GEOLOGICAL SURVEY CIRCULAR 336

GEOLOGY OF THE SHINARUMP NO. 1 

URANIUM MINE, SEVEN MILE CANYON 

AREA, GRAND COUNTY, UTAH

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 DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 336

GEOLOGY OF THE SHINARUMP NO. 1 URANIUM MINE, SEVEN MILE 

CANYON AREA, GRAND COUNTY, UTAH

By W. L Pinch

This report concerns work done on 

behalf of the U. S. Atomic Energy 

Commission and is published with 

the permission of the Commission.

__________Washington, D. C., 1954

Free on application to the Geological Survey, Washington 25, D. C.
, B E A V E R *

'IRON .-'I GAR

WASHINGTON

L K«n«b'p U

A.R I

EXPLANATION

Uranium deposit or group of deposits 

in the Shinarump conglomerate

Uranium deposit or group of deposits 

in the Chfnle formation

25 0

I i i i i I

Figure 1. Map of part of the Colorado Plateau showing the location of the Shinarump No. 1 mine and the distribution of uranium deposits in the Shinarump and Chinle formations.
GEOLOGY OF THE SHINARUMP NO. 1 URANIUM MINE, SEVEN MILE 

CANYON AREA, GRAND COUNTY, UTAH

By W. I. Finch

	CONTENTS

Page Page

Abstract..................................... 1 History and production........................ 4

Introduction.................................. 2 Ore deposits................................. 4

General geology............................... 2 Mineralogy.................................. 5

Stratigraphy............................. 2 Petrology.................................... 6

Stratigraphic section................ 2 Habits of ore bodies .......................... 9

Cutler formation.................... 3 Spectrographic study.......................... 10

Moenkopi formation................. 3 Age determinations of uraninite................ 12

Shinarump conglomerate Origin of deposit............. ................ 12

and Chinle formation.............. 3 Conclusions........ ........... .............. 13

Wingate sandstone................... 4 Literature cited.............................. 13

Jurassic rocks..................... 4 Unpublished reports .......................... 14

Structure................................ 4 Group number classification................... 14

ILLUSTRATIONS

[Plates are in pocket]

Page

Plate 1. Geologic maps and sections of the Seven Mile Canyon and

Shinarump No. 1 mine areas, Grand County, Utah. 

2. Selected maps of mine walls from the Shinarump No. 1 mine. 

Figure 1. Map of part of the Colorado Plateau showing the location of the Shinarump No. 1 mine

and the distribution of uranium deposits in the Shinarump and Chinle formations................ ii

2. Paragenesis of uraninite and sulfide minerals, Shinarump No. 1 mine............................. 6

3. Photomicrographs of polished and thin sections from the Shinarump No. 1 mine .................. 7

4. Cumulative curves of grain size of samples from the Seven Mile Canyon area.................... 9

5. Frequency curves of grain size of samples from the Seven Mile Canyon area .................... 9

6. Curves of grain size of ore-bearing and barren siltstone from Shinarump No. 1 mine............. 10

7. Geologic map and sections of the Shinarump No. 1 mine........................................ 11

TABLES

Page

Table 1. Samples from Seven Mile Canyon area..................................................... .. 8

2. Geometric mean values (in percent) of elements contained in barren and uranium-bearing 

rock from the Shinarump No. 1 mine, copper-bearing rock from nearby copper deposits, 

and uranium-bearing rock from a nearby deposit in the Morrison formation................... 12

ABSTRACT are found in three zones in the lower 25 feet of the Chinle

formation of Late Triassic age. The Shinarump No. 1

The geology of the Shinarump No. 1 uranium mine, mine, which is in the lowermost zone, is located on the 

located about 12 miles northwest of Moab, Utah, in the west flank of the Moab anticline near the Moab fault. 

Seven Mile Canyon area, Grand County, Utah, was

studied to determine the habits, ore controls, and The Shinarump No. 1 uranium deposit consists of 

possible origin of the deposit. discontinuous lenticular layers of mineralized rock, irregular in outline, that, in general, follow the bedding.

Rocks of Permian, Triassic, and Jurassic age Ore minerals, mainly uraninite, impregnate the rock, 

crop out in the area mapped, and uranium deposits High-grade ore seams of uraninite and chalcocite occur
along bedding planes. Uraninite formed later than, or 

simultaneous with, most sulfides, and the chalcocite 

may be of two ages, with some being later than uraninite. Uraninite and chalcocite are concentrated in the 

more poorly sorted parts of siltstones. In the Seven 

Mile Canyon area guides to ore inferred from the study 

of the Shinarump No. 1 deposit are the presence of 

bleached siltstone, carbonaceous matter, and copper 

sulfides. Results of spectrographic analysis indicate 

that the mineralizing solutions contained important 

amounts of barium, vanadium, uranium, and copper, 

as well as lesser amounts of strontium, chromium, 

boron, yttrium, lead, and zinc.

The origin of the Shinarump No. 1 deposit 

is thought to be hydrothermal.

INTRODUCTION

The Shinarump No. 1 uranium mine is located 

about 12 miles northwest of Moab, Utah, in the Seven 

Mile Canyon area, Grand County, Utah (fig. 1). A 

road about a quarter of a mile long connects the mine 

area with U. S. Highway 160. The mineralized zones 

crop out along a northwest-trending escarpment paralleling Highway 160. Vegetation in the area is sparse.

The United States Geological Survey studied the 

geology of the Shinarump No. 1 mine on behalf of the 

Atomic Energy Commission in order to determine the 

habits, ore controls, and possible origin of the deposit. 

Vance Thorriburg, owner of the claims, was most cooperative and helpful throughout the investigation.

Field study began in January 19 52 and was carried 

on intermittently until April 1953. The Shinarump No. 1 

mine workings were mapped in detail by tape and opensight alidade early in 1952. Later a planetable map was 

made of the area surrounding the mine to relate the mine 

geology to the stratigraphic and structural features. A 

total of 31 samples of ore-bearing and barren rock were 

taken in the area and analyzed chemically and spectrographically. Stratigraphic sections were measured near 

the mine and in Little Canyon south of Seven Mile Canyon.

Previous work in the area includes a study of the 

geology of the area between the Green and Colorado 

Rivers by McKnight (1940) and recent studies of the 

Seven Mile Canyon area in connection with exploration 

by the Atomic Energy Commission by Droullard (1951) 

and Droullard and Jones (1952).

GENERAL GEOLOGY

Rocks of Permian, Triassic, and Jurassic 

age crop out in the area mapped. Uranium-bearing 

rock occurs in lower beds of the Upper Triassic 

rocks. Copper-bearing rock occurs in a large 

talus block that may be Dakota sandstone of 

Cretaceous age and in the Moab fault gouge zone. 

Outside the Shinarump No. 1 mine area, uraniumbearing rock also occurs in the Morrison formation of Late Jurassic age (pi. 1). Copper-bearing 

rock occurs along the Moab fault northwest of 

the area mapped.

The nearest igneous rocks crop out in the La Sal 

Mountain laccolith about 20 miles to the southeast. The 

major structural features are the Moab anticline and 

Moab fault. The general geology of the surrounding

area is given by McKnight (1940). Below is a brief 

discussion of the stratigraphy and structure of the 

Shinarump No. 1 mine area.

Stratigraphy 

Stratigraphic section

In the Shinarump No. 1 mine area, the Cutler, 

Moenkopi, Shinarump, Chinle, and Wingate formations 

form an escarpment along the west side of the Moab 

fault. The Upper Jurassic Morrison formation on the 

east side of the fault has been faulted against the 

Permian Cutler formation. Thus, in the area mapped, 

Jurassic rocks between the Wingate (Triassic) and 

Morrison formations are not exposed. A measured 

section of the rocks near the mine follows.

