UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall, Director

Bulletin 936-P

VANADIUM DEPOSITS OF COLORADO AND UTAH

A PRELIMINARY REPORT

BY 

RICHARD P. FISCHER

Prepared in cooperation with the

STATE OF COLORADO and the

COLORADO METAL MINING FUND

Strategic Minerals Investigations, 1942 

(Pages 363-394)

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1942

For sale by the Superintendent of Documents, Washington, D. C. ....... Price 30 cents

CONTENTS

Page

Abstract................................................. 363

Introduction............................................. 364

Production........................................... 364

Regional geology......................................... 365

Ore deposits............................................. 366

Ore-bearing formations...*........................... 367

Shinarump conglomerate.......................... 9 367

Entrada sandstone................................ 367

Morrison formation............................... 371

Mineralogy........................................... 376

Ore.................................................. 379

Lithology........................................ 379

Character .and distribution....................... 379

Ore bodies........................................... 382

Uravan district.................................. 385

Origin and control of ore............................ 387

Suggestions for prospecting...... 0 ....................... 389

Mining and milling....................................... 393

Prospecting.......................................... 393

Mining............................................... 394

Milling.............................................. 394

ILLUSTRATIONS

Page

Plate 53. Index map of part of Colorado, Utah, and Arizona, showing the location of the significant vanadium deposits.................. 366

54. A, Photomicrograph of sandstone impregnated 

with vanadium-bearing hydrous micaj B, 

Typical face of vanadium ore................ 382

55. A, Zone of vanadium ore cutting across bed^ 

ding; 13, Thin zone of rich vanadium ore 

along contact of ore body and barren sandstone ....................................... 382

56. A, Parallel zones, resembling diffusion bands, 

of rich vanadium ore along the edge of an 

ore body; B, Lens of shale-pebble conglomerate, in part mineralized and in part barren. 382

57. Geologic map and section of the Club group of

mines, Montrose County, Colorado............ 386

III
IV ILLUSTRATIONS

Page

Figure 43. East-west cross section through the Rifle

mine (after Blair Burwell).................. 372

Figure 44. Measured stratigraphic sections of the

Entrada sandstone in the Placerville district, showing the^position of the vanadium- and chromium-bearing layers........... 373

Figure 45. Hap of the Placerville district, showing the 

outcrops of the vanadium- and chromiumbearing layers.............................. 374

Figure 46. Cross-section of an ideal ore body............ 384

Figure 47. Geologic map of the Uravan area, Montrose

County, Colorado............................ 386
VANADIUM DEPOSITS OF COLORADO AND UTAH 

A PRELIMINARY REPORT

By Richard P. Fischer

ABSTRACT

Deposits of vanadium-bearing sandstone are widely distributed 

in western Colorado and eastern Utah and have been the principal 

domestic source of vanadium, uranium, and radium. Except during 

a few years when operations were relatively small, deposits at 

one or more places in this region have been intensively mined 

since 1909. Production has increased considerably each year 

since 1937.

Most of the deposits are in the Morrison formation, but there 

are two .important deposits in the Entrada sandstone and several 

small deposits in the Shinarump conglomerate. Recent X-ray 

studies indicate that the principal vanadium mineral, heretofore 

considered to be roscoelite, belongs to the hydrous mica group 

of clay minerals. This mineral, along with other vanadium 

minerals of minor importance, impregnates sandstone. Shale pebbles and clay films on bedding planes in ore-bearing sandstone 

are rich in absorbed vanadium, and fossil plants in and adjacent 

to ore bodies are richly mineralized with vanadium and uranium 

in places. Vanadium ore of milling grade contains from about 1 

to 5 percent V^Oc, and most of it contains less than 1 percent 

UgOg. Ore containing as much as li percent UsOo 13 usually sold 

as uranium ore. The vanadium-bearing hydrous mica is in part 

uniformly disseminated through the sandstone and in part concentrated along bedding planes and in thin zones that cut across 

bedding. As the zones that cut across bedding are curved or 

wavy, they are called rolls by the miners.

The ore bodies are spotty and form irregularly tabular masses 

that lie essentially parallel to the sandstone beds, but they 

do not follow the beds in detail. They range in content from a 

few tons of ore to many thousand tons. The trend of many elongate bodies is indicated by the orientation of the rolls within 

the ore, and this trend also suggests the probable alinement of 

any adjacent ore bodies; mapping of ore bodies and rolls is 

therefore an aid to prospecting and development.

No satisfactory explanation can yet be offered for the origin 

of these deposits. The ore bodies do not appear to have been 

localized by such geologic structures as fractures or folds, 

but within limited areas they are restricted to certain stratigraphic zones.

363
364 STRATEGIC MINERALS INVESTIGATIONS, 1942

INTRODUCTION

Deposits of vanadium-bearing sandstone, containing some 

uranium and radium, are widely distributed in western Colorado 

and eastern Utah, and some occur in northern Arizona (pi. 53). 

These deposits have been the principal domestic source of vanadium, uranium, and radium. In 1939 the Geological Survey, United 

States Department of the Interior, in cooperation with the State 

of Colorado and the Colorado Metal Mining Fund, began a geologic 

study of these ores .in the western part of Montrose County, 

Colo., where many of the largest known deposits of this type 

have been found. The present report, which describes the 

significant geologic features of these deposits, is based on 

this study and on brief visits to many of the other vanadiumproducing areas in the region,,

The work was begun under the guidance of Mr. B. S. Butler 

of the Geological Survey. S. P. St. John, Charles Meyer, 0. J. 

Myers, and A. P. Butler, Jr., have assisted in the field work. 

The producing companies and many individuals in the vanadium 

region gave generous aid and cooperation. H. G. Ferguson and 

F. C. Calkins contributed many helpful suggestions during the 

preparation of the report.

Production 

In 1899 a yellow mineral from the sandstones of the western

4

part of Montrose County was found to contain uranium, vanadium, 

and radium; and this mineral was named carnotite. From 1911 to 

1923 ores containing carnotite were intensively rained in Montrose

County and adjacent areas; radium and uranium were the constituents desired, but from 1915 to 1923 some vanadium was produced 

as a byproduct. Mining of these ores practically ceased in 

1923, when the Belgian Congo pitchblende began to supply radium. 

Since 1937 these ores again have been intensively mined, but
VANADIUM DEPOSITS OF COLORADO AND UTAH 365

this time primarily for vanadium. Vanadium was produced from 

vanadium-bearing sandstone at Placerville, Colo., from 1909 to 

1923, and at Rifle, Colo., from 1925 to 1932. Vanadium ore was 

being mined at both localities in 1941.

