Zoning of the Bitter 

Creek Vanadium-Uranium 

Deposit Near Uravan 

Colorado

GEOLOGICAL SURVEY BULLETIN 1042-F

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

CONTRIBUTIONS TO ECONOMIC GEOLOGY

ZONING OF THE BITTER CREEK VANADIUM-URANIUM 

DEPOSIT NEAR URAVAN, COLORADO

By ALLEN V. HEYL

ABSTRACT

The vanadium and uranium deposit of the Bitter Creek mine south of Uravan, 

Colo., is in the upper part of the Salt Wash sandstone member of the Morrison 

formation. The deposit is divided into three zones, each having distinctive 

geologic features. The zones merge, the first into the second and the second 

Into the third, as the thickness of cover on the ore bodies increases. The deepest 

zone contains nodular and concretionary masses of vanadium-uranium oxides 

associated with pyrite and chalcopyrite. These masses grade into disseminated 

deposits of vanadiferous clays and carnotite nearer the outcrop. Similar but 

less distinctive zones are exposed in many other mines in the Uravan district. 

The zones represent progressive oxidation of older primary (?) concretionary 

vanadium-uranium oxide deposits that contained iron and copper sulfides.

INTRODUCTION

The Bitter Creek vanadium and uranium mine (fig. 28) is in the 

eastern part of the carnotite-producing "Uravan mineral belt" 

(Fischer and Hilpert, 1952, pi. 1) in Mesa, Montrose, and San Miguel 

Counties, Colo., and adjacent parts of Utah. The mine is about 6 

miles south of Uravan, Colo., in the SW.%SW% sec. 1, T. 46 N., K. 17 

W., Montrose County (Fischer, 1944). It is reached by an unpaved 

road from Uravan that leads through Long Park and by a similar 

road from Colorado Koute 90 in Paradox Valley. The mine, which 

is owned by the Vanadium Corp. of America, was operated by Mr. 

Vard Beckman, a lessee, in 1952.

The deposit is in a group of large ore bodies in the Morrison formation in western Colorado, eastern Utah (Fischer, 1944), and northern 

Arizona. Concretionary masses of vanadium-uranium oxides occur 

in the deepest parts of the mine. The oxide ores grade up dip toward 

the outcrop into vanadiferous clays and carnotite (Fischer, 1942;

187
188 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Weir, 1952). Similar but less conspicuous gradations are discernible 

in many of the other mines (particularly those beneath thick covers of 

rock) in the "Uravan mineral belt."

FIELD WORK AND ACKNOWLEDGMENTS

Studies of the Bitter Creek vanadium and uranium deposit were 

begun in the summer of 1952 as part of a program of detailed geologic 

mapping by the U. S. Geological Survey on behalf of the U. S. Atomic 

Energy Commission. K. L. Boardman, W. D. Carter, M. D. Okerlund, 

and other geologists of the U. S. Geological Survey assisted in the 

work.

Acknowledgment is made to the Vanadium Corp. of America, owner 

of the Bitter Creek mine, and Mr. Yard Beckman, lessee, for permitting 

access to their property and providing maps of the mine. Acknowledgment is also made to the U. S. Vanadium Co. for similar assistance 

during our visits to its properties.

GENERAL GEOLOGY

The Bitter Creek ore bodies of vanadium- and uranium-bearing 

sandstone are in the Morrison formation of Late Jurassic age (Fischer, 

1942, p. 368). The ore bodies are in the lower part of the upper sandstone beds of the Salt Wash sandstone member (fig. 28). Most of the 

rock of these upper beds is light brown and buff, but some (the unoxidized part) is white and gray. The sandstone is medium to coarse 

grained, massive-bedded to lenticular and irregular bedded, and crossbedded. The Salt Wash member forms an erosion-resistant cliff and 

bench about GO feet Kigh. Lenses, thin beds, and pebbles of red shale 

have been altered to pale green in and ne^ the ore body (Weir, 1952). 

Locally, fragments of fOSSll plants and trees are abundant; 

bones are fairly common.