Shinarump no. 1 claim section, measured about 

1. 500 feet south of Corral Canyon. Grand County. 

Utah. Line of section S. 65 W.. sec. 27. T. 24 S.. 

R. 20 E.. Salt Lake meridian

[Measured December 1952]

Wingate sandstone (incomplete): 

Top of section, not top of exposure. 

Sandstone, yellowish-gray (5Y8/1) 1 ; 

weathers pale red (1OR6/2); fine-grained 

to very fine grained; bedding not distinct; 

only basal 5 ft examined; estimated height 

of cliff face 220 ft. Chinle formation and 

Wingate sandstone contact placed at sharp 

change from cliff-forming sandstone of 

Wingate to slope-forming shale and sandstone of Chinle. Mudcracks at base of 

Wingate; light-green alteration of upper few 

inches of Chinle and of mudcrack fillings. 

(Unit not measured.)

Unconformity (local?).

Chinle formation:

Shale and interbedded sandstone and conglomerate, pale-red (1OR6/2); sandstone, 

fine-grained; conglomerate contains mostly 

clastic limestone concretions. Sandstone 

and conglomerate beds mostly 1 ft or less 

in thickness. For most part unit forms 

steep rubble-covered slope................... 73

Sandstone, light-red (5R6/6), fine-grained; 

quartzitic; thin horizontal bedding with some 

low-angle crossbedding; forms ledge; 

channels into lower unit..................... 7

Sandstone and mudstone, moderate-red 

(5R5/4), fine-grained; irregular bedding; 

forms ledge ............................... 12

Sandstone and conglomerate, pale-red (5R6/2) 

and light greenish-gray (5GY8/1), fine-grained. 

Conglomerate consists mainly of clastic limestone concretions. Abundant hematitic concretions scattered mainly in sandstone beds, 

some silicified wood, some white calcite filling cavities and fractures. Irregular bedding 

and penecontemporaneous slumping. This and 

upper two beds form a single ledge which divides the Chinle into two units; base of unit 

channels in lower beds and is base of upper 

unit of Chinle formation- .... 1°

1 See footnote p. 3-
Chinle formation Continued Feet 

Sandstone, pale-red (5R6/2) fine-grained,

thin-bedded; with interbeds of yellowish

gray (5X7/2); beds weather with hackly

surface; forms a steep covered slope ........ 64

Conglomerate, yellowish-gray (5Y7/2);

clastic limestone concretions and

some white quartz; pebbles range

from i to 2 inches across; calcareous

cement; irregular bedding; forms ledge ..... 6 

Sandstone and siltstone, moderate

red-orange (10R6/6); sandstone, finegrained, in beds mainly 1ft thick

which form discontinuous channelfillings; small scale crossbedding;

some miniature slumping; unit forms slope. .. 48 

Sandstone, grayish-green (5GY6/1),

fine-grained; composed of quartz grains,

white mica, some carbon flecks; calcareous cement; thin-bedded; weathers

into small irregular crescent-shaped

partings; forms slope; lenticular,

channels into lower unit ................... 4

Siltstone, dark red-brown (10R.3/4);

some white mica and coarse quartz

sand grains; thin-bedded; forms slope;

uranium bearing in places ................. 22

Claystone and siltstone, light-green

(5G7/4) and light -brown (5YR6/4); some

fine quartz grains, white and green

mica, wood fragments; thin -bedded;

forms slope; grades into overlying

beds. Uranium bearing in places;

some wood replaced by uraninite

and becquerelite ............................ 22

Conglomerate, greenish-gray (5GY6/1);

clastic lime pebbles as much as 2 in.

across, some quartz grains, some

limonitic stains; calcareous cement;

uneven bedding; forms ledge. Uranium

bearing in upper part, uraninite forms

rims about some limestone pebbles. ........ 13

Muds tone, pale -red (10R6/2); some limestone pellets. .............................. 2

Conglomerate, pale -green (5G7/2);

clastic limestone pebbles; calcareous

cement; irregular bedding .................. 1

Siltstone and conglomerate, moderate

reddish-orange (10R6/6); conglomerate

contains clastic limestone pebbles

and reworked siltstone pebbles from

the Moenkopi; abundant limonite

staining; some white quartz grains;

irregular bedding; forms steep slope

beneath conglomerate ledge. Uranium

bearing at Shinarump No. 1 mine. ........... _ 7

Total Chinle formation .................. .297

Shinarump conglomerate absent in line of section. 

Unconformity (erosional).

Moenkopi formation: 

Shale and mudstone, pale -green (5G7/2) and

mode rate -red (5R5/4); mica along bedding;

bedding poorly developed ................

Shale, grayish-brown (5YR3/2); some white

mica; bedding poorly developed ...........

Sandstone, mode rate -red (5R5/4) grading

upward into grayish-green (10GY5/2);

coarse-grained, massive. ................

Moenkopi formation Continued Feet 

Sandstone, very pale-orange (10YR8/2) to 

moderate reddish-brown (10R4/6); finegrained, grading to coarse-grained near 

top; angular quartz grains, abundant 

muscovite and biotite; thick-bedded; forms 

rounded slope; some bleaching along and 

across bedding ............................ 11

Total Moenkopi formation.................. 20

Unconformity ?).

Cutler formation:

Sandstone and shale, moderate red-brown 

(10R4/6); some biotite along bedding; 

irregular bedding; forms bench.............. 31

Sandstone, moderate reddish-brown (10R4/6); 

medium- to coarse-grained; some mica; very 

thickly crossbedded; irregular bleaching along 

some beds; weathers rounded; forms ledge..... 24

Shale, pale-red (10R6/2); contains mud-crack 

fillings; bleached in places .................. 1

Sandstone, grayish red-purple (5RP4/2) to 

moderate-red (5R4/6), coarse-grained to 

conglomeratic; some white mica and feldspar, 

abundant biotite; thin-bedded to low-angle 

cross lamination; bleached spheres from 

i inch to 1.5 ft in diameter-cutting bedding; 

friable; forms ledge. (Base of outcrop, 

not base of formation)...................... 10

Total Cutler formation exposed ............ 66

1 Rock-color chart prepared by "The Rock-Color Chart Committee," 

E. N. Goddard and others, National Research Council, Washington, D. C., 

1948.

Cutler formation

Only the upper 66 feet of the total 1,000 feet or 

more of the Cutler formation of Permian age is exposed in the area mapped. The exposed Cutler consists of medium- to coarse-grained sandstone and 

muddy sandstone and pale-red shale. Bleaching along 

fractures and bedding planes is common. Cross-laminated 

sandstone forms a prominent rounded ledge near the 

top of the Cutler. Locally along the Moab anticline an 

angular and erosional unconformity exists between the 

overlying Triassic Moenkopi and the Cutler. However, 

the contact between Permian and Triassic rocks in the 

Shinarump No. 1 mine area is difficult to determine.

Moenkopi formation

The Moenkopi formation of Early and Middle( ?) 

Triassic age is 20 feet thick in the measured section 

near the Shinarump No. 1 mine and pinches out about 

450 feet to the north, and a few miles south, the Moenkopi 

attains a thickness of about 450 feet. Thin-bedded 

shale and mudstone, and massive sandstone make up the 

Moenkopi strata. A distinct moderate reddish-brown, 

abundant mica, and ripple-marking characterize the 

Moenkopi. The overlying Upper Triassic beds were deposited on an erosional surface formed on the Moenkopi 

and, in places, on the Cutler.