Vanadium production' from the Colorado-Utah region, as expressed in pounds of metallic vanadium contained in the mill 

product obtained, is summarized in the following table:

Vanadium production from Colorado and Utah 

(in pounds of metallic vanadium)

"Roscoelite ores" from Placerville, I/

Colorado, 1909-23, inclusive..................... 3,054,374

"Carnotite ores" from Colorado and I/

Utah, 1915-23, inclusive......................... 1,116,455

"Roscoelite ores" from Rifle, 2/

Colorado, 1925-32, inclusive..................... 4,685,449

"Carnotite ores" from Colorado and 2/

Utah, 1924-36. inclusive......................... 183,471

"Carnotite ores" from Colorado and 2/

Utah, 1937-40, inclusive......................... 4,640,336

Total........................................... 13,680,085

i/ Mineral Resources U. S. , 1921*, pt. 1, p. U?3. 1927. 

2j Compiled with the aid of Frederick Bet'z, Jr., from the files of the 

U. S. Bureau of Mines.

REGIONAL GEOLOGY

The region containing most of the vanadium deposits constitutes approximately the northeastern third of the Colorado Plateau physiographic province. Much of this region, being dissected by many rugged canyons, is commonly known as the Canyon 

Lands. Except for some of the canyon bottoms and high mountain 

masses, most of the region ranges in altitude from about 5,000 

to 7,500 feet above sea level. The climate is semiarid except 

in the high mountain areas.

The formations exposed consist mostly of nearly horizontal 

sedimentary beds, disturbed in places by moderately strong monoclinal and anticlinal folds and high-angle faults. The Comb 

Ridge and Water Pocket monoclines and the San Rafael Swell and 

Uncompahgre Plateau uplifts are the largest folds in the region,
366 STRATEGIC MINERALS INVESTIGATIONS, 1942

but strong anticlines underlie Paradox Valley, Spanish Valley, 

and other similar topographic features in the vicinity of the 

La Sal Mountains. Steeply dipping faults displace the beds 

along the flanks of these folds in many places, and competent 

sandstone beds in the vicinity of these folds are much jointed.

The sedimentary beds in western Colorado and eastern Utah 

range in age from late Paleozoic to Tertiary. All known vanadium 

deposits of economic importance are found in the Shinarump conglomerate, of Triassic age, and the Entrada sandstone and Morrison formation, of Jurassic age. The lithologic features, topographic expression, distribution, and variations in thickness of 

the Triassic and Jurassic formations in this region are summarized in the table on pages 368-371,

Moderate-sized igneous bodies of Tertiary age have intruded 

these sediments and are exposed in the La Sal, Abajo, El Late 

(Ute), Carrizo, and Henry Mountains,

ORE DEPOSITS

The vanadium deposits of western Colorado, eastern Utah, and 

northern Arizona, although of wide areal distribution, have a 

narrow stratigraphic range. All known deposits of economic importance in the region are restricted to the Shinarump, Entrada, 

and Morrison formations, and at many places the deposits are 

largely or wholly confined to a single stratigraphic zone in one 

of these formations. The ore, however, is not confined to a 

single sandstone bed or lens. The ore is mostly sandstone impregnated with vanadium minerals, but shale pebbles and clay 

films along bedding planes in 'the ore-bearing sandstone are rich 

in absorbed vanadium, and fossil plants in and adjacent to ore 

bodies are in places richly mineralized. As the vanadium content of the ore is not uniform, highly selective mining is required to obtain ore of the desired grade. Vanadium ore of 

milling grade contains from about 1 to 5 percent V205 , and most
!O7<

EXPLANATION

Deposits in the Morrison formation

*

Deposits in the Entrada/ sandstone

X Deposits in the Shinarump conglomerate

9 {9 20 30 4-0 50 MILES

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VANADIUM DEPOSITS OP COLORADO AND UTAH 367

of it contains less than 1 percent UgOg. Ore containing as much

as if percent U 0Q is commonly sacked and sold separately as 

o o

uranium ore.

The ore bodies are .extremely spotty and form irregularly 

tabular masses that lie essentially parallel to the sandstone 

beds, but do not follow the beds in detail. In places, curved 

or wavy structures in the ore, called rolls by the miners, are 

oriented in a common direction, and this orientation may indicate the trend or elongation of the ore body,, Adjacent bodies 

are also likely to be alined along this trend. The ore bodies 

do not appear to have been localized by fractures or folds.

Ore-bearing formations

Shinarump conglomerate, The only known important deposit of 

vanadium and uranium in the Shinarump conglomerate is at Temple

Mountain, in Emery County, Utah. This deposit has not been

I/ 

visited by the writer but has been described by Hess. Small

deposits in the Shinarump conglomerate occur in southern Utah 

and northern Arizona (pi. 53). These have some features in common with the deposits in the Morrison formation.

Entrada sandstone. At the U. S. Vanadium Corporation's mine, 

about 12 miles northeast of Rifle, Colo., most of the ore is in 

the lower part of a 20- or 30-foot bed of cross-bedded, gray 

sandstone, included in the Entrada sandstone in this report. 

This bed lies on the Dolores formation, and it is overlain by

about 100 feet of characteristic Entrada sandstone. A cross

2/

section through the mine, drawn by Burwell, shows a close relationship between the distribution of the ore and the crossbedding (fig. 43); however, the mineralized sandstone that extends laterally from the ore body forms a single slightly

iy Hees, F. L., Uranium-bearing asphaltite sediments of Utah: Eng. and 

Win. Jour.-Press, vol. llU, pp. 212-2^6, 1922.

2j Burwell, Blair, Mining methods and costs at the vanadium mine of the 

U. S. Vanadium Corooration, Rifle, Colo.: U. 3. Bur. Mines Inf. Circ. 6662, 

fig. 2, 1932.

488684 O - 42 - 2
368 STRATEGIC MINERALS INVESTIGATIONS, 1942

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VANADIUM DEPOSITS OP COLORADO AND UTAH 371

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undulant layer, too thin or too lean to be of 

commercial value. This layer lies in the basal 

few feet of the formation and extends through 

the cross-bedding with only a minor concentration 

of minerals along cross-bedding planes. It is 

continuous for at least a mile along the outcrop.

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restricted to the upper 10 or 15 feet of the

3/

Entrada sandstone (flgo 44) Before the erosion of the present stream valleys a single, 

slightly undulant layer of vanadium-bearing 

sandstone .covered an elongate area of trend at 

least 3 by 9 miles in extent (fig. 45). The 

parts of this layer that are about 2 feet or more 

thick and contain about l|r percent or more of 

VpOc constitute ore bodies. A few feet below 

most of the vanadium-bearing layer is a layer of 

light-green sandstone colored by a finely disseminated chromium mineral (figs. 44 and 45).

