the quasistratigraphic control of the schroeckingerite. Another requirement 

for the formation of large pellets of the mineral appears to be a finegrained host rock, such as shale of the Green River formation.

An experiment performed by Guillotte (unpublished report, 1945) 

bears on this problem. He pulverized specimens of shale containing 

large pellets of schroeckingerite, added water and thoroughly mixed 

the slurry until schroeckingerite completely dissolved. The mud, left 

undisturbed until it had dried out, contained large pellets of newly 

formed schroeckingerite resembling in all respects those in the original 

specimens.

The observation that large pellets of schroeckingerite form in claystone, shale, or siltstone, whereas only disseminated flakes or surface 

incrustations of schroeckingerite form in adjacent sandstone and on 

the ground surface, may be explained by the difference in the capacity 

of the different types of sediments to retain water. As the nearsurface rocks dry out, the finer grained sediments retain water for a 

longer time than the coarser grained sandstone, or than any sediments 

at the ground surface, thus furnishing an environment in which the 

mineral could crystallize relatively slowly and form large pellets or 

aggregates of crystals. If this is so, then one might expect to find 

pellets of schroeckingerite even in sandstone near the permanent 

water table.

Other known factors entering into the problem of the genesis of 

the schroeckingerite deposit are its localization within the Cyclone 

Rim fault zone, and the relationship between solution zones of ironstained sandstone and shale and schroeckingerite. Although the 

deposit has not been delimited, schroeckingerite is, with one exception, confined to the Cyclone Rim fault zone. The exception (the 

ore in exposure B and pit 1, pis. 19 and 21) might be explained by
URANIUM IN THE RED DESERT, WYOMING 273

faulting subsidiary to the major fault zone, although such subsidiary 

faulting has not been established. Although exposures are poor, it 

seems remarkable that schroeckingerite has not been found anywhere else in the Red Desert. It is probable, therefore, that the 

zone of faulting is a major control in the localization of the schroeckingerite deposit.

The close though not constant association of zones of iron-stained 

sandstone and shale and the ore bodies of schroeckingerite suggests 

that they may be related in genesis. However, the fact that not all 

iron-stained zones contain schroeckingerite may only mean that the 

uranium mineral formed in the same environment as did iron oxides. 

The iron oxides were probably formed by the oxidation of ferrous 

hydroxide derived from ground water. Ferrous hydroxide may have 

been derived from distant source beds, such as beds buried beneath 

the stained zones, and transported relatively long distances, or may 

have been derived from local source beds, such as the shale beds at 

the present sites of the stained zones, and transported laterally only 

a few inches or feet. The flow of ground water would tend to be 

localized in the permeable sandstone beds next to the relatively 

impermeable shale beds. On the other hand, water held in the shale 

would tend to migrate laterally into the adjacent sandstone as the 

level of the water table sank during dry seasons, for the sandstone 

would dry faster than the shale thus forcing the water held in the shale 

to migrate into the sandstone. Perhaps the relation in the iron content 

of samples closely spaced across an iron-stained zone, including both 

sandstone and shale and the adjacent mineralized shale bed might help 

resolve the problem of distant versus local source of the iron. Either 

postulation seems to require that the water table be low enough to 

permit air to enter the pore spaces of the sandstone beds. Present-day 

seasonal fluctuations of the water table permit the entrance of air 

only to a depth of about 20 feet. Therefore the iron-stained zones 

reached in auger-drilling at depths of as much as 35 feet beneath the 

water table probably were formed when the water table was much 

lower than it is now, possibly during dry interglacial stages of the 

Pleistocene epoch. The iron-stained zones that in places contain 

schroeckingerite beneath Recent colluvium, and beneath the Pleistocene terrace deposits are proof that iron oxides and schroeckingerite 

are still forming.

The source of the uranium carried by ground water remains problematical. Uraniferous lignite, however, is inferred to be the most likely 

source of the uranium for the following reasons:

1. Uranium apparently is leached from outcrops of uraniferous lignite near the 

area of the schroeckingerite deposit.

2. Uraniferous lignite, in which the uranium is in radioactive equilibrium, underlies the area south of the Cyclone Rim fault zone, as attested by the drill 

cuttings at the site of the California-Wyoming Development Co. oil well. 

The lignite, on the basis of geologic correlation (pis. 16 and 18). probably
274 CONTRIBUTIONS TO THE GEOLOGY OF UBANIUM

is from 300 to 500 feet beneath the surface at the southwestern edge of the 

fault zone (cross section B-B', pi. 19) and if present in the zone of faulting, 

would be closer to the surface and could be the local source of uranium in the 

schroeckingerite.

Uranium and iron thus may have been leached from the uraniferous 

lignite by ground water circulating to depths of a few hundred feet 

and thence carried upward in the porous rocks of the Cyclone Kim 

fault zone, to precipitate preferentially in beds of fine-grained sedimentary rocks above the low level of the ground-water table which 

prevailed during interglacial stages of the Pleistocene epoch. When 

the level of the ground-water table rose during glacial stages of the 

Pleistocene, and in Recent time, uranium was again dissolved, transported upward, and recrystallized as schroeckingerite. An equilibrium may exist, as schroeckingerite may be currently deposited from 

ground water at about the same rate that the mineral is dissolved and 

carried down Lost Creek by surface water. The iron-stained zones 

probably were first formed during the Pleistocene epoch. Once 

formed, the relatively insoluble iron oxide was not dissolved and 

transported by the later rise of the ground-water table, although new 

iron oxide probably is being deposited.

Some alternative theories that might explain the origin of the 

Lost Creek schroeckingerite deposit, or some features of it, are:

1. Uranium, derived from the surrounding crystalline basement rocks, accumulated in the Eocene Green River lakes and schroeckingerite crystallized in 

the near-shore muds as the lakes evaporated. This theory does not explain 

the localization of the Lost Creek deposit within the Cyclone Rim fault zone, 

nor the absence of other schroeckingerite deposits elsewhere in the general 

area where the Green River formation interfingers with Wasatch-type 

sedimentary rocks. Furthermore, it is difficult to understand, because the 

mineral is readily soluble, how there would now be any evidence left of an 

Eocene schroeckingerite deposit.

2. Uranium is leached by descending ground water from overlying source rocks, 

such as the Pleistocene terrace deposits, or the volcanic ash of the Continental 

Peak and Chadron formations of Nace's usage (Nace, 1939), carried laterally 

into the Cyclone Rim fault zone to move updip and form schroeckingerite 

on evaporation. This theory is plausible because of the widespread occurrence of radioactive rocks in the Red Desert, although it does not account 

for the localization of the Lost Creek deposit.

3. Uranium is leached from buried hydrothermal uraniferous vein deposits by 

ascending ground water and carried upward into the rocks of the Cyclone 

Rim fault zone. In other areas, such as in the Marysvale district, Utah, 

schroeckingerite is a secondary mineral, apparently derived from pitchblende. 

The occurrence of schroeckingerite in beidellite clays and the presence of 

the fluorine atom in the schroeckingerite molecule raise the possibility that, 

as in some other mining districts, beidellite and fluorite may be products of 

hydrothermal action. The theory is tenable, although no uraniferous veins 

are known to have been found in the area.

The available evidence, therefore, points toward the source of the 

uranium as buried beds of uraniferous lignite, although additional 

study and exploration will be required to establish the validity of any 

theory of the source of the uranium at the Lost Creek deposit.

ATDS TO PROSPECTING

Careful observation indicates that the Geiger-Mueller counter is 

of little value in detecting schroeckingerite if the mineral is covered
URANIUM IN THE RED DESERT, WYOMING 275

by even a thin mantle of overburden. The ultraviolet lamp is the 

most useful single tool to use in prospecting for schroeckingerite in the 

Red Desert area and if these instruments are used together, reasonably 

certain identification of pellets of the mineral may be made. Small 

disseminated flakes of schroeckingerite are not so readily identified, 

and may easily be mistaken for opal or other material. It was 

observed that wherever efflorescent salts coating the surface of the 

ground had a decidedly greenish-yellow color under ultraviolet light, 

schroeckingerite could be found nearby by digging shallow pits.

The localization of schroeckingerite in shale of the Green River 

formation within the Cyclone Rim fault zone suggests that prospecting 

should be guided by this geologic association. Shale beds, and shalesandstone sequences of beds within the fault zone southeast and northwest of the deposit should be examined as well as similar beds in other 

fault zones in the general area; for example, those in the Monument 

Dry Lake (pi. 17) might also be worth prospecting. Schroeckingerite 

was found in pit 27 (pi. 19) at the southeast end of the area trenched 

in 1948, and in trench P at the northwestern edge of the area. The 

deposit, therefore, has not been delimited, and must extend farther 

both to the northwest and to the southeast.

FUTURE OUTLOOK

Very likely, more schroeckingerite will be discovered by further 

prospecting. The fact that schroeckingerite bodies are more or less 

continuous; the likelihood that the known limits of the deposit will 

be extended by more exploration; the fact that schroeckingerite is 

soluble in water; and the possibility that the mineral is constantly 

replenished by deposition from ground water, suggest that it might 

be possible to produce uranium from the Lost Creek deposit economically under present conditions. The deposit should be explored to its 

limits. At the time the present field work was completed, further 

exploration by the Geological Survey was planned to follow, in general, 

the lines of proposed trenches and auger holes shown on plate 6.

