GEOLOGICAL SURVEY CIRCULAR 111

May 1951

CARNOTITE DEPOSITS IN THE CARRIZO MOUNTAINS AREA, NAVAJO INDIAN RESERVATION, APACHE COUNTY, ARIZONA, AND SAN JUAN COUNTY, NEW MEXICO

By W. L. Stokes UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director

Washington, D. C.

Free on application to the Geojogical Survey, Washington 26, D. C. CARNOTITE DEPOSITS IN THE CARRIZO MOUNTAINS AREA, NAVAJO INDIAN RESERVATION, APACHE COUNTY, ARIZONA, AND SAN JUAN COUNTY, NEW MEXICO

By WX.Stokes

CONTENTS

Page Page

Abstract Ore deposits ...... 2

History and production 2 Introduction ...... 2 The ore ...... 4 Purpose, scope, and acknowledgments 2 Ore bodies ...... 4 Geography ...... 2 Origin ...... 4

Geology Suggestions for prospecting 5

ILLUSTRATIONS

Plate 1. Geologic map of the Carrizo Mountains area, Navajo Indian Reservation, Apache County, Arizona, and San Juan County, New Mexico...... Inside back cover

ABSTRACT

The Carrizo Mountain area comprises The ore deposits consist of sandstone im­ about 950 square miles in the northeastern pregnated with carnotite and a vanadium- corner of Arizona and an adjoining narrow bearing mica. The ore contains from 0. 1 to strip of northwestern New Mexico. Intrusive about 0. 5 percent ^Og and 1. 0 to 5. 0 percent igneous rocks make up most of the mountain VoOc, and much of the ore contains more lime mass and Mesozoic sedimentary rocks are as cementing material than does typical ore exposed on its flanks. from Colorado and Utah. Most of the ore bodies are roughly tabular masses which are The carnotite deposits are in the Salt also irregular in plan, but some are elongate, Wash sandstone member of the Morrison podlike masses, less common and less well- formation. These deposits yielded about developed than those in Colorado and Utah. In 22, 000 tons of ore between May 1942 and Feb­ general the deposits tend to form clusters in ruary 1944. Renewed mining activity in the ill-defined areas. The deposits are believed area began in 1948. to have formed from ground-water solutions shortly after the accumulation of the enclos­ covered carnotite deposits in the northwest ing sands, and localization of the deposits part of the Chuska Mountains. does not appear to have been influenced by re­ gional deformation, or igneous activity. Geography. --The area consists of a 30- minute quadrangle, comprising about 950 The area is relatively unexplored, com­ square miles, in the northeast corner of pared to areas in Colorado and Utah, and Arizona and a narrow strip in the adjoining continued exploration probably will yield new part of northwest New Mexico. Altitudes discoveries. Prospecting should be restrict­ range from about 4, 600 feet at the San Juan ed to the Salt Wash sandstone member of the River in the northeast corner of the area to Morrison formation which contains all the about 9, 400 feet in the Carrizo Mountains. known carnotite deposits. As these deposits The mountain flanks and surrounding country, tend to be grouped in clusters, prospecting where most of the carnotite-bearing rocks are along and behind the exposures of closely exposed, have altitudes of 5,000 to 7,000 feet. spaced deposits will probably be most fruit­ ful. Surface prospecting may yield new dis­ East, north, and northwest of the Car-rizo coveries north and west of the Carrizo Mountains, the surface has low relief and is Mountains, in the area south of Red Rock easily accessible, with only a few scattered Trading Post, and in the Chuska Mountains buttes and mesas; whereas southwest and to the south. South of about latitude 36° 30' south of the mountains the surface is rugged N. , the Salt Wash is considered unfavorable and much dissected by canyons with interven­ for ore deposits. ing steep-walled mesas. Patches of dune sand are common on the less dissected parts of the INTRODUCTION area. The climate is semiarid. Stream chan­ nels, most of which are dry during a large Purpose, scope, and acknowledgments. -- part of the year, radiate from the mountains The Carrizo Mountains area is in the Navajo and ultimately join the San Juan River north Indian Reservation, Apache County, Ariz. , of the area. and San Juan County, N. Mex. Plate 1 shows the geology, in part generalized, and the lo­ GEOLOGY cation of the known carnotite deposits. The map is planned to aid in prospecting for and With the exception of a small mass of developing carnotite deposits by directing at­ Permian strata in the Carrizo Mountains and tention to the outcrop of the ore-bearing Salt outcrops of Tertiary beds in the Chuska Wash sandstone member of the Morrison for­ Mountains, all the exposed sedimentary rocks mation. This report describes briefly the in the area are of Mesozoic age. These rocks geology of the area and the general character are covered in places by a thin veneer of out- of the deposits. Suggestions for prospecting wash gravels, dune sand, or Recent alluvium. also are included. All of the known carnotite deposits in the Car­ rizo Mountains area are in the Salt Wash Most of the field work on which this pre­ sandstone member of the Morrison formation. liminary report is based was done by the .Geological Survey, United States Department The lithologic character, topographic ex­ of the Interior, as part of the strategic-min­ pression, and thickness of the Mesozoic erals program during World War II. The area strata are summarized in table 1. Table 1 was mapped and studied by D. C. Duncan and also identifies the several divisions shown on W. L. Stokes in October and. November 1942, the map (pi. 1) and the map symbols and pat­ and by Stokes and G. M. Sowers in April 1945. terns used to identify them. A report was prepared by Stokes in 1946, but it was withdrawn from publication because of The Carrizo Mountains, which occupy the security regulations at that time. Since then central part of the area, are composed of the report has been revised by R. P. Fischer porphyritic intrusive bodies and masses of to include information obtained from detailed deformed and slightly metamorphosed sedi­ work now in progress by the Geological Sur­ mentary strata. The outline of this complex vey. This work, for the United States Atomic is shown on plate 1, but no detailed geologic Energy Commission, includes a project of study has been made of the mountains. Small deta'led mapping of the area, under the super­ patches of Salt Wash sandstone member of the vision of J. D. Strobell, and a regional Morrison formation are known to be present stratigr-:phic study of the ore-bearing and in places in the mountains, however, and associated rocks, under L. C. Craig. Ac- some carnotite is reported in them. knowledg ent is due Mr, H. S. Stafford of the Atomic Energy Commission and Mr. S. K. ORE DEPOSITS Smyth of Climax Uranium Company, who have History and production. --Carnotite depos­ furnished the map locations of the newly dis­ its were discovered in the area about 1918 and