The rocks of ta«, ^ea have been moderately folded into sever

northwest-trending folds. The mttw cwek ore bodies are in the

northeast flank of the collapsed Paradox anticline, winch te«^u N 

so° w. for at least 35 miles. The crest of the anticline has been 

dropped along steeply dipping normal faults on both flanks of tKe axis 

(Fischer, 1944). Many vertical joints tn-at strike northwestward, 

parallel to the faults and the anticlinal axis, occur in the comport 

sandstone beds. The beds near the mine strike N. 30°-50° W. and dip 

10°-25°NE. (fig. 28).

Carnotite ores of milling grade from the Uravan district contain 

from about 1 to 5 percent of V205 ; most of them contain less than 1 

percent of U3 08 (Fischer, 1942, p. 366-376). The ore from the Bitter 

Creek mine has a relatively high ratio of vanadium to uranium compared with many of the other deposits in the "Uravan mineral belt."
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 189 

GENERAL. FEATURES OF THE BITTER CREEK MINE

The Bitter Creek mine (fig. 28) is on the northeast rim of Paradox 

Valley and is near the center of a semicircular bench about half a mile 

in radius bounded by hills on the east and north sides. The bench is 

about 800 feet above the valley floor, and its surface marks about the 

top of the Salt Wash sandstone member of the Morrison formation, 

A southwest-facing cliff has formed in the resistant Salt Wash imme7 

diately below the bench. The small valley of Bitter Creek cuts westward into the bench a few hundred feet north of the mine and exposes

EXPLANATION

Inclined shaft

-6200'

EXPLANATION

Mine workings, dashed .where

Fault, showing relative movement projected to section

Zonal boundary

FIGURE 28. Generalized map and section of the Bitter Creek mine, showing ore bodies

and zones.
190 CONTRIBUTIONS TO ECONOMIC GEOLOGY

ore for about 900 feet down the dip of the strata on the northeast side 

of the creek. Ore is similarly exposed southeastward from the canyon 

near the top of the cliff for about 1,000 feet along the strike of the 

Salt Wash.

The Bitter Creek ore bodies have been opened along the northwesttrending outcrop by adits, shallow trenches, pits, and opencuts. Four 

adits and the drifts extending from them, called the "100," "200," 

"300," and "400" levels, provide access to the ore bodies from Bitter 

Creek valley (fig. 28). The levels are spaced about 300 feet apart 

down the northeasterly dip of the beds. The drifts extend southeastward and are within the ore-bearing beds along the strike. Each drift 

cuts the several parallel tabular ore bodies at vertical intervals of from

15 to 30 feet. Stopes along the ore bodies connect the several haulage 

drifts to form a rhombic pattern. In the northeast part of the mined 

area a steeply inclined shaft provides access to the deeper "500" and 

"600" levels, which are also connected to the upper workings by stopes. 

The difference in altitude between the ore outcrop and the deepest 

workings In 1952 was about 180 feet. Above the deepest workings 

the cover of rocks was about 180 feet thick.

The ore deposit is larger than most in the Colorado Plateau and 

consists of several parallel tabular ore bodies that extend from the 

outcrop eastward down the dip of the beds more than 2,000 feet. The

016 bodies are about parallel to the sandstone beds and at the same 

horizon, but parts of the ore bodies cut abruptly acrOSS the beds for 

several feet. Such bodies in the Uravan area have irregular outlines 

and range from a few to several hundred feet in width and from a few 

inches to 15 feet in thickness (Fischer, 1942, p. 382-383) . The mineralized parts of the ore bodies are very irregular in shape. Masses of

sandstone Within the bodies are abundant and of many

sizes.

Fossil tree trunks, branches, and leaves are common in the oretoearins s«^<istc«xo. The vanadium and uranium minerals show a

marked affinity for plant and animal remains that were not ea±0^.

before the ore was deposited. Almost all unsilicified loSSll material

that lies within the vanadium- and uranium- bearing ore bodies is 

mineralized,

very few faults are exposed in the Bitter Creek mine, even though 

the outcrop of the ore bodies is only about 1,000 feet northeast of the

nearest 01 WIO raravlv^ -.^o^^ ^ii^^ f auits. The faults exposed

m the mine were formed after ore was deposited.. They are either

reverse faults or bedding-plane faults along shaiy bands, along which

Gfl]j Ul IVTT i»?!1<?s of Aispiacemeixt has occurred.. Some bands of ore

follow or end abruptly against the bedding-plane faUifi, Wffll-flfiSflfil 

joints that are apparently related to the regional structures are abundant, but they have not visibly controlled the ore deposition.
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 191 

