DEPARTMENT OF THE INTERIOR

HUBERT WORK, Secretary

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, Director

Bulletin 763

ARAVAIPA AND STANLEY MINING DISTEICTS 

GKAHAM COUNTY, ARIZONA

BY

CLYDE P. ROSS

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1925
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CONTENTS

Pago

Summary _ ________ ________________________ 1

Introduction ___________________________________ 2

\ Purpose and scope of the report _________________ 2

V .Location and extent of the region ______________ 2

Acknowledgments_____________________________ 3

* Historical sketch _____________________________ 3

Industries__-_________________._____________ 5

^ Climate ___________________________________ 6

- The map ...___________________________ 6

Topography ________ _ 8

Turnbull Mountains.._____________________________ 8

Mescal Range and Deer Creek basin___________________ 10

Santa Teresa Mountains _________________________ 10

Arivaipa Creek________________________________ 11

Stratigraphy and petrology ___ ____________________ 12

Major features_______________________________ 12

Metarnorphic rocks (pre-Cambr.ian)______________________ 13

Final schist_______________________________ 13

Granitic gneiss _ _ _ _____ ______._______ 15

Metamorphic igneous complex .________________________ 16

Stratified rocks _________________ ____ _______ 17

' j Cambrian quartzite _______ _ 17

| Martin limestone (Devonian). ___ _ _ _ 20

Tornado limestone (Carboniferous) _ ____ 22

Cretaceous rocks__ _ _ _ ._ 25

\ Miocene (?) strata _ 29

Gila conglomerate____________ ____ _ 30

Quaternary alluvium _ _ -__ 31

' Intrusive rocks ____ 32

\ Granite of the main batholith___________ _ 32

Quartz monzonite _ _ _ : 34

Wine-pink granite 34

Intrusive rhyolite - 35

Granitic dikes __ ____ _____ 37

, Felsite _____ - 37

\ Trap ____________________ 38

Structure _ : - 39

Pre-Cambrian folding 39

Later periods of earth movement 40

Igneous intrusions . 41

Flexures 42

Normal faults 44

Overthrusts 45

HI

I
IV CONTENTS

Page 

Geologic history.____________________ _ 46

Pre-Cambrian time _______________ ______ 47

Paleozoic time______________________________ 48 

Mesozoic time. _ _ ___ _ 49 

intrusive activity ________________ ___ __________ 51

Tertiary and Quaternary time ___ _ _ _ 51 

Physiography . __________________ _ _ ______ 53

Physiographic processes __ _ 53 

Pediments and terraces __'.______________ _ ____ 54

Mountain sculpture _ ___ ____ 57 

Ore deposits _ 58 

Types________ __________ _ ___________ 58

Age_____ 59 

Grand Reef lode system 59 

Contact-metamorphic deposits ______ _ _________ 63

Copper deposits in the granite of the main batholith_________ 69 

Calcite veins 70 

Barite lodes ___________ ______ ___ _____ 71

Gold veins 71 

Oxidation and enrichment___________ - ________ 72 

Aravaipa mining district 76 f 

General features_______________________________ 76 

Location and extent- _____ 76 

Population __ _ _ 76 

Roads_____ __ 77 

Plan of descriptions of deposits _ _ __ 78 

Mines and prospects __ 78 

Aravaipa Leasing Co___ _____ 78 

Prospects south of the Aravaipa Leasing Co.'s property- __ 86 

La Clede mine _ 86 / 

Silver Coin mine __ _________ 87 } 

Tenstrike group _ _ _______ 88 ' 