Shinarump conglomerate and Chinle formation

The Shinarump conglomerate of Late Triassic age 

is absent in most of the area mapped. McKnight showed 

that the Shinarump conglomerate pinches out along an
irregular east-west line about 15 miles north of the intersection of the Green and Colorado Rivers, and only iso - 

lated outcrops of Shinarump conglomerate were mapped 

north of this line. One such isolated outcrop was mapped 

inthe vicinity of Little Canyon (pi. 1). The Shinarump conglomerate in Little Canyon ranges from 5 to 10 feet in 

thickness and consists of a friable white coarse-grained 

to conglomeratic quartz sandstone. The Shinarump becomes discontinuous and lenticular near the northern 

edge of this outcrop. Siltstone and fine-grained sandstone of the Chinle truncate many of the Shinarump 

lenses. In an opencut adjacent to the Shinarump No. 1 

mine, a white coarse-grained to conglomeratic quartz 

sand lens corresponding to the Shinarump conglomerate 

is truncated by the fine-grained sediments containing 

the ore deposit. Thus, the Shinarump north of the main 

area of deposition was deposited as small thin lenses or 

channel fills and was, at least in part, removed before 

or during the deposition of the overlying Chinle.

The Chinle formation of Late Triassic age is 

297 feet thick in the section measured at the mine. In 

the Seven Mile Canyon area, the Chinle formation may 

be divided into a lower and an upper unit. The base of 

a prominent ledge of fine-grained sandstone and limestone pebble conglomerate that is characterized by 

slump-bedding marks the division of the two units. The 

lower unit is composed of thin- and irregular-bedded 

light-green to pale-red siltstone, sandstone, and limestone pebble conglomerate. Much of this unit is covered 

by talus. A limestone-pebble conglomerate bed about 

10 feet above the base of the Chinle serves as a "marker 

bed" in the Shinarump No. I mine area (see section AB-C, pi. 1). The upper unit is composed mostly of palered shale and sandstone which forms for the most part 

a covered slope. Near the Moab anticline the contact 

between the Chinle and the Wingate sandstone is a local 

unconformity.

Many of the uranium deposits in the area between 

the Green and Colorado Rivers lie near the northern edge 

or north of the pinchout of the Shinarump conglomerate 

(fig. 1). In the Seven Mile Canyon area, the uranium deposits lie north of the Shinarump outcrop in Little Canyon. 

Thus, the uranium deposits are related to the edge of 

Shinarump deposition on a regional and local scale.

Uranium-bearing rock in the Seven Mile Canyon 

area is found in many zones in the lower unit of the Chinle, 

but the ore deposits are found mainly in three zones in 

the lower 25 feet of the Chinle (section A-B-C, pi. 1). 

The Shinarump No. 1 mine is in the lowermost ore zone.

Wingate sandstone

The Wingate sandstone of Late Triassic age consists of massive yellowish-gray fine-grained sandstone 

that weathers pale red and is characterized by surface 

coatings of black desert varnish. In the Seven Mile Canyon area the Wingate, which forms a massive cliff, is 

over 200 feet thick.

Jurassic rocks

In the vicinity of the Shinarump No. 1 mine, the 

Brushy Basin shale member of the Morrison formation 

of Late Jurassic age is faulted against the Permian and 

Triassic rocks. The Brushy Basin consists mainly of

light-green mudstone. Boulders of the Burro Canyon 

or Dakota formations of Cretaceous age cover some of 

the slope of Brushy Basin exposures.

Structure

The Shinarump No. 1 mine is located on the west 

flank of the Moab anticline about 700 feet west of the 

Moab fault. The beds strike N. 15° E. and dip 8° NW. 

at the mine. The joints occur in two sets; one major 

set strikes N. 5°-75° W. and dips 50° NE. to vertical, 

and a minor set strikes N. 35°-70° E. and dips 70° SE. 

to vertical.

The Moab anticline, a result of salt intrusion, extends about 15 miles northwest of the Colorado River. 

The Moab fault, a normal fault, lies a short distance 

southwest of the crest of the Moab anticline. The fault 

extends about 30 miles northwest from the Colorado 

River and has a general trend of about N. 45° W. nearly 

parallel to the axis of the Moab anticline. In the Shinarump No. 1 mine area, the fault has a maximum displacement of about 1, 800 feet and dips about 65° NE. and 

makes a gentle turn to the west near the Shinarump Nos. 1 

and 3 mines.

The Moab anticline was in existence at the end of 

Permian time as shown by the angular and erosional unconformity between the Cutler and Moenkopi formations. 

McKnight reports that the deformation was renewed in 

middle Triassic time, prior to the deposition of the orebearing Chinle strata, and was resumed once again during the Laramide orogeny at the end of the Cretaceous 

period. However, in similar structures on the Colorado 

Plateau, Stokes and Phoenix (1948) and Shoemaker (1951) 

find that the intrusion of salt was continuous from Permian 

to Late Jurassic time; and the author believes the Moab 

anticline had a similar history. McKnight correlates the 

faulting along the Moab Valley anticline with the normal 

faulting of the Wasatch Plateau that is later than preEocene folding and possibly late Tertiary. The Moab 

fault may be related to the Laramide orogeny or the 

collapse of the salt structures later in the Tertiary or 

Quaternary periods. Field relations are so obscure that 

the dating of the Moab fault is uncertain. Evidence genetically relating the uranium deposits in the Seven Mile ' 

Canyon area to the Moab fault is lacking.

HISTORY AND PRODUCTION

In February 1948 Gordon Babbel and Nicholas 

Murphy, of Moab, Utah, discovered the Shinarump No. 1 

mine. During the following year, claims were staked 

throughout the Seven Mile Canyon area, and a few tons 

of ore was shipped in 1949. The mines were idle during 

1950, but in 1951 mining from several prospects was resumed and since then has been continued intermittently. 

Over a thousand tons of ore was shipped from the Shinarump No. 1 mine between 1948 and January 1953. The 

Thornburg Mining Company, Grand Junction, Colo. owns 

the Shinarump mines Nos. 1, 3, and 4.

ORE DEPOSITS

Copper-bearing rocks occur separate from uraniumbearing rocks in the Shinarump No. 1 mine area. Copperbearing rock is found along the Moab fault and in a talus
block that is thought to be Dakota sandstone of Cretaceous age. Copper carbonates are found along fractures and bedding planes as well as disseminated in 

sandstone in a prospect in the talus block. Fractured 

rock along the fault in an abandoned shaft at the base of 

the talus block contains copper carbonates. The copper 

prospects are not commercial in size or grade. Uranium is not known to be associated with the copper.

The uranium-bearing material in the Shinarump 

No. 1 mine area occurs mainly in three zones in the 

lower 25 feet of the Chinle formation. The zones include, in ascending order, a basal siltstone unit, the 

top of the overlying limestone-pebble conglomerate 

"marker bed," and an irregular dominantLy siltstone 

zone 5 to 10 feet above the conglomerate.

The highest zone consists of small calcareous 

nodules of rich concentrations of uranium minerals associated mainly with wood and carbonaceous rubble in 

greenish siltstone and minor limestone-pebble conglomerate beds. Some wood is almost completely replaced 

by uraninite, which has been altered to becquerelite in 

places. If the frequency of occurrence of nodules is 

great enough, the deposit can be economically mined. 

At the Shinarump No. 3 mine this zone, although discontinuous, is as much as 3 feet thick.

The middle zone is in the upper part of the conglomerate "marker bed" where limestone pebbles are. 

rimmed and replaced in part by uraninite. This conglomerate is mineralized north of the Shinarump No. 1 

mine (pi. 1). Most of the uranium-bearing material in 

these two zones is associated with calcite nodules or 

limestone pebbles, carbonaceous material, and gray or 

green rock.

The Shinarump No. 1 mine is in the lowermost ore 

zone, which is made up mostly of siltstone with some 

interbeds of mudstone, sandstone, and conglomerate 

and ranges from 5 to 10 feet in thickness. Where this 

zone is mineralized, the beds are bleached from red to 

gray and green. The saucer-shaped area of bleached 

ore-bearing beds extends from 1 to 15 feet laterally 

beyond the limits of the deposit. The limestone-pebble 

conglomerate "marker bed" is fairly uniform and massive 

throughout the area except above the Shinarump No. 1 deposit and above the deposit in the lower uranium-bearing 

zone at the Shinarump No. 4 prospect, the thinning and 

less massive character of this "marker bed" above the 

deposits in the lower zone may be significant in prospecting for ore in the Seven Mile Canyon area.