Beds of uraniferous lignite have a greater extent than the area 

shown on plate 2. The lignite beds crop out over much of the country 

east of that area, but the beds are folded and faulted, so that detailed 

mapping probably will be required to establish then1 location and 

relationships. Because of the general westward dip of the beds, the 

main lignite beds probably do not crop out much farther west than the 

west edge of the area. Some of the thin lignite seams may thicken to 

the west, however, and other beds may be found by subsequent 

mapping. North of High Point Ridge, the beds are covered by 

Pleistocene and Recent deposits. Accordingly, drilling or other subsurface methods would be required to prospect the country west and 

north of the area, and to obtain samples of unweathered lignite. 

Samples closely spaced across lignite beds of the principal lithologic
276 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

components (coal, carbonaceous shale, etc.), together with bulk 

samples of the entire bed should be taken for chemical analysis. 

Mapping and studies of lignite were being continued by the Geological 

Survey at the time the present field work was completed.

Lignite that may be stratigraphically equivalent to that in the 

Red Desert area may be exposed in the vicinity of the Leucit* Hills, 

north of Rock Springs, Wyo. and the uppermost lignite beds in the 

Washakie Basin, south of Wamsutter, may be worth prospecting.

At present the possibility of commercial exploitation of the uraniferous lignite beds is uncertain. Future need for uranium and other 

trace metals and the potential heat energy of the lignite may, when 

suitable methods of extracting the metals are developed, result in the 

utilization of the uraniferous lignite in the Red Desert area.

LITERATURE CITED

Blackwelder, E. B., 1915, Post-Cretaceous history of the mountains of central 

western Wyoming: Jour. Geology, v. 23, no. 2, p. 97-117; no. 3, p. 193-217.

Bradley, W. H., 1926, Shore phases of the Green River formation in northern 

Sweetwater County, Wyo.: U. S. Geol. Survey Prof. Paper 140-D, p. 121-131.

 1928, Algae reefs and oolites of the Green River formation: U. S. Geol. 

Survey Prof. Paper 154-G, p. 203-223.

 1945, Geology of the Washakie Basin, Sweetwater and Carbon Counties,

Wyo., and Moffat County, Colo.: U. S. Geol. Survey Oil and Gas Inv.

Prelim. Map 32. 

Dake, H. C., 1938, The dakeite locality Wyoming: The Mineralogist, v. 6^

no. 3, p. 7, 8, 23-25. 

Dobbin, C. E., Hoots, H. W., and Dane, C. H., 1927, Geology and oil and gas

possibilities of the Bell Springs district, Carbon County, Wyo.: U. S. Geol.

Survey Bull. 796-B, p. 171-201. 

Evans, R. D., and Goodman, Clark, 1941, Radioactivity of rocks: Geol. Soc.

America Bull. 52, p. 459. 

Fath, A. E., and Moulton, G. P., 1924, Oil and gas fields of the Lost SoldierFerris district, Wyo.: U. S. Geol. Survey Bull. 756, 157 p. 

Fenneman, N. M., 1931, Physiography of western United States: McGraw-Hill

Book Company, Inc., New York and London, p. 143-144. 

Jaffe, H. W., Sherwood, A. M., and Peterson, M. J., 1948, New data on schroeckingerite: Am. Mineralogist, v. 33, nos. 3, 4, p. 152-157. 

Kemp, J. E., and Knight, W. C., 1903, Leucite Hills of Wyoming: Geol. Soc.

America, Bull. v. 14, p. 305-336. 

Larsen, E. S., Jr., and Gonyer, F. A., 1937, Dakeite, a new uranium mineral from

Wyoming: Am. Mineralogist, v. 22, no. 5, p. 561-563. 

Nace, R. L., 1939, Geology of the northwest part of the Red Desert, Sweetwater

and Fremont Counties, Wyo.: Wyoming Geol. Survey Bull. 27, p. 1-51. 

Nelson, R. A., Sharp, W. N., and Stead, F. W., 1951, Airborne radioactivity

survey of the Red Desert region, Sweetwater County, Wyo.: U. S. Geol.

Survey TEM-133, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak

Ridge, Tenn. 

Nov66ek, Radim, 1939, The identity of dakeite and schroeckingerite: Am.

Mineralogist, v. 24, no. 5, p. 317-323.
URANIUM IN THE RED DESERT, WYOMING 277

Schrauf, A., 1873, Schroeckingerite, ein neues Mineral von Joachimsthal: Tscherm.

Miner, mittheilungen, p. 137-138. 

Schultz, A. R., 1907 (1909), The northern part of the Rock Springs coal field,

Sweetwater County, Wyo.: in Coal fields of Wyoming: U. S. Geol. Survey

Bull. 341-B, p. 256-282. 

Sears, J. D., and Bradley, W. H., 1924, Relations of Wasatch and Green River

formations in northwestern Colorado and southern Wyoming: U. S. Geol.

Survey Prof. Paper 132-F, p. 93-107 (1925). 

Smith, E. E., 1907 (1909), The eastern part of the Great Divide Basin coal field,

Wyo.: in Coal fields of Wyoming, U. S. Geol. Survey Bull. 341-B, p. 220-242. 

Tolmachev, Ya. M., 1943, Adsorption of uranyl salts on solid adsorbents: Akad.

Nauk SSSR, Izv., in Nuclear Sci. Abs. no. 2063, no. 1, p. 28-34, (NP-742). 

Westgate, L. G., and Branson, E. B., 1913, The later Cenozoic history of the Wind

River Mountains, Wyo.: Jour. Geology, v. 21, no. 2, p. 144-159.

STRATIGRAPHIC SECTIONS

Stratigraphic section 1 (columnar section 1, pi. 18)

Distance 

Thick- above 

ness base 

Description (feet,) (feet)

Siltstone, yellow, gypsiferous, clayey; ferruginous sand nodules__ 3. 0 110 

Claystone, varicolored (gray, yellow, maroon); uppermost 2

inches is maroon platy shale___________________________- 1.5 107

Lignite and papery carbonaceous shale; lignite bed 2___________ 1.0 105.5

Claystone, silty; weathers white_____________________-_______ 1.0 104.5

Sandstone, light-weathering, buff, micaceous, arkosic; the lowermost 2 feet is concretionary, gritty, and with no black 

minerals________________ _ _______________ 10. 0 103. 5 

Shale, poorly exposed, dark-green, hackly; weathers olive-gray to

yellowish-..______-__-____________________ 5.5 93.5

Sandstone, poorly exposed, coarse, buff; grades upward into siltstone________________________________ 11.0 88

Sandstone, silty, the uppermost 3 feet is clayey; weathers olivegray to buff; large quartz, feldspar, and mica grains_______- 10.0 77

Sandstone, yellow-buff to tan, -lenticular, well-sorted; fine- to

coarse-grained, flaggy and calcareous from 62 to 64 feet_____ 12. 0 67

Claystone, green, yellowish in uppermost foot_________________ 5. 5 55

Sandstone, buff, silty, concretionary (may not be in place)______ 11. 0 49. 5

Claystone, olive to yellow, silty, blocky-weathering____________ 1. 0 38. 5

Sandstone, buff, well-sorted to silty, semiconsolidated (resembles 

sandstone of the Tongue River member of the Fort Union 

formation in North Dakota)____________________________ 7.5 37.5

Claystone, gray to black______-__________-__-_____________- 5.5 30

Lignite, vitreous, blocky-weathering (lignite bed !)____________ 2. 5 24. 5

Sandstone, buff, clayey_____________________-_______________ 4. 5 22

Claystone, carbonaceous_____-_________-__--_-______________ 1. 0 17. 5

Siltstone, olive-green, tan weathering__ ______ _________________ 7. 5 16. 5

Sandstone, varicolored; claystone; and silty claystone__________ 3. 0 9

Sandstone, red, well-sorted, semiconsolidated, micaceous, brownstained on surfaces_________________________________ 6.0 6
278 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

Stratigraphic section 2 (columnar section 2, pi. 18)

Distance 

Thick- above 

ness base 

Description (feet) (feet)

Sandstone, white to yellow, fine-grained, with ferruginous nodules; 

near the top the unit becomes more clayey, more yellow, and 

the nodules become thin lenses-___________________ 14.0 80.0

Claystone, brown, sandy, highly gypsiferous__________________ 3. 0 66. 0

Shale, gray-brown, carbonaceous, platy, gypsiferous.__________ 3. 0 63. 0

Shale, light-gray, paper-thin in uppermost 0.5 foot, underlain by 

light-buff sandstone and platy siltstone above carbonaceous 

shale interbedded with lignite; fine-grained, light-brown sandstone at base____________________________ 40 60.0

Sandstone, tan to red, platy; overlain by bed of maroon ash____ 4. 5 56. 0

Clinker, red, and ash, white (lignite bed 3) ___________________ 2. 0 51.5

Poorly exposed_________________________________ 2. 5 49. 5

Sandstone, coarse-grained, white, well-cemented_____________ 2. 0 47. 0

Poorly exposed (probably olive-gray, platy, claystone)_________ 6. 5 45. 0

Poorly exposed (probably sandstone grading upward into platy

siltstone) _______ _ ____________-_ _______ _ __ 3. 5 38. 5

Sandstone, flaggy, calcareous, medium-grained, current-bedded 2. 0 35. 0 

Sandstone, fine-grained, gray, with carbonate specks; olive shale

and cream-yellow weathering siltstone__________________ 5. 5 33. 0

Siltstone, cream-yellow; 0.5 foot of black to brown carbonaceous 

platy shale; siltstone; 1.5 feet of coarse gray sandstone at 

base________________________________ 7.0 27.5

Siltstone, light-gray, weathers to a cream color; becomes sandy

upward__________________________________ 4.0 20.5

Sandstone, arkosic, weathers to a cream color, and maroon carbonaceous shale; 2.0 feet of maroon, micaceous, platy, 

carbonaceous siltstone at base_____________________ 7. 5 16. 5

Claystone, gray-brown, silty____________________________ 3. 5 9. 0

Sandstone, gray to buff, calcareous, nodular, arkosic, micaceous,

ferruginous. ______________________________________ 5.5 5.5

Stratigraphic section 8 (columnar -section 3, pi. 18)

