Mineral Resources 

of the San Carlos 

Indian Reservation 

Arizona

By CALVIN S. BROMFIELD and ANDREW F. SHRIDE

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGICAL .SURVEY BULLETIN 1027-N

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

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington 25, D. G. - Price $1.25 (paper cover)
	Page 

Abstract_______-_____-___--- _ _____--_----_----__--_._ 613

Introduction...._--_-----_------_---------- _.-__-__-_-__-_____ 613

Location and accessibility.____ _______.-_. _______________ 613

Topography and general setting._____ ________________ ____ 615

History of mining and production.____ ___________________ . 616

Mining regulations of the San Carlos Indian Reservation._____ _. 617

Present status of mining and prospecting-_______ _______________ 617

Purpose and scope of this report and methods of study________j___. 617

Acknowledgments. ________ ___________________ j_____. _______ 618

Previous work in the area-____--____----------_--_------__--___ 618

General geology--------------------------------------------------- 619

Sedimentary rocks_-__________----__-___-___-___-______________ 619

., Pre-Cambrian rocks________________________--______--_ 619

Paleozoic rocks__________________________________________ 624

,. Tertiary sedimentary rocks___-_-----___---__-___--_-_______ 625

' Pleistocene (?) and Recent alluvium_______________________ 626

Igneous rocks--_-___---_-_-_-_-_-__--___ _ _____ _______ 626

Structure___.. _- _ 628

.Mineral deposits.. ____________________ __ ___________ _._ 630

Metallic deposits.-. ._. _ __ -___ ___ 630

Copper___.____-.__________-____ _____ 630

, ,, Copper King or Wylomene claims.____________________ 631

Peacock claims__-______.--____--____-_.___--___-____ 633

,, Bitter Spring prospect_______________________________ 634

Geronimo prospect______________________________ 635

Tribal claims__________________________ 636

... Copper prospect (name unknown)_______________________ 636

Prospect near Bucket Mountain (name unknown)_________ 637

Iron___ _ 637

Iron claims-__-_-----__-___----_-_____-_____-____.__ 638

Seneca iron prospect.__________________________________ 639

Uranium.________________________________________________ 640

Nonmetallic deposits_________________________________________ 641

Asbestos__-____-_---_-_---_----_----_-_-____--_--______ 641

Sawmill Canyon subarea_______________________________ 650

I. S. Hole Canyon subarea____________________________ 652

Salt River-Cienega Canyon subarea.____________________ 653

Bear Creek subarea__________________________________ 664

Cassadore Spring-Oak Creek area.______________________ 670

Apache ridge area____________________________________. ' 672

Hayes Mountains area___-___-_-_-_____--.___________._ 676

"Tufa" stone, gypsum, and diatomaceous earth..__-.__.______ 679

"Tufa" stone...-.__..-______________________ 680

Gypsum __ 681

Diatomaceous earth__________________________________ 683

m
IV CONTENTS

Mineral deposits Continued

Nonmetallic deposits Continued Page

Peridot_______________________,____________ 686

Guano___________________________________ 687

Summary of resources_____________________________-_-.________.__>_ 687

References cited.. _.?_--_-_____.:____________________________________ 688

Index..________________________-_...-...-._-.._____ 691

ILLUSTRATIONS

[Plates 52-54 in pocket] . 

PLATE 52. Geologic map and sections Of the San Carlos Indian Reservation.

53. Index map of the San Carlos Indian Reservation showing 

mineral localities.

54. 'Geologic map and section of the Copper King-Wylomene

copper area.

Page

FIGURE 76. Index map of Arizona showing location of the San Carlos

Indian Reservation_______________________________ 614

77. Geologic column and associated mineral resources, San Carlos

Indian Reservation___..____________________l__________ 620

78. Geologic sketch map of the Peacock copper workings.______ 634

79. Geologic map and section of the "Iron" claims workings..., 638

80.' Geologic map and section of the Silk-Wonder asbestos claims

area ________________________________________________ 651

81. Geologic map and sections of the Emsco asbestos mine______ 655

82. Geologic map and section of the Great View asbestos mine

area__________ ------ 659

83. Geologic map and sections of the Bear Canyon asbest,os,mine_ ... 666

84. Geologic map and section of the Black Mesa asbestos prospect. 671

85. Geologic map and sections of the gypsum area..---_--.---- . 682
A CONTRIBUTION TO ECONOMIC GEOLOGY

MINERAL RESOURCES OF THE SAN CARLOS 

INDIAN RESERVATION, ARIZONA

By CALVIN S BROMFIELD and ANDREW F.

ABSTRACT ;

* At the request of the Council of the San Carlos Apache Tribe the U. S. Geological Survey entered into a cooperative agreement calling for a brief reconnaissance study to determine, as far as practical, the mineral potential of the 

San Carlos Indian Reservation. Five months of field work was done during 

the winter and spring of 1952-53.

About 30 percent of the reservation is covered by alluvial deposits of late 

Tertiary, Pleistocene, and Recent age, and. another 60 percent is covered by 

volcanic, rocks of Tertiary and perhaps Pleistocene age. These rocks are younger 

than the major epochs of metallization in southeastern Arizona. The remainder 

of the area is underlain by pre-Cambrian and Paleozoic sedimentary rocks, preCambrian granite, and pre-Devonian diabase. , !

The reservation is located in two physiographic provinces: the northern part 

Is in the Colorado Plateaus province and the southern part is in the Basin and 

Range province. The boundary between the provinces generally follows the 

southern rim of the Natanes Plateau. The mountain ranges south of the 

Natanes Plateau are, in general, tilted fault-block mountains composed largely 

of south westward-dipping pre-Cambrian and Paleozoic sedimentary rocks. The 

northern part of the reservation is dominated by the Natanes Plateau. West of 

Blue River, the plateau is composed of generally flat-lying pre-Cambrian and 

Paleozoic rocks overlain by Tertiary volcanic flows. East of Blue River, the 

older rocks disappear under the Tertiary volcanic rock and reappear at one 

place only between Arsenic Tubs and Park Creek.

Asbestos is the most important mineral resource on the reservation and most 

of the prospecting has been for this mineral. Asbestos was the only material 

being mined in 1953 (five mines being active). Deposits of tufa stone, peridot, 

guano, copper, iron, gypsum, and diatomaceous earth also occur on the reservation; of these, only tufa stone, peridot, and guano have been mined commercially.

INTRODUCTION

LOCATION AND ACCESSIBILITY

The,San, Carlos Indian Keservation occupies 2,500 square miles in 

east-central Arizona (fig. 76). It extends from Mount Turnbull on

613
614 CONTRIBUTIONS TO ECONOMIC GEOLOGY

100. Miles

FIGURE 76. Index map of Arizona showing location of the San Carlos Indian Reservation.

the SOUth, to the Salt and Black Rivers on the north maximum dis^ 

,tance of 50 miles and from near Globe on the west to the vicinity of 

Eagle Creek on the east a distance of about 70 miles. It includes 

parts of Gila, Graham, and Final Counties.

Most of the inhabitants of the San Carlos Indian Reservation live 

in the towns of San Carlos and Bylas, although a few people live at 

Peridot and Calva. These settlements are joined by a branch line 

of the Southern Pacific Kailroad, which has its terminus at Globe and 

connects with the main line at Bowie, Ari£. The only other perma-
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 615

nent inhabitants are on a few ranches widely scattered over the 

reservation. . As of 1953, there were two paved highways in the area. U. S. 

Highway 70, which passes through Bylas, traverses the southern area 

of the reservation, and part of its .route between Globe and Safford 

follows the Gila valley; and U. S. Highway 60 cuts across the extreme 

northwestern corner of the reservation. Two improved graded roads 

connect the Indian Agency headquarters at San Carlos with U. S. 

Highway 70 at two places. The remainder of the reservation is serviced by dirt roads of varying degrees of improvement. . Much of the 

area is accessible only by trail. Winter snows and summer rains make 

many of the dirt roads impassable for short periods.

TOPOGBAPHY AND GENEBAL SETTING

The San Carlos Indian Reservation lies on the boundary between 

the'Colorado Plateaus and the Basin and Range province. Within 

the reservation the precise boundary between these two physiographic 

provinces cannot always be determined, because lavas of a great volcanic field cover much of the reservation and, in place, obscure the 

division. Roughly, however, a northwest-trending line following the 

southward-facing escarpment of the Natanes Plateau would approximate the south boundary of the Colorado Plateaus province (fig. 76 

and pi. 52).

North of the south-facing escarpment of the Natanes Plateau, 

called the "Natanes Rim" in this report, is an area typical of the 

plateau province. The area is characterized by the general high level 

of its surface and by the approximate horizontal position of its rocks. 

The average altitude is about 6,000 feet; however, several prominent 

features, such as Hilltop and Chiricahua Butte, rise to over 7,000 feet. 

The drainage in this broad area is generally northward to the Salt 

and Black Rivers. These rivers, and their principal tributaries, have 

cut steep rugged canyons into the plateau surface. These canyons 

make parts of the area almost inaccessible.

South of the Natanes Rim is an area that is typical of the Basin 

and Range province. Broad intermontane alluvial-filled valleys and 

several northwest-trending mountain ranges characterize the area.

The mountain ranges are the Turnbull Mountains (on the south 

boundary of the reservation), the Mescal, Hayes, and Gila Mountains, 

and a southeastward extension of the Apache Mountains (called the 

"Apache Ridge" in this report). Mount Turnbull is the highest point 

on the reservation with an altitude of about 7,700 feet. Several peaks 

in the Mescal Mountains are over 6,000 feet, and altitudes of over 

5,000 feet are not uncommon in the Hayes and Gila Mountains. The
616 CONTRIBUTIONS TO ECONOMIC GEOLOGY .

southeastward extension of the Apache Mountains is less rugged than 

the other mountains; here, altitudes range from 3,300 to 4,600 feet.

The broad alluvial-filled valleys are characterized by partly dissected sediments and alluvial slopes which incline gently inward to 

the Gila and San Carlos valleys, and by an extensive basalt-capped 

mesa extending several miles northeastward from San Carlos. Near 

San Carlos isolated basalt-capped mesas, remnants of a more extensive 

surface, project above the general level of the surrounding valley.

The drainage of the broad region lying south of the Natanes Plateau 

is controlled by the westward-flowing Gila River and its principal 

tributaries the San Carlos River and Bonita Creek. The headwaters of Bonita Creek and the San Carlos River are on Ash Flat, a 

broad intermountain plain lying between the eastern part of the 

Natanes Rim and the Gila Mountains. Bonita Creek flows southeastward and drains the eastern portion of Ash Flat, whereas at the 

western end the drainage is northwestward to the San Carlos River.

The lowest altitude on the reservation, 2,290 feet, is in the Gila River 

at the southwest edge of the reservation.

HISTORY OF MINING AND PRODUCTION

The San Carlos Indian Reservation was established in 1872, and the 

area was closed to prospecting and mining at that time. In 1919, 

Congress authorized the opening of Indian reservations to location 

of mineral lands. Most of the prospecting on the reservation was 

done during the first few years following the opening of the Indian 

lands to location. The majority of the claims staked have been for 

asbestos. The Emsco, Bear Canyon, Apache, and Pinetop (known 

earlier as the Falls group) properties, which are the major asbestos

mines, were discovered and located by 1922.

In 1936, under new authority granted by Congress,1 the Apache Indians adopted a constitution, one of the provisions of which withheld 

to the Indians all rights in the granting of leases on mineral lands 

of the reservation.2

In monetary value, asbestos has been by far the most important 

resource on the reservation and most of the prospecting has been for 

this mineral. The total value of the asbestos production probably 

exceeds $500,000. The Emsco and Bear Canyon mines have been the 

largest producers. Second in value to asbestos has been tufa stone. 

The areas known to be underlain by tufa stone have been withdrawn

from location and all quarrying has been by the Indian Service or by

i Act of June 18,1934 (48 Stat. 984), as amended by Act of June 15,1935 (49 Stat. 378). 

3 Sec. Ill Conservation of Assets, Art. V, Constitution and By-Laws of the San Carlos 

Apache Tribe of Arizona.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 617

the Indians. Peridot, the gem quality variety of olivine, has been 

gathered in small amounts by the Indians since the turn of the century. 

A few tons of bat guano have also been produced.

MINING REGULATIONS OF THE SAN CARLOS INDIAN 

RESERVATION

The San Carlos Indian Keservation is unallotted land and claims 

may be located here; however, mineral leases are subject to certain 

regulations.8

Leases are made by the tribal council. Prospecting permits, usually 

covering a period of 90 days, are issued by the council for about $50.00. 

Locations are made and filed in the usual manner, and a lease application is filed with the tribal council. The application must also be 

processed through the office of the Bureau of Indian Affairs in Washington, D. C. Bond, which varies with the acreage involved, must be 

furnished and an annual acreage rental fee is required. Leases are 

generally issued for a period of 5 years, and royalty payment is usually 

10 percent of the value at the mine site of all ores marketed. Appended 

to the lease are provisions regarding the employment of Indian labor 

and the grazing rights of the Indians.

PRESENT STATUS OF MINING AND PROSPECTING

Five mines were active on the San Carlos Reservation during 1953. 

These five, all asbestos mines, were the Apache, Pine Top, Bear Canyon, 

Salt Kiver, and Great View mines. Late in the year, operations were 

stopped at the Bear Canyon and Salt Kiver mines, and work was 

recessed at the Pine Top mine. Prospecting was in progress on the 

undeveloped Chiricahua and Mystery groups of asbestos claims. A 

lease was pending on the Peacock claims, which is a copper prospect.

PURPOSE AND SCOPE OF THIS REPORT AND METHODS OF STUDY

The U. S. Geological Survey, in cooperation with the Council of the 

San Carlos Apachee Tribe, undertook a reconnaissance study of the 

San Carlos Indian Reservation, to determine, as far as possible, the 

mineral potential of the reservation. The procedure followed was (1) 

to make a review of all existing data to determine areas that contain 

mineral deposits, followed (2) by spot examinations of these deposits, 

and (3) by reconnaissance of areas that are geologically favorable for 

the occurrence of such deposits. Many of the deposits visited were 

tested for radioactivity. The Dripping Spring quartzite was also

9 For those interested in the legal details, Part 186 of Title 25, Code of Federal Regulations is followed in the granting of mineral leases on unallotted Indian lands.

367127 56 2
618 CONTRIBUTIONS TO ECONOMIC GEOLOGY

tested for radioactivity. Field work occupied parts of 5 months during the winter and spring of 1952-53.

The geologic map of the reservation (pi. 52) is modified, by the 

addition of detail, from the geologic map of Arizona prepared by 

N. H. Darton (1924). Additions are the result, in part, of reconnaissance maping on aerial photographs and, in part, from interpretation 

of geology from aerial photographs. This geologic map is very much 

generalized, and small outcrops of the several geologic formations are 

not delineated.

ACKNOWLEDGMENTS

During January and February of 1953 Bromfield was assisted in 

the field by W. L. Mclntosh, and during March and April he was 

assisted by J. A. Noel. Shride prepared descriptions of some of the 

larger asbestos deposits from data collected during earlier geologic 

examinations. R. B. Raup, Jr. and D. V. Haines of the Geological 

Survey did the work on radioactivity.

The writers acknowledge the information furnished by M. E. Linn, 

of the TJ. S. Bureau of Indian Affairs, concerning the location of 

several mineral occurrences, and the information on roads and trails 

from P. A. Buss, also of the Indian Bureau. D. E. Green, manager 

of the Bear Canyon asbestos mine, gave the location of several asbestos 

prospects in the Bear Canyon area and acted as guide to one prospect; 

Jeff Davis, of the Lakeside Trading Post, acted as the guide to the 

Tribal claims, and Howard Hale, of Globe, guided the writer to an 

occurrence of diatomaceous earth. Thanks are due to Clarence Wesley, 

chairman of the San Carlos Apache Tribal Council, and to Jesse 

Stevens, vice-chairman of the Council, for providing guides, horses, 

and information. Thanks are also due to the officials of the Bureau of 

Indian Affairs for making it possible to obtain pertinent records from 

their files.

PHEVIOTTS WOUE ITT THE AREA

In 1871, A. R. Marvine (1875, p. 218-225), a geologist with the 

Wheeler Expedition, crossed the region and obtained the first geologic 

information on a part of the area that now lies within the reservation.

His route was southwestward from Fort Apache, across the Salt River 

and Natanes Plateau, into the San Carlos Valley, and over the Apache

Mountains, in 1873, G. K. Gilbert traversed the Natanes Plateau, 

Bonita Creek, and Grila Mountains; he noted the extensive lava fields

characteristic of this part of the area and gave the first description

of the Gila conglomerate (Gilbert, 18T5, p, 525-542), A. x, schwennesen (1921) Studied the geology and water resources of the Gila and 

San Carlos valleys in the San Carlos Indian Eeservation. N. H.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 619)

Darton (1925, p. 242-243, 252-253) gives some geologic data on the 

Mescal and Hayes Mountains, and gives a description of the Natanes 

Plat|eaU. 'Carl Lausen (1927) published a paper on the occurrence 

of peridot near San Carlos, and E. D. Wilson (1928), in a report on 

asbestos in Arizona, gives descriptions of several asbestos deposits on 

the $ah Carlos Indian Eeservation.

Tljie 'only published geologic map that includes the whole region is 

the geologic map of Arizona on a scale of 1: 500,000. This part of the 

state map j is based on reconnaissance work by Darton. A reconnaissance map of the Mescal and Hayes Mountains, which includes the 

southwestern corner of the reservations, is given in "Resume of Arizona 

geology" (Darton, 1925, p. 267).

Thes^e reports, particularly those of Darton, are the chief sources 

of geologic information available concerning the reservation area. 

Other references to the geology of this area are included in the bibliography.

! GENERAL GEOLOGY

Late Tertiary, Pleistocene, and Recent deposits of lake and stream 

origin mask the underlying bedrock over more than 30 percent of the 

reservation area. Volcanic rocks, part of the great Datil lava field of 

Arizona-New Mexico, cover another 60 percent of the area. These 

volcanic rocks are in part contemporaneous with, and HI part older 

than, the late Tertiary and Pleistocene valley-fill deposits. All of 

the volcanic .rocks are later than the major epochs of metallization in 

southeastern Arizona. The remainder of the area is underlain by 

pre-Caimbrian and Paleozoic sedimentary rocks, diabase, and preCambrian granite. Figure 77 is a graphic representation of the 

stratigraphic column with brief descriptions of the formations. It 

also shows the industrial minerals and metals that occur in the several 

formations.

, j SEDIMENTARY ROCKS

The sedimentary rocks within the reservation range in age from preCambrian to Recent; those of late Tertiary and Pleistocene age predominate.

; PRE-CAMBRIAN ROCKS

Younger pre-Cambrian rocks are the oldest sedimentary rocks exposed, in the reservation area. They are widespread in the western 

half of the reservation and crop out in the Mescal and Hayes Mountain^ the Apache ridge, along the Natanes escarpment, and in the 

canyj6n: pf the Salt River. These rocks include, in ascending order, the 

Sca^lanlScpnglomerate, Pioneer shale, Barnes conglomerate, Dripping 

Spring quartzite, and Mescal limestone. Collectively, these formations
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are known as the Apache group. The section is as much as 1,000 feet 

thick.

The Apache group rests on a somewhat irregular erosion surface of 

an older pre-Cambrian granite. Locally, a pre-Cambrian basalt flow 

is at the top of the Apache group. In most other exposures, however, 

post-Apache erosion has removed the basalt, and the overlying Paleozoic rocks lie on the Mescal limestone; however, on the San CarlosSawmill" road, near Plilltop, Cambrian Troy quartzite lies on the 

Dripping Spring quartzite and the Mescal limestone has been removed 

by erosion.

The lowest formation of the Apache group, the Scanlan conglomerate, is made up of quartz and quartzite pebbles and cobbles in a 

light-colored matrix made up largely of granitic debris. It rests on 

the pre-Cambrian granite. The conglomerate ranges from a thin layer 

including scattered pebbles to a bed 15 feet thick.

Overlying the Scanlan conglomerate is the Pioneer shale. The 

formation is composed of sandy shales and a few thin light-colored 

beds of quartzite, which are more common near the base. The formation, though well-indurated, is less resistant to erosion than the 

overlying Barnes conglomerate and Dripping Spring quartzite, and, 

as a result, it tends to crop out as slopes beneath the massive cliffs of the 

overlying rocks. The formation is as much as 150 feet thick.

The Barnes conglomerate, which rests on the Pioneer shale and 

which apparently is a basal conglomerate of the Dripping Spring 

quartzite, is readily distinguished from the Scanlan conglomerate. 

It is composed of abundant well-rounded quartzite and quartz pebbles and cobbles in a red quartzitic matrix. The conglomerate generally is less than 10 feet thick, but in places it is as much as 50 feet 

thick.

Next above the Barnes conglomerate is the Dripping Spring quartzite. This formation is prominent in all exposures of the Apache 

group, and many of the rugged cliffs of the southern escarpment 

of the Natanes Plateau, the Seven Mile Mountains, the northeast 

side of the Hayes Mountains, and the lower parts of the Salt Eiver 

Canyon are composed of this quartzite. The formation can be separated into at least two rather distinct parts: a lower part of lightcolored, medium- to thick-bedded quartzites of medium grain, which 

form the prominent cliffs characteristic of the formation; and an 

upper part of red to rusty-brown and black, thin- to medium-bedded 

siltstones and silty fine-grained quartzites. Some light-colored quartzites are interbedded in the upper part. A distinctive feature in this 

part of the formation is banding resulting from the alternation of black 

to purple siltstones and red to rusty-brown silty quartzites. The
622 CONTRIBUTIONS TO ECONOMIC GEOLOGY

formation ranges in thickness from 300 to 500 feet over the reservation 

area.

The Mescal limestone is the uppermost formation of the Apache 

group over most of the reservation. Generally, it has been split and 

.dilated by the intrustion of the widespread diabase sills; therefore 

continuous, complete sections of the formation are rarely observed. 