On the basis of the major metal content, uranium 

deposits of the Colorado Plateau may be divided into 

vanadium-uranium, copper-uranium, and uranium. The 

Shinarump No. 1 deposit contains only minor amounts 

of copper and vanadium and thus, is a uranium deposit. 

Oxidation of the uranium deposits such as the Shinarump 

No. 1 is generally slight, and deposits of this type are 

less obvious to the prospector because secondary uranium minerals are scarce at the outcrop.

MINERALOGY

Other writers have studied the mineralogy of the 

Seven Mile Canyon area (Weeks, 1952, andRosenzweig, 

in report by Droullard and Jones, 1952). Only the mineralogy of the Shinarump No. 1 mine is discussed here.

Uraninite (pitchblende), ideally UO2 (commonly 

contains UOa), is the principal uranium mineral. It 

occurs as microscopic grains mixed with chalcocite 

and other sulfides replacing carbonaceous material 

and disseminated in siltstone. Rich concentrations 

of uraninite occur in seams as much as a half 

an inch thick along bedding planes.

Some uraninite is slightly altered to a burntorange material resembling gummite, and halos of 

this material are present about unaltered uraninite. 

Schroeckingerite NaCa3 (UO2)(CO3) 3 (SO4)F. 10H2O, ,apale 

yellowish-green mineral, and becquerelite 2UOs.3H 2O, 

a yellowish-orange mineral, occur along fractures 

and bedding planes near the edges of the deposit 

nearest the surface. No secondary vanadium-uranium 

minerals were found.

The sulfides present in the ore are chalcocite, 

pyrite, bornite, chalcopyrite, and blue chalcocite 

(digenite?, solid solution of covellite and chalcocite). 

All the sulfides, except the blue chalcocite, occur as 

scattered grains in both barren and uranium-bearing 

rock. Chalcocite and pyrite are more abundant in the 

uranium-bearing rock. Uraninite is associated with all 

the sulfides but most commonly with pyrite and chalcocite. Some malachite is found coating chalcocite.

Gangue materials include barite, calcite, gypsum, 

and carbonaceous matter. Carbonaceous matter in the 

form of leaves, twigs, and small pieces of wood is 

most abundant right above the uranium-bearing beds. 

There is no megascopic difference in the physical 

properties of barren and radioactive carbonaceous 

matter. Limonite is rare, whereas hematite is abundant in places.

In both barren and uranium-bearing rock, the 

quartz has been etched and crushed. Bornite, chalcocite, pyrite, uraninite, calcite, and barite are later 

than etching. Fractures in crushed quartz are either 

void or contain calcite. Uraninite, pyrite, and chalcocite are associated with poorly sorted parts of a rock 

and, in general, follow bedding planes. Stringers of 

these minerals wrap around and are deflected by the 

large quartz grains. Many blebs of uraninite and pyrite 

are zoned with the uraninite forming rims about finegrained pyrite. Pyrite was observed in very fine fractures in siltstone. Chalcocite occurs in vertical veinlets as much as half a millimeter wide that strike eastwest. Nuclear-track plates on thin sections of these 

veinlets indicated the absence of radioactive minerals. 

However, copper and uranium minerals extend outward 

along bedding planes away from these fractures. Calcite and more rarely barite have filled voids in the rock.

Paragenesis of uraninite and sulfides from the 

Shinarump No. 1 mine is given in figure 2. The conventional line diagram is shown with the circular diagram (Robertson and Vandeveer, 1952) to compare the 

two methods of showing paragenesis. The circular 

diagram shows the minerals observed in contact; 

pyrite, for example, was observed in contact only 

with uraninite and chalcocite. The line diagram shows 

that some pyrite is later than chalcopyrite even though 

the two were never observed in contact. It is difficult 

to show two groups of simultaneous minerals in the 

circular diagram. The two diagrams, thus, complement each other.
BORNITE 

<»$

URANINITE

CHALCOCITE

CHALCOPYRITE

CHALCOPYRITE

BLUE CHALCOCITE

 Simultaneous deposition

Simultaneous

>- Simultaneous with replacing tendency shown by arrows 

-> Replacement, example: chalcopyrite replacing bornite

Lines connect only those minerals observed in contact. 

Minerals arranged clockwise in approximate order of 

deposition. Modified after Robertson and Vandeveer (1952)

Bornite

Chalcopyrite

Blue chalcocite

Pyrite

Chalcocite

Uraninite

Figure 2. Paragenesis of uraninite and sulfide minerals, Shinarump No. 1 mine, Grand County, Utah.

In general, in the Shinarump No. 1 deposit 

uraninite is later than or simultaneous with most 

sulfides. Chalcocite may be of two ages with 

some being later than uraninite. Rosenzweig 

(in Droullard and Jones, 1952), writing about the 

Seven Mile Canyon area, states: "It appears that 

the time of formation of the copper sulfides followed closely or possibly overlapped that of uraninite. " Thus, the paragenetic relationship of uraninite and sulfides in the Shinarump No. 1 deposit 

found by this study is not in complete agreement 

with the Seven Mile Canyon area taken as a unit.

Photomicrographs in figure 3 show some of 

the paragenetic relationships. Chalcocite crosscutting uraninite that has completely replaced 

wood is shown in photomicrograph A. Photomicrographs C and D show the relationship of 

etched quartz grains, uraninite, and chalcocite. 

Note the uraninite-free areas surrounding the 

etched quartz grains. A peripheral line of uraninite is concentric with the shape of the etched 

quartz grain. Stringers of uraninite radiate from 

these peripheral lines. It appears that cracks 

may have formed in the chalcocite and were 

later filled with uraninite. Other, but less likely, 

explanations are that these crack fillings represent the replacement of crushed or distorted 

cellular structure of wood or that chalcocite replaced quartz grains in places and the uraninite 

replaced the interstitial clay material. Photomicrograph E shows a texture interpreted as caused

by the exsolution of chalcopyrite in bornite. Photomicrograph F of a thin section of sample no. 5 

shows the zoning of uraninite and chalcocite about 

a pyrite core.

Blue chalcocite observed in one polished 

section may be digenite, which is a solid solution of covellite and chalcocite; however, the 

common digenite texture is absent. Wandke (1953) 

points out that if the specimen is heated above 

68° C, during the preparation of the sample, 

digenite may be formed from covellite and chalcocite. However, covellite was not observed so 

that either all covellite was adjacent to chalcocite 

and transformed or digenite was present before 

preparation of the sample. The author prepared 

the specimens in sealing wax which may not have 

heated the specimen above the critical temperature. The problem of blue chalcocite (digenite?) 

is important from the standpoint of temperature 

of ore formation (Buerger, 1941).

PETROLOGY

Samples of barren and uranium-bearing rock 

from the Shinarump No. 1 mine (table 1) were 

studied in thin section, slides of light and heavy 

grains, and by size analysis. Generally, the 

ore-bearing rocks are siltstone and fine-grained 

sandstone that are more poorly sorted than the 

barren siltstone and fine-grained sandstone. Barren 

rocks include siltstone, fine- to coarse-grained 

sandstone, limestone-pebble conglomerate, and 

mudstone. Reworked siltstone and sandstone pebbles 

and grains from the Moenkopi are common in 

many beds. Visually, packing is good in both 

barren and ore-bearing rocks. Calcite and clayey 

material cement barren and ore-bearing rock. The 

grains are usually subangular to well rounded.. Angular and broken feldspar is abundant in one uranium-bearing .siltstone sample.