Finnegan group _______ 88 

Bullis group , . 88 / 

Bullis-Landsman group _ __________________ 91

Royal Tinto Mining & Smelting Co __ 92

C. A. Firth group ___ _ _________ 95 ''

Aravaipa Mining Co _____ 95 /

Moltke group _ ____ 98 

Norton group _____ 98

H. T. and C. A. Firth group ________ ________ 99

Tolman-Babcock group __^__ 99 

Bryce-Merrill prospect ____ 100 

Sinn Fein prospect _____ loo /

Rawhide group _ _ _______ 100 

Warm Spring prospect _ _ ___ ________ 100 

Landsman group _ ___ _______ _ ________ 101 

Cobre Grande mine _ ______ ______ 102 

Fisher prospect _ _______ 103 

Stanley mining district _ ___ ______ 105 

General features _ ___ _ ___________________ 105 

Location and extent ________ . _ ___ 105 

Population________________________________ 105 

Roads__________________________________ 106 )
CONTENTS ' V

Stanley mining district Continued. Page

Mines and prospects _ 106

Princess Pat mine _ ! 106

Copper Dike group _________ _____ 107

Cold Spring prospect________________ __ 108

Soldier prospect __________ ____ 108

Copper Belle mine- __________ ___ _ 109

Silver Spar prospect____________________________ 109

Stanley mine___ _____________________ 109

Friend mine___ _.._____________-________ 110

Copper Reef mine-_______________________ 111

Prospects on Rawhide Mountain_________ _ __ 112

Starlight mine___ ___________________ 113

Parks Brothers prospect_______________________ 114

Mitchell barite prospect________.__________ _ 114

Coal fields___________________________________ 114

General features_________________________ 114

Location and extent ____________ ___ 114

Accessibility_________________;__________ 115

History________________________________ 115

Upper field________________________________ 116

Middle field _______________________________ 116

Lower field ______________________________ 117

Index _____________________________________ 119
ILLUSTRATIONS

Page 

PLATE I. Geologic sketch map of the Aravaipa-Stanley region___..__ 8

II. Topographic sketch map of the Aravaipa-Stanley region___ 8

III. A, Stanley Butte and the dissected upland surface at its base, 

from Lone Cedar Mesa; B, Stanley and Little Stanley buttes 

and the dissected upland at their base, from the north___ 10

IV. A, Rawhide Mountain, from the southeast; B, The summit of

Rawhide Mountain, from a point on its northeast face___ 10

V. A, North side of the Santa Teresa Mountains, from Fisher 

prospect; B, Northeast flanks of the Santa Teresa Mountains, 

from Cobre Grande Mountain___________________ 10

VI. A, Cliff of tuff and sandstone of the Gila formation on the 

east side of Turkey Creek; B, Cliff of conglomerate of the 

Gila formation in Arivaipa Box, near T Rail ranch______ 10

VII. A, The south side of the Santa Teresa Mountains and the 

plain at its base; B, Cambrian quartzite in Arizona Canyon 

near Arivaipa ____________________________ 10

VIII. A, Tilted Miocene (?) conglomerate south of the Safford road; 

B, Tilted cross-bedded sandstone with lava below, both of 

Miocene (?) age, in Arizona Canyon just below the Claridge 

ranch.__________ _ _ ____ __ 10

IX. A, North side of Garden Gulch below Friend mine; B, Granite 

near Fisher prospect, in the southeastern part of the Turnbull Mountains_________ _ ________ ^ " 58 

X. A, Grand Reef outcrop, from the ridge on the north side of 

Laurel Canyon; B, Edge view of the Grand Reef outcrop, on 

the north side of Laurel Canyon, from the mill _ 58

XL Claim map of the Aravaipa mining district_______ 58

XII. Magnetite in process of replacement by specularite 66

XIII. Map of the coal fields in the Aravaipa-Stanley region 114 

FIGURE 1. Diagram showing contact-metamorphic deposits in limestone. _ 65

2. Diagram to illustrate oxidation and enrichment 72

3. Section through principal workings at the Grand Reef mine 80

4. Section through Dogwater mine 81

5. Section through Aravaipa mine ___ __ 82

6. Workings of Silver Coin mine___ _____ _ 87

7. Composite level map of Windsor mine __ 89

8. Geologic sketch map of Sam Jones and Copper Bar tunnels 93

VI
GEOLOGY AND ORE DEPOSITS OF THMRAYAIPA 

AND STANLEY MINING DISTRICTS, GRAHAM 

COUNTY, ARIZONA

By CLYDE P. Ross

SUMMARY

The region in which the Aravaipa and Stanley mining districts are situated 

contains the rugged Santa Teresa and Turnbull mountains and the southeast 

end of the Mescal Range. It is not crossed by any railroad, and lack of 

good transportation is a serious obstacle to .its development. The principal 

industries are mining and stock raising; there is also some farming by irrigation. The climate is semiarid but healthful. The rocks consist of preCambrian metamorphosed igneous and sedimentary formations; Paleozoic 

quartzite, shale, and limestone of marine origin; Upper Cretaceous shallowwater marine deposits and volcanic beds; granite and quartz monzonite, 

probably intruded at the beginning of the Tertiary period; lava, pyroclastic 

rocks, and alluvium of Miocene (?) age; the Gila conglomerate (including 

tuff) ; and Quaternary alluvium. The lower part of the Paleozoic section differs from that in neighboring regions. After the intense crustal disturbances 

of pre-Cambrian time, there was extensive warping in the Paleozoic and Mesozoic eras. The batholithic intrusions at the beginning of the Tertiary were 

accompanied by doming and faulting. The overthrusts in the northern part 

of the region probably were produced at this time. Normal faulting continued with diminishing intensity into geologically recent time. There appear to have been five partial cycles of erosion from. the Pliocene to the 

present.

The presence of deposits of silver, copper, and lead in this region has been 

known for 50 years, but only about 35,000 tons of ore has been mined. 