Morrlson formation, In western Colorado and 

eastern Utah the Morrison formation can conveniently be divided into two lithologic units 

of about equal thickness. The lower unit consists of massive lenses of medium- to coarsegrained, rather porous sandstone, partly conglomeratic at some places in Utah, interbedded 

with red and gray shale. These sandstones form 

a series of cliffs, and in many places a sandstone- at the top of the lower unit makes a rather 

conspicuous bench. The upper unit forms a steep

Jjy The Sntrada sandstone at Placerville was formerly 

called "lower La Plata" ty the Geological Survey, a term 

that is still used by many people in that area.
372 STRATEGIC MINERALS INVESTIGATIONS, 1942

slope below the cliff of Dakota (?) sandstone and is composed 

of gray, red, green, purple, and brown shale and of thin beds 

of hard sandstone and limestone Thick lenses of sandstone, in 

part conglomeratic, occur locally in both the lower and upper 

parts of this unit. ' The two units are not sharply separated, 

particularly where sandstone lenses are present in the lower 

part of the upper unit. The measured section of the Morrison 

formation, given on page 375, is typical.

\^^\ McElmo sandstone (cross-bedded)

LS^gj Vanadium-bearing sandstone LEGEND f55*^

tfipctj La Plata limestone

["^S:! Dolores Red Beds 

Q 20 W 60 80 

Scale, feet

Figure U}. East-west cross, section through the Rifle mine of the U. S. 

Vanadium Corporationj Rifle, Colo. (After Blair Burwell, Mining*methods 

and costs at the vanadium mine of the U. S. Vanadium Corporation, Rifle, 

Colo.: U. S. Bur. Mines Inf. Clrc. 6662, fig. 2, 1932.) The beds labelled McZlmo sandstone in the figure are classified as Bntrada sandstone in 

the present report, and the beds below the vanadium-bearing sandstone a? 

Dolores formation.

In the carnotite region of Mesa, Montrose, and San Migue.l 

Counties, Colo., and the adjacent part of Utah, most of the ore

occurs in the sandstone lenses that occupy the stratigraphic 

zone at the top of the lower "unit. Many of these lenses are 

more extensive than other sandstone lenses in the formation; a 

Single lens may be as much as 60 feet thick and several miles 

long. it is the opinion of many observers that the more favorable places for ore are those where the sandstone is relatively 

thick, but some ore has been found where the sandstone is thin. 

Most of the ore is found in the lower parts of sandstone lenses, 

but ore bodies may occur anywhere from the bottom to the top of
in Placerville ofth<fntrada sandstone Measured sections ofthe 1*4.-- district, showing position Figure stratigraphlc 

vanadium- andchromium-hearing layers.

SANDSTONE ENTRADA BEDS RED 

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/ 

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X

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t : 

i \ 

\l M

1 / 

: : 

\ \ 

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RQIQVMVA susodaa jo oovHonoo GUV SAC
374

a lens. The lower part Is apparently more favorable for bodies 

of mi11ing-grade vanadium ore, whereas the upper part is more 

favorable for small bodies of high-grade uranium ore ("tree 

formations"). In some mines, however, there are two or more 

rather distinct levels of milling-grade vanadium ore, separated 

by as much as 20 or 30 feet of barren sandstone. In places a 

thick shale lens lies within, or tongues into, an ore-bearing 

sandstone lens.

Basic dike

Outcrop of vanadium-bearing sandstone 

Chromium horizon

Numbers indicate positions of measured 

stratigraphic sections shown in figure 44

Figure U5. Map of the Placerville district, showing the outcrops of the 

vanadium- and chromium-tearing layers.

As the sandstones that are most favorable for ore occupy the 

upper part of the lower unit and are bench-forming, It is possible in many places to prospect for and outline ore bodies, at 

small expense, by drilling from the surface of the bench. Ore 

has been found In sandstones lower in the formation, but all of 

it, so far as known, in bodies too small to be of much economic 

interest.
VANADIUM DEPOSITS OF COLORADO AND UTAH 375

Section of Morrison formation at the Dolores group of mines, 

near the junction of Dolores and San Miguel Rivers, Montrose 

County, Colorado

Dakota (?) sandstone: Feet

Sandstone, white, weathering brown; medium- to coarsegrained, with lenses of conglomerate; resistant and 

cliff-forming.

Morrison formation: 

Upper unit:

1. Shale, variegated, with thin and discontinuous 

beds of hard sandstone and limestone; poorly 

exposed; forms slope......................... 310

2. Sandstone, light gray, coarse-grained and conglomeratic, massive, friable................. 40

3. Shale and thin sandstone; forms covered slope.. 28 

Lower unit:

4. Sandstone, light brown and light gray, mediumto coarse-grained, massive to lenticularly 

and irregularly bedded, cross-bedded; forms 

 vertical cliff and bench; ore-bearing........ 60

5. Shale, red except upper few feet, which are 

gray, with thin sandstone lenses; forms 

poorly exposed slope......................... 45

6. Sandstone, light brown and light gray, mediumto coarse-grained, massive to lenticularly 

and irregularly bedded, cross-bedded; forms 

vertical cliff............................... 21

7. Sandstone, shaly, with shale lenses; sandstone 

is light gray, coarse-grained, massive, soft 

and friable; shale is reddish and sandy...... 24

8. Sandstone, like No. 6.......................... 8

9. Shale, like No. 5.............................. 12

10. Sandstone, light gray to buff, medium- to

coarse-grained, thick-bedded, cross-bedded;

forms vertical cliff......................... "578" 50

I/ Summerville formation:

Sandstone, argillaceous sandstone, and shale, red, 

gray, and light-colored, in thin even beds or massive; forms a slope and is poorly exposed........... 89

Entrada sandstone.

U/ The Geological Survey has recently extended the formation name "Summerville" to include about 80 feet of beds heretofore included in the lower 

part of the Morrison formation in the western parts of Mesa, Montroae, San 

Miguel, Dolores, and Montezuma Counties, Colorado.

488684 0-42-3
376 STRATEGIC MINERALS INVESTIGATIONS, 1942

The two-fold division of the Morrison formation is also 

recognized south of Monticello, Utah, but ore bodies are scattered throughout the sandstones in the upper half of the lower 

unit instead of being restricted to a zone at the top of this 

unit.

The shales interbedded with the sandstones in the lower unit 

of the Morrison formation are red except immediately below sandstone, where, for a thickness of from 1 to 5 feet, they have 

been altered to gray or greenish gray by solutions circulating 

through the sandstone and penetrating the upper part of the 

shale. This altered shale is the so-called blue clay of-the 

miners and drillers.