The composition of light constituents, specific 

gravity less than 2.9, of the uranium-bearing and 

barren Chinle samples is mostly quartz and chert, 

and minor amounts of microcline, muscovite, orthoclase, 

and oligoclase are present. Some chert grains contain 

pyrite cubes. Heavy nonopaque detrital minerals, specific gravity greater than 2.9, include mostly zircon, 

tourmaline, and biotite, with minor amounts of rutile, 

chlorite, spinel, garnet, and staurolite. Opaque detrital 

minerals include ilmenite, leucoxene, and hematite. 

Authigenic barite is abundant in both barren and uraniumbearing rock and has been precipitated in open spaces. 

Counts of the heavy detrital minerals from barren and 

uranium-bearing samples show no correlation of any 

mineral or group of minerals with uranium-bearing rock.

X-ray spectrometric determinations of material 

smaller than 4 microns, from barren and ore-bearing 

samples made by the trace elements laboratory of the 

Geochemistry and Petrology Branch of the Geological 

Survey, indicate the presence of quartz (fine cryptocrystalline?), hydro mica, and kaolin in every sample. 

Some samples contain small amounts of feldspar, 

calcite, dolomite, chlorite, and montmorillonite.
Figure 3. Photomicrographs of polished and thin sections from the Shinarump No. 1 mine, Grand County, 

Utah. A, Polished section of sample 22 showing replacement of wood by uraninite (U, light gray) and 

chalcocite (Cc, white). B, Polished section of sample 23 showing relation of chalcocite (Cc, white) and 

Uraninite (U). C and D, Polished section of sample 23 showing etched quartz (Q, dark gray) grains 

surrounded by chalcocite (Cc, white), which is free of uraninite (U, light gray), and uraninite filling 

minute cracks in chalcocite that are oriented radially about the quartz. E, Polished section of sample 

26 showing texture interpreted as caused by exsolution of chalcopyrite (Cp, white) in bornite (B, light 

gray), replacement of bornite by chalcocite (Cc, dark gray), and uraninite (U, medium gray) cutting 

all other minerals. F, Thin section of sample 5 with reflected and transmitted light showing bleb of 

minerals, pyrite (Py, light gray) surrounded by border of chalcocite and uraninite (Cc-U, black) in 

sandstone. Note encroachment of quartz (Q, white) by ore minerals.
Table 1. Samples from Seven Mile Canyon area

Sample 

no.

1 

2

3

4

6

7 

8

9 

10 

11 

12

13

14

15 

16

17 

18

19 

20 

21 

22 

23 

24

25 

26 

27 

28 

29 

30 

31

Specific location1

Wall MN 

 do , 

Wall GH 

U«1 1 MINI -- -- - - - - -

_ __7To - _ _ _ - _ - _

-Wall CD 

 do 

Wall EF 

 do 

Wall EF 

 do 

Wall CD 

 do 

 do 

 do 

Wall IJ 

20 feet N. 3° W. of station R3 

28 feet N. 11° W. of station. R3 

Wall CD 

Kellog No. 1 claim2 

North portal3 

Wall IJ 

Wall KL 

Little Canyon 2 

Description

Uranium-bearing unbleached siltstone stringers. 

Uranium-bearing sandstone; very fine to coarse grained. 

Limy siltstone. 

Highly radioactive carbonaceous material. 

Uranium -bear ing muddy siltstone. 

Uranium-bearing silty sandstone. 

Uranium-bearing siltstone . 

Uranium-bearing silty sandstone. 

Uranium-bearing siltstone . 

Muddy siltstone; forms back of mine. 

Limestone pebble conglomerate above ore. 

Uranium-bearing siltstone . 

Limy sandstone below ore. 

Barren siltstone. 

Uranium-bearing siltstone north of fracture. 

Barren siltstone north of fracture. 

Altered siltstone south. of fracture. 

Unaltered siltstone south of fracture. 

Nonradioactive carbonaceous material. 

Secondary copper minerals in Moab fault zone. 

Copper-bearing material from Moab fault zone. 

Fractures filled with chalcocite. 

Uraninite and chalcocite layer. 

Conglomerate below ore. 

Uranium-bearing sandstone from the Morrison formation. 

Uraninite, bornite, chalcocite in seam. 

Barren siltstone from the Chinle formation. 

Barren sandstone from the Shinarump conglomerate. 

Uranium-bearing siltstone, chalcocite veins. 

Uranium-bearing siltstone and sandstone. 

Conglomeratic sandstone from the Shinarump conglomerate

'Plate 2 unless otherwise noted. 2Plate 3 Figure 7.

Figures 4, 5, and 6 show the results of size 

analysis. Sample 31 (figs. 4, 5) came from the 

Shinarump conglomerate in Little Canyon (pi. 1), 

and sample 28 (figs. 4, 5) was taken from near 

the mine from a lens of a. similar sandstone 

which has been eroded and cut out by the overlying ore-bearing siltstone of the Chinle. The 

two samples have the same mineral suite, which 

differs from the suite in the Chinle samples. The 

frequency and cumulative curve-j of the two samples 

are similar. It is concluded that the lens near 

the mine is an erosional remnant of Shinarump 

near the margin of Shinarump deposition. The 

coarse grains in several samples cause bimodal 

frequency curves (fig. 5A, samples 7, 8; fig. 5C, 

sample 24), which suggest a source for the coarse 

grains similar to the Shinarump or that the coarse 

grains came from the Shinarump that was partly 

eroded before the deposition of the Chinle. Uranium-bearing samples are more poorly sorted 

than barren samples.

A special study was made of a single siltstone bed along wall C-D (pi. 2) to find what 

changes might be evident in a mineralized and 

bleached bed. A fracture between the uraniumbearing rock and the unaltered rock is parallel 

to the truncated ore as well as the line between 

bleached and unbleached rock. The possible effect 

of this fracture on mineralization was also studied.

The results of the size analysis of 4 samples 

are given in figure 6. Study of frequency curves 

and thin sections shows the siltstone to be more 

poorly sorted to the north, on the mineralized 

side of the fracture, than to the south. Study of 

the light and heavy detrital minerals shows no 

correlation of any mineral or group of minerals 

with the uranium-bearing part of the siltstone. 

However, spectrographic analysis of these samples 

indicates a marked increase of some elements in 

uranium-bearing rock over barren rock but no 

difference between bleached and unbleached rock. 

The increase of some elements in uranium-bearing 

rock is not reflected as a halo about the uraniumbearing rock. The position of the fracture with 

relation to uranium-bearing and bleached rock is 

probably a coincidence as the spatial relationship 

of this fracture along strike shows no similar relationship to uranium-bearing or barren rock.

The results of the petrographic study show 

the uranium-bearing rock to be more poorly sorted 

than barren rock. Detrital grains in the uraniumbearing and barren rock are essentially the same 

in mineralogy and quantity. The mineralogy of 

the coarse fractions of the ore-bearing beds indicate original source rocks to be schists and 

acid to intermediate igneous rocks. The orebearing beds are thought to be mostly secondcycle and partly third-cycle sediments.
80

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w *°

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20

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2

f-

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V

X^ I-*" ' ' ""

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56 7 8 9 10 11 i;

0SCALE 

A. Ore-bearing Chinle samples

80 

60

20 

0

_ 

I3y.

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B. Barren Chinle samples

10 11 12

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« ,0

£

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0 SCALE

C. Barren Chinle (Nos. 14 and 24) and Shinarump 

(Nos. 28 and 31) samples

Figure 4. Cumulative curves of grain size of samples 

from the Seven Mile Canyon area, Grand County, 

Utah. Scale is the phi scale of Krumbein (1934).