The Mescal limestone is economically significant because it is the 

only host rock in east-central Arizona for asbestos deposits.

The formation is divisible into three members: (1) a lower, thinto medium-bedded, flat-bedded limestone member, (2) a middle, massive limestone member that includes structures interpreted as relicts 

'of algae colonies, and (3) an upper, thin-bedded siltstone and shale 

member.

Along the Salt River Canyon, in the northwestern part of the reservation, the lower member is 150 to 200 feet thick and is composed 

dominantly of impure to moderately pure limestones intercalated with 

calcareous shales. The uppermost 10 to 12 feet of the member and 

two other units, 30 to 45 feet and about 100 to 110 feet, respectively, 

below the top of the member, are of relatively pure, gray, crystalline 

limestone, in beds 1 to 4 feet thick. The remainder of the lower member generally is composed of impure limestone beds, ^ to 4 inches 

thick, alternating with thin beds of calcareous shales or included shale 

partings. Chert occurs in the limestone in the Salt River section, but 

not in large quantities. Some of the carbonate beds are dolomites or 

are dolomitic, but such beds are uncommon.

Southward from the Salt River area the three limestone units thin, 

and individual beds throughout the section are progressively thinner 

to the south. The lowest limestone unit, 100 feet below the top of the 

member, has not been observed in the southern part of the reservation. 

Chert and dolomite are abundant in the lower member southward from 

the NataneS Plateau; in places, dolomite is more abundant than limestone. South of the Natanes Plateau, thin layers of chert characteristically stand out on weathered surfaces.

The middle, or algal, member is composed of thick, massive limestone beds totaling 10 to 140 feet in thickness. The fossil algae (which 

are wavelike in section and which are concentric and saucerlike in 

plan), the massive beds, and the tendency to form cliffs are characteristics of the middle member. In the Salt River area, this member is of 

limestone,' to the south, the member becomes increasingly dolomitic, 

individual beds become thinner, and the algal structures become less 

'readily discernible than in the Salt River area.

The contact between the algae-bearing middle member and the flat, 

slabby limestones of the lower member is sharp, and everywhere on
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 623

the reservation it is easily recognized at the base of the cliff-forming 

portion of the formation. The uppermost 10 to 30 feet of the middle 

member is thinner bedded than the remainder of the member and in 

places includes shale.

 The upper member is dominated by brown siltstones and gray to 

black shales, totaling as much as 110 feet in thickness. A chert bed, 

2 to 4 feet thick, marks the base of the member. Thin chert bands 

are common; in a few places, thin marly limestone beds have been observed in the member. These chert bands, the limestones (where 

present), and the stratigraphic position serve to distinguish the upper 

member of the Mescal from the somewhat similar siltstone and shaly 

units of the upper half of the Dripping Spring formation.

Through the northern part of the reservation, the pre-Cambrian 

basalt and part, or (in places) all, of the upper member of the Mescal 

are missing due to erosion prior to deposition of the Troy quartzite. 

East of Highway 60, in the vicinity of Seneca, part of the algal member 

and all of the overlying Troy quartzite are missing due to erosion that 

pre-dated deposition of the Martin limestone of Devonian age. In 

many places east of the Salt River bridge on U. S. Route 60, the Martin 

limestone is in depositional contact with diabase sills that intruded the 

Mescal limestone can be found below the pre-Martin erosin surface, 

and Martin limestone rests on progressively lower stratigraphic units 

of the Mescal as the Salt River Canyon is traversed upstream from the 

bridge. At a point Y miles east of the bridge, only the basal beds of the 

Mescal limestone can be found below the pre-Martin erosion surface. 

It is probable that in places within this 7-mile interval the Martin limestone rests on the Dripping Spring quartzite. 

The Mescal limestone has not been observed along the Natanes Rim

. south and west of Hilltop to the west boundary of the reservation. 

The Mescal limestone may not be observable along this interval of the 

Natanes Rim, owing to the presence of talus cover or faulting, but 

in part it may be absent as a result of pre-Troy or pre-Devonian erosion. 

This condition apparently exists in the section that is exposed where 

the road ascends the Natanes Plateau a few miles south of Hilltop. 

Here, Troy quartzite overlies Dripping Spring quartzite, and the 

Mescal limestone is absent. Asbestos deposits cannot exist along this

.part of the escarpment if the Mescal is absent. Plate 52, which follows 

the interpretation of the state geologic map for this area, shows Mescal

"limestone along this portion of the Natanes Rim.

Southeastward from Red Whiskers Spring in the Hayes Mountains

. the entire Mescal limestone thins rapidly and changes from a section 

dominantly of limestone to one exclusively of siliceous beds. At 

Coolidge Dam, the formation is only 25 feet thick.
624 CONTRIBUTIONS TO ECONOMIC GEOLOGY

PALEOZOIC ROCKS

West of Blue River, Paleozoic sedimentary rocks overlie the preCambrian Apache group. The Paleozoic formations crop out extensively in the Mescal and Hayes Mountains, in Apache Ridge, along the 

western part of the Natanes Rim, and along the rim of the Salt River 

Canyon.

The Paleozoic sedimentary rocks are represented by the Troy quartzite of Cambrian age, the Martin formation of Devonian age, the 

Escabrosa limestone or Redwall limestone of Mississippian age, and 

the Naco limestone of Pennsylvanian age.

East of Blue River, Tertiary volcanic flows cover the older formations and only three hitherto unreported outcrops expose the underlying rocks. These outcrops' are along a part of the south front of the 

Gila Mountains, along the Natanes rim east and west of Park Creek, 

and in the vicinity of Rincon spring. The base of the Paleozoic section 

in the Gila Mountains is not exposed; the lowest formation is a quartzite similar to the Troy quartzite. Near Park Creek, a basal quartzite 

similar to the Troy rests directly on pre-Cambrian granite. Both of 

these quartzites are overlain by interbedded sandstones, shales, and 

limestones generally like those of the Paleozoic formations in the 

western part of the reservation.

The Troy quartzite of Middle and Upper Cambrian age is the basal 

formation of the Paleozoic rocks on the San Carlos Indian Reservation. It consists of medium- to thick-bedded quartzites usually of 

light color on a fresh face but usually of reddish cast in outcrop. 

Characteristically, the formation, especially toward the base, is coarsegrained and in places conglomeratic. Medium- to large-scale crossbedding is also a common feature in the Troy quartzite. In most 

places, the relative paucity of feldspar grains, the generally coarser

grain and larger-scale crossbedding distinguish the Troy quartzite

from the thick-bedded quartzites of the lower part of the Dripping 

Spring formation. In common with the Dripping Spring quartzite, 

the Troy quartzite forms cliffs. In places, Troy quartzite forms the 

southwest-dipping rim-rocks of the Mescal and Hayes Mountains. 

The quartzite is as much as 400 feet thick.

Quartzites similar in appearance to the Troy are found in isolated

exposures on tne south, slope of the Gila Mountains, and near Park

Creek under the Natanes rim in the eastern part of the reservation.

These quartzites are undoubtedly equivalent to the Troy quartzite but,

considering their proximity to Morenci, it may be as proper to correlate them with the Cambrian Coronado quartzite of that district as

it is to correlate them with the Troy,

The Martin limestone of Devonian age overlies the Troy quartzite, 

The formation consists of limestone, sandstone, and shale. A sand-
MINERAL 'RESOURCES, -SAN CARLOS. INDIAN. RESERVATION 625

stone "unit of variable ^thickness'usually is found at thebase; This 

unit is overlain /by 'a section that includes yellow-brown magnesian 

limestones, sandy in places, interbedded with thin limy shales; 

medium- to coarse-grained crossbedded sandstones; gray to pink 

papery shales; and medium-bedded gray .limestones." The Martin 

limestone ranges in thickness from 200 to 350 feet. The formation 

tends to form slopes and benches between the cliffs of the Troy quartz - 

ite (below) and the cliffs of the Escabrosa or Redwall limestone 

(above).

Above the Martin limestone is about 500 feet of medium-gray limestone of Mississippian age, in part containing nodules of chert. The 

most notable feature of this sequence of limestones is the presence of 

exceptionally massive gray limestones in the lower and middle portions of the formation. These massive beds form a conspicuous limestone cliff, which is a diagnostic feature for the formation in all of its 

outcrops. In the area south of the Natanes Plateau, the name most 

generally used for these rocks is the Escabrosa limestone; north of 

the Natanes Plateau, the name most generally used is Redwall 

limestone.

Next above the limestone of Mississippian age is the Pennsylvanian 

Naco limestone. In the Mescal and Hayes Mountains this sequence 

of generally medium-bedded gray limestones with some intercalated 

shales is as much as 1,200 feet thick.

TERTIARY SEDIMENTARY ROCKS

There are at least two distinct ages of Tertiary sedimentary rocks on 

the reservation. These rocks are separated in time by a marked period 

of orogeny. The older gravels underlie volcanic flows in the western 

part of the Natanes Plateau. Their age is not well known. The 

younger gravels occupy the major valleys south of the Natanes Plateau 

and are correlated with the Gila conglomerate of late Pliocene and 

Pleistocene age.

The older gravels overlie Paleozoic sedimentary rocks and underlie 

older Tertiary andesitic flows in the western part of the Natanes 

Plateau (pi. 52) along the Salt River. The older gravels contain 

coarse detritus among which rocks of the Apache group can be recognized. From this, it is inferred that their source was highlands to 

the south because the rocks of the Apache group are not exposed to the 

north.

The older gravels are part of a more widespread gravel deposit 

which is found to the north and west of the reservation along the 

Mogollon Rim. The gravels can be seen north of the reservation 

along the highway between the Salt River and Show Low where they 

underlie thin volcanic flows and overlie Paleozoic sedimentary rocks.

367127 56 3
626 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Similar gravels have been described by Price (1950) from the Sycamore Canyon area near Prescott, Ariz. where the gravels underlie a 

basalt flow of supposed Pliocene age.

The age of these older gravels is not well known. The older gravels^ 

and the volcanic flows that overlie them, are separated from sedimentary rocks of probable late Pliocene age by a period of major orogeny 

that outlined the structural valleys of the Gila and San Carlos Rivers 

and Bonita Creek. Late Pliocene sediments have been deposited in 

these basins. It is presumed then that the older gravels are Pliocene 

and perhaps older.

The Tertiary sedimentary rocks that fill the Gila and San Carlos 

River valleys and Bonita Creek (pi. 52) to an unknown, but considerable, depth include coarse conglomerates, derived from the surrounding1 

mountains, and lake beds deposits which include limestones, mudstones, 

diatomaceous sedimentary rocks, and gypsum. The conglomerates 

and lake beds interfmger. Usually, the conglomerates are marginal 

to the lake beds that, in general, were deposited in the center of the 

basins; however, at Blue River on the margin of the basin, thick 

fresh-water limestone laps up against the Natanes Plateau.

The conglomerates and lake beds are continuous with the Gila conglomerate at Safford, Ariz. Knechtel (1938, p. 198) has dated the 

Gila conglomerate in that area as late Pliocene in age.

PLEISTOCENE(?) AND BECENT ALLUVIUM

Coarse gravels of Pleistocene (?) age mantle the surface of the late 

Tertiary sedimentary rocks. An erosional unconformity separates 

the two formations. These relations are especially well exposed along 

the road from Coolidge Dam to Bylas.

Recent silts, sands, and gravels occupy the courses of the present-day 

drainage.

IGNEOUS BOCKS

Pre-Cambrian granite IS the oldest IgneOUS rock found within the

reservation. The largest exposures of the granite are in the area between the Natanes Rim and Seven Mile Mountains and northeast from 

the Hayes Mountains to Bucket Mountain (pi. 52). The late preCambrian Apache group lies upon the eroded surface of the granite 

in the Mescal Mountains, Hayes Mountains, the southeasterly extension.

of the Apache Mountains, and in places under the Natanes Rim.

A vesicular basalt flow is found locally at the top of the Apache 

group at several places along the Apache Ridge (pi. 52) and in Bear 

Canyon (not Shown 011 pi. 52 because of the small scale of the map). 

Elsewhere on the reservation the basalt is generally absent, either because the flows did not reach these areas, or because the basalt was removed by pre-Troy erosion. The basalt is reddish to dark brownish
in color and is commonly vesicular. Amygdules in the highly altered 

and decomposed rock contain calcite, chlorite, and epidote (?).

The basalt is overlain unconf ormably by the Troy quartzite of Middle and Upper Cambrian age. Near the west boundary of the reservation in the Apache Ridge the basalt is intruded by later diabase.

Pre-Devonian diabase sills, of great lateral extent and ranging in 

thickness from a knife-edge to several hundreds of feet, intrude the 

Apache group and Troy quartzite. In the Salt River Canyon these 

sills are well exposed along the canyon walls where several thick sills 

have intruded the Mescal limestone. Diabase has also intruded the 

Apache group in the Apache Ridge, the Hayes and Mescal Mountains, 

and in Bear Canyon. In the Hayes Mountains, near the Wylomene 

claims and near Red Whiskers Spring, the diabase intrudes the Troy 

quartzite and is unconf ormably overlain by the Martin limestone. The 

diabase varies from fine- to coarse-grained, and usually has a darkgreen color, though it may weather to shades of brown and olive green. 

It is an important igneous rock in this region of Arizona because of 

its genetic relationship to asbestos mineralization where it intrudes 

the Mescal limestone.

On the flanks of Mount Turnbull granitic and rhyolitic rocks occur. 

These rocks appear gradational one to the other. Their age is uncertain, though Ross (1925, p. 32-33, 35) assigns similar rocks in the 

Aravaipa-Stanley district to the early Tertiary period.

Volcanic rocks are widespread within the reservation area. At least 

two periods of vulcanism, the rocks of which are separated by a structural unconformity, can be distinguished. Older Tertiary volcanic 

rocks, possibly of middle Tertiary age, are found in the Turnbull and 

Gila Mountains and in the northern and eastern parts of the reservation. Basalt flows found interbedded with, and overlying, the Gila 

conglomerate type of sedimentary rocks are younger and unconformable with these older Tertiary volcanic rocks. These younger flows 

are probably of Pliocene and Pleistocene (?) age.

The older Tertiary volcanic rocks present a greater lithologic variety 

than the younger Tertiary or Quaternary (?) or both, volcanic rocks. 

The older volcanic rocks include basalts, rhyolites, andesites, and rhyolitic tuffs and breccias. About 1,000 feet of these flows and pyroclastic 

rocks overlie the exposed Paleozoic rocks in the Gila Mountains. 

Along the Natanes escarpment on the north side of Ash Flat approximately 500 feet of white to pink rhyolitic tuffs are overlain by at least 

500 feet of andesitic flows. These andesitic flows make up much of the 

surface in the western portion of the Natanes Plateau. Thick andesitic 

flows crop out also in the mountainous area in the southeast corner of 

the reservation, east of Bonita Creek.
628 CONtBIBUfIONS TO ECONOMIC GEOLOGY. :

The older Tertiary volcanic rocks have been involved in the faulting 

that resulted in the present distribution of the major physiographic 

features.

The younger Tertiary and Quaternary (?) volcanic rocks, probably 

of Pliocene and Pleistocene (?) age, are represented by basalt flows 

interbedded with, and overlying, the Gila conglomerate type sedimentary rocks. Typical exposures are found north and east of San 

Carlos, where several flows crop out along the mesa sides and a flow 

caps the extensive mesa extending northward and eastward from the 

Triplets. A similar flow forms the surface near Ash Creek Ranch 

on Ash Flat (pi. 52). Several isolated mesas southwest of San Carlos 

are also capped with these basalt flows.

The basalt flows and the interbedded sedimentary rocks, in contrast 

to the older Tertiary volcanic rocks, are generally flat-lying and have 

been little disturbed.

STRUCTURE

Parts of the two major structural provinces are included in the San 

Carlos Indian Reservation area. These structural provinces are the 

Colorado Plateau province and the Basin and Range province (fig. 

76). The area of the Natanes Plateau (pi. 52), which dominates the 

northern part of the reservation, lies in the plateau province and the 

area to the south of the Natanes Plateau, which includes several northwest-trending mountain ranges and intervening valleys, lies in the 

Basin and Range province.

The structural boundary between the Colorado Plateau and Basin 

and Range structural provinces is arbitrarily shown on figure 76 as 

the south rim of the Natanes Plateau. Actually, it is probably a zone 

in which the plateau edge is successively down-faulted into the structural basins which face the Natanes Elm on the south, This is especially true in the general area from the reservation boundary west of 

Sawmill (pi. 52) and east to Blue River. Between Blue River and the 

area just north and west of Ash Creek Ranch the boundary between 

the two provinces is indistinct where late Pliocene basalts associated 

with the Gila conglomerate lap up against the older Tertiary volcanic 

flows. West of this point on the north side of Bonita Creek almost 

to Park Creek (fig. 76) the north side of the valley is linear and is 

probably a fault scarp. The fault or faults along which the valley 

block was lowered are not exposed, but they probably are covered

under the Gila conglomerate "which fills this valley to an unknown but

no doubt considerable depth. East of Park Creek the boundary is 

:not well marked.

The plateau area is characterized by the general horizontally of the 

exposed sedimentary rocks and by the scarcity of faults. In the 

western part of the reservation along the south-facing rim of the
plateau the Apache group and Paleozoic rocks, which are overlain by 

thin Tertiary flows, dip gently northward or are flat-lying. The 

sedimentary rocks are exposed along the rim. as far east as Blue 

River, beyond which they disappear under the Tertiary flows. Near 

Arsenic Tubs on the north side of Bonita Creek valley the Paleozoic 

rocks are again exposed under the volcanic flows (pi. 52), and the 

sedimentary rocks and Tertiary flows have a gentle northeasterly dip.

South of the Natanes Plateau in the Basin and Range province the' 

bedded rocks are tilted at moderate to steep angles. Faults are common and they delineate several northwestward trending ranges separated by alluvial-filled structural basins. These ranges are the Gila, 

Turnbull, and Seven Mile Mountains, the Apache Ridge, and the 

Hayes and Mescal Mountains.

In the Gila and Seven Mile Mountains the rocks generally dip at 

moderate angles to the northeast. The Apache Ridge, Hayes, and 

Mescal Mountains are homoclinal fault blocks in which the rocks 

strike northwestward and dip at moderate to steep angles toward the 

southwest. They present, in part, relatively steep northeasterly facing 

scarps, and southwesterly dip slopes.

The mountains have been uplifted relative to the basins along northwest faults. These faults are now largely covered by fanglomerates 

along the valley sides. Northeast faults, such as those in the Apache 

Ridge, those north of Bylas in the Gila Mountains, and those in the 

Hayes Mountains are generally of relatively minor displacement and 

have little or no reflection in the topography.

A few faults cut the Pliocene lake beds. This can be seen in the 

area of the Iron Claims (fig. 79), where limestone and mudstone of 

the lake beds are faulted against Paleozoic sedimentary rocks. In 

general, however, the lakebeds are flat lying and little disturbed.

The valleys of the Gila River, Bonita Creek and San Carlos basins 

are thought to be structural basins formed by down-faulting between 

the adjacent and relatively upraised mountain blocks. In places, such 

as west of Peridot Mesa and south of Black Mesa, small isolated highs 

of the basin floors have been exhumed by erosion of the overlying 

cover of Pliocene and Pleistocene sediments, but in general the floors 

of the basins are probably covered to a considerable depth by the later 

sediments. The depth of this cover and the configuration of the basin 

floors are not known. At Geronimo, just off the reservation a few 

miles southeast of Bylas, and 810-foot well bottomed in valley fills. 

Near Safford, the thickness of the lake beds is considered to be at 

least 1,600 feet or more (Knechtel, 1938, p. 204).

The age of the major orogeny that uplifted the mountain blocks 

and formed the relatively down-faulted basins has not been closely 

dated. The older Tertiary volcanics are involved in the faulting, but
630

the late Pliocene and Pleistocene Gila conglomerate, and its lake-bed 

f acies and interbedded basalts generally are not. The Gila conglomerate fills the structural basins formed by the faulting. Therefore, 

the major faulting was prior to late Pliocene time.

The mineral deposits of the reservation may be subdivided into 

metallic and nonmetallic classes. The metallic deposits have been 

of no importance, whereas the nonmetallic deposits have accounted 

for all production. Known metallic deposits include copper and iron 

minerals. Nonmetallic deposits that have yielded some production 

are asbestos, building s,tone ("tufa" stone), peridot, and guano. 

Nonmetallic deposits of unknown value include gypsum and diatomaceous earth.

In the following pages, the mineral commodities are considered in 

turn; a general discussion of the known occurrences and the geologic 

factors determining their localization is followed by detailed descriptions of ,the individual deposits. The individual deposits are indexed 

as to location on plate 53. Their geologic setting is shown in plate 52.

METALLIC DEPOSITS 

COPPER

Only small and noncommercial quantities of copper are known on 

the reservation. These include the Copper King-Wylomene claims 

in the Hayes Mountains, the Peacock claims southwest of San Carlos,

jfche Bitter Spring and Geronimo prospects on the flanks of Mount 

Turnbull, and the Tribal claims in the Gila Mountains.

At least three factors must be considered to explain why only minor 

copper deposits are known on the reservation: (1) the age of intrusive 

activity, (2) the position of the reservation with relation to the 

regional geologic structure, and (3) the widespread cover of Tertiary 

and Quaternary rocks.

Metallic mineral deposits and mining districts commonly are 111 

areas of past igneous activity. The metallization is closely associated 

in space and ,time with this intrusive activity. The most important 

period of igneous activity and associated metallization in southeastern 

Arizona was during Laramide time (Late Cretaceous to early Tertiary). All of the large copper deposits in the adjacent areas, such 

as those near Globe-Miami, Morenci, Bay, and Christmas, are considered to be of. this period. Intrusive rock of Laramide age IS miSSing in general from the San Carlos Indian Eeservation except, perhaps, in the part of the reservation around Mount Turnbull. Here are 

granitic and rhyolitic intrusives that may be a continuation of simi-
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 631

lar rocks.of Laramide age (Eoss, 1925, p. 33, 36-37) that crop out 

.just south of the reservation boundary in the Stanley district. This 

part of the reservation may be considered to be on the fringes of 

the Stanley district, which produces only a small amount of copper. 