Mineralogy

Vanadium and uranium, plus the radioactive products of uranium, are the only economically important constituents of the 

ore, which, however, contains traces of copper and silver in 

places. The deposits in the Entrada sandstone are commonly referred to as the "vanadiferous sandstone deposits," or "roscoelite deposits," as. they contain only a trace of uranium. The 

deposits in the Morrison formation, on the other hand, are 

generally referred to as the "carnotite deposits," a term that 

has been carried over from the time of "the earlier operations, 

when carnotite was the desired mineral because of the uranium 

and radium it contained. These deposits, however, contain several times as much vanadium as uranium, and the bulk of the vanadium is apparently in the same mineral form as in the deposits 

in the Entrada sandstone. As most of the ore minerals are

exceedingly fine grained and many of them are Intimately mixed

i 

or intergrown, mineralogic studies of the ore are difficult.

The principal vanadium mineral is micaceous, and it has

heretofore been thought to be roscoelite, the vanadium mica; 

but, as a result of recent X-ray studies by Sterling Hendricks
VANADIUM DEPOSITS OP COLORADO AND UTAH 377

of the Department of Agriculture, it is now thought to belong 

to the imperfectly understood hydrous-mica group of clay minerals. The general formula for this group is probably 2Kp0.3RO.-

^/ 

8R2 0,.24Si02 .12H20. RO includes magnesia (MgO) and ferrous

iron (FeO), and Rg^ includes alumina (AlgO,,) and ferric iron 

(Fe_0 ). Presumably vanadium oxide (Vg03 ) replaces A^Og and 

Pe 0 to form the vanadium-bearing member of this group. The

Ct O

vanadium-bearing hydrous mica forms an aggregate of minute 

flakes, coating the sand grains (see pi. 54, A), and it appears 

to be the earliest ore mineral. Where mineralization was weak 

to moderate, a single layer of this mineral was deposited on 

the sand grains, and the central parts of the pore spaces of 

the sandstone remained empty, or in places were filled by a 

later, nonvanadlferous clay mineral (dickite?). Where the sandstone was more strongly mineralized, the pore spaces are completely filled with the vanadium mineral. This mineral imparts 

to the sandstone a gray or greenish-gray color, which darkens 

as the vanadium content increases.

At several places in Montrose Countyj especially in the 

mines in the Long Park area (see fig. 47), some of the ore, 

when dry and viewed by daylight, has the yellowish-brown color 

of limonite; but underground, while it is still moist and when 

viewed by the light of a carbide lamp, the same material appears 

distinctly reddish, and the miners call it "red oxide ore." 

The color is due to a finely disseminated brown mineral, not 

yet identified, which has replaced, or possibly been formed 

along with, the vanadium-bearing hydrous mica. This type of 

ore is mostly of good grade, containing about 2 percent Vg05, 

but it is rarely rich. It forms masses of various sizes and

irregular shapes within the ore bodies.

\ 

Vanoxite (SVgO^.VgOg.8HV>0) is an important ore mineral in

the Jo Dandy mine of Montrose County, and in the nearby

5/ Grim, R. E., Brag, H. H., and Bradley, W. J., The mica in argillaceous 

sediments: Am. Mineralogist, vol. ?2, pp. 813-829, 1937.
378 STRATEGIC MINERALS INVESTIGATIONS, 1942

prospects; and there is some vanoxite in the ore at many localities in Colorado and Utah. It forms black, prismatic crystals 

partly or completely filling the interstitial spaces of the 

sandstone; it replaces the vanadium-bearing hydrous mica and 

partly replaces the sand grains. Corvusite (V204,6V2C>5.nH20), 

a massive, purplish blue-black mineral, is intimately mixed 

with vanoxite where gypsum is present in the ore-bearing sandstone. This mixture replaces carbonized fossil plants and impregnates the adjacent sandstone, and it is commonly called 

kentsmithite by the miners.

Fervanite (2Pe203 .2V2 05 .5H20), hewettite (Ca0.3V205 .9H20), 

and metahewettite (same composition as hewettite) are secondary 

minerals of similar habit. They may be disseminated in the 

sandstone, but for the most part they form veinlets along fractures that cut the ore. These minerals are closely associated 

with gypsum, which they may replace. Pervanite is brown, hewettite and metahewettite are red; all are fibrous with a silky 

luster.

Pascoite (2Ca0.3V205 ollH20), rossite (CaO,V205 .4HgO), and 

metarossite (CaO.V2 0 5 .2H20) form efflorescent coatings on protected surfaces where vanadium-bearing ground water evaporates. 

They form most abundantly on surfaces of vanoxite and corvusite 

ore. Pascoite is bright orange, rossite and metarossite are 

light yellow.

The principal uranium-bearing minerals are carnotite (approximately K20.2U03 .V205 .3H20) and tyuyamunlte (approximately

CaO.2UO-.VoOt-.4HpO sometimes called calcium carnotite), but ° * D c 6/ 

the two are not easily distinguished. Both minerals are yellow.

Carnotite is apparently the powdery or earthy material that is 

irregularly disseminated through the ore and incompletely replaces fossil plants. Its age relations are. not clear, but it

£/ Hillebrand, W. F., Carnotite and tyuyanmnite and their oreB in Colorado""and Utah: Am. Jour. Sci. , 5th ser., vol. 8, pp. 201-216,
VANADIUM DEPOSITS OP COLORADO AND UTAH ' 379

probably formed relatively early. Tyuyamunitg is apparently the 

finely crystalline material that occupies open spaces, such as 

the pores of the sandstone and open fractures; it may form in 

ore-bearing sandstone or in otherwise barren sandstone even at 

a distance of several feet from ore. It is obviously secondary 

and formed relatively late.

Ore

Lithologyo The lithologic character of the sandstone in the 

ore-bearing beds is variable. The sandstone is massive in 

places, but for the most part it consists of a complex assemblage of lenses and channel fills; irregular bedding and crossbedding are common. In the Morrison formation and the Shinarump 

conglomerate, lenses of shale are irregularly interbedded with 

the sandstone, and shale pebbles, resulting from partial erosion and redeposition of the mud layers that now form the shale 

lenses, are scattered through the sandstone or are concentrated 

as Irregular lenses of shale pebble conglomerates. In these 

two formations fossil plants, consisting of logs, leaves, and 

reeds, are scattered through the sandstone or are irregularly 

concentrated as if they were buried as tangled bunches at the 

time the sands were being deposited. No fossil plant material 

has been recognized in the ore-bearing parts of the Entrada 

sandstone. The sandstone of the Entrada is mostly fine-grained; 

that of the Horrison and Shinarump is mostly medium- to coarsegrained.

Character and distribution.--The ore was formed by selective 

'impregnation of sandstone, absorption by shaly material, and 

mineralization of fossil plants. The vanadium-bearing hydrous 

mica is in part disseminated rather uniformly through the sandstone and in part concentrated in sheets along bedding planes 

(pi. 54, B) or in zones, up to several inches thick, that cut 

across the bedding (pi. 55). The zones may lie in barren or
380 STRATEGIC MINERALS INVESTIGATIONS, 1942

weakly mineralized sandstone (pi. 55, A) or along the contact 

of ore and barren sandstone, forming a sort of shell around the 

ore body (pis. 55, 13 and 56, A). Because these zones are curved 

or wavy they are called rolls by the miners.