Sandstone, white, flaggy, calcareous, coarse-grained, micaceous,

current bedded__________________________________ 6. 5 38. 5

Sandstone, platy, fine-grained, and interbedded platy to paperthin carbonaceous shale; silty in upper part__________ ___ 9. 5 32. 0

Shale, light-brown, carbonaceous, and platy siltstone, with two

thin beds of white sandstone.-____________ _________ 5. 5 22. 5

Lignite, black, platy, vitreous (lignite bed 3), overlying chocolatebrown paper-thin shale and white, fine-grained sandstone 6. 0 17. 0 

Sandstone, white, coarse-grained, flaggy._____________________ 1.0 11. 0

Siltstone, yellow, sandy, interbedded with pale-green sandstone 

and claystone; cream-yellow, current-bedded sandstone at 

base._______________________________ 10.0 10.0
URANIUM IN THE RED DESERT, WYOMING 

Stratigraphic section 4 (columnar section 4> pi- IS)

279

Description

Sandstone, calcareous, fossiliferous, 

(fossil locality F-8) ; fine- to medium-grained, arkosic, micaceous; 

white, silty below; yellow above; 

caps butte _____ _____________

Shale, platy, sandy at top and base__ 

Sandstone, flaggy, calcareous, fossiliferous (fossil locality F-7); 

makes prominent ledge; fine- to 

coarse-grained ____ ____________

Sandstone, green; weathers buff; 

contains turtle plates and gar-pike 

scales; overlies blocky-weathering 

green shale; grades downward into 

white, micaceous fossiliferous

Sandstone, white, micaceous; some 

ledges of calcareous, fossiliferous 

sandstone, and subordinate carbonaceous platy shale, and buff 

sandy siltstone____________ __ __

Shale, paper-thin to platy; in part, 

chocolate-brown and with numerous plant fragments; in part 

silver-gray and with fish scales; 

contains 0.1- to 0.3-foot layers of 

silty, buff, fine-grained sandstone; 

becomes silty upward grading into 

silver to brown loess or siltstone 

in uppermost foot. ____ _____ _

Sandstone, white, flaggy, calcareous; 

fossiliferous; caps bench. _ ______

Sandstone, coarse- to fine-grained, 

white to buff, ferruginous; interbedded with chocolate-brown platy 

shale____________ _ ___ _______

Siltstone, sandy; zone of vertebrate 

fossils _ _ _______ _ _ _ ______

Sandstone, buff to yellow, in part, 

calcareous, ferruginous, micaceous, 

and nodular; becomes silty toward 

ton _ ______ __ ________

Thickness 

(feet)

12. 0 

10

4

6.0 

24 5

16.5 

2.0

1.0 

1.0

18.0

Distance 

above base 

(feet)

106 

940

84. 0

80.0 

740

49.5 

33.0

31. 0 

30. Q

29.0

Radioactivity (scale divisions) 

0.2 mr per hr*

Min

1 

0 

2 

2

0

2 

1

1 

0

2 

3

Max

5 

6 

6 

8

5

5

7

7 

4

8

7

Avg

4 

3 

4 

5

2. 5

3

4

4 

2

5 

5

 Radioactivity at the outcrop determined with standard survey Qeiger-Mueller counter, beta-gamma, 

0.2 mr per hr scale.
280 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Stratigraphic section 4 (columnar section 4, pi- 18) Continued

Description

Thickness 

(feet)

Distance

above base

(feet)

Radioactivity (scale divisions 

0.2 mr per hr*

Min Max Avg

Claystone, carbonaceous, paper-thin; 

in beds 0.3 foot thick; interbedded 

with olive-gray silty, paper-thin 

claystone__ ___________________

Siltstone, buff______________.

Shale, olive-gray, silty; blockyweathering_ ____________________

Sandstone, white, calcareous_______.

5. 5 

1. 0

3.5 

1. 0

11.0 

5.5

4.5 

1.0

10

4 

2.5

'Radioactivity at the outcrop determined with standard survey Qeiger-Mueller countei} beta-gamma, 

0.2 mr per hr scale.

Stratigraphic section 5j['columnar"'sectionJI, pi. 18)

Distance 

Thick- above 

ness base 

Description (feet) (feet)

Sandstone, platy, tan, less silty at top of lowest 4.5 feet; over- 

' lain by 0.5 foot of flaggy, white, calcareous, medium-grained 

sandstone; overlain by 6.5 feet of buff, silty sandstone containing turtle plates, some limonite cement; capped by 0.5 foot 

of flaggy, sparsely fossiliferous calcareous sandstone _______ 11. 5 54. 5

Siltstone, brown-green, ferruginous, sandy lenses; sandy at top__ 3. 0 43. 0 

Shale, chocolate-brown, paper-thin___________________________ 1. 5 40. 0

Sandstone, gray, flaggy, fossiliferous, calcareous, micaceous (fossiliferous locality F-9)_________________________ 3. 0 38. 5

Shale, gray-brown, paper-thin_______________________________ 1. 0 35. 5

Sandstone, calcareous, silty_______________-_---_---_--__--_- 1. 0 34. 5

Sandstone, drab, thin-bedded, and gray, blocky-weathering silty

claystone_____________________________________________ 1. 0 33. 5

Sandstone, gray, micaceous, clayey, with ferruginous bands; olivegreen and more clayey near the top; many turtle bones and 

plates.____________________________________ 10. 5 32. 5

Sandstone, buff to white, with ferruginous layers, poorly sorted,

arkosic.________________________________ 11. 0 22. 0 

Sandstone, yellow-buff, silty_________-_______--_--------___- 3.0 11.0

Shale, chocolate-brown, carbonaceous, paper-thin._ ____________ 2. 5 8. 0

Sandstone, buff, grading downward into platy, gray shale_______ 2.5 5.5

Sandstone, silver-gray, platy, and silty clay stone. _____________ 3. 0 3. 0

Stratigraphic section 6 (columnar section 6, pi. 18)

Sandstone; white to buff, flaggy, fossiliferous, calcareous (fossiliferous locality F-10)________________________ 11.5 35.5

Sandstone; fine-grained, buff-weathering, white to yellow, silty__ 10. 0 24. 0 

Shale; platy to paper-thin, brown, carbonaceous_______________ 11. 0 14. 0

Sandstone; green-gray, calcareous, fossiliferous (ledge-former) __ 3. 0 3. 0
URANIUM IN THE RED DESERT, WYOMING 281

Stratigraphic section 7 (columnar section 7, pi. 18)

Distance

 ^Thick- above

ness base

Description (feet) (feet)

Sandstone, arkosic, salmon-pink, poorly sorted, coarse-grained, 

current-bedded (channel axes trend S. 75° W.), with some flaggy 

masses and white zones; a zone of log-shaped concretions in 

uppermost foot________________________________________ 15. 5 101

Sandstone, white, fine-grained, micaceous in part calcareous;

overlain by carbonaceous paper-thin shale._________________ 1.0 85. 5

Sandstone, coarse, white-weathering, buff with sparse, poorly preserved fossils; red to orange in basal foot___________.---_-_. i 5, 5 84. 5

Shale, silver-gray to olive-green, paper-thin___________________ 11.0 79. 0

Poorly exposed, steep local flexure, offset(?)___________________ 5. 5 68. 0

Sandstone, white to light buff, flaggy, variable amounts of calcareous cement from bed to bed; basal 3 feet white, coarsegrained, arkosic________________________________-_-_-____ 21. 5 62. 5

Shale, drab to olive-green, paper-thin, petroliferous and fossiliferous; 0.1-foot layers of buff, gypsiferous bentonite at 12.0 

feet, 15.0 feet, 35.0 feet, and 36.0 feet. Ostracods and small 

pelecypods collected at 16.5 feet; (fossil locality JBR-2)___ 38. 0 41. 0 

Sandstone, green or white calcareous with 0.5-foofc bed of coquina 

at top; (fossiliferous locality F-ll)______________ 3. 0 3. 0

Stratigraphic section 8 (columnar section 8, pL 18)

Poorly exposed, probably gray-brown, oolitic limestone, algal reef; 

this unit with the underlying unit forms cap rock of the land 

surface to the south and north____________________________ 4.0 44.0

Limestone, sandy, and subordinate sandstone; the limestone is 

brown flaggy, and contains oolitic grains and pale gray-green 

clay galls; the sandstone is buff and flaggy-________________ 5.0 40.0

Oil shale, paper-thin, chocolate-brown to gray, interbedded with 

gray, calcareous, oolitic sandstone, becomes platy, more gray, 

and silty claystone in uppermost 3 feet; abundant ostracods; 

abundant vertebrate fossils (turtle plates and bones, gar-pike 

scales) from 33 feet to 35 feet.____ _ ______________ 27. 0 35. 0

Siltstone, gray-brown_______________________________-______ 2. 0 8. 0

Sandstone, white, gray siltstone, silty sandstone, capped by 0.5-foot

gray medium-grained sandstone (bench-former) ______________ 6. 0 6. 0

Stratigraphic section 9 (columnar section 9, pi. 18)

Not exposed. The base of the Chadron formation is within this 

interval---_________________-_._--_____________ 28 534. 0

Sandstone, coarse-grained buff, and some mudstone; poorly exposed 

from 451 to 506 feet; sandstone has torrential current-bedding 

from 451 to 506 feet and contains pebbles of green chalcedony; 

fossil of large turtle at interval 439 feet to 441 feet_______ 77. 0 506. 0

Conglomerate, gravel and boulder; unit caps and forms Cyclone 

Rim; poorly exposed; pebbles and boulders are predominantly 

brown to black chalcedony and white agate; subordinately 

granitic, volcanic, and metasedimentary rocks._____________ 71.5 429.0
282 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Stratigraphic section 9 (columnar section 9, pi. 18) Continued

Distance 

Thick- above 

ness base 

Description (feet) (feet)

Poorly exposed (probably blocky brown shale, sandstone containing vertebrate remains; also probably includes pale-yellowgreen calcareous ash that was found 1 mile east)--________ 102. 0 357. 5

Sandstone; the uppermost 8 feet is fine-grained, calcareous, 

salmon-colored, or brown; the lower part is micaceous, white, 

in part fossiliferous, calcareous and ledge-forming, in part unconsolidated, poorly exposed. This is the upper sandstone 

unit mapped (pi. 16) _. _______________________ 41. 0 255. 5 

Shale, brown to buff, paper-thin to platy.____________________ 16. 5 214. 5

Sandstone, white to gray, arkosic, in part fossiliferous and calcareous. Fossil localities JBR-5, JBR-4, and JBR-3 at 196 

to 195.0 feet, 183.0 to 185.0 feet, and 170 feet, respectively. 