ZONING OF THE BITTER CREEK DEPOSIT

Three zones in the vanadium-uranium ore bodies are exposed in the 

Bitter Creek mine as the thickness of cover increases (fig. 28). The 

ore in the first zone consists of vanadiferous clay impregnated by a 

little carnotite in disseminations, bands, and along curved surfaces 

called rolls (Fischer, 1942, p. 383) (fig. 29). The ore in the second 

zone is richer than that of the first and contains blue-black vanadium 

and probably uranium oxides in similar rolls (fig. 29). The third and 

deepest zone exposed in the mine (figs. 29 and 30) contains rich 

nodules and concretions, bands and incipient irregular rolls of black 

vanadium oxides, and iron and copper sulfides. The change between 

the first and second zones is completely gradational, but the change 

between the second and third zones appears to be more abrupt. However, the average grade of the ore mined is about the same in all three 

zones (Mr. Vard Beckman, lessee, Bitter Creek mine, personal communication, 1952). The broad diffuse ores of the top zone contain 

about the same total quantities of uranium and vanadium per cubic 

yard mined as the higher grade, but more widely spaced, rolls of the 

second zone, and the rich small nodules of the third zone, which are 

scattered through nearly barren rock.

FIRST ZONE

The first zone (figs. 28 and 29) contains dark-gray vanadiferous clay, 

yellow carnotite, and tyuyamunite deposited in lean disseminations, 

broad bands along bedding planes, and well-formed rolls. These ores 

are the only ones observed at the outcrops near the mine, in the shallow 

open pits along the strike, and at the outcrops down the dip of the beds 

along the Bitter Creek valley at the north edge of the deposit (fig. 28). 

They are typical of the stopes wherever the cover is less than'80 feet 

thick.

The only abundant vanadium mineral in the first zone is a gray 

vanadium hydromica, a clay mineral that has not been fully identified. 

It forms aggregates of minute flakes that coat the sand grains or fill the 

interstices of the sandstone. Its composition is approximately 

(Al,V) 2 (AlSi3 )(K,Na)010 (OH,F) 2 . Some rauvite, CaA-2U03 - 

5V2O5 16H2O, is found in the upper levels of the mine (A. D. Weeks, 

personal communication, March 1953). Small areas and pockets of 

less oxidized ores are found, commonly in moist areas beneath shale 

lenses.

The principal uranium minerals are yellow carnotite minerals 

carnotite, K,(UO2 ) 2 (VO4 ) 2 -3H2 0; tyuyamunite, Ca(UO2 ) (VO4 ) 2 - 

nH2 0 (Frondel and Fleischer, 1952) ; and metatyuyamunite, 

Ca(UO2 ) 2 (VO4 ) 2 4-6H2O. Much of the yellow color of the minerals

390125 57 2
192 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Sandstone

Sandstone

Sandstone

2 Feet

EXPLANATION

Banded ore Disseminated ore Sandstone

FIGURE 29. Changes in composition Of the vanadium and uranium Ol'fiS With 

increasing depth and cover at the Bitter Creek mine. For explanation see 

facing page.
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 193

is masked by the gray vanadiferous clay. (T. W. Stern, U. S. Geological Survey, oral communication, March 1953).

The sandstone is stained yellow and brown by limonite. White 

veins of fibrous gypsum fill a few fractures. Fossil logs, twigs, and 

other plant fragments that have been altered to dull black lignite are 

common. Although a small amount of this lignite is rich in uranium, 

most of it is barren, especially outside the main ore bodies.

The clay ores are in part disseminated rather uniformly through 

the sandstone, in part concentrated in bands along the bedding planes, 

and in part concentrated in curved rolls. Well-developed rolls are 

characteristic of the first and second zones of the deposit (figs. 29A and 

295).

Some rolls are localized at the junction points of two shaly bands. 

In some places these shaly bands appear to be original sedimentary 

shale layers between sandstone lenses, but in other places the shaly 

bands may have formed by the dissolving of the quartz grains along 

bedding planes by the ore solutions.