- 2 - Table 1. --Generalized section of the sedimentary rocks in the Carrizo Mountains area

Map Age Stratigraphic Unit Lithologic character, topographic expression, Symbol and thickness

Mancos shale Shale, thin-bedded, gray. Forms slopes. Only basal part present. i_kmd _ _ j Cretaceous kd Dakota sandstone Conglomeratic sandstone, weathers yellow-brown. Forms cliffs and caps mesas. 30 to 200 feet thick

Shale, gray, light green, and pink; minor thin beds of conglomeratic sandstone. Forms steep slopes. 150 to 350 feet thick. Upper part of § Morrison for­ Sandstone, yellowish gray, friable; minor thin beds rH -U mation (three of greenish-gray shale. Forms cliffs and short Jmu 0] upper units. slopes. 140 to 270 feet thick. cC rH shown collec­ O «M tively on map). Shale, grayish-red, and sandstone, pale -red to c white, friable. Forms low cliffs and steep slopes. O (0 150 to 500 feet thick. rH M M O Salt Wash sand­ Sandstone, light-brown to white, fine-grained, i-io 2 stone member cross -laminated lenticular beds, and minor thin (0 (carnotite- beds of grayish-red shale. Carnotite deposits (0 Jms «J bearing, shown may occur at any strati graphic position in this M separately on unit. Forms irregular cliffs and caps broad i-s3 map). benches and mesas. 60 to 220 feet thick.