Where mineralization was strong, especially along the favorable bedding planes or along the rolls, there has been solution 

of the quartz grains in the sandstone. This process first formed 

microscopic styolitic seams between adjacent sand grains and 

then continued until the grains were completely removed. As 

the quartz grains have not been replaced by the vanadium mineral, 

there has been an appreciable decrease in the volume of the 

mineralized rock. Where considerable quartz was removed, the 

residual concentration of the vanadium mineral formed a soft, 

vanadium-rich, shalelike seam along bedding planes and a "veinlet" along the rolls that cut across the bedding. The volume 

change is most evident where the rolls cut across bedding' planes

at a moderate angle, causing a minor slumping of the bedding

7/ . §/ 

planes (see pi. 55). Ransome, and later Pischer, incorrectly

interpreted these seams as shale seams of sedimentary origin,

9/ 

whereas Hess more correctly considered them to be veinlets.

In places there is a fracture along a veinlet (see pi. 55, A).

Vanadium is richly concentrated in the shale pebbles in the 

ore-bearing sandstone of the Morrison formation; one selected 

sample, consisting of several pebbles, contained 12^- percent 

VgO,.. The mineralized pebbles are black and brittle. Pebbles 

half an inch or less across are mineralized throughout, but the 

larger pebbles are mineralized only in the outer part, the cen- ' 

tral part consisting of barren gray or red shale. The vanadium

2,1 Billet)rand, W, Bc , and Ransoine, ?. L., On carnotite and associated 

vanadiferous minerals in western Colorado: U. S. Oeol. Survey Bull. 262, 

p. lU, 1905.

SI Fischer, R. P., Sedimentary deposits of copper, vanadium-uranium, ani

silver in southwestern United States: Econ. Oeol., vol. 3^, pp. 9^o-951i

1937.

%J Hess, F. L., in Ore deposits of the Western States (Lindgren volume), 

p. U59, Am. Inst. Min. Met. Eng., 1933.
/"' VANADIUM DEPOSITS OP COLORADO AND UTAH 381

was able to penetrate only about a quarter of an inch into the 

, shale pebbles, and it likewise penetrated about a quarter of an 

inch into bedded shale in contact with ore-bearing sandstone 

Vanadium was also concentrated in small grains of clay scattered

i

through the sandstone, and in clay films on bedding and crossbedding planes (see pi. 54, B),

In places the ore tends to follow the lenses of shale-pebble 

conglomerate, and there are two reasons why it might be expected 

to do so everywhere: These lenses should offer permeable channels for mineralizing solutions, and the shale pebbles are able 

to absorb and concentrate the vanadium. But in many places the 

boundary of the ore cuts sharply across these lenses (pi. 56, B) 

for no apparent reason. Where the boundary of the ore is especially sharp, pebbles as small as an inch across are richly 

mineralized on the side lying within the ore and barren on the 

other side.

The fossil plants in the Morrison formation consist of tree 

trunks and branches, reeds, and leaves. Most trunks were drifted 

into place the ends appear rounded and the branches are broken 

' or worn off. Several trunks found in the Club group of mines 

(pi. 57), however, evidently had merely fallen over from the 

place of growth, for attached to the root system is a disk of 

clay that is several feet in diameter and a couple of feet thick. 

These trunks are enclosed in massive sandstone and lie about 6 

or 8 feet above a shale bed that appears to have been the soil 

in which the trees grew.

The logs are in various states of preservation: many are 

partly replaced with dolomite, calcite, or silica, which may or 

may not enclose some residual carbonaceous matter; some are 

partly hollow or filled with sand; some are changed to coal; and 

some are partly replaced with ore minerals. Most logs are somewhat flattened; the ore-bearing logs have been more flattened, 

in general, than those that were replaced with carbonate or
382 STRATEGIC MINERALS INVESTIGATIONS, 1942

silicao The reeds and leaves are altered to carbonaceous films; 

in places they occur singly, but in many places they were buried 

in the sands as tangled bunches.

In general, the plant material is mineralized only where it 

is enclosed in ore-bearing sandstone. Some logs that project 

from an ore body into the surrounding barren sandstone are 

mineralized within the ore body and barren outside it; other 

logs -projecting into barren sandstone are mineralized from end 

to end as if the mineralizing' solutions followed the logs. Not 

all of the plant material in ore-bearing sandstone is richly 

mineralized, however, and the coaly material especially is 

essentially barren. In places small pockets of high-grade ore 

are associated with plant'material in otherwise barren sandstone 

and at some distance from known ore bodies; these are commonly 

called tree formations by the miners. The ore minerals partly 

fill cavities resulting from disintegration of the fossil plants 

or incompletely replace the woody structure; it is rare to find 

the woody structure well-preserved in ore-bearing material. The 

ore mineral most commonly associated with the mineralized fossil 

plants is carnotite, but in places a dark gray, claylike, vanadium-rich material is also present.

Ore bodies

The ore bodies range from small masses only a few feet 

across, containing only a few tons of ore, to large tabular 

bodies of irregular outline several hundred feet across, containing as much as a hundred thousand tons of ore; most bodies contain from a few hundred to a few thousand tons of ore. The 

tabular ore bodies tend to lie essentially parallel to the sandstone "beds, but they do not follow the beds in detail. The 

limit of the vanadium-bearing sandstone in many bodies is sharply defined and in places is actually the limit of commercial 

ore 0 Elsewhere the limit of commercial ore is less clearly
GEOLOGICAL SURVEY BULLETIN' 9.36 PLATE 54

A. PHOTOMICKOCRM'll OK SANDSTONK I M I'K K(J N A I Kl) WITH \ \\ADIUMBEAKING HYDROUS MICA (DARK). Xy.r>.

B. TYPICAL FACE OF VANAUIIM OKE.

The ore (dark) in composed of vanadium-bearing hydrous mica in part diseetninated in the sandstone and in parl concentrated in sheets along bedding planes. This fa<-e of ore is about 2 

feel thick and assays about 2 percent VjOj. Club group of mines.
GEOLOGICAL SURVEY BULLETIN 936 I'LATE 55

riie ore (dark) culn across the bedding, forming a roll, in barren sandstone (light). Note the 

slumping of the bedding planes across ibe central part of this zone, and the development of a 

fracture along the plane of greatest disturbance as a result of the removal in solution of the 

grains of quartz sand. Club group of mines.