Only scattered and meager copper showings have been prospected in 

this part of the reservation.

' In addition to igneous activity and associated metallization, the 

position of the reservation with relation to the regional geologic structure is of importance. As discussed in a previous section the reservation lies on the boundary between two structural provinces: a plateau 

province, characterized by little-disturbed, relatively flat-lying sedimentary rocks, and a mountain province characterized by more disturbed and faulted areas giving rise to individual fault-block mountains and more complex structures. All of the large copper or basemetal deposits are in this "mountain region" of Arizona, because it was 

in this region that structural deformation provided loci for igneous 

intrusion and associated metallization. The strongest metallization, 

however, seems to be concentrated in cross zones at intervals along 

this northwest-trending main belt. The deposits of the Globe-Miami 

district are confined to a northeast-trending zone about 6 miles wide. 

The northeastward continuation of this zone would pass just west 

of Chromo Butte and skirt the west boundary of the reservation. 

This might suggest the possibility of a few small outlying metalliferous deposits along the west boundary of the reservation. However, 

the metallization decreases in intensity southwest and northeast from 

the Schultze granite stock between Miami and Superior and appears 

to be dying out in the vicinity of McMillenville and Eichmond Basin 

where the deposits are small and the principal metal is silver.

There is probably another northeast-trending belt of mineralization 

and igneous intrusions that takes in Lone Star Mountain (northeast 

of Safford), Morenci, and Metcalf. Thus, it is possible that base-metal 

deposits are present under the cover of lavas and alluvial deposits in 

the extreme southeastern part of the reservation; but the discovery of 

these will depend on methods of prospecting that are not yet developed 

and perfected.

COPPER KING OR WYLOMENE CLAIMS

These claims are in the southern part of the Hayes Mountains in sec. 

9, T. 3 S., E. 17 E.,4 on the east side of Dick Spring Canyon, about 3 

miles south of Tincup Spring (pi. 53). The claims are in a rugged 

area at an altitude of 4,500 feet. They are accessible only by foot or

4 The San Carlos Indian Reservation Is unsurveyed and all section, township, and range 

descriptions given in this report are projected land locations as shown on Department 

of Interior, Bureau of Indian Affairs map of the reservation, edition of 1945.
632 CONTRIBUTIONS TO "ECONOMIC GEOLOGY

horseback from the end of a road which branches from U. S. Highway 

70 at the Lakeside Trading Post and ends in a canyon east of the claims. 

The claims are accessible as follows: v

Miles Directions

0.0____________. At Lakeside Trading Post, take truck trail west.

0.2____________ Fork, turn right.

3.4___________. Fork, turn left. Right fork goes to Indian Spring.

9.2____________. Park vehicle in wash. Claims are about 1 mile 

westward. No. trail. Workings are near top 

of basalt-capped knob on south-trending ridge 

(pi. 54).

Claims known as the Copper King No. 1 and 2 were first located in 

this area in 1919 by Frank Cain, A. H. Gibson, and J. C. Gibson, and a 

lease was obtained in 1921. The lease became delinquent through nonpayment of rental fees. In 1927, the claims were relocated as a part of 

the Wylomene group by Pollard K. and Wylomene Pearson. A lease 

was obtained, and a small amount of work was done. This lease, in 

turn, ended in litigation through nonpayment of rental fees. The 

claims have since been inactive. The workings include a pit, two adits 

(one of which is caved), and two shallow shafts. No production is 

recorded.

In this area, the Apache group and Troy quartzite, both intruded by 

diabase, are overlain with apparent conformity by the Martin and 

Escabrosa limestones. These rocks strike from N. 25° W. to N. 50° W. 

and dip at angles from 25° to 30° SW. An erosion remnant of a Tertiary (?) basalt flow lies on. the beveled surface of the tilted preCambrian and Paleozoic rocks (pi. 54). Faults and fissures, trending 

east and northeast, cut the pre-Cambrian and Paleozoic rocks.

Copper minerals have been found in two northeast-striking fissures 

cutting the diabase. One of these two fissures is near the southeast 

margin of the Tertiary (?) basalt flow. This fissure strikes N. 70° E. 

and dips 80° to 85° NW. A pit exposes a weakly copper-mineralized 

vein which ranges in Width from a knife-edge to a maximum of 8 

inches. The diabase is stained by iron oxides for a few feet on either 

side of the stringer. Minerals include azurite, malachite, chalcocite, 

and specular hematite. A grab sample from a small pile of sorted ore 

assayed 0.02 ounce gold and 0,9 Ounce silver to the ton, and 8.62 percent

copper.

Several hundred feet north of this pit is a 60-foot adit and 20-foot

Shaft On a fault of nearly vertical attitude trending N. 60° E. The

diabase Is iron oxicta stained for Several feet away from the fault. 

Along fracture and minor slip surfaces, copper carbonates are erratically distributed. Minerals were malachite and chalcocite. None of 

this material was observed in place, and it evidently occurred in narrow 

stringers and pods along the fault.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 633 

PEACOCK CLAIMS

These claims are about 1 mile east of Bucket Mountain in sec. 30, 

T. 1 S., R. 18 E. (pi. 53), and they are easily accessible by a truck trail 

that turns southward from the new Cutter-Peridot highway at a point 

5.7 miles west of Peridot. The claims are approximately % mile south 

of the highway. .... . . William Stevens, James Stevens, and John Case, located-.the Peacock claims in 1919. Shortly thereafter, T. Fink .and :H. <J..Hagen 

obtained an option to purchase, but afterdoiiig.a small amount of work 

the option was relinquished. No subsequent work.was done, and the 

lease lapsed. Recently, H. J. Hagen applied, .for a lease on the 

property, and at the time of this writing, the" lease was still pending. 

There has been no production from this property/

The area is one of low relief and is located on the gently sloping 

pediment area that border's the Hayes Mountains on the east. The 

claims are at an approximate altitude of 3,700 feet.

The country rock in the area is predominantly granite which is intruded by small irregular bodies and narrow dikes of fine-grained 

dioritic rock. The granite is cut by north- to northwest-striking 

faults and fractures and is locally replaced by quartz, sericite, and 

chlorite.

Several pits, cuts, and two shallow inclines have been driven on a 

north-trending shear zone in granite (fig. 78). This zone dips from 

40° to 65° W. at its northernmost exposure, but in the southernmost 

pit the dip is reversed and is 70° E. The zone of crushed and sheared 

granite is in part occupied by a discontinuous vein having a maximum 

width in one pit of 9 to 18 inches; in the other pits, the vein is absent 

or is represented by one or more stringers. The vein contains quartz, 

calcite, barite, rhodochrosite, and sparse pyrite grains. Malchite 

stain is also present in minor amounts, but the tenor of the vein material in copper is very low.

In the area extending about 600 feet to the east of the north-trending shear zone a number of pits, shallow trenches, and a 35-foot vertical shaft have been excavated (fig. 78). None of these exposes any 

veins or shows any marked content of copper-metallized rock. The 

shaft was sunk on a northwest-trending slip surface that shows minor 

amounts of copper carbonate stain.

It is probable that in the area of the Peacock workings there has 

been some weak disseminated copper mineralization. However, it appears meager and limited in areal extent. There is little residual 

limonite, probably owing to the rarity of pyrite, and there are very 

few voids with "relief" limonite of the type usually interpreted as 

indicating the former presence of copper sulfides.

367127 56 4
634 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Geology and topography by C. S. Bromfield 

and J. A, Noel. April 1953

FIGURE 78. Geologic sketch map of the Peacock copper workings.

BITTER SPRING PROSPECT

Some old workings are near the upper end of Bitter Spring trap, on 

the northwest slopes of Mount Turnbull, in sec. IT, T. 4 S. B. 20 E. 

(pi. 53). The locale can be reached only by foot or horseback. The 

prospect is accessible from San Carlos as folloWS:

Miles Directions

0.0__________, From San Carlos, travel 30.4 miles via Peridot 

road to U. S. Highway 70, thence east toward 

Safford. :

30.4___________. Turn right on truck road to south.

38.0_________ . Turn left on dim truck trail.

38.5 . Park, and follow horse trail east for about 1.5 

miles to Bitter Spring trap. Prospect at upper 

end of fenced area.

Claims in this area were located by F. C. Oockett in 1920. An adit

of unknown length, now flooded, and a shallow shaft, now Caved, are

the only workings that were noted. No production is recorded.

Tne area is Of moderate rilggedness on the intricately dissected 

slopes of Mount Turnbull. At the workings the altitude is about
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 635

4,650 feet. The country rocks in the vicinity of the workings are 

largely rhyolitic and andesitic volcanic rocks,'but at two place there 

are small outcrops of limestone of indeterminate age. Each of these 

small outcrops is weakly mineralized and has been prospected.

At one of the outcrops, on the east side of a north-trending gulch 

above Bitter Spring trap, a shallow shaft has been sunk on a contact 

between limestone and rhyolitic rock. At this contact, a little magnetite has replaced the limestone. Minor malachite stains on magnetite, 

as well as a little pyrite, were noted. The mineralization is less than 

10 feet in length.

The second of these isolated limestone outcrops is a few hundred 

feet south of the first outcrop, on the west side of the gulch. The 

exposures are poor, but near the bottom of the gulch an adit has been 

driven S. 15° W. on a quartz-pyrite-magnetite zone of mineralization. 

The zone is 5 to 10 feet wide. Upslope, for a distance of 100 to 150 

feet, magnetite float is found along the projected strike of the zone. 

No copper or other minerals were noted. Within 25 feet of the zone, 

andesitic and rhyolitic float is found, but the soil cover obscures the 

contact between these rocks and the limestone.

A sample of the quartz-pyrite mineralized rock assayed 0.01 ounce 

of gold per ton, and 1.0 ounce of silver per ton.

GERONIMO PROSPECT

Some workings, including a 100-foot shaft and two shallow cuts, 

are located 3 miles southwest of Bylas in the foothills of the Turnbull Mountains in sec. 11, T. 4 S., E. 21 E. (pi. 53). These workings 

are believed to be a part of the claims known originally as the Geronimo group, which were located July 1,1920, by B. F. Baker and others. 

Subsequently, a lease was obtained; in 1929, the lessees were in 

arrears with their payments, and the lease was lost. There was no 

production.

In this area, a medium- to fine-grained dioritic rock is intrusive 

into granite. The age of the rocks is not known. Both rocks have 

been faulted and fractured, but no attempt has been made to determine 

the structural relations.

The shaft has been sunk on an outcrop of dioritic rock that is chloritized and cut by narrow fractures along which scattered grains of 

quartz, pyrite, and chalcopyrite occur. The individual fractures 

average less than a centimeter in width. Though the shaft is inaccessible, rock on the dump indicates that sulfides were not abundant in 

the shaft. Iron oxides have formed, but unoxidized sulfides can be 

found at the surface. This indicates that erosion has kept pace with, 

or has exceeded, the rate of oxidation and that little or no secondary 

enrichment can be expected at depth. The length of the zone along 

which sulfides sparsely coat fractures is a few tens of feet.
636 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TRIBAL CLAIMS

The claims known locally by this name are about 5 miles north, and 

a short distance east, of Bylas at the foot of the southern slope of the 

Gila Mountains in sec. 33, T. 2 S., R. 22 E. (pi. 53). They are not 

accessible by road; however, they can be reached by jeep or truck by 

fording the Gila River at Bylas and going north 5 miles on the bed of 

a southerly-draining wash.

These claims were first located in July 1920 by James Stevens, William Stevens, Richard Bylas, and John Rope. The claims were visited in January 1953 in the company of Jeff Davis, who acted as a 

guide. There has been no production.

At the foot of the Gila Mountains in this area, Cambrian quartzites 

and Devonian and Carboniferous limestones are exposed. These are 

overlain by Tertiary volcanic flows. In general, the Paleozoic rocks 

strike northwestward and dip at low angles toward the southwest or 

northeast.

The workings consist of three shallow cuts which expose a weakly 

metallized vein over a length of 200 feet along a fault striking N. 75° 

W. and dipping 75° NE. This fault brings Cambrian quartzite on the 

south against Devonian to Carboniferous limestones on the north. 

At the center cut, the fault zone is composed of about 2 feet of greenish to reddish clay gouge and about 2 feet of milky-white quartz veinlets containing calcite, specular hematite, malachite, and possibly a 

little fine-grained pyrite. The vein is in sharp contact with the clay 

gouge on the f ootwall side, but the hanging wall contact with the limestone is bordered by irregular, narrow stringers of specular hematite 

and quartz which penetrate into the limestone.

About 200 feet northwest at the westernmost pit, located where the 

fault is exposed in a saddle, the vein is composed largely of quartz 

veinlets, specular hematite, and minor amounts of malachite-stained 

rock, Here, in the partly caved pit, some much weathered, light-colored porphyry was observed, thus suggesting the presence of a dike in 

places along the vein. The easternmost pit is in talus and does not

expose the vein.

A grab sample from a small pile of sorted TOIII matter from near tkc

central pit assayed 0.01 ounce of gold and 0.4 ounce of silver to the ton, 

and 2.27 percent copper.

COPPER PROSPECT (NAME UNKNOWN) 

This prospect is 4 miles north, of San Carlos and about % mile east

of the San Carlos-Sawmill road (pi. 53). Here, erosion has created a

topography Of gullies and low mesa-like divides in generally flat-lying

late Tertiary lake beds. The maximum relief is a few tens of feet,
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 637

Three pits have been dug along the east side of a gully that follows 

a fault striking about N. 20° W. and dipping steeply to the west. On 

the west side of the fault are calcareous silty sandstones, which are 

faulted against alternating thin beds of limestone and tan siltstones 

on the east side of the fault.

Copper, principally in the form of malachite, exists in small amounts 

as incrustations along seams and solution cracks in a 2-foot limestone 

bed, which is underlain by siltstones and overlain by silty sandstones. 

The copper is almost completely confined to the limestone, though in 

the most northerly of the three pits, at the contact with the limestone, 

some malachite stain was found in the overlying slightly calcareous 

sandstone bed. The pits are not on the fault but are within 10 feet of 

it, and they expose this meager copper mineralized rock over a length 

of 70 feet. No copper minerals were observed along the fault.

The occurrence of copper near the fault, though perhaps accidental, 

suggests an access for the copper-bearing.solutions: The writer does 

not think that this meager ocurrenee is derived from the oxidation of 

indigenous primary, copper minerals; instead, it probably is due to 

precipitation from migrating .ground water containing some available 

copper.

PROSPECT NEAR BUCKET MOUNTAIN (NAME UNKNOWN)

Approximately 1 mile southeast of Bucket Mountain in sec. 36, T. 1 

S., R. 17 E. (pi. 53) are several pits on a "bull" quartz vein cutting preCambrian granite. Presumably, these pits were made in a search for 

base or precious metals. The vein is typical of a number of veins of 

this type found in the granite in this general area. The trend of the 

vein is about N. 30° W., and the thickness ranges from 1 to 3 feet. 

Sporadic float and outcrop indicate that the body or vein is at least 125 

feet long. The quartz, which is white and vitreous, is in places stained 

rusty brown to red on fracture surfaces; pyrite is rarely seen, but pink 

feldspar crystals were noted. . ;

IRON

Several small iron deposits are on the reservation. These consist of 

(1) scattered deposits on the flanks of Mount Turnbull, in which magnetite and minor amounts of copper minerals replace small isolated 

remnants of limestone along the contact of the limestone with lightcolored felsitic rocks (see description of Bitter Spring prospect) ; (2) 

a deposit near Seneca, where magnetite replaces Mescal limestone near 

a diabase intrusion; and (3) a deposit southwest of San Carlos, where 

hematite replaces a limestone breccia. All of these deposits appear 

too small to be of significance as commercial sources of iron.
638 .CONTRIBUTIONS TO ECONOMIC GEOLOGY

I.;... . ' IRON CLAIMS

Three miles west of San Carlos and about half a mile south of the 

Southern Pacific Railroad tracks in sec. 16, T. 1 S., R. 18 E. (pi. 53), 

'conspicuous concentrations of massive hematite are exposed along a 

northwest-trending fault. Claims are known to have been located in 

this area by Martin Wright, and others, in September 1926, and by 

William Sparks in June 1927. No production of any mineral is recorded. The deposit is explored by a vertical shaft about 100 feet 

deep (but now inaccessible), two short adits, and several cuts and pits 

(fig.T9).

- »».

Outcrops of massive p

hematite in this area

__

t .Limestone and siltstone

Escabrosa. limestone, or 

Martin limestone, or berth

3100'-

aooff fs/SS SS S/S^

'".'////////s^

'^'^IxX

 Dump

Fault, showing-dip; dashed where 

approximately located. U,. upthrown side; D, downthrow)sub 

""Conceaied'fau'lt 

a

Strike and dip .of beds 

 B 

Shan

Opencufand adit

Illlinillllll

Dump Ts A'

fe S*:''* 

Fault zone ^ggz^j: 

%> \

Contour interval 20 feet 

Datum from barometer elevation

Geology and topography by C. S, Bromfield, 1953

FIODBB 79. Geologic map and section of the "Iron" claims workings.
MINERAL RESOURCES/ SAN CARLOS INDIAN RESERVATION 639

In this area, two low hills of Paleozoic quartzite and limestones are 

surrounded by late Tertiary lake beds which are overlain by basalt. 

In general, the area is one of broad meandering washes between flat 

.basalt-capped, mesas or low rounded hills. The upturned rocks of 

Paleozoic age ; are an. isolated southeastward projection of the ridge 

that extends from Chromo Butte southeastward to Gilson Creek. 

Near the workings, the Paleozoic rocks strike northwestward, dip to- 

.ward the northeast, and are in contact with the late Tertiary rocks 

along a fault zone that strikes northwestward and has a general northeastward dip of about 60°. Paleozoic quartzite and limestone compose the f ootwall block, and late Tertiary rocks compose the hangingwall block. The f ootwall limestone is generally shattered adjacent 

to the fault zone, and brecciated limestone is common within the fault 

zone. v Near the workings, the fault zone is about 150 feet wide. The 

relations are shown in the plan and section of figure 79.

Within this fault zone, in an area about 150 feet long, prominent 

masses of iron oxides crop out. Coloration of soil indicates iron oxides 

may be present in some abundance for another 150 feet to the northwest along the strike, whereas to the southeast, though some iron 

oxides may be present, the float indicates the fault zone to be largely 

of a limestone-chert breccia. The iron oxides are in part a replacement of the limestone breccia and in part a filling of fractures. In 

places, large masses of unreplaced limestone-chert breccia are in sharp 

contact with massive hematite, and, in contrast, other contacts appear 

gradational. Some of the hematite masses contain unreplaced chert 

fragments. The iron oxides have been brecciated since their 

formation.

The hematite ranges in color from black to orange, but is commonly 

deep brick red; it ranges in firmness from pulverulent to compact; the 

compact material is the most common. Small quartz crystals line 

cavities in hematite. No other minerals were noted. The writer does 

not believe that this material represents a gossan, because there is no 

indication of the presence of former sulfide minerals such as boxwork, 

or earthy oxides. On the contrary, the hematite is massive and in 

places appears to have directly replaced the limestone breccia.

SENECA IRON PROSPECT

Several small lenses of magnetite occur in the Mescal limestone just 

north of the road to the Phillips asbestos mine and about half a mile 

west of U. S. Highway 60 in sec. 19, T. 4y2 N., R. 18 E.

Diabase is intrusive into the Mescal limestone, and, at and near the 

contact at least three thin lenses of magnetite, ranging from 100 to 400 

feet in length and from 2 to 3 feet in thickness, replace the limestone. 

The lenses parallel the bedding which strikes northwest and dips from 

5° to 10° NE.
640 CONTRIBUTIONS TO ECONOMIC GEOLOGY

URANIUM

Several occurrences of uranium have been discovered recently in the 

Dripping Spring quartzite in two areas one area is north of Roosevelt 

Lake at the south end of the Sierra Ancha, and the other is a short distance southeast of Young, Ariz. These prospects suggest the possibility that other occurrences of radioactive material, some of which might 

be of commercial importance, may be found by more intensive prospecting within the Dripping Spring quartzite. This formation is widely 

distributed in the western part of the reservation (pi. 52). On plate 

52, more than half of the outcrop indicated by the symbol p-Cds is 

Dripping Spring quartzite, and less than half of the outcrop indicated 

by this symbol consists of the underlying Barnes conglomerate, Pioneer shale, and Scanlan conglomerate.

Several days were spent by R. B. Raup, Jr., D. V. Haines, and the 

senior author in making a reconnaissance for radioactivity in the Dripping Spring quartzite. The metalliferous occurrences of the reservation were also checked for radioactivity; no abnormal radioactivity 

was observed except in the Dripping Spring quartzite. Traverses were 

made through this formation in the Mescal and Hayes Mountains, the 

Apache ridge, the south rim of the Natanes Plateau, and in the Salt 

River Canyon near U. S. Highway 60. Radioactivity was measured 

with a scintillation survey meter. Although no material was found 

to be of commercial grade, the Dripping Spring quartzite was found to 

have higher radioactivity than adjacent formations. In addition, the 

radioactivity was found to be higher in the upper siltstone part of the 

formation than in the lower light-colored quartzite part of the formation.

A complete section typical of the Dripping Spring quartzite in the 

reservation is exposed in Ranch Creek, 5 miles south of Cutter. Here, 

the lo\ver light-colored quartzite part of the formation, approximately 

120 feet thick, lias an average scintillation counter reading of 0.015 

milliroentgens an hour (mr per hr), background 0.010 to 0.012 mr per 

hr, and the upper silty quartzite part of the formation, approximately 

300 feet thick, has an average reading of 0.025 mr per hr. The highest 

reading obtained was in a zone, about 15 feet thick, approximately 

20 feet above the base of the upper part. In this zone, the average 

readings ranged from 0.040 to 0.080 mr per hr.