SECOND ZONE

The second zone extends about TOO feet down the dip of the beds from 

about the "200" level to a point just above the "500" level. The thickness of cover above the zone ranges between 80 and 120 feet. The

EXPLANATION OF FIGUKE 29

Changes in composition of the vanadium and uranium ores with increasing thickness of cover at the Bitter Creek mine.

A. Vanadiferous clay and carnotite socket roll in the "100" level of the Bitter 

Creek mine. This ore is typical of the first zone of oxidation, wJiich lies 

between the surface and a depth of 80 feet. The roll is located at the 

junction of two shaly layers separating sandstone lenses. The ore contains 

several percent of V2OE, and some of it forms dark-gray rhythmic diffusion 

bands that curve between the shaly layers. The ore is locally stained by 

carnotite.

B. Vanadyl vanadate socket roll typical of the "300" and "400" levels at depths 

of from 80 to 120 feet below the surface. The ore consists primarily of 

black vanadium vanadates and oxides (corvusite and a small amount of 

montroseite) and uranium oxide, and it is richer than the vauadiferous 

clay. Only a small amount of ore is disseminated between the bands.

0. Nodular and banded low-valence vanadium oxide ores on incline between the 

"500" and "600" levels. Ore in the nodules shown contains from 10 to 20 

percent of V20B (montroseite and a small amount of corvusite). Note the 

structural similarities of the nodules shown in C and the socket rolls shown 

in A and B, and note the probable incipient stage of diffusion of the large 

nodule (compare the large nodule with the small one and with the nodules 

shown in fig. 30). The bands along the shaly layers consist of lean black 

vanadium oxide ore and brown iron oxides, which apparently are products 

of alteration and redeposition of material that was once part of the nodules.
194 CONTRIBUTIONS TO ECONOMIC GEOLOGYsecond zone (fig. 29Z?) resembles the first, but vanadyl vanadates and 

some oxides, rauvite, and possibly uranium oxides are the principal 

ores; the margins of the ore bodies and some rolls are more irregular; 

and the ore is richer and most of it is concentrated in bands rather than 

in disseminations. Vanacliferous clay, the principal vanadium mineral of the first zone, is much less common, and the yellow carnotite 

minerals (carnotite, tyuyamunite, and metatyuyamunite) were not 

observed. The principal minerals are greenish-black or blue-black 

corvusite, VoCVCVsCVrLO, which is abundant; black montroseite, 

VO(OH) or (V,Fe)O(OH) ; and undetermined uranium oxides and 

rauvite (Stern, T. A., U. S. Geological Survey, oral communication, 

March 1953). In many of the older stopes, orange pascoite, 

2CaO-3V2O5 -llH2O (Weeks and Thompson, 1953, p. 59), coats the 

richer ore and indicates the ore is partly oxidized. The ore-bearing 

sandstones are stained by limonite, and gypsum fills small fractures. 

The margins of the tabular bodies and some of the rolls are somewhat more irregular and the ore minerals are less widely and less evenly 

distributed through the rock than in the first zone, but the boundaries 

of the ore bodies grade more abruptly into barren wall rock. The ore 

bands and rolls are bluish black, owing to the vanadyl vanadate and 

oxide minerals. Fewer and leaner masses of disseminated ore lie between the rolls and ore bands (fig. 295) than in the first zone; in 

general, however, the ore of the second zone is richer and less evenly 

distributed than that of the first. In places, lean disseminations of 

reddish-brown vanadium ore occur. This ore apparently consists of

a mixture of vanadyl vanadates, some red hewettite (CaV6Oi6 -9H20),

and iron oxides, and it contains 2 to 3 percent V2O5 .

A few widely scattered irregular nodules of rich montroseitecorvusite-uranium oxide ore are found in the second zone closely associated with bands and masses of disseminated vanadium oxides.

THIED ZONE

The deepest zone,, exposed in the "500" and "600" levels, contains 

numerous rich black concretions, nodules, bands, spotty disseminations,

a few very irregular rolls of vanadium and uranium oxides, and iron 

and copper suifides (figs. 29(7 and 30). The nodules contain very high

grade ore, ranging from 10 to 30 percent V2O5 and 0.1 to 0.75 percent V5 9S (Mr, yard DecKman, lessee 01 Bitter Cl« minfc, oral commiimcation, 195Q) Inowever7 the quantity of uranium in. iricliviclual nodules

differs greatly. The nodules occur as irregular lumps that have sharp

projections, as knobby and "amoeboid" bodies, and as ellipsoidal concretions, all of which may be from a few inches to 5 feet across (figs. 