HABITS OF ORE BODIES

The Shinarump No. 1 mine was mapped in plan 

on a scale of 1 inch equals 20 feet (fig. 7), and 

maps of walls and faces were made on a scale 

of 1 inch equals 5 feet (pi. 2). Plate 1 and 

figure 7 show sample locations. Uranium minerals 

are not generally visible, so a Geiger counter was 

used to outline the extent of uranium-bear ing rock. 

Arbitrary cutoffs in counts -per-minute were used 

to appraise the uranium values of the mine as 

stated in figure 7.

The uranium-bearing rock is almost a continuous lenticular layer that approximately follows 

the bedding but locally and in small detail cuts 

across the bedding. Ore-grade material is in discontinuous lenses (ore shoots) which tend to be 

elongate about north-south. The ore averages 1 or 

2 feet in thickness with a maximum of about 5 feet. 

The grade of the ore ranges from 0.10 percent to 

1.00 percent UsO8 with small masses greater than

1.00 percent U 3O 6 . Near the edges of the deposit, 

the ore layer tends to rise in the beds so that 

the deposit in cross section is saucer shaped 

(maps of mine walls AB, CD. pi. 2). The north edge 

of the deposit has an east-west trend. The orebearing beds lie essentially flat and fill irregularities of an erosional surface. Structural contours 

on the top of the Moenkopi indicate that no channel 

scour is present in the vicinity of the mine.

Most of the deposit is composed of siltstone 

and fine-grained sandstone impregnated with microscopic grains of uraninite, chalcocite, and pyrite. 

High-grade layers as much as half an inch in 

thickness of chalcocite and uraninite are found 

along some bedding planes. In one place, the 

high-grade ore is concentrated along the base of 

a bed that overlies a less permeable appearing 

bed (pi. 2, map of mine wall IJ). Vertical veinlets 

of chalcocite lead upward to this concentration.

The original color of sediments that contain 

the deposit is thought to have been red that was

-101 23456

* SCALE 

A. Ore-bearing Chinle samples

-1 123456

<t> SCALE 

B. Barren Chinle samples

-1 23456

«S SCALE

C. Barren Chinle (Nos. 14 and 24) and Shinarump 

(Nos. 28 and 31) samples

Figure 5. Frequency curves of grain size of samples 

from the Seven Mile Canyon area, Grand County, 

Utah. Scale is the phi scale of Krumbein (1934).
80

I 60 

U

W 40 

ft

20 

0 ,__ 

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C.

Sample Numbers

Bleached /

/ Fracture

Figure 6. Curves of ore-bearing and barren siltstone 

from Shinarump No. 1 mine, Grand County, Utah. 

A, Cumulative curve; B, frequency curve; C, 

Source of samples. Scale is the phi scale of 

Krumbein (1934).

altered later by solutions which may have deposited 

the ore. The only apparent change brought about 

by the alteration was a bleaching of red to gray 

and green. The bleaching extends 1 to 15 feet 

beyond the limits of the mineralized rock and 

locally the limit parallels the shape of the mineralized layers in detail.

Prospecting guides to additional deposits similar to the Shinarump No. 1 in the Seven Mile Canyon area are (1) presence of bleached siltstone; 

(2) presence of carbonaceous matter; (3) presence of copper sulfides, especially chalcocite; and 

(4) thinning of the limestone-pebble conglomerate 

"marker bed. " The last ore guide is probably only of 

local importance.

SPECTROGRAPHIC STUDY

Semiquantitative spectrographic analyses of 

20 samples were examined statistically. l The

1 Reported assays by Semiquantitative spectrographic analysts were 

made by the trace elements laboratory of the Geochemistry and Petrology 

Branch of the Geological Survey at Denver. The assays that are normally 

expressed in groups of powers of 10 were reported in subgroups whose theoretical range is shown on page 14. The geometric mean was obtained by 

applying a simple formula, which may be found in any elementary text on 

statistics, such as Waugh (1943), to the midpoints of the subgroups (class 

marks).

geometric mean values in percent of 32 elements contained in groups of samples from barren and uraniumbearing rock from the Shinarump No. 1 mine, copperbearing rock from nearby copper prospects in the Moab 

fault, and uranium-bearing rock from the Kellog No. 1 

mine (pi. 2) in the Morrison formation are shown in 

table 2. The samples were tested for 26 other elements but 

none were detected. In all groups of samples, common rock 

forming elements show no systematic variation. Comparison of barren and uranium-bearing rock from the 

Shinarump No. 1 mine shows a substantial increase in 

the uranium-bearing rock of the elements boron, beryllium, cobalt, copper, gallium, molybdenum, nickel, 

lead, silver, uranium, vanadium, yttrium, and zinc. 

In the uranium-bearing samples of the Shinarump No. 1 

mine, mean values for barium, copper, vanadium, and 

titanium are as high as the grade of much of the uranium ore produced from the mine. The few samples 

from the copper deposits show affinities to the barren 

rock at the Shinarump No. 1 mine except for the element silver (see table 2). The values from a single 

sample of uranium-bearing rock from the Kellog No. 1 

mine in the Morrison formation show similarities to 

the uranium-bearing rock from the Shinarump No. Imine.

Selenium content cannot be determined by spectrographic methods, but it is suspected to be present 

in considerable quantity near the uranium and copper 

mines and along the Moab fault because selenium and 

sulfur indicator, or tolerant, plants are present in 

these areas.

Chemical and radioactivity analysis of uranium 

shows the uranium ore to be nearly in equilibrium. 

This equilibrium and the general lack of secondary 

minerals indicate that the ore is relatively unoxidized 

and that ground water has had little effect upon the ore.

High radioactivity is found in some seams of 

carbonaceous material. Comparison of the spectrographic analysis of megascopically identical, relatively nonradioactive materials with the analysis of 

highly radioactive carbonaceous materials (sample 

nos. 19 and 4, respectively) shows the radioactive 

carbonaceous material to contain at least one order 

more of barium, zinc, cobalt, nickel, uranium, and 

silver. This is similar to the differences in the mean 

metal values of barren and of uranium-bearing rock in 

the mine. However, in the radioactive carbonaceous 

material, the values of these elements are high; barium 

assays about 30 percent, zinc assays about 5 percent, 

and cobalt and nickel assay over 1 percent. The great 

inequilibrium of the radioactive carbonaceous material 

indicated by the comparison of 6.6 percent equivalent 

value for uranium and 0.17 percent chemical value for 

uranium is due to radon. The relatively nonradioactive 

carbonaceous material is nearly in equilibrium.

The results of the spectrographic analyses indicate that the solutions which deposited the copper in 

the Moab fault zone were probably different than those 

which deposited the uranium in the Chinle and Morrison 

formations. The uranium-bearing solutions probably 

contained important amounts of barium, vanadium, 

uranium, and copper as well as lesser amounts of 

strontium, chromium, boron, yttrium, lead, and zinc. 

The abundance of sulfide minerals in the deposits indicate that the solutions were probably reducing in 

character and sulfur rich.

10
4570N

Unbleached zone

4580' 

4570'

Uran

EXPLAN

Backfill 

Boundary of uraniu

dashed whe

Chalcocit

Contact, dashed 

Strike and d

Barren 

Extent of working

Sample 

0 

Survey 

Boundary 

RADIOACTIVITY MEASURED ALONG 

GEIGER C

More than 2000 counts p

more 

More than 2000 counts per min

Between 20 and 2000 counts 

80 Feet

Figure 7. Geologic map and sections of the Shinarump No. 1 mine, Grand County, U
Table 2. Geometric mean values (in percent) of elements contained In barren and uranium-bearing 

rock from the Shlnarump No. 1 mine, copper-bearing rock from nearby copper deposits, and uraniumbearing rock from a nearby deposit In the Morrlson formation.