Although these readings, and those of other traverses of the Dripping Spring, do not indicate a commercial grade of radioactive

material, they indicate a significant concentration of radioactive material in the Dripping Spring quartzite, particularly, in the upper 

part of the formation. It is possible that other places may exist where 

conditions were favorable to greater concentration; therefore, further 

prospecting is warranted. . , v
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 641

As a result of his examination of an occurrence at the Ked Bluff 

prospect at the south end of the Sierra Ancha, near Roosevelt Lake, 

Kaiser (1951, p. 26) offered the following suggestions for the most 

favorable places to prospect for similar uranium deposits in this 

region of Arizona: "(1) The upper member of the Dripping Spring 

quartzite, with special attention to the lower third of this member. 

(2) Favorable rock in the vicinity of-dikes and faults. (3) Northwesterly-trending fracture zones that cut Dripping Spring quartzite."

The observations of Kaiser in the Red Bluff area as to the relative 

favorability of the upper part of the formation are also valid for the 

widespread exposures of the Dripping Spring quartzite on the reservation. Therefore, in prospecting, the upper part of the formation, 

which is characterized by rusty-brown and black, thin-bedded siltstones and fine-grained silty quartzites, should be distinguished from 

the medium- to thick-bedded, medium-grained, light-colored quartzites 

of the lower part of the formation.

NONMETALLIC DEPOSITS 

ASBESTOS

The asbestos of east-central Arizona, and of the San Carlos Indian 

Reservation, is chrysotile the principal asbestiform mineral used 

in commerce. The demand for chrysotile asbestos is large and is likely 

to remain large. However, because of high production costs and 

difficulties of marketing, Arizona chrysotile cannot easily compete, 

with asbestos from other sources for use in the construction industries. Arizona chrysotile has a low magnetic iron content and is 

particularly useful for electrical insulation. Asbestos from the San. 

Carlos Reservation and other Arizona sources is likely to remain 

in demand for uses that require low-iron content. Arizona asbestos, 

of length and quality suitable for textiles, usually sells at premium 

prices.

Typically, the asbestos of east-central Arizona occurs as crossfiber veins in 6- to 18-inch thick zones of limestone that are partly 

or completely metamorphosed to serpentine. These serpentine zones 

parallel the bedding of the Mescal limestone. The deposits are spatially associated with thick sills and narrow dikes of diabase that 

intruded and caused metamorphism of the limestone. As noted, 

earlier in this report, limestone of Devonian, Mississippian, and 

Pennsylvanian age exist on the reservation. Asbestos does not occur 

in these limestones because they were deposited after the diabase was 

intruded and therefore were not subjected to the metamorphic processes 

that resulted in the formation of asbestos. . . ,

367127 56 5
642 V. -CONTRIBUTIONS TO ECONOMIC GEOLOGY

In east-central Arizona, most of the asbestos deposits lie flat; however, a number of the occurrences of the San Carlos Reservation are 

exceptions. Essentially horizontal deposits are to be expected in the 

northern part of the reservation in the part of the reservation that 

is within the boundaries of Colorado Plateau geologic province. 

South of the Natanes Plateau, in the Basin and Range portion of the. 

reservation, the Mescal limestone (and therefore the asbestos deposits) 

can be expected to be moderately to steeply tilted.

Typical deposits of asbestos are roughly elliptical in plan, and are 

distributed over areas of from 1,000 to 20,000 square feet. The Bear 

Canyon deposit, which was the largest known deposit on the reservation and one of the largest discovered in Arizona, has been developed 

by stopes totaling 100,000 square feet in area (fig. 83).

Most of the asbestos deposits are mined by a modified room and 

pillar method. Because the asbestos-bearing serpentine zone is but a 

small part of the stope face that must be opened, and because the 

asbestos veins are only a part of the serpentine zone that must be 

extracted for milling, 10 to 50 tons of rock must be mined per ton 

of asbestos marketed. In general, 25 to 35 tons of rock are moved 

per ton of asbestos fiber produced.

Studies of approximately 100 Arizona asbestos deposits, including 

several on the San Carlos Reservation, indicate that four geologic 

factors were essential in order that asbestos be formed in sufficient 

quantities to be mined. If adequately understood, these factors can 

be very useful as criteria in prospecting or in appraising the potential of asbestos deposits. These factors are: (1) favorable stratigraphic units (certain favorable limestone beds), (2) proximity of 

the diabase to these beds, (3) thrust and bedding-plane faults, and 

(4) small open folds in the limestones.

Although small quantities of asbestos can be found in most beds of 

the pre-Cambrian Mescal limestone, deposits of sufficient areal extent 

and thickness to warrant mining exist, with few exceptions, only in, 

or immediately adjacent to, the thickest, most massive beds of the 

lower, flat-bedded member of the Mescal limestone. In th© nortKwestern part of the reservation the part of the reservation where the 

Mescal limestone is exposed in the Salt River Canyon adjacent to 

U. S. Highway 60 the beds that are favorable to concentrations of

asbestos occur within the following stratigraphic units:

(1) The uppermost 2 to 7 feet of the lower member of the Mescal

limestone in other words, the limestone beds immediately below the

maSSiV6 middle (algal) limestone member (see p. 20-23).

(2) A 10- to 12-foot-thick section of limestone beds about 30 feet

below the top of the lower member. This unit is mad© up
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 643

that are 8 inches to 3 feet thick; partings between beds include little 

shale or clay.

(3) A section of beds that is as much as 20 feet thick, approximately 40 feet above the contact between the Mescal limestone and the 

underlying Dripping Spring quartzite (about 100 feet below the algal 

member). A few beds in this unit are 1 to 3 feet thick, but most beds 

of the unit are 3 to 6 inches thick.

The units 30 and 100 feet below the top of the lower member are 

readily recognized because they crop out as prominent ledges, in contrast to the bulk of the lower member which crops out as slopes or is 

poorly exposed. The unit at the top of the lower member can be 

readily identified because it crops out immediately below the massive 

algae-bearing limestone, which forms thick ledges or cliffs in many 

places on the reservation. With the exception of the above-described 

units, most of the lower member is of thin limestone beds, y2 to 4 

inches thick, intercalated with calcareous (limy) shales and clays. 

The thinner-bedded limestones commonly contain serpentine and in 

places contain asbestos; however, the asbestos is not present in minable 

quantities in such beds.

Only the more massive, purer units should be seriously considered 

for prospecting. There are no prominent examples known on the San 

Carlos Reservation of an asbestos deposit in the unit at the top of the 

lower member. However, these beds should be considered for prospecting, because approximately one-half of the known Arizona asbestos deposits are in this unit. The Apache and Bear Canyon deposits 

are in the more massive limestones 30 feet below the top of the member. 

The Emsco and Salt River deposits are examples of asbestos deposits 

in the lowest favorable unit. The Pine Top harsh asbestos is the only 

deposit on the reservation known to be in an exceptional stratigraphic 

position. In the vicinity of this deposit the upper part of the algal 

(middle) member of the Mescal limestone is made up of impure, flatbedded limestones, 6 inches to 2 feet thick, rather than of the thickbedded algae-bearing limestones that make up most of the middle 

member. Similar limestones have not been observed in the middle 

member elsewhere on the reservation. The cliff-forming, algae-bear-' 

ing middle member is not a favorable host for asbestos deposits. In 

many places, determination of the stratigraphic position of asbestos 

deposits is difficult because thick diabase sills separate the limestones 

containing asbestos and those including a readily recognized stratigraphic horizon, such as the contact between the middle and lower 

members. However, this should be of little concern to the prospector 

if he uses the rule that only the thicker, ledge-forming limestones 

(excepting the middle member) are likely to contain minable quah: 

tities of asbestos.
644 CONTRIBUTIONS TO ECONOMIC GEOLOGY

Asbestos was1 formed in considerable quantities only where sills or 

dikes of diabase were intruded into, or near, the favorable limestone 

beds. Few minable deposits are more than 25 feet above, or below, a 

diabase sill; most of the significant deposits are associated with diabase 

intrusions' that cut across the favorable limestone beds. Some of the 

larger deposits the Emsco and Bear Canyon deposits are examples on 

the reservation are in "slivers" of limestone partly, or completely, 

surrounded by diabase (see cross-sections, figs. 81 and 83).

Pre-mineral faults along the planes between beds and thrust faults, 

which transect the beds at small angles, were probably the most significant factor in determining the areal extent of the asbestos deposits. 

These bedding-plane and thrust faults seldom resulted in displacements of more than a few inches, and the effects' of faulting are in most 

places obscured by later metamorphism of the limestones. Therefore, 

pre-mineral faults are difficult to discern. For the prospector's guidance, the following features may indicate that pre-mineral beddingplane faulting affected large areas:

(1) Vertical, or near-vertical, small faults, some of which include 

small amounts of serpentine, apparently are numerous in areas of widespread bedding-plane faulting. In rare instances, narrow dikes of 

diabase occupy some of these faults and are offset by faults along bedding planes.

(2) Much of the contact between limestone and diabase may be 

faulted, and both the limestone and diabase adjacent to the contact 

may be impregnated with serpentine.

(3) An irregular contact between diabase sills and limestone may 

indicate that diabase was intruded into much-faulted limestone.

(4) Narrow veins of a white or pink, opaque, relatively hard serpentine, which is in contrast with the generally green or brown, translucent, soft serpentine common to the deposits, is suggestive of faulting 

before and during mineralization. The above features are suggestive, 

but not diagnostic, to prove widespread bedding-plane faulting.

(5) Bedding-plane faulting can be judged to have been distributed 

over areas of moderate to large size if clear-cut evidence of thrust faulting is observed. This evidence may consist of limestone beds that are 

offset adjacent to a fault-plane which cuts across bedding planes at a 

low angle. If such a fault is pre-mineral, unusual concentrations of 

serpentine and possibly asbestos may be observed in the favorable beds 

near the fault. Also, thin limestone beds that are observed to contain'

little or no serpentine in most exposures may be largely converted to 

Serpentine near such faults. Narrow serpentine zones that transect 

the limestone beds at low angles represent thrust faults completely 

obliterated by later metamorpKism. If dikes of diabase exist, they
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 645

should be closely observed for evidence of low-angle offsets along thrust 

faults.

Small open folds, caused by intrusion of the diabase, were favorable structural loci for the concentration of serpentine and asbestos. 

Commonly, these folds occupy an area 20 to 50 fee,t wide and 50 

to 100 feet long. The height of an anticline, dome, or syncline may 

be 5 to 15 feet. The stope boundaries of the Emsco mine (see fig. 

81) roughly outline a dome.

Two precautions should be used in appraising folds in the Mescal 

limestone as indicators of possible asbestos deposits. Firs.t, prediction 

that the folds will continue for more than a few tens of feet from 

the observed exposure is hazardous. The folds are the result of the 

diabase magma forcing its way into the limestone in a haphazard 

pattern,.and therefore many folds are not continuous along a definite 

line of weakness. Second, care should be taken that the topographic 

expression of moderately or steeply dipping beds is not confused with 

the outcrop pattern of folds.

The premise that unusual quantities of serpentine are a good indication of a possible nearby body of minable asbestos is widely held 

among mine operators and prospectors. The phrase "unusual quantities of serpentine" means a zone of serpentine more than 4 or 5 

inches thick, or large amounts of serpentine erratically distributed 

through a 2- to 5-foot thickness of limestone. In general, this premise 

is true, but exceptions are so numerous that this criterion should be 

used with much caution in prospecting. The ratio of asbestos to 

serpentine in the metamorphosed - limestones varies greatly. For 

some deposits that have been mined, the ratio of asbestos to serpentine is approximately 1 to 1; for other deposits, the ratio is less than 

1 to 10. Some beds of the Mescal limestone characteristically were 

metamorphosed to soft, talc-like serpentine. This type of serpentine, 

which may be difficult ,to distinguish from other varities especially 

in a weathered outcrop has not been observed to include asbestos 

veins. Some limestones of the formation were altered to a serpentine that occurs in wave-like, in many places discontinuous, bands. 

Although large amounts of such serpentine may exist, and although 

locally this serpentine may include wide veins of asbestos, few such 

deposits are continuous; consequently, the mining of asbestos from 

such deposits has not been esconomically feasible. In places, considerable amounts of serpentine, which includes asbestos veins, have 

been observed in the massive cliff-forming algae-bearing limestones 

of the middle member of the Mescal. Such deposits have proved not 

to be minable. If the above exceptions are kept in mind, the degree 

of serpentinization of the limestones can be effectively used as suggesting a possible minable deposit of asbestos.
646 CONTRIBUTIONS TO ECONOMIC GEOLOGY

, Bedding-plane faults in the limestone were the result of adjustment 

during diabase intrusion. Therefore, asbestos deposits of Arizona 

can be segregated into two categories: (1) those deposits localized in a 

narrow belt where adjustments between beds were confined to the 

vicinity of a single discordancy between diabase and limestone, and 

(2) deposits localized where bedding-plane adjustments prepared the 

limestones over an area of considerable lateral extent. Most examples 

of extensive bedding-plane faulting occur where several discordant 

diabase-limestone contacts exist within an area of a few acres. Most 

of the asbestos deposits of east-central Arizona fall in the first category and are readily recognized as limited in potential. In general, 

deposits of the first category have a potential of 10 to 50 tons of all 

grades of asbestos; exceptionally, deposits of this type may yield a 

few hundred tons of fiber. Deposits of the second category may yield 

a few hundreds to a few thousands of tons of asbestos. Therefore in 

prospecting, those areas where multiple discordancies between diabase 

and favorable limestones exist warrant the greater attention. Folds 

and thrust faults are likely to be common in such areas; the limestones including those nt>t favorable to the formation of asbestos 

also are likely to be much metamorphosed where multiple structures 

exist.

The usability of chrysotile asbestos depends in large part on adequate tensile strength and flexibility. In a number of instances, pros^ 

pectors have been disappointed on developing an asbestos deposit because the asbestos had been altered by percolating ground waters and 

thus rendered useless or of low value. The asbestos of most outcrops 

is of poor quality due to weathering; the prospectors should estimate 

the depth away from the outcrop that weathering and leaching of the 

rock is likely to persist. If the limestone and serpentine along vertical, or near vertical, fractures and joints is chalky, bleached, or pulverulent, and if these openings have been widened by solution, the 

asbestos is likely to be deleteriously altered for a considerable distance from the outcrop. The asbestos-bearing limestones that crop 

out along steep canyon walls also are likely to have slumped from 

their original position where there has been considerable alteration 

by percolating waters. The same criteria can be used, in part, to judge 

whether or not mine workings will stand without timber.

Chrysotile asbestos also has a range of physical characteristics inherent in the original mineral and not related to the later leaching and

decomposition noted in the preceding paragraph. Chrysotile may be 

soft, silky, and very flexible (soft fiber) or brittle and relatively inflexible, like a broom straw (harsh fiber). Usually, soft fiber has high 

tensile strength, and harsh fiber has low tensile strength. All gradations in degree of brittleness and tensile strength exist between soft
MINERAL RESOURCES, SAN" "CARLOS- INDIAN" RESERVATION 647

fiber and harsh fiber. Semiharsh fiber has a moderate degree of flexibility and moderate tensile strength, but it cannot be used for all 

purposes for which soft fiber can be used. Harsh fiber has a much 

smaller range of uses than soft fiber and therefore is in little demand. 

Both soft and harsh asbestos occur on the reservation.

The Mescal limestone and associated diabase instrusions crop out 

only over a small part of the western third of the San Carlos Reservation (pi. 52); therefore asbestos deposits can be expected only in 

a few areas. Five areas that can be considered for asbestos potential are: (1) the extreme northwestern part of the reservation 

roughly that part visible from the portion of U. S. Highway 60 that 

traverses the Salt Kiver Canyon, (2) the area of Mescal limestone 

outcrop that extends northwest from Blue River to the western boundary of the reservation along the southwestern escarpment of the 

Natanes Plateau, (3) the small area of outcrops of the Mescal, located 

1 to 2,1/2 miles south and southwest of Cassadore Spring along Oak 

Creek and its tributaries (pi. 52), (4) the ridge termed in this report 

Apache ridge, southeast of Chromo Butte, and (5) the Hayes-Mescal 

Mountains area.

The Mescal limestone of the northwestern part of the reservation is 

the most likely host for asbestos deposits of all the Mescal limestone 

on the reservation. This part of the Mescal includes competent limestones favorable to the localization of asbestos, and the limestones are 

intricately intruded by diabase. This area, because of ready access^ 

has been thoroughly prospected; therefore it is unlikely that many 

(new asbestos occurrences will be found. Additional asbestos resources may result from more extensive exploration of known occurrences. However, most of the deposits of the northwestern part 

of the reservation have been moderately well to thoroughly explored.

The Salt River upstream from its junction with Sawmill Creek is 

in a steep-walled canyon that is difficult of access. Mescal limestone 

crops out in this section of the canyon as far east as sec. 30, T. 5 N.:, 

R. 19 E. In section 30, all of the Mescal limestone except the bottom 

half of the lower member was eroded prior to deposition of the Martin 

limestone. This easternmost outcrop of the Mescal includes two 

asbestos deposits on the north side of the river; no asbestos was found 

in reconnaissance of the Mescal on the south side of the river on the 

San Carlos Reservation. Prospecting is probably warranted between 

section 30 and Sawmill Creek; however, it is possible that the Mescal 

is missing due to pre-Martin erosion through a large part of this interval. No asbestos deposits have been reported in this part of the 

canyon.

Most of the Mescal limestone that crops out along the southwestern 

rim of the Natanes Plateau is difficult of access, and the potential for
648 CONTRIBUTIONS TO ECONOMIC GEOLOGY

asbestos deposits in this belt is poorly known. West of the vicinity of 

Hilltop the distribution of limestone and diabase is poorly understood; 

the Mescal outcrop pattern shown on plate 52 for this area is extrapolated from knowledge of the position of adj acent formations. Until 

field work, beyond the scope possible in this investigation, demonstrates the existence of Mescal limestone in juxtaposition with diabase, 

the potential for asbestos deposits cannot be appraised along this part 

of the escarpment. It is possible that the Mescal limestone was eroded 

.prior to deposition of the Paleozoic sedimentary rocks, or it is possible 

that it may not crop out because of fault displacement.

The Bear Canyon mine, the largest producer of asbestos on the 

reservation, is near the southeastern end of the outcrop of the Mescal 

limestone that parallels the Natanes escarpment. The limestones of 

this area are favorable for the localization of asbestos, and diabase is 

intruded in proximity to the favorable limestone units in several places 

in the vicinity of, and up, Bear Creek from the Bear Canyon mine. 

The upper tributaries of Bear Creek have been rather thoroughly 

prospected. Unfortunately, most of the deposits discovered have contained harsh or semi-harsh asbestos. However, favorable units of 

the Mescal limestone have been folded and intricately inflated by 

diabase in this area; therefore, continued search could result in the 

discovery of significant deposits of asbestos.

South of Cassadore Spring the area available for prospecting is 

small. Although this area could easily be made accessible for mining, 

and1 is adequately accessible for prospecting, the asbestos found to 

date has not been in sufficient quantities to encourage development. 

, Although Mescal limestone crops out along a large part of Apache 

ridge (pi. 52), much of the limestone is not intruded by diabase; 

therefore, asbestos deposits cannot be expected along the length of 

a large part of the ridge. The limestone beds immediately below the 

middle member of the formation, and a 5- to 10-foot limestone unit 

approximately 40 feet below the top of the lower member, are favorable to the formation of asbestos; the lowest favorable unit of the 

Salt River part of the reservation has not been observed in this area. 

Where diabase is not intruded into the Mescal, the outcrops of unmetamorphosed dolomitic limestone of Apacke ridge are buff to

brown in color and no serpentine can be observed. By use of this 

criterion, large parts of the Mescal along Apache ridge can be rejected for prospecting. The metamorphosed limestones, in which 

additional asbestos deposits might be found, are gray to white in 

color and serpentine is not uncommon.

Two general areas for prospecting are known on Apache ridge. 

One of these areas is adjacent to the western boundary of the reservation. Asbestos deposits discovered to date in this part of Apache
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 649

ridge have been too small to warrant development. The second area 

is in the vicinity of the Apache mine, 5 miles northeast of Cutter. 

There has been production from the Apache mine since 1951, and a 

number of asbestos-bearing outcrops are known within yz mile °f the 

mine. The existence of favorable limestone beds in proximity to 

minor diabase intrusions, and the number of known occurrences of 

asbestos in the vicinity of the Apache mine, suggests that considerable 

prospecting is warranted along this part of Apache ridge. The formations of this subarea dip as much as 30° to the south and west, and 

northwest-trending faults offset the formations in a number of places. 

Because of the dip of the formations, and because of the depths to 

which water percolation along faults and joints has caused decomposition of serpentinized limestones, difficulty in mining can be anticipated if other significant deposits are discovered. A minor deterrent to prospecting in this area is the fact that asbestos of many of 

the known occurrences tends to be harsh.

Reconnaissance of the Hayes Mountains and of that part of the 

Mescal Mountains included in the reservation suggests that these 

mountains are not promising areas for minable quantities of asbestos, 

because the limestones of .these mountains are not of the type favorable to the localization of significant asbestos deposits. Individual 

limestone beds of the lower member of the Mescal become thin, and 

the lower member includes progressively more calcareous shale as the 

Mescal limestone is traversed from north (in ,the vicinity of the Salt 

River) to south (in the Hayes and Mescal Mountains). Thin-bedded 

and shaly limestones of this area probably were not favorable hosts 

for the localization of asbestos. South of Red Whiskers Spring in 

the Hayes Mountains, the formation thins, and the lithology changes 

from a section characterized by thin cherty limestone beds intercalated 

with calcareous shales to a section made up almost exclusively of chert 

and siltstone. Asbestos does no.t occur in siliceous sections of the 

Mescal.

In the Hayes Mountains, asbestos is likely to occur in minable 

quantities only at one horizon (at the base of the middle member). 