This is the lower sandstone unit mapped (pi. 16)__________ 26. 5 198. 0

Shale, gray to brown, paper-thin to platy; some %-inch beds

of sandy limestone ________________________ 10. 0 171. 5

Sandstone, calcareous, and sandy limestone__ _____ ______ 2. 0 161. 5

Claystone, gray, platy; interbedded with 1-foot beds of white to 

buff siltstone or sandstone in upper 11 feet; overlying olivegreen, platy to paper-thin shale that grades upward into 

clayey siltstone_____________________________ 22. 5 159. 5

Sandstone, calcareous, platy, current-bedded; weathers white___ 2. 0 137. 0 

Claystone, sandy and claystone; blocky-weathering, light-tan, 

gray-green, maroon, or buff; bentonitic in interval from 104.5 

to 110.0 feet______________________________ 34. 0 135. 0 

Sand, fine-grained, in part cemented by calcite to form sandstone; sparsely fossiliferous-______________________ 5. 5 101. 0

Sandstone, light gray-green, clayey.________________ 3. 5 95. 5

Limestone, clayey______________________________ 3.0 92.0

Shale, olive-green, paper-thin_____________________ 4. 5 89. 0

Limestone, fossiliferous, and 0.2 foot of paper-thin shale._______ 2. 5 84. 5

Sandstone, fine-grained micaceous flesh-colored________________ 6. 2 82. 0

Sandstone, white, ashy(?), fine-grained, highly gypsiferous; and 

oolitic limestone containing abundant ostracods; (section 

crosses fault striking N. 80° E., dipping steeply, Stratigraphic 

displacement is 3 feet down on southwest side); overlies gray, 

paper-thin shale with abundant ostracods_____________ _ 3. 5 75. 8

Limestone, white, clayey, with concretions. ___________________ 0. 3 72. 3

Claystone olive-green, sandy_______________________________ 5. 0 72. 0

Siltstone, clayey, platy, gray-green (weathers light green); the

basal foot is buff-yellow._____________________ 10. 0 67. 0 

Sandstone, arkosic, poorly sorted, buff, weathers white; varies in 

degree of cementation; the uppermost foot is a calcareous, 

ledge-forming micaceous sandstone that grades laterally into 

siltstone_______ _ _______________________ 11. 0 57. 0 

Claystone and shale, poorly exposed; gray (weathers white), 

gypsiferous; more gypsiferous, gritty and lighter in color near 

top-___.________________________________________ 17. 5 46. 0

Sandstone, poorly exposed, light-brown, silty____________ 15. 5 28. 5

Conglomerate, brown, containing pebbles, boulders of granitic 

rocks, chert, feldspar, quartzite; weathers white________ 11. 0 13. 0

Shale, green, blocky, poorly exposed ____________ 2. 0 2. 0
URANIUM IN THE RED DESERT, WYOMING

ANALYSES

283

TABLE 3. Analyses of material other than lignite, carbonaceous shale, schroeckingerite, or water, Red Desert, Wyo.

No. of sample

DW-102 (8:294) 

DW-112 (8:295) 

DW-108 (8:305). 

WNS-2 (S:2)._ _

WNS-3(S:4)._ _

WNS-6(S:8) ......

WNS-8(S:10). 

WNS-9(S:11)__ 

WNS-12(S:17)._..

WNS-15(S:20)....

WNS-17 (S:24). 

WNS-19(S:27)-... 

WNS-20 (S:28). 

WNS-23(S:31). 

WNS-24(S,:32). 

WNS-25-33. 

Locality of sample 

(pi. 16 unless otherwise noted)

Center of Lost Creek Dry 

Lake. 

.... . do.. __

Arapahoe Creek. _______

north of Hadsell shearing 

pens.

Dry-lake bed (pi. 17) .......

shearing pens.

kingerite deposit. 

Lake bed 2 miles east of Eagles

Nest.

In sump of water well at site 

of Californian-Wyoming Development Co. oil well. 

Antelope Hills, about 20 miles 

northwest of Hadsell shearing pens. 

Bank of Lost Creek, IJi miles 

north of Hadsell shearing 

pens.

A wide area northwest of the 

Lost Creek schroeckingerite 

deposit. 

Trench Ks (pi. 21), Lost Creek

schroeckingerite deposit.

Material of sample

Moist clay, about 1 foot beneath surface.

about 3 inches beneath surface. 

Fluorescent, green, gypsiferous

sandstone and claystone.

silt). 

Clay- .. .

Gray and brown clay with 

specks of lignite.

Gabbro dike intruding graniteFluorescent, gypsiferous, silty, 

claystone and sandstone.

halite, and gypsum). 

Selected pebbles of fluorescent 

agate-chalcedony.

Volcanic ash (dolomitic calcite

and volcanic glass).

Equivalent 

uranium 

(percent)

0.004 

.003

.005

.006

.005

.008

.005

.005

.003

.003

.007 

.000 

.004 

.001

.010 

.025

Uranium 

(percent)

0.001 

.002

.003

.002

.002

.001

.001

.002

.002

.002

.004 

.001 

.002 

.001

.000 

.011

TABLE 4. Analyses of water samples (in parts per million), Red Desert, Wyo. 

(Does not include samples taken from auger holes in 1950)

No. of sample

DW-102 (8:296) 

DW-85(S:264)_.__ _

WNS-10 (8:14). 

WNS-22(S:30) .

DW-85 (8:265).....

WNS-3(S:3)._ _ WNS-7(S:9). .

WNS-9 (S:13)._._.

WNS-17 (8:25) .

WNS-21 (8:29)....

Locality of sample 

(Pi. 16)

Draw. (Sampled May 5, 

1949.) 

Spring at mouth of Osborne 

Draw. (Sampled July 29, 

1949.)

(Sampled October 6, 1949.)

schroeckingerite deposit. 

Chain Lake (muddy water) _

volr in part on lignite bed l. 

Pit 14, Lost Creek schroeckingerite deposit.

Wyoming Development Co. 

oil well.

23 miles northwest of Hadsell shearing pens (not 

shown on pi. 16).

Uranium

0.00

.44

.01 

.13

00

.03

.01

46.00 

.03

.01

Hcor

70

83

136

114

2,147

102

486

COj 

2

7

6

17

242

0

34

SO r103

127

78

54

1,956

28

6,590

ci19

20

20

5

1,960

68

40

Total 

solids

294 

110

8,290

173

14,120 

640

200
284 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 5. Spectrographic analysis (in perc&nt) of samples of uraniferous lignite,

Red Desert, Wyo. 

[Paul R. Barnett, U/S.'GeologicallSurvey, analyst] i11*

No. of sample 

(locality on pi. 17)

DW-103 (8:297)... 

DW-103 (S:298).-- 

DW-103 (8:299)... 

WNS-1 (8:1).- 

WNS-4 (8:5). 

WNS-4 (8:6) 

WNS-5 (S:7) 

Lignite 

bed

1

1 

1 

1

2 

2 

2

Material of sample

Lignite

Carbonaceous sh 

Shale and lignite 

Lignite and c 

ceous shale. 

Lignite and shah 

Lignite

ale.. _

irbonaLignite and carbonaceous shale.

No. of sample

DW-103 (8:297)... 

DW-103 (8:298)... 

DW-103 (8:299).... ... .. 

WNS-1 (8:1) 

WNS-4(S:5) 

WNS-4 (8:6). . 

WNS-5 (S:7). 

No. of sample

DW-103 (8:297)-.. 

DW-103 (8:298)--. ... ... . 

DW-103(S:299)___... 

WNS-1 (8:1) 

WNS-4 (8:5) 

WNS-4 (8:6). ... .

WNS-5 (S':7). 

Ti

O.OX 

.X 

.X

.ox

.X

.ox

Sr

O.OOX

.oox 

.oox

.oox 

.oox 

.oox

Mn

O.OX

.ox 

.ox

.oox 

.oox 

.ox

Ca

o.x

.X 

.X

.X 

.X 

.X

Uranium 

in ash

0.019 

.004 

.008 

.022

.008 

.015

.011

V

O.OOX

.ox 

.ox

.ox 

.ox 

.ox

Ce

O.OX

.ox 

.ox

.ox 

.ox 

.ox

Cu

O.OOX

.oox 

.oox

.oox 

.oox

.oox

Or

O.OOX

.oox 

.oox

.oox 

.oox 

.oox

La

O.OX

.ox 

.ox

.oox 

.ox 

.oox

Pb

C)

O.OOX

.ox

.oox 

.ox

y

O.OOX

.oox 

.oox

.ooox 

.oox 

.ooox

Fe

o.x

X 

X 

X 

X 

X

.ox

Co

0.001 

.001 

.001

.ooox

Be

Tr. 