29G and 30). Many of the bands also consist of rich ore, but the grade 

is lower than that of the nodules. The disseminations are relatively 

small, spotty, and local. Some disseminations consist of a lean brown
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 195

Sv>

x <;___

. fS^LigmtT^^i. 

Band of ore containing^** 

small rich nodules 

and diffuse vanadium _ 

and uranium oxide

' Shale pebble conglomerate (pebbles are olive green and slickenslded)

<=b

Band of limonite stain-'

Brow

py

of uranium oxide

Ore rich in vanadium oxide, 

low in uranium oxide

vn sandstone containing- \ -.

rite and a small amount - Blue-black ore, very rich in oxides

of vanadium and uranium

FIODBB 30. Black vanadium and uranium oxide nodules in light-brown sandstone at the 

"600" level. Original pyrite has been altered to limonite except in the nodules.

mixture of vanadium and iron oxides. The rolls are composed of very 

rich ore but are imperfectly formed (fig. 29tf). Within some rolls 

irregularly shaped barren masses interrupt the roll surfaces. 

Smoothly curving diffusion bands are rare.

Montroseite, a small amount of corvusite, and unidentified black 

uranium oxides are the principal ores in the third zone. Vanadif erous 

clays apparently are rare or absent. Pyrite is abundant and occurs as 

small disseminated grains in the black nodules, as uranium-bearing 

concretions, and as sparsely disseminated grains in unoxidized parts 

of the ore-bearing sandstone. Grains of chalcopyrite were noted in 

several nodules. Barite is present, but gypsum is rare or absent. 

Limonite locally forms diffusion bands around the nodules and rolls, 

and it is intermixed with vanadium oxides and vanadates in local 

patches of brown disseminated ores, which are more typical of the 

second zone. In some places these brown ores contain hewettite, 

CaV6O16 9H20, in soft red masses.

Carbonaceous material (fig. 30) consisting of fossil wood and other 

plant fragments is common. It is shiny black and resembles asphalt 

but appears to consist mostly of lignite mixed with small quantities of 

a viscous liquid substance resembling gilsonite, thucolite, or anthraxolite. In a very few places the liquid fraction has flowed into adjacent 

small cracks (fig. 30). Most of the carbonaceous material in the ore 

zone contains vanadium or uranium, but most of it in the barren rock 

does not. Many of the ore nodules and concretions enclose or adjoin 

the carbonaceous areas.
196 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The rock is moist in the third zone, and pools of ground water have 

collected in the deepest parts of the mine. The zone appears to be 

at the upper limit of either the main ground-water table or a local 

perched water table.

Some of the host sandstone is brown and stained with limonite, but 

the rest is white or gray and contains pyrite grains instead of limonite. 

Where the sandstone is yellow or brown, many of the vanadiumuranium nodules are large, have irregular shapes (fig. 29(7), and are 

surrounded by diffusion bands of limonite; bands and disseminations 

of leaner vanadium ore commonly occur near them. The boundaries 

of the nodules are not as sharp as they are in the white or gray sandstone, and the nodules have large centers of lean ore. Irregular rolls 

occur in the yellow or brown sandstone, but they are not common. 

More limonite and less pyrite are present than in the white or gray 

sandstone.

In the white or gray sandstone the vanadium-uranium nodules and 

concretions are commonly well rounded and have few projections. 

They are probably composed mostly of mbntroseite, uraninite, and 

pyrite. They occur as isolated black ellipsoids in barren sandstone 

associated with a few adjacent bands or disseminations of ore. The 

boundaries of the concretions are sharp. Some of the concretions are 

Concentrically banded and closely resemble manganese oxide concretions. The concretionary ore in white or gray sandstone is believed 

to represent the upper edge of a fourth zone of unoxidized ores.