The massive limestones of the bottom few feet of the middle member, and the thin, but relatively shale-free beds of the topmost 5 

to 10 feet of the lower member, are the only limestones of the Mescal 

of this area that are likely to be sufficiently competent to have favored 

formation of considerable quantities of asbestos. Although occurrences of asbestos do exist at several horizons in the lower member 

in the Hayes Mountains, the only occurrences promising enough to 

encourage exploration have been found at the contact between the 

middle and lower members. None of these occurences have proved 

large enough to be mined.

3R7127 56 6
650 CONTRIBUTIONS TO ECONOMIC GEOLOGY

For convenience, descriptions of individual deposits of the northwestern part of the reservation are included under the following 

geographic headings: Sawmill Canyon subarea, I. S. Hole Canyon 

subarea, and the Salt River-Cienega Canyon subarea.

SAWMILL CANYON SUBAREA

In the past, several claims have been made in the area at, and near, 

the junction of Sawmill Canyon with the Salt River Canyon. This 

junction is located about 2 miles east of the U. S. Highway 60 bridge 

crossing of the Salt River, in sees. 29 and 30, T. 5 N., R. 18 E. (pi. 

53). The area is accessible only by foot or horse trail from U. S. 

Highway 60 south of the river, or from the north side of the river 

by a steep road, which descends from U. S. Highway 60 to within 

about 100 feet of the north bank of the Salt River. The claims can 

then be reached by fording the river on foot.

WONDER CLAIMS

In this area, the Salt River flows in a southerly course and is joined 

by Sawmill Creek, which at its mouth has a westerly course. The

Wonder Claims are located along the Salt River, just south of its 

junction with Sawmill Creek. These claims were first located by 

John E. Malone in December 1921, and a lease was obtained in July 

192~2. Some prospecting and a little underground work was done. 

No production is recorded, and the lease lapsed because of delinquent

rental payments, In 1947, Skinner, Reidhead, and Lovier relocated

this ground and some of the adjoining Silk claims as the Apache 

claims. A lease obtained in 1948 was subsequently cancelled because

ho work was done.

A segment of generally flat-lying Mescal limestone located from 100

to 150 feet above the bottom of the canyon is enclosed between two thick

diabase sills (fig. 80). The segment of limestone at the workings is

about 70 feet thick. A. 9- to 12-incK tKick serpentine band that contains several asbestos veins occurs about 6 to 7 feet above the lower 

diabase sill and about l foot below the bottom, of the middle member.

The main workings consist ol two adits located about 100 feet apart 

along the outcrop.

A^t tire, soutliex-ni-riost sxtlit, wKicK is 2C feefc long- -\vitK a. 20-foot lefthand branch, % to 2 inches of soft to semiharsh fiber is exposed; at the

mouth of the second adit, which is 18 leet long, and. which is located

100 feet north of the first adit, only ^4 to 1 inch of fiber is exposed and

little or no fiber is exposed at the face.

About 300 feet northeast along the outcrop is a cut that apparently 

explores the asbestos horizon described above. In the cut, a vein of %- 

inch semiharsh fiber is exposed 4 to 5 feet above the diabase contact and
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 651

1 foot below the algal limestone contact. Another intermittent 

asbestos vein, ranging from a knife-edge to %-inch in thickness, occurs 

about 10 inches below this horizon.

SILK CLAIMS

The Silk claims on the north side of Sawmill Canyon \vere located 

by William M. Malone in 1921. A lease was obtained in July 1922, 

and some underground work (fig. 80) was done that resulted in a 

reputed production of 3 tons of fiber. The workings are situated

Mescal limestone

(pCmm, middle member;

p ml, lower member)

Contact, dashed where 

approximately located

Datum from baromater o(eyo/ion

Compass and pace traverse Geology by C. S. Bromfield and W. L. Mclntosh, 1953

FIGURE 80. Geologic map and section of the Silk-Wonder asbestos claims area.
652 CONTRIBUTIONS TO ECONOMIC GEOLOGY

about 150 feet above the canyon floor at the top of a nearly vertical 

diabase cliff. An aerial tram, still in existence, was built across Sawmill Canyon to facilitate transportation of supplies and equipment. 

There is no trail to the workings, which can be reached only by scaling 

the cliff.

The main workings are on the same segment of Mescal limestone on 

which the Wonder and Apache claims are located. Here on the north 

side of Sawmill Canyon, the segment of limestone included between the 

diabase sills is approximately 23 feet thick, considerably thinner than 

that at the main workings on the Wonder claims.

Two asbestos zones are exposed 4 feet and 10 feet, respectively, above 

the lower sill. The lower zone is at the floor of the workings and consists of a serpentine band about 9 inches thick. About 1% to 2 inches 

of harsh fiber are exposed. The upper serpentine band, about 1 foot 

below the bottom of the middle member, is 9 to 12 inches thick and contains 1 to 2 inches of fiber.

About 30 feet to the east, the asbestos veins are covered by talus, but, 

where last observed along the outcrop; the upper serpentine band contains a maximum of % inch of fiber; the lower band is not exposed. To 

the west, the asbestos veins are poorly exposed by two pits within 200 

feet of the main workings. One of these, within 100 feet, shows 1 to 

1% inches of harsh fiber. Only small amounts of fiber was seen in the 

westernmost cut.

I. 8. HOLE CANYON SUBAREA

I. S. Hole Canyon is drained by a north-flowing tributary of the 

Salt River; the juncture of the river and the tributary is located about

1 mile east of the Salt Kiver bridge (pi. 53). The canyon is rimmed

by Martin limestone and Troy quartzite. These formations are underlain by a thick diabase sill which forms the major part of the rock

exposed in the canyon sides. A thin segment of Mescal limestone

both overlain and underlain by diabase sills occurs in places near the

canyon'bottom.

UNNAMED ASBESTOS PROSPECT

An old cut is located on the east side of I. S. Hole Canyon at a point

^ii inil©. sovitlx of its Txioiatli; no details of the history of this cut have

been found. In the bottom Of the cut an asbestos-bearing serpentine 

band is incompletely exposed. The segment of Mescal limestone is

about 8 feet thick at this place, and the asbestos horizon is about 5 feet

EVUjOYO Vtl9 Jv~vv'^r <li«-V>a-se <sontnot. _A_ £e-ro- tesns odp Jreet along tlxe outcrop

to the south the limestone segment pinches down to a thickness of about 

3 feet; a similar distance to the north the segment thickens to 12 feet

or more,
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 653

^ Only :y2 to % inch of harsh to semiharsh fiber is exposed in the pit. 

About 50 feet along the outcrop to the north some 1-inch fiber float 

! was found.

' SULPHUR, SPRINGS CLAIMS'

\ At the head of I. S. Hole Canyon, in sec. 29, T. 4y2 N., R. 18 E. (pi. 

53), 1 mile east of Seneca, a few pits have been dug on an outcrop of 

Mescal limestone that is intruded by diabase below, and overlain by 

Troy quartzite. The location can be reached by a poor truck trail 

leading east from U. S. Highway 60 at Seneca.

' * Two claims, known as the Sulphur Springs 1 and 2, were located 

here by Ned Brown in 1950. No earlier history is known. The only 

observed workings were a cut and a 10-foot adit, which were located 

about 15 feet apart along the outcrop.

-* The Mescal limestone here strikes N. 70° W. and dips 35° NE. Dia- 

_. base is not exposed, but float and soil about 30 feet downslope below

-Jt the asbestos suggest that diabase intrudes the limestone a short distance

; below the outcrop.

"^ The fiber zone exposed in the two workings is composed of white to 

light-green serpentine, which is 24 to 30 inches thick. In the cut, iy2 

^ to 2 inches of soft fiber is present. The stub adit to the west contains 

^ 2 inches of fiber in numerous narrow veinlets averaging less than % 

of an inch in length. Some slip fiber was seen. The base of the limestone is 5 feet above the fiber zone.

Lateral extension of the fiber zone is untested. Outcrops are poor, 

and stripping or facing of the outcrop would be necessary to properly 

' test its extent.

SALT RIVER-CIENEGA CANYON SUB AREA

Diabase is in discordant contact with favorable limestone units in 

many places in Salt River-Cienega Canyon. The area was thoroughly 

prospected in the early 1920's and has been frequently reviewed by 

prospectors, especially after the building of U. S. Highway 60 which 

made the area readily accessible. The deposits described below are the 

only deposits in the area that have attracted especial attention from 

prospectors and mine operators. It should be noted, however, that in 

addition to the described deposits, a number of asbestos occurrences, 

all presumed to be small (by mine operators), crop out along Cienega 

Canyon between the Emsco and Pine Top deposits.

EMSCO MINE

.The Emsco mine is approximately 1% miles southwest of the 

Highway 60-Salt River bridge and a few hundred feet east of the 

west boundary of the reservation. The deposit, which crops out on
654 CONTRIBUTIONS TO ECONOMIC GEOLOGY

a steep canyon wall, is accessible from Globe by 38 miles of paved road, 

3.3 miles of good dirt road, and about 1,500 feet of poor trail. Claims, 

including this deposit, were located in 1921. The principal years of 

production were 1928-30 and 1936-38. Wilson (1928, p. 58) reported 

that during intermittent operations before 1928 about 30 tons of crude 

fiber were produced. From records of the U. S. Bureau of Indian 

Affairs it is estimated that 80 tons of No. 1 and No. 2 fiber, and 130 

tons of No. 3 fiber (Arizona classification), plus 2,700 tons of mill rock, 

were mined between 1928 and 1941. No information is available as 

to the quantity of asbestos recovered from the mill rock. Most of the 

asbestos taken from this deposit was soft; much of the remaining 

asbestos either is harsh or is in such small quantities that mining 

is not feasible. The mine has been abandoned and stripped of all 

equipment.

The asbestos of the Emsco deposit is in two zones that are 14^ feet 

apart; these zones are in a sliver of Mescal limestone, 35 to 40 feet 

thick, overlain and underlain by thick diabase sills. The limestone 

sliver is bounded on the southeast side by a southwest-trending diabase 

dike that connects the sills. Approximately 100 feet northwest of the 

northernmost portal of the mine the outcrop of this sliver terminates 

against crosscutting diabase (fig. 81); travertine covers this discordance at the surface, therefore the strike of the contact can only be 

postulated.

The favorable limestone beds were folded upward in the area now 

outlined by the stope (fig. 81), on intrusion of the underlying diabase 

sill, and were folded downward adjacent to the dike, which bounds the 

sliver on the southeast. The resulting structure is dome-like (see sec. 

B-B', fig. 81). The area of greatest deformation is now approximately outlined by a stope, 200 feet in diameter, on the upper asbestos 

zone. In this area, stresses imposed by the "doming" were relieved 

along numerous small-scale thrust and bedding-plane faults. Asbestos 

was concentrated where faults are most numerous.

The upper zone was the most productive; asbestos has been mined 

from the lower zone only where it is adjacent to a minor discordancy 

in the underlying sill (see sec. A-A', fig. 81).

The lower zone has been explored by several hundred feet of drifts 

that extend southwestward from the stoped area. In many places, the 

beds adjacent to the lower horizon contain little serpentine and no 

asbestos. In other places, traces of asbestos can be noted, and in a few 

places along these drifts the serpentine zone is 4 to 9 inches thick and 

includes asbestos veins aggregating 1 to 3 inches in thickness. The 

thickest concentrations of asbestos exposed by the drifts are harsh 

fiber.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 655
656 ' CONTRIBUTIONS TO ECONOMIC GEOLOGY

The upper horizon is explored southwest of the stope by a few 

raises from the drifts that explore the lower horizon, and by a drift 

that extends 350 feet southwest from the main stope. Traces of asbestos can be observed in a few places where the upper horizon is 

exposed by these workings; in general, very little serpentine exists at 

the level of the upper horizon where it is exposed south and west of 

the stoped area.

The exploratory workings southwest of the stoped area penetrate 

flat-lying limestones that were deformed very little by intrusion of 

the diabase. Very little bedding-plane adjustment can be observed 

in these flat-lying beds. There is a distinct correlation between the 

lack of folds and faults and the lack of asbestos in the explored areas.

The limestone adjacent to the dike that bounds the limestone sliver 

on the southeast are most likely to have been deformed and therefore 

favorable to localization of asbestos. Unfortunately, the exploratory 

workings are not adequate to confirm the existence of the dike south 

and southwest of the stope area. Northeast-trending low-angle faults 

of minute displacement, which can be seen in the southernmost mine 

workings, may represent the belt of fractures along which the dike 

was intruded, and thin (6-inch) discordant diabase sills along a few 

of these fractures may represent thinned extensions of the dike. If 

this interpretation is correct, it is doubtful that additional minable 

asbestos bodies exist in the immediate vicinity of the Emsco asbestos 

deposit. As an alternative, the diabase dike may not have pinched 

out; instead, it may have been diverted in a southerly direction, as 

interpreted on figure 81. If the dike bends in a southerly direction, 

there is a possibility that additional ore shoots exist adjacent to the 

dike. It has been adequately demonstrated that the area encompassed by the exploratory drifts southeast of the stopes is devoid of 

minable quantities of asbestos.

PINE TOP ASBESTOS CLAIMS

The Pine Top deposits are 1 mile south-southwest of the Highway 

60-Salt River bridge, and crop out on the steep north slope of a hill 

that overlooks the "Mule Hoof Bend" of the Salt River. The deposit

is readily accessible from. U- S. Highway 60 by 114 mileg of dirt rOad.

From oral reports of several past operators it is estimated that 100; to 

125 tons of harsh fiber and 2 to 3 tons of soft fiber were mined from 

these deposits prior to 1943. Since World War II possibly as much as 

a few hundred tons of harsh fiber have been mined from the Pine Top 

deposits. The following descriptions are from notes made by Shride

in July 1946; recent mine developments have not been observed by the 

writers.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 657

'.Two asbestos-serpentine zones, 8 feet apart, occur near the top of 

the middle member of the Mescal limestone. In this locality, there is 

a gradation upward from the massive, relatively pure, algae-bearing 

limestones usually observed in the middle member to impure, silty, 

thinly laminated, flat-bedded limestones. The lower of the two zones 

is at the top of a 2-foot thick, siliceous limestone bed and is 4 to 6 feet 

above a diabase sill approximately 200 feet thick. These zones, which 

include only harsh asbestos, have been exposed intermittently along 

1,800 feet of east-trending outcrop by benches and short adits. The 

limestones dip 5° to 12° SE. (average 6°) at the west end of the outcrop and 6° to 13° (average 10°) at the east end of the outcrop. Exposures are almost continuous for 500 feet along the westernmost part 

of the outcrop, which has been exposed by benching. Only thin veinlets of asbestos can be observed in parts of the lower zone; in other 

parts of the zone, two or more veins totaling 6 inches in thickness exist. 

The easternmost 300-foot part of the outcrop tends to slough; therefore, asbestos is observed only intermittently at the outcrop. However, in 1946, four adits two of which were 140 feet long exposed 

considerable quantities of harsh fiber along this easternmost interval 

of the outcrop.

The asbestos horizons of the 1,000-foot interval between the eastern 

and western parts of the outcrop are, in most places, poorly exposed; 

however, the broken material in a few pits and dumps suggests that 2 

to 3 inches of harsh asbestos exists in places within this interval.

- The eastern part of the Pine Top area is the most promising site 

for large quantities of asbestos, because of the presence of thrust 

faults and minor flexures in the limestones. This is the only part of 

the deposit in which the harsh asbestos has been found in sufficient 

quantities to encourage much underground mining. Veins aggregating 3 to 8 inches in thickness were observed in several places; most 

of the asbestos seen was in the upper zone. A stope, 120 feet long 

and 20 to 60 feet wide, had been made in this part of the deposit before 1916. It is said that considerable additional stoping has been 

done since 1949; however, only harsh fiber was mined.

Everywhere in east-central Arizona that deposits have been observed in the impure beds near the top of the middle member of the 

Mescal limestone the asbestos has been very harsh. Although considerable quantities of asbestos may be found in this part of the limestone on the Pine Top claims, probably all of it is harsh. It should 

be noted also that the host beds for the harsh asbestos are very friable. 

Therefore, considerable timbering is necessary, and large stopes are 

difficult to keep open. .Unless a special market can be developed for 

this asbestos, the harsh-fiber deposit of the Pine Top claims will probably continue to be difficult to exploit economically.
658 CONTRIBUTIONS TO ECONOMIC GEOLOGY 

Additional asbestos-serpentine zones crop out approximately 300 

feet below, and on the same north-facing hillslope as, the harsh-fiber 

deposit of the Pine Top claims. The 200-foot sill that underlies the ; 

harsh-fiber deposit overlies a section of algae-bearing limestone approximately 80 feet in thickness. A partial section of the lower 

member (about 50 feet thick) exists immediately below this part of 

the middle member and is, in turn, underlain by another thick diabase 

sill. ' '

Veins of soft to semiharsh asbestos are exposed for several hundred 

feet along the outcrop at horizons, 1, 4, and 27 feet below the top of 

the lower member of the Mescal limestone. Along most of the outcrop of the three zones the asbestos veins total less than 1 inch in 

thickness. An 80-foot adit, and a stope 20 feet wide and 40 feet long, 

expose a segment of the zone 1 foot below the middle member. Only 

a few tons of soft asbestos were mined from this zone. At the outcrop in the vicinity of the adit and the stope, which are 30 feet apart, 

1 to 2 inches of asbestos exist. However, the asbestos veins pinch out 

in places. For example, at the portal of the 80-foot adit 2 inches of 

asbestos occur; but 30 feet into the adit the veins pinch out, and in 

the last 50 feet of the adit only traces of asbestos can be found.

The serpentine zone 1 foot below the middle member contains more 

asbestos than the other two zones. Although the asbestos of this zone 

is mostly of good quality, the fiber exposed is not in great enough 

quantities to be minable. There are no indications of geologic structures that would be suitable for exploration in the vicinity of these 

outcrops.

QBEAT VIEW MINE

This property is in sec. 35, T. 5 N., K. 17 E. (pi. 53) about half a 

mile east of the southern extremity of Mule Hoof Bend on the Salt 

River. The workings are a few hundred feet west of U. S. Highway 

60 at an altitude of 4,400 feet.

George P. Bartlett, John C. Bartlett, Andrew J. Dunaway, and John 

B. Cobb located claims in this area in 1921. A lease was approved in 

January 1922, and a small amount of work was done including an 

adit and several cuts. In early 1953 Ernest Victor was. working this 

prospect.

At the main workings is an asbestos-bearing serpentine band, V/2

to 2 feet thick, in the Mescal limestone. This band kas been explored

by an 80-foot adit with two left-hand branches, 40 and 35 feet long 

respectively. A concordant diabase sill is about 9 feet below this, 

zone. Fifty feet south of the adit portal the diabase becomes discordant and breaks sharply up across the beds. To the north along 

the outcrop, at a point about 100 feet from the adit, the sill is disr 

cordant and cuts downward away from the asbestos zone (fig. 82).
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 659

Geology and topography by C. S. Bromfield, and J. A. Noel. 1953

FIQDBB 82. Geologic map and section of the Great View asbestos mine area.
660

At the south end of the outcrop the asbestos-bearing serpentine zone 

abuts against the crosscutting diabase. Immediately adjacent to the 

diabase contact the serpentine zone is essentially barren of asbestos^ 

but asbestos appears within 20 feet, and for about 50 feet along the 

outcrop the fiber averages from 1 to 2 inches in thickness. In a 

stub adit, 100 feet north along the outcrop from the diabase only i/2 

inch of fiber is present; in a cut 200 feet from the contact no fiber 

was seen.

Within the workings the fiber averages between iy2 and 2% inches 

in aggregate length. Most of the fiber is semiharsh though some 

of it is of better quality. The face of the 80-foot adit is in diabase, 

and apparently it has penetrated the discordant diabase dike against 

which the asbestos-bearing band abuts at the surface. At the face, 

this discordant contact strikes approximately N. 50° E. and dips from 

30° to 35° NW.

As indicated by the surface and underground exposures, the. best 

asbestos showing appears to be limited to an elongate zone 40 or 50 

feet wide which trends northeastward and parallel to the discordant 

diabase contact.

From the lower fiber zone (which is just below the base of the middle member) to the top of the hill, approximately 150 feet of Mescal 

limestone is exposed. In addition to the lower fiber zone, five more 

fiber zones were noted. Of these five, the best two have been prospected in a small way.

One of these two zones about 20 feet above the lower workings is, 

explored by a cut that exposes a 6- to 9-inch serpentine band containing y2 to 1V2 inches of semiharsh fiber. The zone is an algal lime-; 

stone of the middle member. A 2:foot diabase dike, located 3 feet 

above this fiber horizon, crosses the bedding at a low angle and may' 

follow a thrust fault (see cross-section, fig. 82). . ; 

. The other prospected fiber zone (also in the algal limestone) is about' 

80 feet above*the main lower workings; this zone is prospected by two; 

cuts and two stub-adits. Some fiber was being "gophered" here in 

June 1953. These workings are distributed along an outcrop length

of 120 feet and expose a fiber zone which contains an aggregate of 1.

to 2 inches of fiber. This zone shows evidence of faulting, and slip

fiber is present. The areal extent of this fiber zone is definitely limited

by the discordant diabase contact to the south, east, and north, and by

the topography on the west. The other zones contain short harsh fiber

in veins ranging from % to ^ inch in thickness.

Though six asbestos zones are apparently present, repetition of the

beds is. suggested by the section, and it is believed a thrust fault may 

be present (sec. A-A, fig. 82). If this interpretation is correct, there 

are actually only four asbestos-bearing zones. Several small-scale
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 661

thrusts of northwest trend and southwest dip are exposed in the underground workings. Movement on these thrusts amounts to only a few 

inches. Several low-angle slip surfaces of northwest trend and northeast dip are present in the massive algal limestone above the main 

lower workings, but these are not shown on the map.

SALT RIVER (SORSEN-WILLIAMS) CLAIMS

The Salt Eiver claims are located ty mile southeast of the U. S» 

Highway 60-Salt River bridge. Highway 60 ascends the south wall 

of the Salt River Canyon, as a series of "horseshoe-like" loops. The 

westernmost exposure of asbestos on the Salt River claims is at the 

top of the roadcut of the lowest of these loops. From this point southeastward and southward, asbestos crops out discontinuously through 

an interval of 1,800 feet along the rim of the lowest topographic bench 

of this part of the canyon.