It. THIN ZONE OF RICH VANADIUM ORE iDMiKi \I.O\C CONTACT OF ORE 

BODY (TO RIGHT) AND BARREN SANDSTONE (UI'I'EK LEFT).

Club group of mines.
GEOLOGICAL SURVEY 936 PLATE 56

I

A. I'AKALLEL ZONES. RESEMBLING DIFFUSION BANDS, 

OF RICH VANADIUM OKE (DARK) ALONG THE EDGE 

OF AN OKK BODY.

Saucer Bimin mine.

B. LENS OF SHALE-l'KBBLi; COMM.OM KKATK, I,N PART M1NEUALI/ED (DARK) 

AND IN PART BARREN (LIGHT).

The boundary of the ore, in the middle of the picture, cuts sharply across the shale-pebble lens.

Little Uick mine.
VANADIUM DEPOSITS OF COLORADO AND UTAH 383

defined, and mineralized sandstone too thin or too lean to be 

profitably mined extends considerably beyond the limit of minable ore. The ore bodies are so irregular in form that they cannot readily be classified. They consist of well-defined and 

poorly defined masses, both of which may be present in a single 

ore body.

The bodies with well-defined limits vary greatly in lateral 

dimension but are thin; usually the thickness of the ore is only 

a few feet, but in places it is as much as 15 feet. Although 

irregular in detail, bodies of this type are essentially lensshaped many tend to be somewhat convex upward (see fige 46), 

The ore is of good grade; much of it contains over 1^ percent 

VgOgo One of the peculiar characteristic features of these 

bodies is the tendency for the better-grade ore to lie along 

the margins of the bodies.

Where the boundary of the ore is especially sharp, vanadium 

minerals have been concentrated in a thin zone along the contact 

of ore and barren rock, forming what the miners call a roll 

(see pp. 379-380). Actually, the term roll as used by the 

miners often applies to the body of good ore that is adjacent 

to or partly enclosed within this curved surface. Two general 

types of rolls have been noted along the sides of the ore 

bodies: one is a roll convex outward from the ore body, and 

the other is convex toward the ore body, with thin tongues of 

ore extending along favorable bedding planes beyond the limit 

of the commercial ore (see fig. 46). One type of roll may merge 

laterally into a roll of the other type, the form of the roll 

apparently being controlled by the lithologic character of the 

sandstone rather than by some pre-ore structure imposed on the 

sandstone. Rolls also form wavy surfaces on the tops and bottoms of the ore bodies and seem to be more common and better 

developed on the top than on the bottom. Along the rolls, where 

mineralization was strong, some quartz has been dissolved (see
384 STRATEGIC MINERALS INVESTIGATIONS, 1942

pp. 379 and 380), and the resulting concentration of the vanadium-bearing hydrous mica makes a plane of weakness to which the 

rock breaks in mining. At most places where rolls lie along the 

edges of the ore bodies, mineralization of the sandstone extended only an inch or two beyond the surface of the rolls.

Hany of the rolls are small and irregular, but some of the 

larger and better developed ones are elongate, and some extend 

continuously for 50 or 60 feet. The conspicuously elongate 

rolls are oriented in a common direction in many ore bodies.

Figure U6. Cross section of on ideal ore body with well-defined limits, 

showing (1) lens shape, tending to be somewhat convex upward, (2) tendency for the better grade of ore to lie along the margins of the body, 

and (3) undulant rolls on the top and curved rolls on the sides of the 

body (on the left side of the sketch the roll is convex outward from the 

ore body, and on the right side the roll is convex toward, the body with 

thin tongues of ore extending beyond the limit of minable ore).

This direction seems to coincide with the trend or elongation of 

those ore bodies, and any adjacent ore bodies are likely to lie 

along this trend. The orientation of the rolls may thus be a 

useful guide in prospecting. \

The bodies with poorly defined limits are mostly large and 

thick bodies of low-grade ore (1 to Ij percent VgOg) in relatively massive, clean sandstone. The ore decreases in grade 

laterally and vertically, and weakly mineralized sandstone may 

extend considerably beyond the limits of commercial ore. Rolls 

are not common in bodies of this type. Examples of such.ore 

bodies are found at several places in Dry Valley, Utah, in the
VANADIUM DEPOSITS OP COLORADO AND UTAH 385

Ophir mine and in the Jo Dandy mine, Montrose County, Colo., and 

in the Bear Creek mine of the Placervllle district, Colo. icy '- It has been reported by Coffin, and it is the opinion of

some miners, that joints related to regional structures may \

locally either cause an abrupt change in the thickness in the 

ore or may border the ore, as if these joints controlled the

lateral movement of the ore-depositing solutions. But during 

>

many months of detailed study of these ores no joint related to

] regional structures was seen that definitely controlled the 

thickness or distribution of the ore. In places, the intersection of a roll surface and joint plane with a mine wall gives, 

on casual observation, the false impression of such control. 

In other places, postmineral faults, which have a horizontal 

displacement of a few feet but a vertical displacement of only 

a few inches, cause the ore to appear to end or abruptly change 

i in thickness at the fault plane. All joints related to regional 

/ structures are believed to have been formed later than the early 

ore minerals.

Uravan district. Figure 47 is a simplified geologic map of 

the Uravan district, Colo., showing the plan of the ore bodies 

that have been mapped by the Geological Survey, the location of

the vanadium-bearing prospects and outcrops, and the outcrop of

\ 

the base of the principal ore-bearing sandstone. The ore bodies

in the Long Park area, in the southern part of the district, are 

alined in a northwesterly direction. Rolls and trends are not 

well developed in the individual ore bodies, but the majority of 

/ those that have been noted have northwesterly directions. Mos.t 

of the rolls in the Saucer Basin mine (near the west end of the 

cross section) have an easterly trend. No trends have been observed in the ore bodies of the Dolores group of mines, in the 

northwest corner of the district.

.10/ Coffin, R. C., Radium, uranium, and vanadium deposits of southwestern' Colorado: Colorado Qeol. Survey Bull. l6, p. 162, 1921.
386 STRATEGIC MINERALS INVESTIGATIONS, 1942

The ore bodies of the Club group of mines, about a mile 

southwest of Uravan, form one of the largest known groups in

Morrlson formation showing base of

Vanadium ore bodies

(Dots show possib/e

extension of ore bod/es)

X

Vanadium-bearing outcrop 

or prospect

Fault

ME.

2 Miles

Figure U7. Geologic map of the Uravan area, Montrose County, Colorado. 

the region, and they have yielded more than 150,000 tons of 

ore. It is estimated that this ore contained about 7,000,000 

pounds of Vo05 , but only a small part of the vanadium contained
Diamond- dri/l hole 

(projected)

Diamond-drill hole 

(projected)

td d
VANADIUM DEPOSITS "OP COLORADO- AND UTAH 387

in the ore mined during the period 1911-1923 was recovered. 