ZONING OF OTHER DEPOSITS IN THE TJRAVAN AREA

Zoning of vanadium-uranium ores is found in many of the more 

deeply buried deposits in the "Uravan mineral belt." In most of these 

deposits only the first and Second zones are present, but in some the 

third zone is present. The black ores of the SeCOIld and third zones 

Occur in places where the rock cover is sufficientlj thick (Weeks and 

Thompson, 1953, p. 11-12). The CKang6 in the zoning of the ores is 

gradual over a distance of several miles in some places, as i^ the Long 

*»«~u group of mines (Fischer and Hilpert, 1952, fig. 5). The group 

of Ore bodies iS in a n^ «early parallel to the regional strike, and the 

thickness of the overlying rocks increase g^a^uy toward the southeast. The northwestern part of the group contains cann**t» ^ 

vanadiferous ciay ores beneath thin cover. The black ores of the 

second zone begin to occur in email patches, exposed in Long Fark 

No. 6 mine, as the cover becomes thicker southeastward- r^ng park 

No. 1 mine, about half a mile southeast of Long Park No. 6 and at 

greater depth, contains only the black oxide bands, rolls, and disseminations of the second zone. The ore body exposed in the Whitney 

mine, half a mile southeast of Long Park No. 1 and beneath the deepest
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 197

cover at Long Park, contains nodular ore similar to that of the third 

zone at Bitter Creek.

The ore body of the Virgin mine is located down dip at the east edge 

of Long Park. The mine was the deepest in the "Uravan mineral 

belt" in 1952, reaching a depth of 345 feet. Here are found blanket 

deposits of black vanadium-uranium oxide ores that contain coffinite, 

a black uranium mineral having an X-ray pattern like that of thorite 

(Stief, Stern, and Sherwood, 1955). The ore is even less oxidized than 

that at Bitter Creek.

Black ores of the second and third zones are found in ore bodies of 

Club Mesa (Fischer and Hilpert, 1952, fig. 4) that lie beneath thick 

caps of rock (fig. 31), even though the ore bodies may lie up the dip

Burro Canyon formation

1 Mile

Approximate horizontal scale 

EXPLANATION

Contact, approximately located Zonal boundary Ore body

FIGURE 31. Generalized section eastward through Club Mesa, Uravan, Colo., showing 

relations of zones to ore bodies and to thickness of cover.

from the outcrop. The strata in Club Mesa str.ike northwestward 

and dip gently northeastward. Ore bodies near the rim of the mesa 

(those of the Club, Mill No. 2, and Saucer Basin mines) are overlain by 

a thin cover of rock and consist of vanadiferous clay and carnotite ores. 

Ore bodies beneath the thick overlying rock near the central mesa cap 

of the Burro Canyon formation (that of the LaSal mine, those to the 

west and north of the LaSal mine, and the westernmost part of that of 

Mill No. 1 mine) consist mostly of blue-black ores that contain corvusite, a little montroseite, rauvite, black uranium minerals, and probably some vanadiferous clays all typical of the second, or'partly 

oxidized, zone. Ore found by deep drilling beneath the central mesa 

cap is black and unoxidized, similar to that at the Virgin mine.

ORIGIN OF THE ZONES

Further geologic study of the Bitter Creek ore deposit and of other 

ore deposits in the "Uravan mineral belt" is needed before the origin 

of the zones can be stated with certainty.
198 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The zonation probably indicates progressive oxidation of primary 

concretionary vanadium-uranium oxide deposits containing iron and 

copper sulfides to secondary vanadiferous clays and carnotite. Primary oxide deposits blanket ore known to exist in many places beneath 

thick rock cover and beneath the water tables, such as at the Virgin 

mine, Long Park group; La Sal No. 2 mine, Gateway district, Colorado ; and Mi Vida mine, Monticello district, Utah. Above the water 

table and nearer the surface the primary oxide deposits have been 

oxidized through several progressive stages to carnotite and vanadiferous clay ores (Weeks, Cisney, and Sherwood, 1953; .Weeks and 

Thompson, 1953). Oxidation of sulfides to oxides in the Bitter Creek 

ores most certainly occurs in the pyrite and chalcopyrite associated 

with the vanadium and uranium minerals.

Concretionary montroseite black ore that contains unoxidized sulfides occurs only in small blocks of gray and white sandstone exposed

in the deepest, moist parts of the mine. These blocks may be remnants 

of a fourth zone, not yet fully exposed, in which oxidation of the primary ores has not started.

The rest of the ore in the third zone is in yellow or brown limonitestained sandstone and probably represents initial stages of oxidation. 