A few pits and short adits, made prior ot 1940, exposed a part of this 

outcrop. However, no attempt was made to extensively prospect the 

asbestos deposits of this area until W. W. Sorsen and W. C. Williams, 

as the Sorsen-Williams Mining Co., started an exploration program 

in 1951. During 1951, 1952, and 1953, several hundred feet of the 

rimrock were cleared of debris by bulldozing to expose the asbestosserpentine zones. The western part of the outcrop was further tested 

by two adits, 80 and 100 feet long respectively, and one area near the 

eastern end of the outcrop was explored by an adit and drifts totaling 

600 feet in length.

The asbestos of the Salt River claims occurs at two or more horizons 

in competent, medium- to thick-bedded limestones. These limestones 

are those of the favorable stratigraphic unit that is a few tens of feet 

above the base of the lower member of the Mescal limestone. The beds 

are generally horizontal in attitude.

A sill, at least 500 feet thick, overlies the limestone. The contact 

between the diabase and the underlying limestones undulates; this 

undulation is significant in a discussion of these deposits. Along 

three intervals of the rimrock, the base of the sill is in contact with 

limestones stratigraphically lower than those favorable to asbestos 

localization, and in three places on the claims the base of the sill is 

stratigraphically above the favorable beds. The favorable beds can 

be visualized, in cross-section, as occurring near the tops of "islands" 

or "hummocks" of limestone that are separated by shallow troughs 

filled by diabase.

The following description refers to the exposure of asbestos in the 

roadcut of Highway 60. Much of the contact between the sill and 

the limestones and much of the rimrock exposure of the asbestos 

zones can not be seen at the present time because debris has slumped
662 - . CONTRIBUTIONS TO .ECONOMIC GEOLOGY,.

down across the stripped outcrops. Therefore,; the descriptions are 

based on exposures observed at various'times during ,the 1951-53 

exploration program. '. . 

i Asbestos apparently exists continuously for a distance of 450 feet 

southeast of the roadcut exposure. This zone, which is 1 to 3 feet 

below the diabase sill, is 4 to 8 inches thick and includes veins of 

soft asbestos totaling % to 3 inches in thickness. The cumulative 

thickness of the veins in most exposures is 1 to l1/^ inches. The 

asbestos, limestone, and overlying diabase of this interval are much 

decomposed due to weathering. Near-surface slump and creep of the 

limestone and diabase has occurred. The exposures observable in 

bulldozer cuts and in the 100-foot adit suggest that broken heavy 

ground can be expected through a minimum distance of 150 feet away 

from the outcrop. Because the asbestos will be decomposed, and 

because mining costs would be excessive in the broken ground, the 

asbestos deposit adjacent to this interval of the outcrop would be 

very difficult to explore or mine.

In an interval 450 to 550 feet southeast of the roadcut, the outcrop 

is partly covered by debris; however, it is likely that through this 

interval the contact between the limestone and the overlying diabase 

is troughlike, and the sill is in contact with limestone of a lower stratigraphic horizon than that of the asbestos zone. Therefore it is 

probable that there is no asbestos in ,this 100-foot interval.

Southeast of this troughlike depression the asbestos-bearing limestones are exposed in the contact on the nose of a small ridge that 

.trends northeastward. On this nose, the base of the sill is 5 to 15 feet 

above the asbestos-serpentine zones. The asbestos-bearing outcrops 

are truncated on the east side of the ridge where the contact with 

the overlying sill cuts discordantly down across ,the limestone. This 

discordancy trends westerly and dips to the south; thus, the asbestosbearing limestones are truncated southward into the hill, and only a 

small area benea,th the nose of the ridge is available for prospecting. 

Quarry faces on the north and east sides of the nose, and an 80-foot 

adit on the east side of the nose, expose two serpentine-asbestos zones, 

which are 1 foot apart. Each zone ranges from 3 to 6 inches in thickness. The upper zone includes veins of asbestos totaling % to 2y2 

inches in thickness; the veins of the lower zone are % to % inch

thick. The fiber tends to be harsh, but it is of moderate strength. 

Most of the veins are minutely parted, and the fiber is short.

Between the asbestos deposit on the nose of the ridge and a third 

deposit to the south, the base of the diabase sill (through a rimrock 

length of 650 feet) is at a stratigraphic horizon below that of the 

favorable limestones. Therefore, asbestos-bearing limestones do not 

exist through this 650-foot interval.
MINERAL. RESOURCES, SAN CARLOS INDIAN RESERVATION 663

At the south end of this interval, -the diabase-limestone contact 

transgresses discordantly upward and across the limestone beds. 

Southward from this discordancy, which probably strikes toward the 

northwest, the sill is concordant at a stratigraphic horizon about 15 

feet above an asbestos-serpentine zone in the limestones. The base of 

the sill persists at approximately this horizon before cutting down 

across the horizon 300 feet farther south. The asbestos-bearing limestone in this southernmost limestone remnant is exposed along a bulldozer cut, 250 feet long, and by an adit and several drifts totaling 600 

feet in length. The southern half of the bulldozer cut is barren of 

asbestos. Asbestos occurs as continuous veins only along the northernmost 120 feet of the cut, in the vicinity of the mine portal. In 

places in the mine workings there is no asbestos, but, throughout most 

of the area exposed by the workings, veins totaling i/£ to 3 inches in 

thickness occur in a 4- to 15-inch zone of serpentine, or partially serpentinized, limestone. Commonly, a thin sill, 4 to 15 inches thick, is 

6 to 12 inches above the asbestos horizon, but in a few places the sill 

was intruded at this horizon. Asbestos was not deposited where the 

sill inflated the limestone at the favorable horizon. The asbestos of the 

southern deposit is soft and, in general is of moderate tensile strength, 

but weathering has caused partial decomposition of some of the 

asbestos.

Northwest-trending fractures are numerous where the southern deposit is exposed by mine workings. As a result of water solution along 

the fractures, and of slumping of the blocks bounded by the fractures, 

vertical openings as much as 2 feet wide exist throughout much of the 

deposit. As a result, the ground is very heavy the limestone above 

and below the ore zones caves readily, and workings are difficult to 

maintain.

Asbestos is exposed in the south deposit in adequate quantities to 

be mined, if the ground was not heavy. Some asbestos was produced 

during 1953, but mining was stopped when the mine openings became 

large enough that further exploitation was difficult. The concentration of serpentine and asbestos seems to be greatest in the northernmost 

of the mine workings, and therefore it seems reasonable that asbestos 

would increase in quantity toward the discordant northwesterlytrending diabase contact that must exist a few tens of feet northeast 

of the mine workings. In this direction, it is also reasonable to suppose that the openings along fractures would be wider, the rock would 

be more difficult to support in mine workings, and the fiber would be 

more decomposed. Therefore, this extension of the deposit would be 

difficult to explore or exploit.
664 CONTRIBUTIONS TO ECONOMIC GEOLOGY

ASBESTOS PBOSPEOTS NORTHEAST OF SENECA

Some workings, including three short adits and a cut, explore ait 

outcrop of Mescal limestone on the west slope of the hill lying northeast of Seneca about 1 mile northeast of Seneca, in sec. 20, T. 4^/2 N.r 

R. 18 E. (pi. 53). No monuments were seen on the property, and there 

is no history available about the workings, which are visible from 

U. S. Highway 60.

At this place, a segment of pre-Cambrian Mescal limestone, about 

20 to 30 feet thick, is underlain by a thick diabase sill and is overlain 

by pebbly crossbedded Cambrian Troy quartzite. The hill on which 

the prospects are found is capped in part by Tertiary basalt flows.

Several minor workings explore the outcrop of the Mescal limestone over a length of about 400 feet. Two short adits at the northern 

end, within 50 feet of each other, were driven on a 1-foot asbestosbearing serpentine band which occurs 1% to 3 feet above the diabaselimestone contact. The average aggregate amount of fiber in, and between, these workings is y2 to % inch. An equivalent amount of the 

columnar jointed serpentine, which includes minute veinlets of chrysotile and which is termed "bone" by the miners, is also present.

The southernmost working shows i/2 to % inch of harsh fiber in a 

12- to 15-inch green serpentine band. The diabase is about 4 feet 

below the fiber zone at this locality.

BEAR CREEK STJBAREA

BEAK CANYON DEPOSIT

The Bear Canyon asbestos mine is approximately 14 miles northeast 

of San Carlos and is accessible from San Carlos by 19^4 miles of dirt 

road (pi. 53). Tertiary basalts and gravels, which lap against the 

south-facing escarpment of the Natanes Plateau, have been stripped 

away along the canyon of Bear Creek to expose Mescal limestone and 

diabase.

The Bear Canyon mine has been one of the largest producers in theArizona asbestos district; approximately 1,200 tons of all grades 

of asbestos have been mined from this deposit. The main period 

of production, between 1927 and 1930, was by the Bear Canyon Asbestos Co., a subsidiary of the Keasbey and Mattison Co. of Ambler,, 

Pa. During this period, long fiber was the main material recovered 

from the ore, and it is likely that large amounts of short fiber were discarded into mine and mill dumps. Because a large part of tiaese 

dumps has been carried away during flood stages of Bear Creek, comparatively little short-fiber asbestos remains in the dumps to be recovered if a salvage operation was feasible. Although a part of the 

asbestos recovered from the ore was soft and of good tensile, strength, 

and flexibility, a large part was harsh and little in demand. There-
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 665

fore, between April 1930 (when the Keasbey and Mattison Co. abandoned the property) and 1949 (when a market for harsh and semiharsh fiber became available) little mining was done in the Bear Canyon deposit. Since 1949, a few hundred tons of soft, semiharsh, and 

harsh asbestos have been mined. During 1953, several hundred feet 

of exploratory ^drifts an(j raises were driven. These mine workings 

have defined the outlines of the limestone block in which the asbestos 

occurs and have shown that little further production can be expected 

from the Bear Qanyon deposit. However, the deposit is worthy of 

description because it is an excellent example of a deposit that is large 

because of the.genetic association with multiple geologic structures.

Most of the asbestos of the Bear Canyon deposit occurred in a 30- to 

50-foot thick limestone block, or "sliver", overlain and underlain by 

diabase sills (fig. 83). Laterally, the block is almost completely isolated from the main limestone mass by diabase. The block is bounded 

on the southeast by a cross-cutting portion of the enclosing diabase 

intrusion, along a contact that strikes N. 15° to 30° E. and dips 50° to 

70° NW.; 750 feet to the northwest, a diabase dike of parallel trend 

bounds the block on the northwest (fig. 83). This dike, which limits 

the ore-bearing block, is not exposed at the outcrop but pinches out 

underground approximately 70 feet northeast of the southwest portal 

of the mine. From the southwest end of this dike, several vertical 

4- to 12-inch thick dikes trend S. 20° E. along the axis of a fold in the 

limestone. Southwest of this swarm of dikes,..the limestones dip 4° 

to 10° to the north; northeast of the swarm, the dip is 11° to 16° (average 12°) NE. The limestone block is -terminated down-dip to the 

northeast by a cross-cutting<portion of the enclosing sill; this contact, 

which is 1,100 feet northeast of the dike swarm, strikes N. 30° W., 

approximately parallel to the dikes.

Asbestos was concentrated particularly along an arch, which parallels the dike-that bounds the northwest side of the deposit, and adjacent to the fold along which the dike swarm was intruded. Preasbestos bedding-plane and thrust faults caused much shattering and 

preparation of the limestones for. mineralization in the vicinity of 

both of these folds. A lesser concentration of asbestos was formed in 

the vicinity of a minor northwest-plunging syncline or trough (fig. 

83) in the northwestern part of the block. Along the contact that 

bounds the block on the southeast the limestone was folded and fractured only locally; the resulting concentrations of asbestos were small. 

The central part of the stoped area included only marginal amounts 

of asbestos, as evidenced by pillars remaining in the workings (fig. 

83). If the northeast-trending discordant intrusion that bounds the 

block on the southeast had not existed, it is probable that only those
666 CONTRIBUTIONS TO ECONOMIC GEOLOGY
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 667

parts of the area adjacent to the two folds parallel to the northeasttrending dike and the dike swarm would have been sufficiently mineralized ito warrant mining.

This deposit also affords examples of folded limestones that do not 

include much asbestos, and of favorable limestones which are adjacent 

to discordant diabase intrusions but which are essentially barren of 

asbestos. The limestones in the vicinity of the small stope that is 

shown on the northernmost part of figure 83 dip as much as 30 degrees 

and would appear to be particularly favored for the localization of 

asbestos. In this part of the area, however, the stresses caused by 

intrusion of diabase were apparently relieved by movement on one 

bedding-plane along which a thin diabase sill was intruded. The 

beds of the limestone block, where they are terminated to the northeast against diabase, were little deformed except along short portions 

of the contact; therefore, only a small amount of asbestos was formed 

adjacent to this contact.

The limestone on the northwest side of the dike that bounds the 

deposit on the northwest has been tested by raises and drifting. 

Asbestos was found in appreciable quantities only where stoped near 

the southwestern termination of the dike. It will be no.ted that this 

stope is adjacent to the intersection of the northeast-trending dike and 

the northwest-trending dike swarm. At this intersection, some warping of the beds and some adjustment between beds took place before 

asbestos was formed. North of this stope, the limestones on the west 

side of the dike, where exposed by raises, were little deformed and 

therefore contain little asbestos.

The main asbestos-serpentine zone that was exploited in the Bear 

Canyon deposit is 16 feet above the lower diabase sill (or approximately 40 feet below the bottom of the middle member of the Mescal). 

In general, this zone ranged from 10 to 20 inches in .thickness and 

included asbestos veins totaling 2 to 6 inches in thickness. Other 

serpentine zones, which included asbestos only in the areas of greatest 

mineralization, are 2%, 4%, and 7 feet below the main zone.

A large part of the asbestos produced from the Bear Canyon deposit 

was harsh or semiharsh. Some of the semiharsh fiber had moderate 

tensile strength. Much of the asbestos produced was soft and of good 

tensile strength.

PROSPECTS ALONG TJPPEB BEAR CREEK

Four prospects were visited briefly in the area north of the Bear 

Canyon mine. Three of .these are on claims leased by the present 

operators of the Bear Canyon asbestos mine. Recently, the operators 

built an access road to one of these prospects; the road passes near 

the other two prospects.
 68

The first prospect visited lies about y2 mile north of the Bear Canyon 

mine along, the west slope of the ridge between the east and west fork 

of Bear Creek (pi. 53), and a few hundred feet north of that junction.

Here, the Mescal limestone strikes N. 20° W. and dips 10° NE. and 

is cut by a discordant diabase body striking N. 10° E. and dipping 60° 

SE. The diabase bounds the asbestos-bearing limestones on the west. 

Asbestos has been developed in the limestone in a white to light-green 

serpentine zone, which, near the diabase contact, has a thickness 

of 6 inches. The asbestos-bearing zone is 2 to 3 feet below the base of 

the middle member. An adit, whose portal is at the diabase-limestone

 contact, has been driven in the limestone for a distance of about 75 

feet N. 55° E.; apparently, the adit diverges from ,the discordant

 contact. An average aggregate thickness of 1% inches of semiharsh 

fiber is developed within a few feet of the contact. As now exposed, 

the asbestos is confined to within 15 ,to 20 feet of the discordant diabase 

contact.

The second prospect is on the east side of the east fork of Bear 

Creek, about y2 m^Q northeast of the previously described prospect 

(pi. 53). Several hundred feet east of the access road, a prominent 

bluff of Mescal limestone crops out.

The limestone has been intruded by a thick diabase sill that forms 

a slope below the bluff. An adit has been driven 15 feet into the cliff 

on an asbestos-bearing horizon located 20 feet above the diabase sill. 

Asbestos is localized in an 8- to 10-inch cream to white serpentine band; 

the maximum fiber length observed in the lower 4 inches of the band 

was 3% inches, although the average was about 2 inches. The fiber is 

harsh.

Near the face of the adit, a narrow diabase dike, which dips flatly 

into the face and cuts the fiber zone, is exposed. On the side of the dike 

nearest the face, the fiber zone is absent. It is probable that there has 

been displacement of the fiber zone along the plane now occupied by the 

dike.

Five feet above the asbestos horizon exposed in the adit is another

asbestos-bearing serpentine band. One cut formerly exposed the 

band but is now caved; harsh fiber float, 1% to 2 inches in aggregate 

length, is found near this cut.

A cross-cutting diabase body cuts off the fiber zones about 100 feet 

to the southeast along the outcrop from the adit. Asbestos float can 

be found for a distance of about 100 feet to the northwest. The exposed fiber zones are 50 and 55 feet below the top of the lower member.

The third prospect is also on the east slope of the east fork of Bear 

Creek a few tenths of a mile south of the last-described prospect (pi.

53). It is at the end of the newly built access road. A block of Mescal 

limestone, underlain by diabase, crops out on the south side of a gully
MINERAL RESOURCES; SAN CARLOS INDIAN RESERVATION 669

tributary to Bear Creek. At the east end of a prominent limestone 

outcrop, diabase cuts upward and across the limestone beds. The contact of the limestone and the diabase strikes N. 5° W. and dips steeply 

to the west. The limestone beds are arched downward against the 

discordant diabase contact, and the axis of the arch parallels the diabase contact. A branching adit has been driven on the west side of 

the contact in the limestone adjacent to the diabase. One branch follows the axis of the arch for 25 feet, and the other branch diverges 

from the contact on a bearing of S. 29° W. for about 45 feet.

In the adit, a serpentine band, which ranges in thickness from 6 to 

15 inches, contains a maximum of 3 inches of fiber and averages from 

1^/2 to 2 inches. The fiber is semiharsh. The workings show fiber 

over a width of 25 feet from the limestone-diabase contact. Five feet 

above this fiber zone, another zone that is exposed for a few feet contains at least 2 inches of semiharsh fiber. About 80 feet to the west of 

the two zones at the adit, a pit discloses a poorly exposed zone containing a total of 1 to 2 inches of fiber. The fiber in the pit is weathered 

and appears to be semiharsh. The outcrops are poor, and the fiber 

zones do not outcrop between the two occurrences.

A fourth prospect is on the east fork of Bear Creek about 1 mile 

north of its junction with the west fork (pi. 53). It is on the east 

side of the creek a short distance above the creek bottom. This claim 

was visited by James A. Noel, from whose notes this description is 

taken.

This area is not included in the group of claims held by the operators of the Bear Canyon asbestos mine. W. J. Andrews located 

the Upper Bear claims in this vicinity in September 1928. An adit 

about 40 feet long was driven N. 85° E. on a meager showing of fiber. 

There was no production.

Relatively flat-lying Mescal limestone has been intruded by a diabase sill, and within several feet above the contact two serpentine 

bands have been formed. The lower band is 3 inches thick and contains a maximum of 1 inch of fiber; the upper band, about 3 feet above, 

is 4 to 6 inches thick and contains a total of %0 to % inch of fiber. 

The fiber is semiharsh.

PROSPECT WEST OF BLUE RIVER

The rocks of the Apache group, which crop out under the Natanes 

Rim, disappear east of'Blue River under a cover of Tertiary volcanic rocks. Just west of Blue River, the Mescal limestone has its 

easternmost exposure on the reservations; in this area, in sec. 17, T. 

2 N., R. 20 E. (pi. 53), are some surficial workings on a showing of 

asbestos. This prospect is located 3 miles east of the Bear Canyon 

deposit and about % mile west of the Whitetail Spring road, at an
670 CONTRIBUTIONS TO ECONOMIC GEOLOGY 

altitude of about 4,500 feet on the southeast side of a hill capped with 

volcanic rocks.

Here, approximately 40 feet of thin-bedded Mescal limestone is 

underlain by diabase and is overlain by red to rusty-brown siltstones 

and quartzites and brown to yellow-brown silty limestone of undetermined age, and Paleozoic limestones. The hill is capped by Tertiary basalt. The beds strike N. 45° E. and dip from 5° to 10° SE.

An opencut and a short stub-adit have been driven on an-asbestos 

vein that occurs at a horizon about 25 to 30 feet above the underlying 

diabase-limestone contact. A white to gray-green serpentine band, 

about 18 inches thick, contains % to % inch of chrysotile asbestos. 

The fiber is harsh to semiharsh in quantity. A small pit about 300 

feet northeast of this location shows YIQ inch of fiber.

CASSADORE SPRING-OAK CREEK AREA 

BLACK MESA DEPOSIT

Asbestos showings have been prospected in sec. 30, T. 2 N., K. 19 E. 

(pi. 53) about 2 miles south of Cassadore Spring and just north of 

Black Mesa. The San Carlos-Sawmill E-oad passes within 1 mile 

of the area, and it can be reached by following the road for about iy2 

miles north of Cassadore Spring, turning east at a corral on the mesa, 

and then proceeding south for 2 miles along a southerly-sloping ridge 

line that parallels the San Carlos-Sawmill Road. The history and 

original names of the claims are in doubt, although it is known .that 

several claims were located in this area in 1922 by J. C. Anglin. 

There has been no production.

The area is at an altitude of about 3,600 feet. Here a branch of 

Oak Creek has stripped away the overlying late Tertiary basalt and 

aluvium cover and has exposed Mescal limestone, which is intruded 

below by a thick diabase sill and above by a thin diabase sill. The 

Mescal limestone is tilted from 15°. to 30° to the east. Serpentine 

and asbestos have been developed in the limestone near the locally

discordant diabase sills (fig. 84).

Fiber occurs in two zones; one zone is located just below the base 

of the middle member and the other is 20 feet lower in the section. 

The upper zone has little or no fiber and is of only minor importance ; the second or lower fiber zone contains more fiber.