Sandstone, pale -red to light-brown. Forms rounded cliffs. 20 to 60 feet thick.

Sandstone, reddish-brown and light-brown, inter- bedded. Forms prominent banded cliffs or red earthy slopes. 50 to 150 feet thick. San Rafael group (undifferenti- Limestone, light-gray. Present only in eastern ated on map). part of area. Feather .edge to 5 feet thick.

Sandstone, reddish-orange to reddish-brown. Forms vertical cliffs or steep slopes. 40 to 90 feet thick.

JTr Shale, grayish-red, and thin-bedded sandstone, brown to white. Forms prominent benches. Pres­ ent only in western part of area. 45 to 115 feet thick.

Glen Canyon Sandstone, white and reddish-orange, thick parallel group (undif- beds with large-scale cross -lamination. Forms Jurassic(?) ferentiated on high vertical or smoothly rounded cliffs withledgy map). slopes at base. 700 to 800 feet thick.

Triassic "Red Shale, red to purple, with some red to white sand­ Beds" (undif- stone, and conglomerate, and gray limestone. Triassic ferentiated on Forms badlands topography. Up to 900 feet thick, map). base not exposed. many claims were located in the next few 2. 25 percent V^Or ; the uranium content is years. Little mining was done until 1942, not known. This ore was produced from de­ however, when war conditions increased the posits on the east, north, and west flanks demand for vanadium-bearing ore. From May 1942 through February 1944, the area Compiled by the Geological Survey from yielded about 22, 000 tons of ore averaging Metals Reserve Company records.

- 3 - of the Carrizo Mountains. The less accessible layers. These layers are nearly parallel to country southwest of the mountains was pros­ the major bedding to the sandstone, but a pected during this period, and though many close examination shows that they cross the deposits were found, further development was bedding at various angles. The thickness of halted because of the decline in ore require­ the layers ranges from a feather edge to as ments in 1944. Activity started again in 1948, much as 15 feet. The ore bodies are also ir­ and since then many mines have resumed op­ regular in plan, and they range from several eration, new mines have been developed, and feet to a few hundred feet in width. Small new discoveries have been made, particular­ bodies consisting of layers less than a foot ly in the southern part of the area. thick are minable only if they are at or near the surface and high grade. The ore. --The carnotite deposits in the Carrizo Mountains area are similar in most Some individual ore bodies, as well as respects to those in the larger and more pro­ some masses of ore in the tabular layers, are ductive districts of Colorado and Utah 2 . elongate and podlike. Such masses generally are called "rolls" by miners, but rolls are The ore, consisting mostly of sandstone neither as common nor as well developed in impregnated with ore minerals, contains from the Carrizo Mountains area as in the Colorado- 0. 1 to more than 0. 5 percent ^Og or more Utah region. and from 1. 0 to 5.0 percent V^Oc. Fossil- plant remains are present in most deposits in Some of the deposits in the area consist of the area, and some are mineralized, but high- two layers of ore that partly or completely grade replacements of fossil-plants are less enclose a thin lens-shaped mass of yellow- common than in Colorado and Utah; large fos­ stained, essentially barren sandstone con­ sil logs are comparatively rare. taining fragments of fossil plants. Although the ore layers are mostly thin, in places they Carnotite (K2mineral that has been definitely two layers merge at the edge of the enclosed identified. It is bright yellow, and is dis­ lens, forming a pod-like mass or roll. seminated throughout the sandstone, partly replacing fossil plants and coating joint and Although isolated ore bodies are known, bedding surfaces. in general the bodies are clustered in ill- defined areas a few thousand feet across. The identity of the principal vanadium (See pi. 1). Within these clusters, many mineral has not been definitely established, bodies are connected by thin, weakly mineral­ although its chemical composition is close to ized layers. These layers are not continuous that of roscoelite, the vanadium-bearing mica. between all ore bodies, however, so that even It is fine-grained and micaceous, and coats within the clusters much of the ground is non- the sand grains, partly or completely filling ore-bearing. the pore spaces of the sandstone. It gives a gray or greenish-gray color to the rock. In a Origin. --The carnotite deposits are few places brightly colored calcium vanadates thought to have formed from ground-water and dark-colored vanadium oxides are present solutions, which were introduced into the ore- in sufficient amounts to be considered ore. bearing beds shortly after the sands accumu­ lated, and then localized by physical and Calcite partly cements most of the sand­ chemical conditions within the Morrison for­ stone of the Morrison formation, and is pres­ mation. It is not possible to predict the exact ent in various amounts in the ore. Much of location of carnotite ore deposits, because the the ore in the Carrizo Mountains area con­ conditions under which the ore was formed are tains considerably more lime than does typical not clearly understood. Nevertheless, it is ore from Colorado and Utah. Ore containing evident that these conditions were widespread more than 6 percent CaCO^, or that containing and favored the formation of carnotite depos­ more than a 3:1 ratio of CaCOo to V^O,-, is its in many places in the area. classed as "high-lime ore. " As high-lime ore is difficult to treat in the mills, it is pur­ The localization of the deposits does not chased by AEC only under special contract, appear to have been influenced by structures usually at a slightly lower price than ore in resulting from regional deformation, igneous which the lime content is low. activity, nor by the topographic development of the area. In some deposits exposed at the Ore bodies. --Most of the ore bodies in the surface, however, the original metal distri­ Carrizo Mountains area are irregular tabular bution may have been somewhat rearranged by secondary concentration or leaching at the outcrop. In these places, the character and 2 Fischer, R. P. , Vanadium deposits of. grade of the ore may be expected to change Colorado and Utah: U. S. Geol. Survey Bull. slightly behind the natural exposures. 936-P, 1942.