[Geometric mean in percent calculated from spectrographic analysis. Looked for but not found: As, Au, Bi, Ce, Ge, In, IT, Hf, Hg, Li, Nb, Os, P, Pd, Pt, Re,

Rh, Ru, Sb, Sin, Ta, Te, Th, Ti. Yb, and W]

Element

CM

M_ ____ _ __ _ _____

TJo _____ __ _ __ __ _

TiVa_ ___ __ _

Mn 

Ca 

Mg 

Ba 

Q in

HTH __ _ __ ___

<7f> __ ___ _

Cr 

Ga 

Q «

La 

Chlnle 

barren 

rock1

 zn

2

1

.1

1

.03

5

.6

.07 

.02

.2

.02

.006

.0004

.002

(0

Chlnle 

uraniumbearing 

rock2

30

4

2

.3

2

.02

2

1

.2

.03

.2

.04

.01

.002

.002

0

Copperbearing 

rock3

30 

2

.4

.07

.5

.03 

2

.2

.1

.007 

.06

.02

.002

0

0

0

Morrlson 

uraniumbearing 

rocku

30

.3

.3

r\f.

2

.03 

2

.3

.02

.02

.2

.02

.02

.0002

0

0

Element

Be 

Y 

Ce 

Nd 

V 

Nl 

Co 

Oi i

Pb 

Zn 

Cd 

Mo 

Sn 

Ag 

u 

Chlnle 

barren 

rock1

0.0001

.01

.002

( 5 )

( 5 )

.02

.0009

.0003

.05 

.002

0

0

( 5 )

0 ( 5 )

0

Chlnle 

uraniumbearing 

rock2

0.001

.05 

.01

0

0

.2

.008

.008

.2

.03

.03 

( 5 )

.003 ( 5 )

.0007

1

Copperbearing 

rock 3

0

.005 

.001

0

0

.03 

.002

.002

5

.003 

0

0

.001

0

.002

0

Morrlson 

uraniumbearing 

rocku

0

r\f\£.

.003 

0

0

.2

.003 

.02

2

.2

.003 

.02

0

.02

.06

1 Result of analyses of 10 samples from Shinarurap No. 1 mine.

2 Result of analyses of 7 samples from Shinarurap No. 1 mine.

3 Result of analyses of 2 samples.

AGE DETERMINATIONS OF UEANINITE

The following is a resume of the lead-uranium 

age determinations of some uraninite specimens 

from Triassic and Jurassic sedimentary rocks of 

the Colorado Plateau by Stieff and Stern (1953). 

As part of their study on the origin of uranium 

deposits in the Triassic and Jurassic sedimentary 

rocks of the Colorado Plateau, 21 samples of 

uraninite from 13 deposits were collected for 

Pb 206U236 age determinations. These uraninites 

are believed to be the most reliable of more than 

100 samples from the plateau on which age determinations have been made. The average age of 

the uraninites from the Morrison is lower by a 

factor of two than the best estimate of the age 

for the Morrison formation. The average age of 

the uraninite samples including the Chinle formation in the one from Shinarump No. 1 mine (fig. 7), 

from the Shinarump conglomerate is lower by a 

factor of three than the best estimate of the age 

of the Shinarump conglomerate. The average age of 

samples from the Upper Jurassic Morrison formation does not differ significantly from the average 

age of samples from the Upper Triassic Shinarump 

conglomerate. The average age of samples from the 

two formations agree very closely with the best 

available estimates for the age of the end of the 

Cretaceous or the beginning of the Tertiary periods.

Stieff and 'Stern conclude that 

4 Values of 1 sample. 

Detected in too few samples to take geometric mean.

ORIGIN OF DEPOSIT

For many years the uranium deposits on the 

Colorado Plateau, which included mostly oxidized 

vanadium-uranium deposits (carnotite-type) of the 

Morrison and Shinarump formations, were considered 

to have been formed shortly after the deposition 

(penesyngenetically) of the enclosing sediments 

(Fischer, 1942). However, owing to concentrated investigations during the past several years and to the discovery of relatively unoxidized uranium deposits of the' 

vanadium-uraniurn, copper-uranium, and uranium types 

in many different formations of the Colorado Plateau 

and adjoining regions, several hypotheses that had been 

previously discarded are being reconsidered. These include hydrothermal origin, downward leaching of uranium from volcanic strata, and petroliferous origin. A 

brief statement of the fundamentals of each of the hypotheses follows.

The penesyngenetic hypothesis may be best expressed by quoting Fischer.

The primary ore minerals are thought to have been 

introduced into their present position not long after the 

sands were deposited. If this is true, the metals were 

probably transported and deposited by ground waters, and 

the ores were probably localized by delicate chemical and 

physical conditions that now cannot be definitely recognized. This hypothesis probably requires at least three 

separate periods of ore deposition, to account for the 

ore in the Shinarump, Entrada, and Morrison formations.

Most of the lead-uranium data that we have obtained strongly suggests that the deposits are not 

syngenetic but were emplaced in the sediments during the Tertiary, long after the enclosing sedljnents 

were laid down. If, however, the deposits are syngenetic in origin, an event must have occurred at the 

end of the Cretaceous or during the Tertiary which 

completely redistributed the uranium and localized the 

ore in its present sites.

12

Since his studies, deposits have been found in the Hermit, 

Cutler, Moenkopi, Chinle, Todilto, Dakota, Mesaverde, 

Wasatch, Uinta, and other formations on the Colorado Plateau.

The concept of a hydrothermal origin of the uranium 

deposits received impetus from the results of age determinations of uraninite specimens from uranium deposits of the 

Colorado Plateau (Stieff and Stern, 1953). The hydrothermal
hypothesis suggests that uranium-bearing solutions were 

related to Tertiary igneous activity and that solutions 

moved vertically along fractures and then laterally until 

reaching favorable loci where the uranium was deposited.

Downward leaching of uranium from volcanic 

strata has been suggested because of the thick 

series of strata containing abundant volcanic debris that overlie both the Salt Wash sandstone 

member of the Morrison formation and the Shinarump conglomerate. Waters and Granger (1953) 

suggest that the devitrification of this volcanic 

material provides the silica for silicification of 

wood as well as for the addition of silica in the 

ore-bearing sandstones. Others (Proctor, 1949, 

and Love, 1952) have suggested these and other 

strata containing volcanic material as source rocks 

for the uranium.

Uranium-bear ing material and petroleum have 

the same suite of trace metals, and thus a common origin has been suggested (R. Erickson, oral 

communication).

Any hypothesis must account for all of the 

following relations or facts before it can be accepted as a satisfactory explanation of the origin 

of the deposits:

(1) Sedimentary structures, such as channels 

and lenses, and sedimentary features 

such as bedding planes, graded bedding, 

and impervious "barriers controlled the 

location of most of the ore deposits.

(2) Bleaching of red mudstones to gray or 

green accompanies most deposits.

(5) Most deposits are in continentaltype sediments.

(h) Most deposits are associated with carbonaceous material..

(5) The common age indicated by age determinations .

(6) The persistent association of uranium with 

vanadium in the Morrison formation and 

the variety of element associations including vanadium and copper in the 

Triassic formations.

The origin of the Shinarump No. 1 deposit, which 

is clearly later than enclosing sedimentary rocks, is 

thought to be hydrothermal. Age determinations by 

Stieff and Stern (1953) indicate that the uraninite in this 

deposit formed at the end of the Cretaceous or the beginning of the Tertiary periods. The mineral assemblage, particularly the presence of uraninite, blue 

chalcocite (digenite ?), and bornite-chalcopyrite solid 

solution, strongly suggests a temperature of formation 

warmer than the temperature of normal ground water. 

The localization of the ore is related to the pinchout 

of the Shinarump conglomerate on a regional and local 

scale and to sedimentary features such as bedding 

planes, graded bedding, and sorting, within orebearing beds. Carbonaceous and clayey material may 

have acted as a chemical and physical attraction for 

the localization of the ore. Ground water probably 

played an important role in the precipitation of the 

uranium and sulfides.