Pits and trenches show asbestos in a few places along an outcrop

that is 800 feet long. The two eastermost pits are on the upper zone

at the base of the middle member where they expose i/2 inch, or less,

of semiharsh fiber. To the west along the outcrop, the diabase sill

becomes discordant and cuts downward and away from the middle

member, and about 40 feet of thinbedded limestone makes its appearance between the algae-bearing limestone and the diabase. Here, on
FIGDBB 84. Geologic map and section of the Black Mesa as
672 CONTRIBUTIONS TO ECONOMIC GEOLOGY

the lower zone, four pits covering an outcrop length of 150 feet reveal 

fiber in a serpentine band that ranges from 9 to 15 inches in thickness.. 

The pits disclose fiber that averages 1% to 2 inches in aggregate length. 

No asbestos is in the southernmost pit on the west-facing hillside..

(fig. 84).

ASBESTOS OCCURRENCE ON OAK CREEK

A small outcrop of Mescal limestone, which is intruded by diabaseand overlain by Troy quartzite, occurs in sec. 24, T. 1 N., R. 18 E. 

(pi. 53) about 5 miles northeast of San Carlos on the east side of 

Oak Creek. The outcrop of older rocks, which dip gently to the east,, 

is surrounded by flat-lying Tertiary lake beds. The limestone is the* 

Algal type of the middle member of the Mescal limestone and has 

locally been irregularly altered to green serpentine near diabase contacts. The names and history of the claims in this area are unknown.. 

Some rather short fiber was seen in one locality.

APACHE RIDGE AREA

\ . PROSPECT NEAR CHROMO BXJTTE

A few pits and underground workings are found in an outcrop of 

Mescal limestone in sec. 5, T. 1 N., R 16 E., adjacent to and just 

inside, the western boundary of the reservation. This occurrence is 

3 miles south of Chromo Butte and 5 miles northeast of Globe (pL 

53). The prospect is accessible as follows:

Miles Directions

0.0___________. Junction of U. S. Highway 60 and 70, Globe, Ariz. 

4.0___________. Turn right on ranch road at south end of landing

field.

4.1_________. Gate, and fork. Take left-hand road. 

5.0___________. Fork; take dim road to left (right fork goes to

ranch house). 

6.3____________. End of road at reservation fence. Prospect is

about % mile north along, and just inside the

reservation fence.

The area is one of low hills with a maximum relief of not more 

than 200 feet. The workings, which include several cuts and a 

branching adit, are at an altitude of about 4,300 feet in a saddle at

the head of a south-draining wash,

At the "workings, about 15 feet of thin-bedded white to gray limestone is underlain by a sill and is overlain by 10 feet of algal limestone and 70 feet of rusty-brown siltstones interbedded with a fewbranching adit, are at an altitude of about 4,300 feet in a saddle at 

Mescal limestone. The beds strike N. 55° W. and dip 25° to 30°

sw.
MINERAL .RESOURCES, SAN CARLOS INDIAN RESERVATION 673

. At least three minor fiber zones were noted within 7 feet above-the 

diabase-limestone contact. A cut on the contact shows an asbestos 

vein of a maximum width of *4 inch in a 3-inch white to yellow serpentine band. Five feet above the contact in the adit a second 3-inch 

.serpentine band contains % to 1 inch of soft to semiharsh fiber; 1 to 

iy2 feet higher a third 3-inch serpentine band contains % to ^ inch

 of fiber.

About 50 to ,60 feet southeast of the workings along the diabase 

limestone contact the diabase breaks across the limestone bedding and 

.apparently wedges out within a few tens of feet. To the northwest

 of the workings, as far as the boundary fence, the contact is approximately concordant with the bedding in the limestone.

APACHE CLAIMS

The asbestos deposits of the Apache claims are on Apache ridge 

.approximately 10 miles east of Globe. The claims are accessible from 

the Globe-San Carlos road by 3.6 miles of dirt road which is readily 

traveled except during wet weather.

These claims were first prospected in 1922, and small amounts of 

asbestos were shipped prior to 1925. The properties were idle from 

the middle 1920's until the Metate Asbestos .Mines Co. took a lease on 

the claims in 1950. During the 1951-53 period, these properties have 

been one of the principal sources of asbestos on reservation lands.

The Mescal limestone, and an underlying diabase sill, dip 20° to 

30° SW. in this area. Through a part of the area, erosion has 

stripped away the middle member of the Mescal and overlying strata, 

thus leaving a thin plate of the lower member as a capping on a thick 

sill of diabase. This capping crops out as a hogback near the crest 

of the northwest-trending Apache ridge.

Two deposits have furnished most of the production from these 

claims. One deposit crops out near the crest of the hogback; a second deposit crops out 400 feet to the south on the dip slope of the 

hogback and has been developed down-dip below the bottom of a 

small valley at the base of the dip slope. These deposits will be referred to as the north and south deposits, respectively. The limestones are offset approximately halfway between the two deposits by 

a high-angle, east-trending pre-diabase fault that is downthrown 

about 20 feet on the north.

The limestones of the lower member are, in general, very thin 

bedded and shaly in this part of the reservation. However, one competent limestone bed, 4 feet thick, occurs approximately 40 feet below 

the top of the member. The minable serpentine-asbestos zones on the 

Apache claims occur at the top and bottom of this bed.
674 CONTRIBUTIONS TO ECONOMIC GEOLOGY

North of the east-west fault between the two mines, the underlying 

diabase sill is 12 to 15 feet stratigraphically below the favorable 4- 

f oot bed and is concordant northward to the vicinity of the north deposit. The outcrop along the ridge line to the northwest of the north 

deposit indicates that the diabase was intruded upward and across the 

beds of the lower member at a slight angle and that it truncates the 

favorable bed. This discordant contact is so poorly exposed that 

the strike of this part of the contact is poorly known, but it probably 

is somewhat north of east.

Immediately south of the easterly-trending fault, the diabaselimestone contact is concordant and at a stratigraphic horizon 2 feet 

above the favorable limestone. Along the outcrop, this contact continues southward at this horizon to the northeastern portal of the 

south mine. At this portal, the diabase-limestone contact cuts abruptly downward through the limestone section. The strike of this 

discordant contact is S. 70° W. The contact truncates the favorable 

limestone bed and bounds the northwest side of the south deposit. 

Northwest of this discordancy, the diabase-limestone contact parallels 

the bedding at a stratigraphic horizon 2 feet above the favorable limestone bed; south and east of the discordancy, the diabase is, in general, 

concordant with the bedding and the contact is 8 to 10 feet below the 

favorable limestone bed.

Asbestos of both the north and south deposits occurs in sizable concentrations only where the competent 4-foot limestone bed was deformed adj acent to discordancies in the sill. The discordancy adjacent 

to the north deposit is poorly exposed. However, this ore shoot 

plunges S. 60°-TO° W., and it is very likely that the strike of the discordant diabase-limestone contact approximately parallels this direction. Minute details of folds and fractures exposed in the mine

suggest that the favorable limestone bed is truncated against diabase

at a distance of only a few feet northwest of the mine workings.

In the north deposit, the asbestos exists in quantity only at the 

bottom of the 4-foot favorable bed; fiber is exposed in the upper zoner 

at the top of the favorable bed, only in one small area. Nowhere in 

the vicinity of the north deposit does the degree of Serpentinization 

suggest that minable quantities of asbestos will be found at the upper 

horizon. Where mined, the lower serpentine zone is 10 inches thick 

and includes veins of asbestos totaling 2 to 6 inches in thickness. The 

asbestos and serpentine content of the zone decreases abruptly to the 

southwest, 30 to 50 feet away from the inferred position of the line 

along which the diabase truncates the favorable bed. The ore shoot, 

has been exposed for a length of 120 feet. The asbestos is semiharsh 

and much weathered. As a result, the fiber is weak, shatters on mining, and requires much hand sorting. The limestone that
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 675

the north deposit is no more than a few tens of feet thick, and fractures 

and joints along which water can percolate downward are numerous. 

Therefore, although the asbestos content of the southwest face of the 

stope where mining was discontinued is about the same as that of the 

area stoped, and although it is likely to persist in quantity to the southwest beyond the mine face, future development is likely to expose asbestos of comparable poor quality.

The asbestos of the south deposit occurs in minable quantities in 

a shoot, 20 to 80 feet wide, that parallels the discordant dibase contact bounding the deposit on the northwest. As of January 1954, 

this shoot had been mined throughout a length of 515 feet. The diabase was intruded discordantly along a fracture that trends N. 70° 

E. Southeast of this discordancy the diabase is generally concordant 

and is 8 to 10 feet below the ore-bearing bed. In detail, a few irregularities in the linear discordant contact exist. These irregularities can be visualized as "mounds" or "hummocks" of the diabase that 

project above the planar surface of the concordant diabase sill and 

merge with the discordant portion of the sill. These "hummocks" 

are most pronounced adjacent to the discordancy, and the limestone 

is much folded and fractured at these places.

The ore shoot is narrow, and the cumulative thickness of asbestos 

veins is least where the discordant diabase-limestone contact is relatively linear in plan view. In contrast, the ore shoot is. widest and 

asbestos is in greatest quantities in the vicinity of the diabase "hummocks"; in these places, pre-mineral folding and fracturing of the 

limestone was more widespread.

Most of the asbestos in the southern deposit is at the top of the 

favorable bed. The bottom of the 4-foot bed includes minable quantities of asbestos only sporadically where the limestones are much deformed. The top zone is 10 to 20 inches thick and includes veins 2 

to 8 inches thick. Locally, 3 to 4 inches of asbestos have been exposed 

in the lower zone. The asbestos tends to be harsh; some soft fiber of 

good quality has been mined from this deposit.

It is difficult to predict continuity for this type of asbestos occurrence. If there is persistent high-angle discordant contact between 

the favorable limestone beds and diabase, asbestos may be anticipated 

adjacent to the discordant contact. If, at intervals along this contact, "hummocks" of diabase exist on the sill that underlies the asbestos-bearing bed, then the serpentine zones are likely to be continuous and it is likely that asbestos will occur in significant quantities. 

In contrast, if the discordancy persists without adjacent "diabase 

hummocks" the ore shoot may narrow and asbestos may exist in quantities too small to be minable. Development parallel to the discordant 

contact will be necessary to prove the persistence of this deposit.
676 CONTRIBUTIONS TO ; ECONOMIC : GEOLOGY. . L . ' :,. .

Several occurrences of asb.estos prop-out north and northwest of the 

north deposit (described above). The outcrops that include these 

occurrences are in part covered by surface debris; therefore it is difficult to appraise these deposits.' Most of the occurrences appear to be 

confined to the immediate vicinity of discordant limestone-diabase 

contacts. The number of asbestos occurrences, and the juxtaposition 

of diabase and favorable limestone beds in a number of places near 

the Apache mine, suggests that additional prospecting is warranted 

in this vicinity.

HAYES MOUNTAINS AREA 

CHIKICAHTJA PROSPECT

The Chiricahua prospect is in the north-central part of the Hayes 

Mountains, about 13 miles southeast of Globe. The prospect is accessible from U. S. Highway TO as follows:

Miles Directions 

0.0 . Go south on Highway 70 from the junction of

Highway 70 and the San Carlos, road. 

5.0 . Turn right (west) on dirt road. 

6.3 . Follow right (west) fork of road across stream

bottom.

10.3 _ ____. Chiricahua deposit is at base of limestone cliffs 

above road. (Last 4 miles of road are difficult 

to travel by light truck.)

The Chiricahua deposit crops out along a steep east-facing escarpment at an altitude of about 4,500 feet. At this locality, the Mescal 

limestone strikes N. 10° W. and dips 20° to 25° SW. This attitude 

reflects post-Paleozoic deformation and is not related to deformation 

caused by diabase intrusion. Four asbestos-serpentine zones parallel 

the bedding of the limestone and are exposed almost continuously for 

400 feet along an outcrop that roughly parallels the strike of the 

formation. The only development is one shallow pit, probably dug

in the early 1920's; however, the natural exposures of the fiber-bearing 

zones are good.

The asbestos veins of the upper zone are distributed through partly 

serpentinized limestone that constitutes the uppermost 12 to 18 inches 

of the loAver member of the Mescal. The next lower fiber-bearing 

zone is a 2- to 4-inch thick serpentine layer that is 2% feet below the 

top of the member. The third zone is 2 to 4 inches thick and is 6^2

feet below the top of the member. The fourth, or lowest, asbestosbearing zone is 9^ feet below the contact between the lower and

middle members and, in most places, consists of less than 6 inches of

partly serpentinized limestone.

On the Chiricahua claims, the limestone beds of the lower member 

range from 1 to 8 inches in thickness; most beds are less than 3 inches
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 677

thick. In the northern part of the reservation, a part of the limestone of the equivalent stratigraphic section is medium-bedded. 

Scanty asbestos content of the Chiricahua claims is probably, at least 

in part, related to the lack of competent limestones in the section.

The outcrop that includes the most asbestos is exposed by the shallow 

pit. At this place, all of the four serpentine zones include asbestos, 

and a thick underlying concordant sill is 1 foot below the lowest 

 zone. Sixty feet south of the pit, the diabase sill cuts discordantly 

downward through 12 feet of the limestone before continuing concordantly to the south. The asbestos veins of the four zones pinch 

out about 20 feet south of this discordancy. One hundred feet north 

of the pit, the diabase cuts discordantly upward and across the lowest 

asbestos horizon. Eight inches above the horizon, the sill is again 

concordant and continues to be concordant along the outcrop to the 

north for at least 200 feet. Folds that would be favorable to the 

localization of concentrations of asbestos were not observed in the 

area. The limestones that are adjacent to the two discordancies in the 

sill contact are distorted very little.

In most places along the 400-foot outcrop the four zones include 

little serpentine or asbestos. Where asbestos exists in the upper zone 

it is soft and of good tensile strength; the fiber veins are discontinuous, 

and asbestos occurs only sporadically along the outcrop. At the pit, 

asbestos veins of the upper zone total iy2 inches; elsewhere along the 

zone the maximum content is 1 inch. The asbestos of the lowest three 

zones is harsh and of moderate to poor tensile strength. Asbestos in 

the second zone ranges from traces to as much as y2 incn in thickness. 

At the pit, the third zone contains ^4-inch of asbestos; in most places 

along the outcrop no asbestos is visible. Asbestos veins of the lowest 

zone total */2 to 1 inch in thickness. Beyond a point 300 feet north of 

the prospect pit all horizons are covered by soil and talus.

MYSTEKY PROSPECT

The Mystery asbestos occurrences are y2 mile (airline) southwest 

of the Chiricahua prospect and are accessible from the Chiricahua 

prospect by 0.9 mile of dirt road.

Two asbestos deposits crop out in this area. The most extensive 

asbestos-serpentine zones crop out along a steep, east-facing hillslope. 

The zones are observable almost continuously for 300 to 350 feet 

roughly parallel to the strike of the enclosing limestones. The limestone beds of this deposit strike N. 10°-20° W. and dip 25°-30° SW. 

Two (and, in places, three) asbestos-serpentine zones are well exposed. 

The topography is such that the deposit is well exposed in the strike 

dimension and moderately well exposed in the dip dimension. Therefore, the observed zones probably are typical of the deposit.
678 CONTRIBUTIONS TO ECONOMIC GEOLOGY .- ; j :, ',

The uppermost of the three zones is about 60 feet below the top of 

the lower member of the Mescal limestone. Most limestone beds of 

the stratigraphic section that includes the asbestos range from 1 to 3 

inches in thickness and are interbedded with calcareous shales. None 

of the purer, more-brittle beds of the section exceed 8 inches in 

thickness.

The upper serpentine zone, which is the most persistent, is 3 to 6 

inches thick and includes asbestos veins ranging from % to 1% inches 

in cumulative thickness. The average thickness of the veins in this 

zone is probably less than 1 inch. The fiber is semiharsh and of poor 

strength.

The veins of the second zone, which is 1 foot below the top zone, 

average */% inch in cumulative thickness in the best-mineralized parts 

of the outcrop. In places, this zone contains no asbestos; in other 

places, a maximum of % inch of fiber occurs. The asbestos, which is 

semiharsh, is in a 4- to 5-inch thick bed of partly serpentinized 

limestone. .

Minute veinlets of asbestos, in only a few places totaling as much as 

% inch, occur sporadically along a 6-inch thick zone of incompletely 

serpentinized limestone that is 12 to 18 inches below the second zone. 

Only traces of asbestos occur throughout much of the outcrop of this 

zone. . . At the north end of the outcrop, the top of a thick diabase sill 

is 3 inches below the top serpentine zone. Thirty feet south of ,the 

northernmost exposure of asbestos the diabase sill cuts at a steep 

^ngle downward and through the limestone. South of this discordancy, beneath most of the deposit, the top of the sill is 6 to 8 ;feet 

below the top asbestos zone. No folds in the limestones can be 

observed, even in the vicinity of the discordancy. ' '.- ; 

Approximately 250 feet northeast of the southernmost outcrop of 

the deposit described above, and 150 feet lower in altitude, a second 

asbestos deposit crops out in the bottom of a narrow, southeasttrending gully. This deposit is immediately below the1 Contact between the middle and lower members of the Mescal. A part of the 

interval between this deposit and the one previously : described is 

covered by thick talllS. However, because the base of the middle 

 member of the Mescal is obviously about 200 feet lower at thfc second 

deposit than at the first, displacement occurs in the talus-covered 

area along a fault or a discordant diabase intrusion. The limestones

strike N. 25°-30° W. and dip 23° SW. A concordant diabase sill 

Underlies the asbestos deposit at a stratigraphic distance of about 15 

feet. :

The original north-trending outcrop of this deposit was 20 feet 

long and included an asbestos-serpentine zone, 24 to 30 inches thick,
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 679

that contained veins of soft asbestos totaling 2y2 to 4 inches in thickness. During June and July 1953, adjacent outcrops were stripped of 

overburden, a quarry face was cut into the original crop of the zone, 

and a 135-foot adit was driven westward and northwestward on the 

strike of the asbestos-bearing beds. Veins, totaling a maximum of 

H/2 to 2% inches of asbestos, are exposed in places in the quarry 

face. The zone pinches out 30 feet north of the portal of the adit, 

but it is continuous to a point 20 feet to the south of the portal where 

the zone is covered by thick talus. The asbestos pinches out 20 feet 

west of the portal of the adit. Only traces of asbestos are exposed in 

the remainder of the adit.

The concentration of asbestos exposed in the original outcrop was 

localized where several pre-mineral small-scale beddjng faults had 

prepared the limestones for mineralization. Exposures along the 

quarry face and in the adit indicate that fracturing of the limestone 

was less intense in all directions from the point represented by the 

original discovery.

PROSPECT NOETH OF BED WHISKEB8 SPRING

Along the hill slope just north of Ked Whiskers Spring in sec. 20, 

T. 2 S., R. 17 E., (pi. 53), in the Hayes Mountains, the Mescal limestone has been split into at least three segments by widespread diabase 

intrusions. The upper segment is the algal limestone of ,the middle 

member. The next-lower segment contains meager asbestos showings 

and consists of thin-beded cherty limestone and siliceous beds. This 

segment ranges in thickness from a knife-edge to 15 feet. The beds 

strike northwest and dip 25° SW.

Two horizons have intermittent showings of asbestos along an outcrop length of several hundred feet. , These two horizons are separated by a 7-inch light-colored siliceous.bed: Fiber with a maximum 

aggregate length of 1 inch was seen, however, the average length of 

the fiber is % to y2 inch. The fiber is semiharsh to harsh. The lower 

diabase-limestone contact, which is generally concordant with the beds, 

is locally undulating, and the asbestos zones are from a few inches 

to 3 feet from ,the contact.

"TUFA" STONE, GYPSUM, AND DIATOMACEOUS EARTH

The lake beds and interbedded tuffs, which crop, out over a large 

part of the San Carlos-Gila River basin, contain several nonmetallic 

resources that may be of future value.. These include "tufa" stone, 

gypsum, and diatomaceous earth.

The lake beds crop out over most of the area north of the Gila River 

to the Triplets, thence to several miles west of San Carlos, and north 

of San Carlos to Black Mesa. They underlie much of the basalt-
680 CONTRIBUTIONS TO ECONOMIC GEOLOGY

capped mesa north of the Triplets. An excellent and easily accessible 

exposure is at the north end of this mesa where the road crosses Blue 

River; here, a thick sequence of lake-bed limestones is exposed in the 

canyon walls. Prospecting throughout the area in which lake beds 

are exposed might disclose other deposits of gypsum and diatomaceous 

earth, and possibly some deposits of low-grade clay.

"TUFA" STONE

Second to asbestos in value has been the "tufa" stone production 

on the San Carlos Indian Reservation. This stone was utilized early 

in the construction of buildings at San Carlos (known as Rice prior 

to 1931). The quarry area is about 1 mile northwest of San Carlos 

in sec. 2, T. 1 S., R. 18 E. (pi. 53), and can be reached from San 

Carlos by a road leading northwestward from the west side of the 

Indian Bureau school campus.

By order of the Secretary of the Interior on February 5, 1931, the 

areas known to be underlain by the "tufa" stone were withdrawn from 

prospecting, location, and leasing. Specifically, all areas in sees. lt 

2, and 3, T. I S., R. 18 E.; sees. 4, 5, 6, 7, 8, 9, 16,17, and 18, T. 2 S.r 

R, 18 E.; and sees. 27,28,29,32,33, and 34 T. 1K, R. 18 E., were closed. 

All rights to these deposits are reserved to the Indians of the 

reservation.

The stone an attractive white, light-weight tuff is known locally 

as "tufa" stone. It occurs in approximately horizontal beds interbedded with the late Tertiary or Quaternary lake beds that occupy 

a major part of the San Carlos River basin. The tuff ranges from 

1 to 5 feet in thickness and averages 2^/2 feet in thickness over a wide 

area. It is underlain by calcareous, tan to brown mudstones and is 

overlain by mudstones and interbedded limestone. Overburden in 

the vicinity of the quarry, and northwest for a mile or more, ranges 

from a few feet to about 20 feet. Easily available reserves are very 

large.