Tr. 

Tr.

"Tr."

Mg

O.X 

X 

.X 

.X

.OX

.ox 

.ox

Ni

0.003 

.002 

.003

.001 

.001

.001

Mo

O.OOX 

.OOX

.oox

.oox 

.oox 

.ooox

B

O.OX

.ox 

.ox

.X

.ox 

.ox 

.ox

Zn

&

.X

Sc

O.OOOX

.oox 

.oox

.oox 

.oox 

.ooox

Ga

O.OOOX

.oox 

.oox

.ooox 

.oox

Zr

(0

O.OOX

.oox

.oox

Ba

O.OOX

.ox 

.ox

.ox

.X

.ox

Si

o.x

X 

X

X 

X 

X 

X

Looked for but not found: As, Tl, In, Ge, Re, Sn, Nd, Ta, U, Nb, Pt, W, Bi, Sb, Cd, Au, Ag. 

i Looked for but not found.

TABLE 6. Analyses (in percent) of radioactive lignite, carbonaceous shale, clinker, 

and ash, Red Desert, Wyo.

No. of sample 

(locality on pi. 17)

Thickness of 

sample 

interval 

(feet)

Type of sample

Lignite bed and 

material of sample

Equivalent uranium

Uranium Ash

Uranium in 

ash

Lignite and carbonaceous shale (map symbol )

WNS-1 (8:1)-.-....

D W-103 (8:297) ....

DW-103 (8:298) -

DW-103 (8:299) 

WNS-4 (8:5) ......

WNS-4 (8:6) ....

WNS-5 (8:7) ....

WNS-11(S:15) 

WNS-13(S:18) ..

12

0.7

3.3

2.0

15-20

10

10

6

sample

sample

.... -do .......

.....do .. ......

.... -do.. 

.....do ........

Bed 1, lignite and

carbonaceous shale. 

Bed 1, lignite .....

shale. 

Bed 1, carbonaceous

shale, with thin lignite seams.

carbonaceous shale.

carbonaceous shale. 

Bed 2(?), lignite and

carbonaceous shale. 

Bed 3, lignite 

0.010

.007

.008

.010

.015

.005

.003

.004

.002

0.007

.003

.003

.004

003

003

003

.003

.002

38.7

24.1

85.7

69.1

74.7

32.2

26.0

9.1

0.022

.019

(VU.

.008

.008

.015

.011

.015

Clinker and ash (map symbol A)

WNS-1 (S:12) ...

WNS-11 (S:16) ..

WNS-16(S:21)-_ ..

WNS-16(S:22)...._

WNS-14(S:19) ..

3

3

3

feet.

baked clay.

"Rarl 1 ftQb

0.014

007

.007

.013

.012

0.005

.003

.003

.006

.005
URANIUM IN THE RED DESERT, WYOMING 285

TABLE 7. Analyses of rock samples, Lost Creek schroeckingerite deposit, Red

Desert, Wyo.

[The prefix ME to the sample number indicates the sample was taken by the Minerals Engineering Co., 

in 1948 and analyzed by the Brown Engineering Co., Grand Junction, Colo.; the prefix TW indicates 

the sample was taken by C. C. Towle and D. G. Wyant in 1949 and analyzed by the U. S. Geological 

Survey. Equivalent uranium was determined by reference to a standard uranium sample in which the 

uranium is in equilibrium with all its decomposition products. Corrected equivalent uranium was 

determined by reference to a standard uranium sample in which the uranium is in equilibrium with UXi 

(Thorium 234) and UXj (Protoactinium 234) only.]

No. of sample

ME-1925 _. 

ME-1927 ..

TW-30 ... .

ME-1936 .

ME-1935 ..

TW-33- 

ME-1938-... 

ME-1939-...

ME-1929 ..

ME-1931 ..

TW-35 ....

ME-1930 .. 

ME-1919 ..

TW-28 

ME-1923 .

ME-1921...-

TW-23-. 

ME-1934 

TW-24_.._.__

ME-1933-...

ME-1941 _ 

TW-22 ....

ME-1940 ..

TW-21 ....

ME-1952 

TW-20 ....

TW-18 ...

TW-15-......

TW-17 . 

TW-14 ....

TW-13 .... 

TW-10 ....

TW-ll--..... 

TW-6 ....

ME-1948 ..

TW-5.. ......

ME-1945 __

ME-1946- 

TW-7A...... 

TW-7B......

TW-8 ... ..

ME-1943-... 

TW-9 .....

Locality of 

sample 

(Pi. 21)

.....do ......

. .do . .

.....do........

.....do........

-..-do.........

 do. .

 ..do........

 . .do..--..

 .do... .... .

 do... 

... ..do.. ......

Trench £_.___

Trench E'.....

 .do .

 do . 

 do 

.....do.. ......

 do.. 

Trench G.. ...

..... do 

Trench H.. .. .

.....do. .....

.....do... .....

 do. 

 do... 

Trench K. ... .. 

.....do.........

. .do ..

.....do.... .....

 do 

.... .do... ......

..... do ...

Trench K\... . 

Trench K*... .

..... do .... .

Material of sample

Clayey conglomerate, claystone, sparse schroeckingerite, efflorescent white 

salts.

Gravel, no schroeckingerite...

Claystone and schroeckingerite.

Claystone and schroeckingerite.

Claystone, schroeckingerite, 

and efflorescent white salts.

Claystone and schroeckingerite.

Claystone, sandstone, and 

sparse schroeckingerite.

Green claystone and schroeckingerite.

Green claystone and schroeckingerite. 

Claystone, sandstone, and 

gravel (Qta) (includes 0.8 

foot of claystone and 

schroeckingerite). 

Terrace material (Qts) and 

clay; no schroeckingerite. * 

Green claystone and gravelly 

claystone; includes 1 foot of 

claystone and schroeckingerite. 

Green clay and white salt, 

terrace material (Qts); no 

sehroeckingerite . 

Terrace material (Qta); no 

. schroeekingerite.

Terrace material (Qtj) trace 

sehroeckingerite. 

Composite sample, terrace 

material, (Qtz) and clay.

Green siltstone, schroeckingerite.

Green claystone, sparse 

schroeckingerite.

Terrace material (Qta) and 

some clay.

Dimensions of 

sample

Length 

(ft)

5

2.5

8 

4 

5 

5 

16 

6 

5

5 

30

4 

20

12

12 

4

8

12

25

14

35

?

Thickness 

(ft)

0.67 

.25 

1.7

1

.5

.83 

.5

.8 

.5 

.5

.5 

.75 

1.3

.3 

1 

1

.83 

1.3

.83 

.5 

1.5

.82 

1

.83

.8

4

4.5 

3

3.5

4

4.5 

5

4.5

1

.5

.75 

.42 

1.3 

.5 

.8

1.0 

4.0

Equivalent 

uranium 

(percent)

0.041

.005

.15

.082

.018

.020

.048

.070

.067 

.054

.004 

.11

.005

.007

.004 

.009

.007

.37

.004 

.058 

.029

.007

Corrected equivalent 

uranium (percent)

0.066

.008

.24

.13

.029

.032

.077

.11

.11 

.086

.006 

.18

.008

.011

.006 

.014

.011

.059

.006 

.093 

.046

.011

Uranium (Percent)

0.1] 

.15 

.0,

.!( 

.05 

.0( 

.0* 

.15 

.U

.oe

.2]

.1: 

.L

.11

.11 

.1C 

.02

.K

.02

.08 .0' 

.Of

.If 

.Of

.1'

.1C 

.07

.OC 

.14

.OC

.OC

.OC 

.01

O.OC

.11 

.0£

.14 

.14 

.OC 

.05 

.04

.IS 

.OC
286 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

TABLE 7. Analyses of rock samples, Lost Creek schroeckingerite deposit, Red

Desert, Wyo. Continued

No. of sample

ME-1909-... 

ME-1950 .. 

TW-4........

TW-3- 

TW-39 

TW-1.. ......

TW-2. -.____.

ME-1906 ._

TW-32 

TW-34 . __

TW-31 _

TW-29 

ME-1905 ..

ME-1901 .. 

ME-1902 _. 

ME-1903 ._

TW-27.. 

TW-36. ...

ME-1907 -

TW-26 .... 

ME-1904.....

TW-25 .

ME-1908 

TW-19.......

ME-1917 .- 

TW-16 ....

ME-1918 

TW-12A 

ME-1913 .. 

TW-12B..... 

ME-1910 ..

ME-1911 

TW-38- __

ME-1914 ..

TW-37 

ME-1916-...

Locality of 

sample 

(Pi. 21)

Trench Ki. _

Trench L.. ...

.-...do.........

.... .do. ....... .

Trench M ..

Lost Creek 

bluff, 

 ..do ......

Pit 27.. .......

.....do ......

Pit 23.. .......

Pit 24-. .......

 ..do ......

Pit 18 (north 

Bide). 

Pit 18 (south 

side). . 

.....do ........

....-do.........

Pit 18 

Pit 21. ...

Pit 20-. ....... 

Pit 19 

 doHole 38 ... ..

.....do ......

Pit 16 (west 

side). 

Pit 16,. .......

Pit 16 (east 

side). 

Pit 14 (north 

side). 

Pit 14 (south 

side), 

. do.. ....

Pits. 

Pit 4..........

 do .... .

Pit 2.. ........

 do ...... 