- 4 - SUGGESTIONS FOR PROSPECTING eralized layers connect many of the ore bodies within clusters; these layers should be Compared with many of the carnotite-pro­ followed in seaiching for new ore. ducing areas in Colorado and Utah, the Carrizo Mountains area is relatively unexplored and Between these clusters, even where the undeveloped, and continued prospecting can be Salt Wash member is well exposed, only 3 expected to yield new discoveries. Although few small deposits have been found. Prospect­ all of the geologic conditions that influenced ing in such ground can not be expected to yield the localization of ore have not been definitely many new deposits. On the other hand, undis­ determined, certain observed facts regarding covered clusters of deposits can be expected the distribution and character of the deposits in the ore-bearing sandstone where it is poor­ are useful as guides for prospecting. ly exposed or covered.

All of the known carnotite deposits in the A few miles south of the southern margin Carrizo Mountains area are in the easily rec­ of the Carrizo Mountains area (latitude 36° ognizable Salt Wash sandstone member of the 30'), the Salt Wash is very fine-grained, con­ Morrison formation, and prospecting should tains a high proportion of shale, and is con­ be restricted to this member (pi. 1). On the sidered unfavorable for carnotite ore. Several west, southwest, and northwest sides of the miles farther south the Salt Wash thins to a mountains all the deposits are in the lower feather edge. half of this member; southeast of the moun­ tains no deposits have been found in the lower Surface prospecting might yield new dis­ 50 feet of the member, but the middle part is coveries north and west of the Carrizo Moun­ ore-bearing. tains, where the Salt Wash member of the Morrison formation is poorly exposed between Most of the known deposits in the Carrizo sand dunes and in shallow washes on wide­ Mountains area are grouped in poorly defined spread benches; in the relatively inaccessible clusters, usually only a few thousand feet in Chuska Mountains, where exposures are poor; width. (See pi. 1.) Prospecting along and be­ and along the poorly exposed outcrop south of hind the outcrops that show closely spaced Red Rock Trading Post. The Salt Wash mem­ deposits offers the best opportunity for the ber is present and might be ore-bearing in discovery of additional ore. Thin, weakly min­ the central part of the Carrizo Mountains.

- 5 -