There are several small mines and numerous prospects, but development has 

been hindered by inaccessibility and lack of capital, so that the possibilities of 

the region as a metal producer have not even yet been adequately tested. At 

the present time mining, except for necessary assessment work, is practically 

at a standstill, but with improvement in conditions governing the mining industry in general development here will probably be renewed, and the future 

of the region may be regarded optimistically.

A lode system 11 miles long crops out west of the Santa Teresa Mountains. 

The lodes consist of fractured and replaced rock of various kinds and banded 

vein matter. The gangue is largely quartz and fluorite. The principal sulphides are galena with argentite in it, chalcopyrite, sphalerite, and pyrite. 

There are contact-metamorphic deposits which have been developed for copper; curious copper deposits in granite, which are closely related genetically 

to the intrusion; two types of veins related to the Tertiary volcanism, one 

containing principally copper with calcite as the characteristic gangue mineral, the other containing silver minerals with a gangue of quartz, barite, 

and fluorite; and some unimportant quartz veins containing gold. There has 

been some oxidation and a little enrichment.

1
AEAVAIPA AND STANLEY MINING DISTRICTS, ABIZ. 

INTRODUCTION

This report is the result of a little less than two months' field 

work in the summer of 1922. In order to obtain a basis for the 

study of the mineral deposits it was necessary to understand the 

general geology of the region. Consequently a geologic map was 

prepared, and a study of the stratigraphic and structural relations 

of the rocks was undertaken. As no adequate topographic map of 

this region had ever been made, however, it was necessary to prepare 

such a map to serve as a base for the geologic mapping. This restricted the time that could be devoted to geologic work. Nearly 

all the mines and prospects in the region mapped were visited. A 

few prospects on which little development work has yet been done 

were omitted for lack of time. The purpose in view was to gain 

an insight into the types of ore deposits rather than to make detailed examinations of individual mines such as would be undertaken by an engineer in commercial practice.

The facts gathered regarding the general geology of the region 

and the inferences drawn from them are presented both because 

they are necessary to a clear understanding of the ore deposits and 

because of their scientific interest. Available knowledge regarding 

the geology of southeastern Arizona is still incomplete, and the results of this investigation partly fill the gap. The mode of origin 

and general features of the ore deposits are discussed, and all the 

mines and prospects regarding which any information is available 

are described. The data in the report, though unavoidably incomplete, should be sufficient to give anyone a good general idea of the 

districts and their ore deposits. It is hoped that the descriptions 

of the ore deposits will aid mining men in the region to arrive at 

such an understanding of the characteristics of the deposits on their 

own properties as will assist them in planning future development.

There is some confusion as to the form of the word " Arivaipa." 

This spelling has been adopted by the United States Geographic 

Board for the canyon, creek, valley, and village and is etymologically 

correct. The name of the post office is, however, officially spelled 

"Aravaipa" by the Post Office Department, and the two mining 

companies in whose names the word occurs have followed the postoffice spelling, which is also in accord with local usage.1

LOCATION AND EXTENT OF THE REGION

This report covers the Aravaipa and Stanley mining districts and 

a corner of the Black Kock mining district, in Graham County,

1 On December 3, 1924, after this report was In type, the United States Geographic 

Board reversed its former decision and adopted the spelling "Aravaipa " for the canyon, 

creek, valley, and village.
INTRODUCTION 3

Ariz. (see PI. I), and includes a description of the coal fields on 

Deer Creek in Pinal County.

The greater part of this region has not been surveyed by the 

General Land Office, but it lies approximately in Tps. 4 to 7 S., Rs. 

18 to 21 E., and comprises a total area of about 300 square miles.

The region is not yet,crossed by any railroad, but the Bowie-Globe 

line of the Arizona Eastern Railroad passes within 10 miles of its 

northern border. Klondyke, the center of most activity in the region 

at present, is about 56 miles northeast of Tucson, 48 miles southeast 

of Globe, and 62 miles southwest of Clifton, measured in straight 

lines. Because of the lack of direct transportation facilities the distances that must be traveled to reach any of these places from 

Klondyke are much greater.

ACKNOWLEDGMENTS

It is a pleasure to acknowledge the hearty cooperation of the residents of the Aravaipa-Stanley region. A list of all who gave information, hospitality, and assistance in the course of the field work 

would include the majority of those engaged in mining in the region 

and a number not directly interested in that industry. Messrs. Jack 

Adair, of Klondyke, and H. T. and C. A. Firth, of Arivaipa, gave 

information and assistance of much value/ Others are mentioned 

in appropriate places in the text. To acknowledge specifically all 

the courtesies received would require too much space, but all may feel 

assured that their assistance is appreciated.

Mr. H. A. Wentworth, president of the Aravaipa Leasing Co., has 

been most kind in furnishing maps and information regarding the 

various properties in the Aravaipa district, on which his company 

has done work. Among other things, he supplied notes by C. E. 