Pitl . ......

Material of sample

Sandy green claystone with 

schroeckingerite. 

Green claystone with schroeckingerite. 

Green claystone with schroeckingerite. 

Claystone and schroeckingerite. 

Sandstone, claystone; no 

schroeckingerite.

Claystone and sparse schroeckingerite.

Clayey conglomerate, claystone, salts, and sparse 

schroeckingerite. 

Green claystone and schroeckingerite.

Claystone, some sandstone 

with schroeckingerite. 

Grab sample of ore pile from 

pit.

Claystone and schroeckingerite.

Claystone and schroeckingerite.

Green daystone with schroeckingerite.

Terrace material (Qtj) and 1 

foot clay.

Green siltstone with schroeckingerite.

Claystone, no schroeckingerite.

Claystone, sparse schroeckingerite.

Claystone, white salts, sparse 

schroeckingerite.

Dimensions of 

sample

Length 

(ft)

27

Thickness 

(ft)

0.75 

.8

.5 

.8 

1 

1.3

.7

1.3 

1

.8

1.3

1.5

.8

1

3

1.3

.8

.8

.5

Equivalent 

uranium (percent)

0.081 

.041 

.070 

.015 

.006

.039

.005 

.015

.050

.041 

.046

.12

.14

.097

.008

.034

.007

.038

.016

Corrected equivalent 

uranium (percent)

0.13 

.066 

.11 

.024 

.010

.062

.008 

.024

.080

.066 

.074

.19

.22

.16

.013

.054

.011

.061

.026

Uranium (percent)

0.08 

.09 

.11

.064 

.091 

.013 

.009

.13 

.049

.004 

.022

.055

.14 

.20

.14

.03 

.063

.065

.04 

.14

.09 

.17

.03 

.15

.28 

.008 

.14 

.048 

.24 

.004

.08 

.11 

.058

.04 

.018

.08
URANIUM IN THE RED DESERT, WYOMING 287

TABLE 8. Analyses (in parts per million) of surface- or ground-water samples, 

Lost Creek schroeckingerite deposit, Red Desert, Wyo.

No. of 

sample

DW-85-264 .

WNS-10-14. 

WNS-22-30. 

DW-85-265 .

WNS-9-13.-

DS-2-199 . 

DS-3-200 . 

DS-4-201.... 

DS-5-202 - 

DS-6-203 . 

D8-7-204 .

DS-S-205 _

DS-9-206 _

DS-10-207...

DS-12-208 

Locality of sample 

(pl. 21)

Spring at mouth of 

Osborne Draw. 

.....do............ 

 .do. . 

Lost Creek below 

bridge. 

Pit 14.............

Auger-hole E8-3.. 

Auger-hole ES-4.. 

Auger-hole ES-5.. 

Auger-hole ES-6..

Auger-hole E8-10. 

Auger-hole ES-12.

Date of 

sampling

May 5, 1949..

July 29, 1949 . 

Oct. 6, 1949 

1949 

1949 

1950 

1950 .......... 

1950 ......... 

1950- ......... 

1950 __ . ....

I960.. ........

1950 ....

1950 ....

1950 

1950 

U

0.44

.01 

.13 

.00

46.00 

.66 

.42 

.60 

.48 

.48 

.50 

.14 

.04 

'.88 

.07

C0^~

7 

6

"ir~

34 

11.1 

18.5 

18.5 

6.6 

8.7 

10.0 

10.6 

7.4 

9.2 

14.5

HOOJ83 

136 

""Hi"

486 

144.2 

190.3 

134.0 

162.1 

135.9 

123.8 

126.0 

134.5 

138.0 

100.5

SO"

127 

78 

""54"

6,590 

998.0 

932.0 

2,035.0 

893.4 

800.0 

184.4 

751.0 

823.0 

6,521.0 

2,566.0

ci20

20 

......

40 

22.6 

30.8 

31.2 

16.4 

15.2 

28.7 

19.5 

19.9 

78.3 

35.9

Total 

solids

294 

110

14,120

U« in 

sludge

20.0 

30.0 

20.0

PH

....

7.85 

8.35

s.oa

8.00 

8.20 

7.90 

8.00 

7.90 

8.10 

8.00

i Based on dried weight of sludge. 

J Insufficient sludge for analysis.

TABLE 9. (in parts per million) of plant and soil samples, Lost Creek 

schroeckingerite deposit, Red Desert, Wyo.

[Analyst, Helen Cannon]

Locality of sample 

(Pl. 21)

Spring at mouth of 

Osborne draw. 

Do.... ........... 

Do.. ....... ...

Do 

Do ... ..... ....

Outcrop (<*)_- . ... 

Do. ...... ...

Do .........

No. of 

sample

P la.... 

Plb___ _._ 

P 2. _ ...

P 3.-.. .

SI... .....

P 3a_... _. . 

P 4 .

S 2 .....

Material of sample

Water plant, unidentified, wet, as collected..

Greasewood (Sarcobatus vermiculatus) tops... 

Greasewood (Sarcobatus vermiculatus) roots 

in schroeckingerite-bearing clay. 

Soil at base of plant at depth of 1 foot __ 

Uranium

28

36 

1.7 

39 

10 

14 

7,400

270

Vanadium 

oxide 

(VnOj)

80

40 

00 

500 

40 

00 

400

100
288 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

AUGER-HOLE DATA

TABLE 10. Lithology of cuttings from shallow auger holes drilled by the U. S. 

Geological Survey in 1949, Lost Creek schroeckingerite deposit, Red Desert, Wyo.

Reference no. 

(pl. 19)

H-l. .............

H-2 __.__.-._._.

H-26 ...........

H-27 .. _ ......

H-28 ...........

H-30 _____ -

H-32... ...........

Description

Claystone, gray-green, silty, gypsiferous 

Claystone, siltstone, and green to bufE 

sandstone.

Claystone, green; contains schroeckingerite and gypsum.

Sandstone, white _________ ....

Clay, purple, silty _______ . __ .....

Claystone, gray to brown, containing 

schroeckingerite siltstone.

Claystone, gray, silty, and gray Claystone. 

Gravel and green, white, and bufE sand ..

Siltstone, gray-green, and flakes and pellets of gray platy shale.

Siltstone, green, clayey, and some sandstone. 

Claystone, gray... __________ .....

Depth 

in feet

0-1.3

1. 3-3. 0 

3. 0-5. 0

5. 0-6. 0 

0-0.5

0. 5-1. 3

1. 3-2. 3 

0-2.0

2.0-3.0

3.0-4.0

4.0-4.5

0-1.0 

1. 0-2. 0

2. 0-3. 5

3.5-4.5

4.5-4.8

4. 8-5. 2 

5. 2-5. 6

0-2.0

2. 0-2. 5

2. 5-3. 0 

0-9.7

9. 7-10. 2

10. 2-10. 5

10. 5-11. 2

11. 2-13. 4

13. 4-16. 0 

0-4.0

4. 0-6. 1 

6. 1-7. 4

7. 4-7. 6

7.6-8.0

Remarks

Terrace deposit.

Radioactivity: 2 scale divisions (mifliroentgens per 

hr) above background 

which averages 2.5 scale 

divisions. 

Terrace deposit.

Radioactivity: 32 scale divisions above background. 

Terrace deposit(?), colluvium(?).

No schroeckingerite.

Iron-stained zone at 3.3 feet.

Terrace deposit (?).

Shale is the ore-bearing bed 

in trench F. No schroeckingerite.

Platy shale fragments at 6.8

feet. 

Radioactivity: average of 10

scale divisions above background. 

Solution zone. Radioactivity: 5 scale divisions above 

background. No schroeckingerite.
TABLE 11. Lithology, content of uranium and equivalent uranium, and radioactivity of 

drilled by the U. S. Geological Survey in 1960, Lost Creek schroecking

[Radioactivity: samples, determined in the field with standard survey Qeiger-Mueller counter, beta-gamma shie

minimum 1, maximum 4, average 2.5 scale divisions; wall rock, determined with the same Geiger-Muel

milliroentgen-per-hour scale except for some parts of wall rock in holes ES-3, ES-5, and ES-6, where star (*

at surface of hole, minimum 6, maximum 11, average 8 scale divisions.]

Sample No. Lithology (sample log)

Field radio

Samples

Depth 

(ft)

Scale divisions 0.2 mr per hr

Min Max

Auger-hole ES-1

DS-1- 1.. ......

Clavstone. gray-green sandy; more than 10

0-2 

2-3 7 12

Avg

10

DS-1- 1.. ......

3.. ......

4

5.. 

6.. 

7...- 

percent fluorescent material (including 

schroeckingerite).

clayey arkose, 4-4.5 feet; more than 10 percent fluorescent material (including 

schroeckingerite) .

shale, 5.5-6 feet.

material.

rescent material. 

.....do. 

End of hole.

0-2

2-3

3-4.5

4.5-6

6-7.5

7.5-8

8-9

7

5

1

1

1

1

12

12

6

6

7

6

10

8

3

3

3

3.5
290 CONTRIBUTIONS TO THE GEOLOGY OP URANIUM

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Claystone, green-gray sllty; water table at 14 

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Claystone, green-gray sandy, 16-16 feet; greengray sllty claystone, 16-17 feet. 

Claystone, gray-green sllty, with thin redbrown layer (stained by iron oxides) at 18.5 

feet; brown sandstone at 19 feet. 

Siltstone, red-brown, 19-20 feet; gray-green 

clayey sandstone, 20-21 feet.

brown siltstone 22.6-23 feet.

Sandstone, gray pebbly, 25-27.5 feet; brown 

claystone 27.6-28 feet.