The stone is usually quarried by hand and wedged out in blocks 12 

by 12 by 36 inches in size. When quarried, the stone reputedly weighs 

76 pounds per cubic foot; when dry it weighs 55 pounds per cubic foot. 

It is soft and easily cut, but it contains a few scattered basaltic fragments that average between ^ an(l Vz incn *n diameter.

The matter of strength in a stone that is to be used for construction 

is important. No data on crushing strength were available to the 

writer, but the strength appears to be adequate. All major government buildings in San Carlos including schools, offices, hospital,

churches, and many residences have been constructed of this stone. 

All of these one-story buildings are in excellent condition. Larger,
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 681

two-story structures have been built of the tufa stone examples are 

the Catholic and Baptist Churches of Globe, Ariz. :

GYPSUM ' .

Gypsum is found on the San Carlos Indian Eeservation at a location 3 miles west of San Carlos and south of the railroad tracks, in sec. 

]6, T. 1 S., R. 18 E. (pi. 53).. These deposits have never been commercially exploited. The Reverend F. J. Uplegger, Lutheran missionary to the Apaches, utilized a small %tnou'nt-some years ago to 

make a plaster for inscriptions. It.was found quite.satisfactory for 

this purpose.

The area is in the San Carlos River basin, a broad intermontane valley. The topography is characterized by gently sloping surfaces that 

are crossed by meandering washes and gullies; a few .hills and basaltcapped mesas project above these surfaces. The area is underlain in 

large part by late Tertiary or Pleistocene (or both) lake beds. The 

gypsum occurs in these lake beds.

The gypsum beds crop out along the north slope of a low basaltcapped hill where they can be traced intermittently for about 2,500 

feet (fig. 85). At the northwest end of the outcrop they are covered 

by the gravels of a northeast-trending wash; at the southeast end, 

about 400 feet south of the last exposure of gypsum beds, the Tertiary 

sediments are faulted against Paleozoic rocks. In general, the beds 

dip from 15° to 25° to the southwest and strike northwest; however, 

at the northwest end of the outcrop the beds are nearly flat, or have a 

slight northward dip (see sec. A-A', fig. 85).

A section of gypsum-bearing lake beds, ranging in thickness from 

100 to 150 feet is exposed in gullies on/the hillslope. Within this section, three to five gypsum beds are exposed and are interbedded and 

overlain by tan mudstones, which are in part gypsif erous. These beds 

are succeeded by thin- to medium-bedded gray limestones, which are, 

in turn, overlain unconformably.by a basalt flow that caps'the hill 

(% 85). .:' . ; .. _ V;.;

The base of the gypsum-bearing section is not exposed it is covered 

by later gravels which cover the surface of the flat that slopes gently 

northward for a distance of % mile to Gilson Creek. Numerous low 

mounds of gypsite 5 and gypsum .protrude through the otherwise flat 

gravel surface. Efflorescence is characteristic on the surface of these 

mounds. The gypsum-bearing section, as suggested by these mounds, 

may be considerably thicker than the part that is better exposed along 

the hillslope. It is possible, however, that faulting may result in some 

duplication. The thickest gypsum bed occurs near the top of the secGypsite Is an earthy mixture of gypsum and clay or sand.

MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 683

tion and ranges in thickness from 3 to 10 feet. Two other gypsum 

beds, averaging about 2 feet in thickness, are located in the 50-foot 

stratigraphic interval below this bed.

The gypsum is generally white and granular and in the outcrops 

has a few seams and pockets of clay scattered through it.

In an area covering about 9 acres along the hillside the thickest 

gypsum is covered by overburden ranging in thickness from a knifeedge to 30 or 40 feet. As a rough estimate, perhaps 100,000 tons of 

gypsum might be recovered from the thickest bed by open-pit methods. 

Downdip, the gypsum passes under limestone, siltstone, and the 

basalt that caps the hill; here, underground methods would be needed 

to recover the gypsum. The amount, grade, and thickness of the 

gypsum underlying the flat north to the railroad is unknown. However, gypsiferous mounds protruding through the soil indicate that 

the whole area is underlain by a gypsiferous section. In any future 

consideration of the area as a source of gypsum, drilling would be 

useful in determining the extent, thickness, and the grade and distribution of the thickest and purest beds.

This deposit is similar to the occurrence of gypsum in the San Pedro 

valley near Feldman, Ariz. Gypsum from the latter locality has 

been used by the Billito Cement Plant near Tucson, Ariz., and has been 

used in agriculture.

Gypsum deposits of good quality are widespread in this country, 

and demand is limited in a large part to local markets. Gypsum is 

utilized in southern Arizona as a fertilizer on alkaline soils. The 

gypsum and gypsite from this deposit could probably be used for 

this purpose as well as for use in the manufacture of cement. Tests 

would be needed to determine whether this gypsum could be used for 

plaster... A favorable feature of the deposit is its location less than 

% mile from the railroad.

DIATOMACEOTJS EARTH

In 1950, Eugene Case (an Apache Indian) brought specimens of 

a light, white rock to A. H. Hale, traffic agent for the Southern Pacific 

Railroad at San Carlos and now serving in that same capacity at 

Globe, Ariz. Mr. Hale recognized the material as diatomaceous earth. 

He accompanied the writer to the deposit whose location he has aptly 

named "Skeleton Wash," after the microscopic diatom skeletons that 

compose diatomaceous earth.

The original find was in sec. 26, T. 1 N., K. 18 E. about 2% miles 

north and a little east of San Carlos (pi. 53). The diatomaceous earth 

is found in association with the late Tertiary or Pleistocene (or both) 

lake beds. These lake beds and associated interfingering and periph-
684 CONTRIBUTIONS TO ECONOMIC GEOLOGY

eral coarser materials, in part interbedded with basalt flows, occupy 

a large part of the San Carlos-Gila River basin within the reservation boundaries. These rocks are tentatively considered to be the 

equivalent of the Gila conglomerate, which, in the vicinity of Safford 

and ,the San Pedro Valley, have been shown to be of upper Pliocene 

age.

The deposit at "Skeleton Wash" may be reached by taking the San 

Carlos-Sawmill road north from San Carlos across Seven Mile Wash 

to the top of the ridge, where the main road turns toward the north; 

then take the right fork, which runs down the east side of the ridge to 

a point where the road crosses the first southerly-draining wash. Proceed north (up-wash) for about 1 mile, taking the first right fork of 

the wash. The deposit crops out prominently on the west bank of the 

wash, where interbedded limestones and diatomaceous beds form a 

cliff about 20 feet high.

The area is one of flat, gently-sloping ridges dissected by southerlydraining washes. The maximum relief in the area is probably not 

more than 100 feet.

From the prominent outcrop, the diatomaceous beds can be traced 

discontinuously northward for approximately 600 feet. Immediately 

to the south of the prominent outcrop, on the west side of the gulch, 

the beds are cut off by a northerly-trending fault. The beds are approximately horizontal; however, in detail, they have an undulating 

surface.

The section, as exposed in the wash and gully sides, is approximately as follows:

Section in "Skeleton Wash" 

Top not exposed. * «*

Limestone, white to buff, very thin-bedded, dense; contains some

interbedded, very thin diatomaceous beds__________________ 10 

Diatomaceous earth, white to light-yellow, probably clayey in part;

contains eomc very tkin limestone beds______________________ 6

Limestone, light-buff to white, dense 6

Diatomaceons earth, white, soft______________________ 2 

Limestone, white to buff, very thin-bedded, dense; some very thin

diatomaceous beds probably included __________ 10 

Tuffaceous sandstone, gray-green to Olive-green, CODglOmeratiC j contains numerous basaltic pebbles and cobbles________________ 20+

54+ 

Base not exposed.

Further reconnaissance in the lake beds -within the San Carlos-Grila

River basin brought to light other occurrences of diatomaceous earth, 

particularly in sees, I and 11, T. 2 s., n. 19 E. This locality can be 

reached by taking the dirt road going east from the newly built rodeo 

grounds east of Peridot. The road log is as follows:
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 685

Miles Directions 

0.0 . Rodeo grounds east of Peridot. Take dirt road

going east toward Salt Creek. 

3.0 . Fork, take left turn. 

3.6 . Fork, take right turn. 

7.1 . Locality is about % mile south of road.

Here, about 4 miles south of the Triplets and 8 miles southeast of 

the location in Skeleton Wash, an outcrop of diatomaceous earth forms 

an especially prominent white cliff on the south slope of an isolated 

basalt-capped butte. The length of the outcrop is about 1,000 feet. 

The beds strike to the northwest and dip 20°-25° NE. They are cut 

by northwest-trending faults, one of which has a displacement of 30 

feet. The section is as follows:

Generdtfze'd -section south slope of basalt-capped lutte in sec. 1, T. 2 8., R. 19 E.

Talus cover. Feet 

Diatomaceous marl, white, thin-bedded___-______-_ _ 50+ 

Tuffaceous sandstone, gray-green, conglomeratic; contains numerous 

basaltic pebbles-__________i_______ _ 2

Diatomite, white, calcareous, some very thin hard limestone beds____ 30 

Diatomite and limestone, alternating, thin-bedded_ 15 

Tuffaceous sandstone, gray-green to olive-green, conglomeratic; contains numerous basaltic pebbles, cobbles, and boulders 100+

197+ 

Base not exposed.

Laterally, the section is variable; the diatomaceous zone below the 2- 

foot conglomeratic tuffaceous sandstone bed ranges from 45 to 60 feet 

in thickness. In a section l/2 mile to the northeast, on the slopes of 

another butte, apparently the same zone is about 40 feet thick but contains mostly limestone, marl, and impure clayey diatomaceous beds.

At both the location in Skeleton Canyon and the location south of 

the Triplets thin limestone beds are common in the section, and the 

diatomaceous beds themselves generally contain considerable amounts 

of lime as an impurity and laterally grade into diatomaceous marls. 

Several samples showed amounts of lime ranging from 10 to 20 percent.

The deposits examined contain too much impurity in the form of 

lime and clay to compete with larger and purer deposits such as those 

in California, Oregon, and Nevada. The best material was in the 

2-foot bed in "Skeleton Wash", but this bed is too thin to be of economic 

value.

The chief uses of diatomite are as filters, fillers, insulation, and in 

lightweight aggregate and abrasive. The low-grade San Carlos material would not be suitable for use as a filtration material (the chief 

use of diatomaceous earth) because of the high amounts of reactive 

impurity. The material might be suitable for the making of lowgrade insulation brick. Limited, local use might be found for some 

of the material as a heat insulator; diatomaceous earth from the San
CONTRIBUTIONS TO ECONOMIC GEOLOGY.

Pedro valley has been used in Tucson for this purpose. Diatomaceous 

earth has been used in making lightweight aggregate, but the strength 

of the aggregate'is low.

PERIDOT

The presence of peridot, the gem variety of olivine, near San Carlos 

(Rice) has been known for many years. The geology of the occurrence 

has been studied adequately by Lausen (1927). The area is immediately southwest of San Carlos and can be reached from there by the 

power-line road (pi. 53), which ascends and crosses Peridot Mesa.

Peridot Mesa is roughly rectangular in plan and extends from iy2 

to 2 miles in a northerly direction and from 2 to 2^ miles in an easterly 

direction (pi. 52). The mesa is capped by a basalt flow, 10 feet to 

more than 100 feet thick, which is underlain by flat-lying tuffs, siltstones, and gravels. These sedimentary rocks are regarded as the 

equivalent of the Gila conglomerate and therefore of Pliocene or 

Pleistocene age. The basalt may be late Tertiary or Quaternary.

The peridot occurs in roughly ellipsoidal bombs, or segregations, in 

basalt and cinders erupted from a volcanic cone which occupies the 

southwest corner of Peridot Mesa. This cone rises in a gentle slope 

to a height of about 100 feet above the surrounding mesa, and it is 

about 1/2 mile in maximum diameter. Its southwestern perimeter has 

been eroded away. In an exposure in Peridot Canyon, a basalt flow 

containing a concentration of the peridot segregations ranges from 5 

to 15 feet in thickness. The ellipsoidal segregations make up 25 to 40 

percent of the rock volume and average from 3 to 8 inches in maximum 

diameter.

Stones have been gathered by the Indians from a number of places on 

Peridot Mesa, particularly from the rim of the cone, in washes adjacent 

to the cone, and in small canyons that breach the north rim of the mesa. 

Most of the stones are not broken from firm basalt, but are gathered 

from the debris resulting from erosion of the basalt. The gathering 

and selling of the peridot over the years has been sporadically carried

on by individual Indians who sell their gleanings, usually in quantities 

of only a few pounds, to collectors and stone cutters in Globe; Occasionally, the local trading posts have bought a few pounds.

In recent years, Luther Martin of Globe has been the principal purchaser. According to Mr. Martin, he has paid $3.00 to $5.00 per pound, 

and he estimates that it takes approximately 10 pounds of "mine run" 

material to get 1 pound of usable gem material. The so-called "mine 

run" material itself, however, represents selected stones chosen by the 

one who collects' the material, therefore the actual ratio of usable stones

in the segregations would be much lower than 1 in. 10. Martin estimates that he has bought about 600 pounds of peridot. He cuts and
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 687

polishes the stones, makes jewelry from them or sells the cut stones to 

mineral collectors. The finished stone brings about $5.00 a carat; the 

average stone runs from 1 to 3 carats; the largest he has cut was 15 

carats; a 22-carat stone is reputed to exist.

Recently Mr. Martin has left Globe, and this outlet for the stones is 

no longer available. A local curio shop in Globe occasionally buys a 

few pounds for sale in the rough to the tourist trade.

GUANO

 Several guano caves have been found on the reservation, and from 

one of these a small production was obtained. This cave is on the San 

Carlos River about 10 miles northeast of San Carlos (pi. 53). Here, 

the San Carlos River has eroded a deep precipitous canyon into the 

basalt-capped mesa which occupies the broad area north and east of the 

Triplets. The cave, located near the floor of the canyon, can be reached 

by a trail that descends the canyon wall at a point opposite the Rocky 

Creek junction, which is located about 2 miles downstream from the 

cave.

The cave its probably not more than 30 or 40 feet long and 50 feet 

wide. Bat guano has accumulated to a depth of several feet over 

the irregular floor of the cave. C. A. Kumke, who formerly was 

interested in the cave, stated that hand drilling indicated a thickness 

of guano of as much as 10 feet in places.8 Elbert Stevens had a lease 

on the claims in 1933 and 1934 and removed about 63 tons which sold 

for $15 a ton.,

Other guano deposits were not visited. The Hart Tine Bat and 

Twin Peaks deposits are similar occurrences in lava caves. The Cave 

Creek deposit, 21 miles north of San Carlos, probably occurs in one 

of the caves in the Redwall limestone that are common along Cave 

Creek, Black River, and Bronco Creek.

Although there are a number of these guano deposits scattered 

over the reservation, their individual potential is rather small. The 

recoverable guano from any one cave probably does not exceed a 

few hundred tons.

SUMMARY OF RESOURCES

No production is recorded from any of the minor base-metal occurrences known on the reservation. These occurrences do not appear to 

be of commercial value at present. The extensive cover of rocks 

younger than the main period of metallization in southeastern Arizona 

and the general absence of Laramide intrusives are contributing 

factors to the lack of extensive base-metal deposits.

6 Oral communication.
688 CONTRIBUTIONS Vo ECONOMIC GEOLOGY

The discovery of the Eed Bluff uranium deposit north of Koosevelt Lake in the Dripping Spring quartzite, coupled with the fact 

that the formation has a higher degree of radioactivity than that 

normal to adjacent formations, suggests that additional economic concentrations of uranium might be found. Until the spring of 1954,. 

there had been no prospecting for uranium within the reservation.

The nonmetallic deposits of the reservation are the most important,, 

and of these, asbestos is outstanding. The areas of outcrop of Mescal 

limestone that are most favorable for asbestos prospecting are the 

Salt River area, the Bear Canyon area, and the Apache mine area. 

Areas that are considered poor for asbestos prospecting include most 

of the Apache ridge and the Hayes Mountains.

Lake bed deposits of late Tertiary or Pleistocene age (or both),, 

which underlie a large area, contain several nonmetallic resources 

of possible future value. These include "tufa" stone, gypsum, and 

diatomaceous earth. "Tufa" stone, with its huge reserve, would seem 

to offer commercial possibilities as a building stone; especially if, in 

conjunction with its utilization for this purpose, other uses could be 

developed, such as in lightweight aggregates. Gypsum is present in 

some quantity, and the deposit is easily accessible to the railroad. 

Perhaps the gypsum and gypsite could be utilized as agricultural 

fertilizer to counteract the alkaline soils so common in this part of 

Arizona. Similar deposits have been worked commercially in the 

San Pedro Valley near Feldman, both for this purpose, and for use by 

a cement plant near Tucson, Ariz. Diatomaceous earth is also found 

in the lake beds, but the deposits thus far investigated have contained 

impurities in the form of calcium carbonate and clay. Other 

nonmetallic resources include peridot and bat guano.

REFERENCES CITED

Darton, N. H., 1925, R6sum6 of Arizona geology: Arizona Bur. Mines Bull. 119,

p. 242-244, 252, 257, 263. 

Gilbert, G. K., 1875, Report on the geology of portions of New Mexico and Arizona,

in Wheeler, G. M., U. S. Geog. and Geol. Surveys W. 100th Her. Kept., v. 3,

p.509,513-514, 527-528. 

Kaiser, E. P., 1951, Uraniferous quartzite, Red Bluff prospect, Gila County, Ariz. t

U. S. Geol. Survey Circ. 137. 

Knechtel, M. M., 1938, Geology and ground-water resources of the valley of Gila

River and San Simon Creek, Graham County, Ariz.: U. S. Geol. Survey

"Water-Supply Paper 796-F1 .

Kunz, G. F., 1904, Peridot: Mineral Resources U. S., p. 959. 

Lausen, Carl, 1927, Occurrence of olivine bombs near Globe, Ariz.: Am. Jour. Sci., 

5th ser., v. 14, p. 293-306.

Marvine, A. E,., 1875, Report on the geology of route from St. George, Utah, to 

Gild RlYer, AriZ., in Wheeler,-G. M., U. S. Geol. and Geol. Surveys W. lOOth

Her. Rept, v. 3, p. 218-225.
MINERAL RESOURCES, SAN CARLOS INDIAN RESERVATION 689

Price, W. E., Jr., 1950, Cenozoic gravels on the rim of Sycamore canyon: Geol. 

Soc. Am. Bull., v. 61, no. 5, p. 501-507.

Regan, A. B., 1903, Fort Apache region: Am. Geologist, v. 32, p. 265-308.

 1932, Geological notes on the Fort Apache region: Kansas Acad. Sci. 

Trans., v. 35, p. 260-273.

Ross, C. P., 1925, Geology and ore deposits of the Aravaipa and Stanley mining 

district, Graham County, Ariz.: U. S. Geol. Survey Bull. 763.

Schwennesen, A. T., 1921, Geology and water resources of the Gila and San Carlos 

valleys in the San Carlos Indian Reservation, Ariz.: U. S. Geol. Survey 

Water-Supply Paper 450-A.

Thurmond, F. L., 1921, A prospecting trip through the San Carlos Indian Reservation : Arizona Min. Jour., v. 5, no. 3, no. 11-12.

Turner, S. F., and others, 1946, Ground-water resources and problems of the Safford Basin, Ariz.: U. S. Geol. Survey Misc. Pub. (mimeographed).

Wilson, E. D., 1928, Asbestos deposits of Arizona: Arizona Bur. Mines Bull. 126.

INDEX

Page

Abstract_._____________ ___ 613 

Acknowledgments.. .. 618 

Apache Ridge area, Apache claims.. 673-676 

prospect near Chromo Butte. __ 672-673 

Asbestos.__ - 641-679

Bear Creek subarea, Bear Canyon deposit.. 664-667

prospect west of Blue River.._ 669-670

upper Bear Creek prospects... . 667-669

Bitter Spring prospect...--. . - 634-635

Bucket Mountain, unnamed prospect near... 637

Cassadore Spring-Oak Creek area. Asbestos on

Oak Creek....-......... . 672

Black Mesa deposit... - 670-672 

Copper.... ..__ . 630-637

Copper King-Wylomene claims.. 631-632

Diatomaceous earth. 683-686 

Escabrosa limestone, general features. 625

Oeronimo prospect-__ 635 

Guano...._________ ____ 687 

Gypsum__________ - 681-683

Hayes Mountains area, Chiricahua prospect 676-677 

Mystery prospect.... 677-679 

prospect north of Red Whiskers Spring... 679

I. B. Hole Canyon subarea, Sulphur Springs

claims...__ ___ ... 653

unnamed prospect_... _.. 652-653

Igneous rocks, general features. 626-628

Iron.__.___ _.. . 637-639

Location of the area. ________ _ 613-615 Uranium

Page 

Martin limestone, general features. ------- 624-625

Methods of study during the investigation.. 617-618 

Mining in the area, history.----------.-..- 616

present status.. 617 

Mining regulations. .. 617

Naco limestone, general features .. 625

Paleozoic rocks, general features.. 624-625 

Peacock claims. . ... . 633-634 

Peridot.. . 686-687

Pleistocene alluvium, general features........ 626

Pre-Cambrian rocks, Apache group... 621-623

general features... _ ..__ 619-623

See also Igneous rocks.

Previous work in the area..... ____. 618-619 

Production in the area..... . 616-617

Recent alluvium, general features____ 626 

Redwall limestone, general features... 625

Salt River-Cienega Canyon subarea, Emsco

mine...-.____-____... 653-656

Great View mine... . 658-661

Pine Top claims. 656-658

prospects northeast of Seneca____ 664

Salt River (Sorsen-Williams) claims. . 661-663

Sawmill Canyon subarea, Silk claims._ 651-652

Wonder claims... . . 650-651

Scope of the investigation..... . 617

Seneca iron prospect.. ___ 639

Stratigraphic column, description..... 620

Structure in the area......._ ___. 628-630

Tertiary rocks, general features 625-626 

Topography of the area..... 615-616 

Troy quartzite, general features 624 

Tufa stone...... . 679,680-681

640-641

o

691