13

CONCLUSIONS

The Shinarump No. 1 deposit, which is located on the 

west flank of the Moab anticline, is inthelowermostsiltstone 

beds of the Chinle formation that truncate erosional remnants 

of Shinarump conglomerate. Uranium deposits in the Seven 

Mile Canyon area and elsewhere to the south and west are 

near the margins of Shinarump deposition. There is no evidence to show a definite genetic relationship of the Moab 

fault to the uranium deposits in the Seven Mile Canyon area.

The ore is relatively unoxidized. Uraninite 

(pitchblende), a primary mineral, is the most abundant ore 

mineral. It occurs as small grains disseminated in sandstone and replacing wood structure. Uraninite, which is associated mainly with chalcocite and pyrite, is later formed 

than most sulfides except chalcocite, whichis, in part, later. 

Chalcocite occurs in vertical fractures that trend east. The 

ore minerals occur in more poorly sorted parts of siltstone 

and in stringers of coarse sand in siltstone.

The ore deposit is not in a channel fill but 

in flat-bedded sedimentary rocks that were deposited 

on an irregular surface. Guides to ore in the Seven 

Mile Canyon area inferred from the study of the 

Shinarump No. 1 deposit are the presence of bleached 

siltstone, carbonaceous material, and copper sulfides. 

The deposit lies below thin parts of the limestonepebble conglomerate "marker bed. "

The origin of the Shinarump No. 1 deposit is probably hydrothermal. Mineralizing solutions hydrothermal 

and, in part, ground water are thought to have been 

reducing in character and to have contained important 

amounts of barium, vanadium, uranium, copper, and 

sulfur as well as lesser amounts of strontium, chromium, boron, yttrium, lead, and zinc.

LITERATURE CITED

Buerger, N. W., 1941, The chalcocite problem: Econ. 

Geology, v. 36, no. 10, p. 19-44.

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

and Utah: U. S. Geol. Survey Bull. 936-P.

Kruinbein, W. C., 1934, Size frequency distribution 

of sediments: Jour. Sed. Petrology, v. 4, p. 65-77.

Love, J. D., 1952, Preliminary report on uranium deposits in the Pumpkin Buttes area, Powder River 

Basin, Wyoming: U. S. Geol. Survey Circ. 176.

McKnight, E. T., 1940, Geology of the area between 

Green and Colorado Rivers, Grand and San Juan 

Counties, Utah: U. S. Geol. Survey Bull. 908.

Robertson, F., andVandeveer, P. L., 1952, A new diagrammatic scheme forparagenetic relations of the ore 

minerals: Econ. Geology, v. 47, no. 1, p. 101-105.

Shoemaker, E. M., 1951, Internal structure of the Siribad 

Valley-Fisher Valley salt anticline, Colorado and Utah 

(abs.): Geol. Soc. AmericaBull., v. 62, no. 12, part 2.

Stokes, W. L., and Phoenix, D. A., 1948, Geology of 

the Egnar-Gypsum Valley area, San Miguel and Montrose Counties, Colorado: U. S. Geol. Survey Oil 

and Gas Inv., Prelim. Map 93.

Wandke, A. D., 1953, Polishing phenomena in the

copper sulfides: Econ. Geology, v. 48, no. 3, p. 225-232.

Waters, A. C., and Granger, H. C., 1953, Volcanic 

debris in uraniferous sandstone and its possible 

bearing on the origin and precipitation of uranium: 

U. S. Geol. Survey Circ. 224.

Waugh, A. E., 1943, Elements of statistical method: 

McGraw-Hill Book Co., Inc., p. 99.
UNPUBLISHED REPORTS

Droullard, R. F., 1951, Prospective bulldozer operations in the Seven Mile area: U. S. Atomic Energy 

Commission RMO 689.

Droullard, R. F., and Jones, E. E., 1952, Geology of 

The Seven Mile Canyon uranium deposits, Grand County, 

Utah: U. S. Atomic Energy Commission RMO 815.

Proctor, P. D., 1949, Geology of the Harrisburg 

(Silver Reef) mining district, Washington County, 

Utah: Unpublished doctoral dissertation, Ind. Univ.

Stieff, L. R., and Stern, T. W., 1953, The leaduranium ages of some uraninite specimens from 

Triassic and Jurassic sedimentary rocks of the 

Colorado Plateaus: U. S. Geol. Survey Trace 

Elements Inv. Rept. 322.

Weeks, A. D., 1952, Summary report on mineral - 

ogic studies of the Colorado Plateau through 

April 30, 1952: U. S. Geol. Survey Trace Elements Memo. Rept. 431.

GROUP-NUMBER CLASSIFICATION

Assay 

(report in 

percent)

XX. +

XX.

XX.-

X.+

X.

X.-

,x+

.X

.XGroup 

no. 1

1+

1

1-

2+

2

2-

3+

J>

>

Class range

46.4 -100.0

21.5 - 46.3

10.0 - 21.4

4.6 - 9.9

2.2 - 4.5

1.0 - 2.1

.46 - .9

.22 - .45

.10 - .21

Class mark

68.1

31.6

14.7

6.8

3-2

1.5

.68

 32

.15

Assay 

(report in 

percent)

O.OX+

.OX

.ox-

.OOX+

.oox

.oox-

.OOOX+

.ooox

.oooxGroup 

no. 1

4+

4

4-

5+

5

5-

6+

6

6-

Class range

0.046 - 0.09

.022 - .045

.010 - .021

.0046 - .009

.0022 - .0045

.001 - .0021

.00046 - .0009

.00022 - .00046

.0001 - .00021

Class mark

0.068

.032

.015

.0068

.0032

-.0015

.00068

.00032

.00015

^Subgroups overlap somewhat, but about 80 percent of cases will be io correct subgroup.

14 XHT.-DUP. sec., WASH., D.C.«T«II
GEOLOGICAL SURVEY R. 20 E. S. L M.

CIRCULAR 336 PLATE 1

Summerville formation

Eotrada sandstone, Moab tongue

Shinarump conglomerate

Cutler and Rico formations

Strike and dip of beds

After McKnlght, 1940 

3 Miles

Copper prospect

25 

Sample number

EXPLANATION

Contact, dashed where inferred

Fault, showing dip; U, upthrown side; 

O, downthrown side

located quarter corner Strike and dip of beds

_7O

Strike and dip of joints 

Strike of vertical joint!

Ground underlain by uranium-bearing rock

Shinarump conglomerate.

Contour Interval 40 feet 

D»tum la metn ft* level

SHINARUMP SHINARUMP NO 1 MINE

NO 3 MINE Uranium-bearing rock

Conglomerate "marked bed'

Topography modified after advanced 

topographic quadrangle Moeb 4 NW. 

Grend County, Utah GEOLOGIC MAPS AND GENERALIZED SECTIONS OF THE SEVEN MILE CANYON AND SHINARUMP No. 1 MINE AREAS, GRAND COUNTY, UTAH

Geology by W. I. Finch 

Surveying by M. L. Mitigate, 

W. I. Finch, and others
GEOLOGICAL SURVEY CIRCULAR 336 PLATE 2

SKETCH SHOWING LOCATION OF 

MAPS OF MINE WALLS

SHINARUMP 

NO I MINE

4575-

4675'-

Muddy siltstona. bentonitic

 OX* 

Carbonacaous matartai

Boundary of uranium-bearing rock

Trace of Joint or fracture surface Hi plane of watt

Sample number

i i i

Boundary of red (unbleached) sediments, 

hachure Indicate* red side

:' : ' JJ^^7^7^^^

-4575'

4570'

Datum is mean sea level

Geology by W. I. Finch

SELECTED MAPS OF MINE WALLS FROM THE SHINARUMP No. 1 MINE, GRAND COUNTY, UTAH