Sandstone, gray-green sllty, 29-31 feet; graygreen sllty pebbly sandstone with a little 

green clay, 31-83 feet. 

Claystone, brown sllty, 33-34 feet, gray-green 

sandy claystone, 34-36 feet; brown claystone, 

36-38 feet.

Claystone, green-gray, 41-41.5 feet; coarse 

white sandstone, 41.6-42.5 feet, brown-gray 

carbonaceous(?), 42.6-43 feet. 

Caved rock (gray-green clay, brown carbonaceous^) clay, and a little sand).

Claystone, brown sandy (Iron-stained), 49-49.2 

feet; gray to brown sandy claystone, 49.2- 

60.8 feet; brown-white sandstone, 50.8-51 

feet.

13-15 

15-17 

17-19

19-21 

21-23

23-25 

25-28

28-29 

29-33

33-38

38-39 

39-41 

41-43

41.6-43

43-49 

49-51

51

0 5 2 

Anger-hole ES-3

DS-8- 36 . .

37 

38.. ......

89.. __ ..

stone, 1-2 feet; less than 0.01 percent fluorescent material (including schroeckingerite).

clayey sandstone, 2.6-3 feet; less than 0.01 percent fluorescent material (including schroeckingerite).

much as J4 inch across; 0.01 percent fluorescent material (including schroeckingerite).

minor amounts of brown silt; 0.5 percent 

fluorescent material (including schroeckingerite).

0-2

2-3

3-4

4-6

1

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0.5

1

7

11

6

11

3.5

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2.5

5
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51-.- 

52... _ ..

53. ___ ..

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56.. ......

57........

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59........

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68.. -

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71. 

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of gypsum (?) which fluoresces pale yellowwhite.

brown iron-stained sandstone; trace of gypsum (?).

siltstone with subordinate sandstone, claystone, and gypsum(7), 8.1-10 feet.

gray to gray silty elaystone with sparse gypsum (?), 11-12 feet.

feet; red-brown sandy elaystone, 12.9-13 feet; 

brown-gray to white, clayey, medium-coarse 

sandstone, 13-14 feet; 0.01 percent fluorescent 

material.

of fluorescent material.

amounts of gray elaystone, 14.5-15.5 feet; 

gray clayey siltstone, 15.5-16 feet.

silty elaystone; traces of fluorescent material.

amounts of elaystone and fine sandstone.

sandy siltstone, intermixed; traces of fluorescent material.

white, fine sandy siltstone, 22-22.5 feet; 

brown-gray siltstone with some elaystone 

and sandstone, 22.5-24 feet; water table at 

22.5 feet.

stone and sandstone. 

 -do - 

. do... ._ 

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0-2

2-4

4-4.5

4.5-6

6-7

7-8

8-10

10-12

12-14

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14.5-16

16-18

18-20

20-22

22-24

24-24.5

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28-29

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7

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3

3.5

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3.5

3.5

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294 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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URANIUM IN THE RED DESERT, WYOMING 295

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100. ....

101- 

102 __ . _

103 ____

104........

105 ____

amount of claystone, 15-15.7 feet; maroonbrown sandy clayey siltstone, 15.7-15.8 feet; 

gray-green sandy siltstone, 15.8-16 feet; 

brown clayey siltstone, 16-16.2 feet; graygreen claystone, 16.2-17 feet; (water table at 

16.2 feet).

sandy clayey siltstone, 18-19 feet; green -gray 

silty sandstone, 19-19.5feet; gray-green sandy 

clayey siltstone, 19.5-20 feet; brown sandy 

siltstone, 20-20.5 feet; green-gray silty sandstone, 20.5-21 feet.

to brown-gray sandy silty claystone, 22-23 

feet; gray sandy clayey siltstone, 23-23.5 feet; 

brown-gray silty sandstone, 23.5-24 feet.

24-25.5 feet; gray-brown silty sandstone, 

25.5-26 feet; gray to brown-gray sandy silty 

claystone, 26-27 feet; gray sandy clayey siltstone, 27-29 feet.

stone, 29-32 feet; brown-gray sandy clayey 

siltstone, 32-33 feet. (Caved at 31 feet) .

15-17

17-21

21-24

24-29

29-33

33-34

34

Auger-hole ES-7

DS-7-106 

107.. ..'

108- ......

109 ..

110 ...

Sand, brown silty, 0-1 foot; brown sandy silty

clay, 1-2.5 feet; pale-buff sandstone with 

some siltstone, 2.5-3 feet. Sample contains 

some gypsum.

feet; brown-red sandy silty claystone, 4-5 

feet. Traces of fluorescent material in addition to minor amount of gypsum.

0.5-1 percent fluorescent material in addition to very small amount of gypsum.

siltstone; 0.5-1 percent fluorescent material 

in addition to minor amount of gypsum.

with some gray siltsone intermixed from 

10.5-11 feet.

0-3

3-5

5-7

7-9

9-11

0.5

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1

0

0

8

7

7

6

6

3.5

3

3.5

2.5

3
298 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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121.

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123..

124..

125..

126. 

127-

Claystone, green-gray sandy sllty, 36.6-37 

feet; gray-green sandy clayey slltstone, 37- 

38 feet.

Olaystone, gray-green sandy sllty, 38-39.5 feet; 

gray-green sandy siltstone with a little claystone, 39.5-40 feet.

Olaystone, gray-green silty, intermixed with 

gray-green sandy clayey siltstone.

Claystone, bluish-gi ay-green silty and a little 

sandstone.

Claystone, bluish gray-green silty intermixed 

with gray-green sandy clayey siltstone.

Siltstone, bluish-gray-green very sandy clayey.

Siltstone, very sandy clayey 

46-47.5 feet; gray-brown to gray-green sandy 

Claystone and clayey siltstone, intermixed, 

47.5-48.5 feet; bluish-gray-green very sandy 

clay-siltstone, 48.5-50 feet.

End of hole___________________.

36.5-38 

38-40

40-41

41-44

44-45

45-46

50

Anger-hole ES-8

DS-8-128-... Sand, brown to brown-bufl silty pebbly, with 0-2 0 

sparse gypsum(?).

129.. Sandstone, buff, with a smaller amount of silt- 2-4 0 

stone pebbles, and gypsum(?).

130.... Siltstone, red-buff sandy, 4-4.5 feet; gray- 4-6 0.5 

brown sandy siltstone, 4.5-6 feet; 0.1 percent 

fluorescent material and sparse gypsum (?).

131.... Siltstone, buff-gray sandy, 0.5 percent fluor- 6-8 1 

escent material and some gypsum (?).

132__ Siltstone, buff-gray sandy, 8-8.5 feet; buff silty 8-10 1 

sandstone, 8.5-9.5 feet; gray sandy siltstone, 

9.5-10.5 feet; 0.1-0.5 percent fluorescent material and some gypsum (?).

133__ Siltstone, buff-gray sandy, 10-11.5 feet; green- 10-12 1.5 

gray sandy siltstone, 11.5-12 feet; 0.1-0.5 percent fluorescent material and sparse gypsum (?).

134__ Siltstone, .buff-gray sandy, 12-13 feet; buff- 12-14 1 

gray silty sandstone, 13-14 feet; less than 0.1 

percent fluorescent material.

135___ Sandstone, gray sllty, 14-14.2 feet; pale yellow- 14-15 1 

buff sandy siltstone, 14.2-15 feet; 0.5 percent 

fluorescent material in addition to some 

gypsumf?).

136.. Siltstone, buff-gray sandy, 16-16.5 feet; water 15-17 1 

table at 16.5 feet; pale-buff silty sandstone, 

16.5-16.9 feet; gray sandy clayey siltstone, 

16.9-17 feet; 0.5 percent fluorescent material.

5.5

7

6.5

7.5

7.5

3.5

4
300 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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149.

150.

151.

152.

Sandstone, brownish pale-buff to brown-gray 

pebbly and a little siltstone; 0.5-1 percent 

fluorescent material.

In part caved rock from 20-22 feet. Brownish 

pale-buff to brown-gray pebble sandstone 

with subordinate buff-gray-white sandy 

siltstone; sample contains 0.1-0.5 percent 

fluorescent material.

Siltstone, buff gray-white sandy, with traces of 

fluorescent material.

Sandstone, pale-buff to pale-brown, very silty; 

sample contains 0.1 percent fluorescent 

material.

Siltstone, light-gray sandy, and intermixed 

pale-buff silty sandstone from 26-27 feet; 

water table reached at 27 feet; pale-buff silty 

sandstone with minor amounts of light-gray 

sandy siltstone, 27-29 feet; sample contains 

traces of fluorescent material. (Caved at 

27 feet.)

End of hole. __________________

20-22 

20-23

22-24 

24-26

26-29

0 

0.5

7.5

6.5

4 

3.5

3.5 

3.5

Auger-hole ES-10

DS-10-153-. Sandstone, brown silty with a few pebbles: 0-2 

sample contains 0.1-0.5 percent fluorescent 

material.

154---. - Sandstone, buff-brown silty, 2-2.7 feet;brown 2-4 

sandy siltstone with some claystone, 2.7-3 

feet; brown-red to grayish-red-brown silty 

claystone with some sandstone, 3-4 feet; 

0.5 percent fluorescent material and minor

155.- Siltstone, red-brown to brownish-gray-buff 4-6 

with intermixed claystone and sandstone; 

sample contains about 0.5 percent fluorescent material.

156. .- Siltstone, brown-gray to buff-gray with some 6-8 

claystone and sandstone from 6-7.5 feet; 

green-gray siltstone with some sandstone, 

7.5-8 feet; 2-5 percent fluorescent material.