Plate 57 shows in detail the ore bodies and the mine workings 

of this group. The limit of the vanadium-bearing sandstone, 

shown by the heavy line on plate 57, was determined by direct 

observations underground and by many drill holes not shown on 

the map.

The ore bodies of the Club group mostly belong to the type 

having well-defined limits, although some of the ore is massive 

and of low grade and has poorly defined limits. The group of 

ore bodies as a whole is alined in a northeasterly direction, 

but individual elongate bodies and the conspicuous lobes of the 

bodies of irregular outline are oriented about N. 70° E. This 

trend is even more clearly shown by the orientation of the 

larger and better developed rolls within the ore bodies (see pi. 

57). The area most favorable for prospecting lies southwest of 

the mines. Here, however, the ore-bearing sandstone is rather 

deeply buried and for that reason has not been much prospected.

Many of the logs or trees that were buried in the sandstone 

and have been exposed in the mine workings are also oriented in 

an easterly or northeasterly direction (pi. 57). In most mines, 

however, the logs do not have a common orientation and hence 

are not considered to be reliable indicators of ore trends.

Origin and control of ore

The origin of the ore and the factors that controlled its 

localization cannot yet be satisfactorily explained. The ore 

minerals impregnate sandstone and in their present form were 

deposited from.solutions after the sands were deposited, but 

the nature of the solutions is not understood, nor is the immediate source of the metals apparent. ,

All joints related to regional structures are believed to 

have formed later than the early ore minerals (see p. 385). 

There are only four known localities in the region where ore
388 STRATEGIC MINERALS INVESTIGATIONS, 1942

minerals, other than the obviously secondary minerals, appear 

to be localized by faults. At Temple Mountain, Emery County,

!!/

Utah, according to Hess, vanadium and uranium minerals were 

dissolved from ore bodies in the Shinarump conglomerate and were 

deposited in small quantities along fractures in the overlying 

Chinle formation and "lowest Jurassic sandstone" (Wingate). 

Along a disturbed and faulted zone at Richardson, Grand County,

Utah, vanadium and uranium minerals have been sparsely deposited

12/ 13/ 

in sandstone considered to be Wingate. Coffin reports

carnotite stains in Carboniferous and Dolores (Triassic) beds in 

faulted areas in Gypsum Valley, San Miguel County, Colo. (The 

unit mapped as Dolores by Coffin also includes beds now recognized as Wingate sandstone and Kayenta formation in addition to 

the Dolores formation.) Along Roc Creek, in Montrose County, 

Colo., small quantities of vanadium and uranium minerals occur 

in Wingate sandstone near a down-faulted block of ore-bearing 

Morrison. All other faults cut and displace the ore and appear 

to be later than the ore. Furthermore, when the region is viewed as a whole, the spacial distribution of the ore bodies fails 

to suggest any genetic relationship to faults or folds,, The 

only practical importance of faulting and folding consists in 

their having affected the position of the productive beds.

In most areas the ore is largely or wholly confined to sandstone of a certain stratigraphic zone. Some favorable conditions must have existed in this zone to localize the ore, but 

these conditions have not been recognized. Sandstones similar

or identical in-appearance to the sandstone of the favorable 

stratigraphic zone lie below or above this zone, but contain

little or no ore. Within the favorable atratigraph.ic zones,

however, the ore bodies, are not confined to a single cardstone

ll/ Hees, P. L., Uranium-tearing asphaltite sediments of Utah; Eng. and 

Win. Jour.-Press, vol. llU, p. 27U, 1922.

12/ Dame, C. H. , Geology of the Salt Valley anticline and adjacent areas. 

Grand County, Utah: U. S. Geol. Survey Bull. 863, pi. 1, 1935.

li/ Coffin, H. C., op. clt., p. 153.
VANADIUM DEPOSITS OF COLORADO AND UTAH 389

bed or to a single lithologic type of sandstone. Shale pebbles,, 

clay films along bedding planes, and fossil plants commonly 

localize high concentrations of the metals within ore bodies, 

but aince these lithologic features are as abundantly present in 

the adjacent barren sandstone as in the ore, they cannot have 

controlled the position of the ore bodies. No evidence has been 

found of ^echanical deposition and concentration of vanadlumand uranium-rich material that might have accumulated as the 

sands were deposited and might, therefore, have served as the 

immediate source of these metals.

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.

SUGGESTIONS FOR PROSPECTING

As long as the origin of these deposits remains undetermined, 

the localization of the ores cannot be satisfactorily explained, 

but certain observed facts regarding their localization may be 

useful as guides in prospecting.

Stratigraphic zones locally favorable for ore should be 

recognized and prospecting and development restricted to them. 

In the Placerville district the ore-bearing Entrada sandstone

is immediately overlain by the Pony Express limestone member of

14/

the Wanakah formation, which makes an easily recognized stratigraphic marker. At the Rifle deposit the top of the underlying 

red beds similarly serves as a stratigraphic plane of reference.

lUy The Pony Express limestone metnber has been called the LaPlata limestone In the San Juan Mountain region.
390 STRATEGIC MINERALS INVESTIGATIONS, 1942

In the Morrison formation, on the other hand, there is no definite bed or plane that can be used as a stratigraphic guide. 

The ore-bearing sandstone is underlain by red shale, which is 

altered to gray or greenish-gray in the upper few feet the blue 

clay of the miners and drillers (p. 376). It Is a common practice to bottom drill holes In the red shale immediately below 

the blue clay. Not all holes should be abandoned immediately 

on reaching red shale, however, for in places a lens of red 

shale, altered to gray or greenish gray in the upper few feet, 

Is interbedded with or lies within the ore-bearing sandstone 

(see cross section, pi. 57). Since many vanadium ore bodies lie 

in the lower part of the ore-bearing sandstone, it is desirable 

to drill through this sandstone. Where holes are drilled near 

canyon walls, subsurface stratigraphic conditions can be Interpreted from exposures along the cliffs. Where drilling is 

undertaken some distance from canyon walls several holes in a 

group should be continued to a considerable depth in order to 

explore subsurface conditions and definitely establish the base 

of the ore-bearing sandstone.