For example, only some of the sulfides (pyrite and chalcopyrite) have

been oxidized, and considerable quantities of these sulfides remain in 

the nodules. The irregular knobby nodules of black vanadium ores 

(fig. 30) may represent incipient stages of enlargement by diffusion

and disintegration of spheroidal concretions of the primary ores of the

fourth zone. Diffusion and disintegration may have been caused, at

least in part, by slow solution in wafers aciainea by the oxidation 61 tke

associated sulfides. A diffusion band of brown limonite has formed

around the dissolving nodules (fig. 29(7). As the margins of the

nodules moved outward by diffusion, expanding centers Of lean ore

developed. The disseminations and bands of lean blue-black vanadium ores that surround the partly disintegrated nodules may consist 

mainly of corvusite reprecipitated from acidic vanadium-bearing solutions. Keprecipitation probably occurred when alkaline ground water

neutralized the solutions a,s they moved, from the vanadium oscide

nodules through more permeable parts of the adjacent rock,

Figure 29C illustrates the diffusion of two nodules near the edge of 

a sandstone lens between layers of shale. The larger nodule is believed to represent a more advanced state of diffusion than the smaller

one. It is more irregular, has a larger central core of lean ore, is completely surrounded by a diffusion band of limonite, and from it bands ol lean vanaflyl vanaaate ore ana Dro^n iron osiaos appear u> ^^

advanced in two directions along the layers of shale. If the larger 

nodule had diffused and disintegrated further, it might have developed 

into a roll similar to the one shown in figure 29#.
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 199

The chemical and physical processes involved in the formation of 

rolls are not well understood. Eolls may represent the advancing 

diffusion fronts of acidic solutions containing vanadium and uranium 

derived from many nodules and pyritized areas. The curved diffusion 

fronts may have formed by reaction between acidic vanadium-bearing 

solutions near the curved edges of the sandstone lenses and alkaline, 

oxygen-bearing vadose waters percolating through the more permeable 

centers of the lenses.

The second zone, which consists of rolls of blue-black vanadium ore 

(fig. 29Z?) and a few nodules, may represent an intermediate oxidation 

stage. Most of the nodules that once occurred in the zone have been 

dissolved. The rolls probably developed from the dissolved nodules 

by a redeposition process, such as the one suggested in the two preceding paragraphs. The pyrite and chalcopyrite have been oxidized and 

some of the resulting sulf ate ions have been deposited as gypsum. The 

carbonaceous material has been further altered by the solution and 

removal of the asphaltic fraction, leaving only the lignite.

The shallowest zone (fig. 29A) represents a more complete oxidation 

stage. The vanadium and uranium minerals, which oxidize in several 

stages and more slowly than the iron and copper sulfides, have further 

diffused and oxidized to vanadiferous clays and yellow carnotite 

minerals. The fact that the average grade of ore per cubic yard mined 

from the first zone is about equal to that mined from the less oxidized 

zones below, strongly suggests that the surface ores are more diffused 

and that they have been oxidized rather than leached. In diffused 

ores, such as the vanadiferous clays, the uranium and vanadium content of small samples is less, owing to the wider dispersion of the 

minerals of these ores throughout the rock, and to the oxidation of the 

minerals to minerals that contain smaller percentages of the elements 

in them.

The zones may have originated in several other ways, as follows:

(1) They may represent progressive changes in the original deposition 

of the ores caused by differences in the ore-bearing solutions or in local 

conditions, such as increased quantities of carbonaceous fragments;

(2) the nodular ores near the present water table may have resulted 

from a redeposition and secondary enrichment of ores deposited as 

bands and rolls in the first and second zones, the first zone being an 

oxidation product of the second zone; (3) large deposits of carnotite, 

which are typical of the "Uravan mineral belt," seem to be coincident 

with the area of the Pennsylvania evaporite basin (Weeks and Thompson, 1953), which may be the source of the potassium that locally forms 

primary carnotite ores.