157-. -. Siltstone, green-gray sandy, 8-10.5feet; brown- 8-11 

ish-green-gray sandy siltstone, 10.5-11 feet;

I-2 percent fluorescent material.

158-- Siltstone, brown-gray to green-gray sandy, 11-13

II-12 feet; gray-green siltstone with a small 

amount of sandstone, 12-13 feet; 0.5-1 percent fluorescent material.

6.5

14

3.5 

4

4.5

4.5
302 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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167 

168-.. .

169.......

170.......

171.. ..

Claystone (or shale), brown silty platy, with 

some sandstone and traces of fluorescent 

material. 

Claystone, brown silty (hard, platy), with a 

little sandstone; 0.01 percent fluorescent material. 

Claystone, brown slightly silty (hard, platy), 

contaminated with overlying material; contains 0.01 percent fluorescent material. 

Claystone, brown slightly silty, (hard, platy), 

14-17.5 feet; brown to yellow-brown sandy 

clayey siltstone, 17.5-17.7 feet; brown-gray to 

gray sandy siltstone, 17.7-19 feet; sample is 

contaminated and contains 0.5 percent fluorescent material. 

Siltstone, gray, and buff slightly green-gray 

clayey siltstone, intermixed; traces of fluorescent material. (Caved at 20 feet.) 

Siltstone, gray and brown-gray claystone; 

sample is contaminated with overlying material and contains 0.01-0.05 percent fluorescent material.

8-10 

10-12 

12-14 

14-19

19-21 

21-23

23

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DS-12-172.... 

173 

174..- 

175 

176.. ..

177.. __ .

178.. __

179 -

Sandstone, buff-brown very silty, 2-3 feet; 

grayish green-white slightly sandy siltstone, 

3-4 feet; sample contains some gypsum. 

Siltstone, grayish-green-brown sandy clayey, 

4-5 feet; gray-brown silty claystone (hard, 

platy), 5-6 feet; sample contains sparse gypsum. 

Claystone, maroon-brown silty, (hard, platy), 

6-7.5 feet; light-green claystone, 7.5-8 feet; 

sample contains traces of fluorescent material 

in addition to minor amounts of gypsum. 

Claystone, gray-green silty, with traces of 

fluorescent material. 

Siltstone, gray-green clayey, 10-11.7 feet; 

brown to gray-brown clayey siltstone, 11.7-12 

feet. Sample contains traces of fluorescent 

material. 

Caved rock (gray-green clayey siltstone and 

brown clayey siltstone). 

Siltstone, gray-green, with minor quantities of 

brown silty claystone; sample contains traces 

of fluorescent material

0-2 

2-4

4-6 

6-8

8-10 

10-12

10-12 

12-14
304 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

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194... ....

195... ....

196.......

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much as three-fourths of an inch in diameter) .

are as much as 1 inch in diameter; some Clinch grains are feldspar).

14-15.7 feet; gray-green and maroon-brown 

silty claystone, 15.7-16 feet (trace of fluorescent material).

gray-green claystone).

brown sandy siltstone, 19.5-21.5 feet; palebuff sandy siltstone, 21.5-22 feet (trace fluorescent material).

sandy siltstone, 23-24 feet; sample contaminated with caved rock.

some pebbles; sample contaminated.

and gray-green waxy claystone with minor 

sandstone, 32-33 feet; buff-brown clayey 

siltstone, 33-34 feet (trace of fluorescent 

material). Sample contaminated.

(Caved at 34 feet.) 

Hole abandoned at 35 feet without reaching 

water table.

8-10

10-12

12-14

14-16

16-18

18-22

22-24

24-29

29-34

34-35

& 

..f::. 

'

INDEX

Page

. _ . .. 252,265,268-269,283 

spectrographic_ ______ 250,263 

Antelope Hills... .... 240,255,283

Ash, lignite, uranium content-__.__.._ 252 

volcanic 242,253,274

Auger holes, deep. 265,271 

shallow..__. ____ _.___ 258,59

Bachman, G. 0., Densen N. M., and Zeller,

H. D., work cited________ 253 

t, P. E., work cited.. . _. 263 

aent complex.... . 242,283 

Berman, Jos., work cited. 261,262 

Bridger formation_-__._-______ 240,256 

Brown, E. W., cited 248 

Browns Park formation_ . 242

Caldte-.. - 262

' Cannon, Helen, cited.. . 265

Chadron formation. 242

Chain Lakes - _ 240, 242,245, pis. 16,17

^ Claystoae..___- 241,245,248,256,257,263,268,272

<£p^akerandash.__ 1 250,252

Continental Peak formation of Nace-.. ___ 241,

244,256,274

Correlation, radioactivity measurements__ 244 

, rock units 242,248,268

Cyclone Eim.^_ . ___ 240,243,255 

Cyclone Rim fault zone..- 243,272,273,274

 Densen, N. M., Bachman, G. 0., and Zeller,

H. D., work cited . . 253

^Eocene lakes_ _ __ 243,244,274 

Eocene rocks 240-241,242,264

history___________________ 243 

Equilibrium, radioactive..__ 252,253,261,262,265 

Equivalent uranium_ - _ 244,245,252 

Evans, R.D., and Goodman, Clark, work cited. 245

Fades, transition to.. 241,245 

Faults 243,259-260,264,273,285,286 

Field work..___ _____ 239,255,257-260 

Fluorescence___ __ 261,262-263,267,269,270 

Folds 242,243,259,260,264 

Fossils __ _. _____ 248,249,256

Granite Mountains_ _ __-_- 240,242 

Great Divide Basin. 229,243

Green Mountains_ _ - 240,255 

Green River Basin. 240 

Green Eiver formation... . 240,241,245 

Ground water, flow__ ______ 273,274 

Guillotte, G. B., work cited _ 272

Gypsum . 250

Lake basins, Pleistocene. 240,241,2451

Page

Leaching of uranium... 254 

Lenticularity of rock units_ _... 241 

Leucite Hills, lava of..__... .. ..... 245

Lignite, associated rocks_ - 248 

beds... .. 246-247

extent. _____ .. . 246 

formation of.. 243 

in test well__.__..___._.__ 246,254 

in seismic-survey shotholes. 248 

quality for fuel_____ _ -_. 250 

radioactivity of- -------------------- 246,250

Lithologic units__ ..._ _ __ 256 

Logging of auger holes . 271 

Lost Creek schroeckingerite deposit, associated

minerals____ - 261 

control by faults_._ 273 

description_______ . 256 

exploratory work ... 255,265-271,27S 

geography_______ - 255 

grade of ore____________ 264,265 

iron-stained zones. __ 257,263,273,274 

ore bodies 256,261,263,264 

ownership_._... 255

Masursky, Harold, and Pipiringos, G. N.,

work cited... 242,243

Nace, E. L., work cited... 241,242 

Nelson, J. M., and Slaughter, A. L., work 

cited_____ 

Oil-and-gas tests,_______ . 243 

Oligocene rocks (See also Chadron formation). 253 

Outcrops. 250,252,255-256

Petretic, Geo., work cited.. 265 

Pipiringos, G. N., and Harold Masursky,

work cited. 242,243

Pits. 257-258,265

Pleistocene rocks______ 242 

Prospecting.. . 276

Radioactivity measurements 244

anomalies in auger-hole, logs . 271

comparison______ 244-245

in auger holes .. 267

with airborne equipment 251

with car-mounted equipment 250

Recent sediments.._ - 242,244

Eed Desert, description 239-240

Roads 240,255

Rock Springs uplift.. 240 

Eosholt, John, cited 252

Samples, rock.. 252,

253,265,268,269,283-286,289-306

plant ___..... 265,287

water 265,271

307
308 INDEX

Page

Sampling- . --.. - . 245,

246,250,252-253,262,263,266-267,268-269,271

Sandstone...... 248,250,256,257,262,263,268,272,273

Schroeckingerite.- ____ 257,260-61 

accumulation.-. . ..._______ 272 

deposition. . ....... 261,264,272

detection of. 275 

flakes 261,272 

In eolluvium_ ... .._______ 264 

pellets-. _ . . 261,263 

formation.. _______ 272 

relation to iron oxide-stained zones____ 273 

relation to water table __.. 270,273,274 

transportation....___ .______ 261,273

Shale. 241,242,248,256,257,263,273,274

lacustrine or Green River-type. 241,256

carbonaceous, uranium in ___ 246,250,252

with lignite...__ ... 248,249,250

Sierra Madre Range... ..... ...... 240

Siltstone 263,264,268,272

Slaughter, A. L., and Nelson, J. M., work

cited..... 246,250,262

Source of uranium______________ 273-274 

Supply points.. ..___.________ 240 

Sweetwater Mountains... ... 240,242

Terraces.__ ..._ 244,256,261,274

Page

Thickness of rocks .... ..... .... 242 

Thompson, M. E., work cited .. 262 

Topographic features__________ . 240 

Towle, C. C., and Wyant, D. Q., work cited.. 262 

Trenches____ ... .. 259

Uraniferous lignite, origin . .... 253-254 

Uranium, in lignite, epigentetie origin *5*

syngenetic origin 254 

Uranium content, fluorescent chert_ . 245

lignite . 252-253

sludge from test well- . 263 

Uranium minerals, schroeckingerite.. 260-61

unknown minerals_ . . 262-263

Vegetation..... . . 240 

Volcanic rocks of the Leaucite Hills.. .. 242,245 j

Wasatch formation . 240,5 

Water supply... . . . 240, pi. 

Water table . 271 

movements__..__.. __ . 273-274 

Wyant, D. G., and Towle, C. C., work cited_ 262

Yen, T. C., cited. 248

Zeller, H. D., Densen, N. M., and Bachman,

G. 0., work cited .____----- 253