Many ore bodies are elongate, and in places the trend of 

this elongation is indicated by the orientation of rolls in the 

ore. The mapping of ore bodies and rolls shows this trend, thus 

pointing to the areas most favorable for additional prospecting 

and aiding in planning development. In one mine studied, the 

mine workings first opened were elongated in a northeasterly 

direction, but the orientation of the rolls suggested a northwesterly trend. Subsequent arilIin5, encircling those mine 

workings, disclosed, previously lansiispoc-bed. extensions of tKe or-e

body to the northwest and southeast. The trend indicated by 

the elongation of an ore body, or by the rolls within an ore

body, may also Indicate the general alinement of any nearby ore

bodies.
VANADIUM DEPOSITS OP COLORADO AND UTAH 391

Where rolls lie along th'e sides of ore bodies the sandstone 

tends to break to the curved surface of the roll, leaving what 

looks like a face of high-grade ore. As the ore minerals penetrate the sandstone only an inch or two beyond this surface, 

however, channel samples cut from mine walls at such places have 

no practical use and give an entirely false concept of the value 

of this face. Diamond drilling from the surface has so far 

proved to be the most satisfactory method of subsurface prospecting where the sandstone favorable for ore is not too deeply 

buried. With the light drill rigs commonly used in the ColoradoUtah region, it is rarely feasible to drill deeper than about 

125 feet, but these rigs have the advantage of being easily 

moved and set up. A common practice is to encircle an ore body 

with drill holes when underground workings cease to develop new 

ore. The trend indicated by rolls or a pronounced elongation of 

the ore body should aid in determining the most favorable places 

to drill, but not all drilling should be restricted to the indicated trends, for some ore bodies, such as those in the Club 

group of mines (pi. 57), are alined in an en echelon pattern, 

and in places elongate bodies have been found lying side by side 

rather than end to end.

Because of the extreme spottiness of ore bodies and the 

large ratio of barren to mineralized ground (fig. 47), wildcat 

drilling, at some distance from known ore bodies, should be 

largely restricted to established alinements. Wildcat drilling 

across the recognized alinement in Long Park, Montrose County, 

Colo., has disclosed several ore bodies more than a thousand 

feet from ground previously known to be mineralized.

Subsurface prospecting by underground drifting is useful in 

places, especially where diamond drilling is not feasible because 

of excessive depth to the ore-bearing sandstone. It is inadvisable to drift blindly through barren sandstone, but it is 

good practice to follow thin tongues of vanadium-bearing
392 STRATEGIC MINERALS INVESTIGATIONS, 1942

sandstone that extend laterally beyond the limits of commercial 

ore drifts following these tongues have led to new ore bodies. 

As the sandstone is not hard, such drifting is not very costly, 

and it may, too, be partly paid for by the vanadium-bearing 

sandstone broken in the drift, for the mineralized tongues, 

though too thin to be mined for their own sake, contain in places 

as much as 3 or 4 percent VgOco This manner of prospecting is 

especially applicable in the Placerville district, where steep 

valley walls and thick overburden make diamond drilling impracticable.

Of the several methods of geophysical prospecting that have 

"been tried, the detection of radioactivity "by the Geiger-Muller 

counter appears to be the most effective. This method detects 

only the radioactive disintegration products of uranium, but as 

significant quantities of uranium are everywhere associated with 

the vanadium ores in the Morrison formation and the Shinarump

conglomerate, the method should be applicable in diamond drilling

15/ 

and underground prospecting. Kelly found that apparently

barren sandstone, cored from a horizon as much as 20 feet above 

ore, gave distinct gamma-ray evidence of radioactivity. It is 

believed that a similar effect should be obtained from sandstone 

a short distance laterally from ore bodies. As the rock surrounding ore is not visibly altered and contains no distinctive 

minerals, drill holes that penetrate barren sandstone within a 

short distance of ore show no visible evidence that ore is near. 

This sandstone, however, may well be somewhat radioactive, and 

with the aid of the Geiger-Muller counter it might ,be possible 

to find evidence of the proximity of ore in holes as much as 15 

or 20 feet from an ore body. Further systematic studies are

 needed to establish' and evaluate the possibilities offered hy 

this technique.

15/ Kelly, S. F., Geological studies of vanadium-uranium deposits "by geo- 

 sical exploration methods: Win. Cong. Jour. , vol. 27, pp. 27-35, 19^»
VANADIUM DEPOSITS OP COLORADO AND UTAH 393

The Geiger-Muller counter appears to have similar application

underground in indicating bodies or pockets of ore that lie

16/ 

near mine workings but have been overlooked during mining.

Electrical, magnetic, and electrical-resistivity methods of 

geophysical prospecting cannot be successfully applied directly

to the ore itself, but an indirect application of the electrical

IT/ 

resistivity method is reported to have met with some success.

Where the ore-bearing sandstone is not too deep, this method can 

be applied to determine the thickness of the sandstone and to 

delimit areas in which the sandstone, being unsually thick, is 

presumably more favorable for ore»

MINING AND MILLING 

Prospecting

Two general methods of prospecting are now employed: (1) 

The most common practice is to follow the outcrop of the orebearing sandstone, looking for showings of ore on the cliff face, 

and for float of ore on the slopes below. (2) Diamond drilling 

is confined mostly to areas indicated as favorable on the basis

of past production or by established ore trends. Where depth

\

to the ore-bearing sandstone is not excessive the usual limit

\

being about 125 feet mines approaching exhaustion are encircled

by drill holes, the spacing of the holes being controlled by 

local conditions. In wildcat drilling, at some distance from 

known ore bodies but along established alinements, it is common 

practice to drill holes 100 feet apart on a line across the 

trend. Where ore is encountered, holes are drilled at closer 

intervals, but no attempt is made to block out more ore than is 

necessary to justify the estimated cost of opening the body for 

mining.

l6/ Kelly, S. f., op. cit., p. 35. 

\]J Idem, pp. 27-35-
394 STRATEGIC MINERALS INVESTIGATIONS, 1942

Mining

Mining methods differ with the size of the mine. In small 

mines, where no more than three or four men are employed, the 

common practice is merely to follow the ore in mining. Drilling 

is done by hand or with a jackhammer driven by a small, portable 

compressor. Average production ranges from ^ to 1 ton of ore 

per man-shift. In larger mines more systematic mining methods 

are used. The general practice is to drive one or more drifts 

through the ore, possibly to the commercial limits of the body, 

and to mine from these by irregularly spaced side drifts, leaving pillars of low-grade ore and barren rock. Vertical stulls 

are used in places. Ore pillars are robbed and the ground allowed to cave on final retreat from the mine. Tramming is done 

by hand, but electric, compressed air, or gasoline-driven hoists 

are used for raising the ore up inclines. Air compressors are 

driven by gasoline or Diesel engines. Production ranges from 1 

to 2 tons of ore per man-shift. In order to avoid too much hand 

sorting an effort is made to shoot ore and waste rock separately.

Milling

Ore is trucked to the mills from many widely scattered operations. At the mill the ore is crushed, mixed with common salt, 

and roasted, converting the vanadium minerals into a soluble 

sodium vanadate, which is then leached by water. Acid is added 

to the solution, preclpltatin5 tne sodium vanadate. The precipitate may be sacked and atiipp©a in tKia form, but at most 

mills it is fused before shipment.

O