Further study of the deposit is needed to explain (1) the rather 

abrupt change from the black vanadate roll type of ore body of the
200 CONTRIBUTIONS TO ECONOMIC GEOLOGY

second zone to the nodular and concretionary ore body of the third 

zone, without a marked transition zone; (2) the scarcity of discernible 

"ghosts" of dissolved nodules in the upper parts of the deposit; (3) the 

ellipsoidal black nodules in the gray and white sandstone, which may 

be primary ores or may represent another transition stage developed 

from a still earlier form of ore deposit; and (4), if the nodular types 

of ore are primary, the formation of vanadium-uranium concretions 

under reducing conditions.

SUMMARY

Three distinct zones and small remnants of a possible fourth zone 

are exposed in the Bitter Creek mine.

First zone. Vanadiferous clays, carnotite minerals, limonite, and 

gypsum in very well developed rolls, bands, and disseminations. The 

ore is low grade, oxidized, and occurs in brown sandstone.

/Second zone. Blue-black vanadium ores and possibly uranium 

oxides, associated with limonite, in less regular and less well developed 

rolls, in many bands, and in less diffuse disseminations. Nodules are 

few and widely spaced. The ore is richer than that in the first zone. 

A gradational change occurs between this zone and the first zone.

Third zone. Rich black vanadium-uranium oxide ore in irregular 

nodules and concretions, in a few rich bands, and in incipient irregular 

rolls, forming a spotty ore body. Pyrite and chalcopyrite are present 

but are partly oxidized to limonite. Within this zone are small areas 

of white and gray sandstone. None of the sul fides in the sandstone are

oxidized, and the black oxides in the sandstone are in ellipsoidal concretions,

The zones probably were formed as a result of oxidation of primary 

black concretionary ores and associated sulfides. The oxidation of the 

suifides by ground water at or near the ground-water table could have

resulted in the formation Of acidic solutions that redissolved the black 

oxide ores and redeposited them in rolls between solution f rontS. Rfideposition probably occurred as the solutions were neutralized by and

reacted with descending vadose alkaline waters. Further oxidation 

may have produced the vanadiferous clays and the carnotite stains.

Zoning of this type is not restricted to the Bitter Creek mine but

may be common throughout the "Uravan mineral belt," The recent 

mining has exposed many other black ores beneath the thicker parts 

of *Ke mesa. ca,ps. AS mining increases in the areas of thicker COVCF,

a much larger proportion of the ores obtained win probably be biack

rather than yana^iferous clays and carnotite oreS.
ZONING, BITTER CREEK VANADIUM-URANIUM DEPOSIT 201 

SELECTED BIBLIOGRAPHY

Fischer, R. P., 1942, Vanadium deposits of Colorado and Utah, a preliminary 

report: U. S. Geol. Survey Bull. 936-P, p. 363-394, 5 pis., 5 figs.

 1944, Simplified geologic map of the vanadium region of southwestern 

Colorado and southeastern Utah: U. S. Geol. Survey Min. Inv. Prelim. Map 

3-226.

Fischer, R. P., and Hilpert, L. S., 1952, Geology of the Uravan mineral belt: U. S. 

Geol. Survey Bull. 988-A, 13 p., 3 pis., 5 figs.

Frondel, J. W., and Fleischer, Michael, 1955, A glossary of uranium- and thoriumbearing minerals, third edition: U. S. Geol. Survey Bull. 1009-F, p. 169-206.

Stief, L. R., Stern, T. W., and Sherwood, A. M., 1955, Preliminary description of 

coffinite a new uranium mineral: Science, v. 121, p. 608-609.

Waters, A. C., and Granger, A. C., 1953, Volcanic debris in uraniferous sandstones 

and its possible bearing on the origin and precipitation of uranium: U. S. 

Geol. Survey Circ. 224, 26 p., 12 figs.

Weeks, A. D., Cisney, E. A., and Sherwood, A. M., 1953, Montroseite, a new, 

vanadium oxide from the Colorado Plateau: Am. Mineralogist, v. 38, nos. 11 

and 12, p. 1235-1241.

Weeks, A. D., and Thompson, M. E., 1953, Identification and occurrence of 

uranium minerals from the Colorado Plateau: U. S. Geol. Survey Bull. 

1009-B, p. 13-62.

Weir, D. B., 1952, Geologic guides to prospecting for carnotite deposits on Colorado Plateau: U. S. Geol. Survey Bull. 988-B, p. 15-27, 9 figs.

U. S. GOVERNMENT PRINTING OFFICE) 1987