Minor, former superintendent of the Grand Reef mine, which were 

of great assistance, especially in regard to those portions of the mine 

now inaccessible. Mr. E. H. Bachman, of Globe, furnished assay 

maps of the Windsor mine prepared by him. The preparation of 

the report has also been aided by the cooperation of fellow members 

of the United States Geological Survey. Kirk Bryan generously 

supplied unpublished information and critically read the chapter on 

physiography. E. S. Larsen and C. S. Ross aided in some of the 

petrographic work, and W. T. Schaller helped in the determination 

of some of the minerals. Others gave suggestions of value. My 

wife, Ruth C. Ross, gave assistance in preparing the text and some 

of the illustrations.

HISTORICAL SKETCH

The Stanley and Aravaipa districts lie within the region acquired 

from Mexico by purchase in 1853. Remnants of cliff dwellings in the 

canyon known as Arivaipa Box testify to its settlement in very early

106914 25 2
4 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

times. Until the early seventies this area was but little visited by 

white men. The Apaches dominated the country so completely that 

settlement was practically impossible. Even as late as the eighties 

and early nineties there were sporadic Indian troubles, but some 

prospecting was in progress. The difficultly accessible canyons in the 

rocky Turnbull and Santa Teresa mountains, are said to have been 

favorite refuges for rustlers and other lawless characters in the early 

days. About 1872 two large cattle ranches were established in Sulphur Spring Valley,la and then or soon after cattle presumably 

ranged up into Arivaipa Valley.

Some of the mineral deposits now owned by the Aravaipa Mining 

Co. were known, and a little work was done in the late seventies, and 

it is even reported that a small smelter was erected at this time by 

Col. W. C. Bridwell, commonly known as " Buford." The coal in 

the upper end of the Deer Creek drainage basin was discovered by 

Bob and. David Anderson about 1881. The Copper Belle deposit, 

near Stanley, was found about 1883, and the Friend, a few miles to 

the west, about the same time. Probably other deposits in the vicinity of Stanley were known at this early date, but the area north of 

Stanley Butte was then included in the San Carlos Indian Reservation and was not open for the location of mineral claims. The croppings of what is now known as the Grand Reef, in the Aravaipa 

district, are so prominent and striking that they were probably discovered very early. The veins on Imperial Hill were found in the 

seventies.

A considerable part of the development of the mines in the Aravaipa district was carried on in the nineties. The Arizona shaft of 

the Aravaipa Mining Co., the deepest shaft in the district, was put 

down to its present depth of 580 feet between 1890 and 1895. The 

Grand Reef mine also attained its present depth of 300 feet in the 

nineties, and the veins on Imperial Hill were worked about this time. 

The boundary of the San Carlos Reservation was shifted north to its 

present position in 1896, and the country between this and the old 

line, locally known as " the strip," was thrown open to prospectors, 

resulting in some mining activity in the Stanley district. No accurate data as to ore shipments from mines in either district in these 

early years are available, but they can not have been large. Small 

test shipments of coal were made from the " upper field " to Globe, 

and small quantities of lead-silver and copper ore were mined, and 

presumably part of it was shipped.

In the first few years of the present century there appears to have 

been little activity in either district. Between about 1906 and 1920 

some of the mines and prospects were reopened. Work at the Star-

« Meinzer, O. E., Water resources of Sulphur Spring Valley, Aria.: U. S. Qeol. Survey 

Water-Supply Paper 320, p. 13, 1913.
INTRODUCTION 0

light mine started in 1903, and the claims were patented in 1907, but 

the mine was closed about 1910. The Friend, Stanley, Copper Reef, 

and Princess Pat mines and several prospects were worked intermittently up to 1918 or a year or so later. In the Aravaipa district 

there was also some ore mined, largely by lessees. Most of the development work on the Royal Tinto group was done in 1906 and 1907. 

Some ore was shipped from the Aravaipa Mining Co.'s property by 

lessees about 1906. The Grand Reef mine was leased to local people 

in 1915. A mill was erected and ore in small quantities was shipped 

until the final shutdown in 1921. During the last two years of this 

period the mine was operated by the Aravaipa Leasing Co., which 

now owns the property. A few cars of ore have been shipped from 

the properties south of the Grand Reef, of which the most developed 

are those owned by Ted Quinn and James Quinn. Prospecting in 

both districts has been carried on by a number of people, but very 

little ore has- been shipped except from the properties mentioned. 

Little or no ore has been shipped from either district since 1920.

INDUSTRIES

Stock raising vies with mining as the principal industry of the 

region. Cattle belonging to ranchers in Arivaipa Valley, near Stanley, and in the valley of Gila River range in the mountainous country, 

a large part of which is included in the Santa Teresa division of the 

Crook National Forest. Herds of goats wander over the country 

north and west of the Turnbull Mountains and also; south of the 

Santa Teresa Mountains. On the slopes of the valley of Gila River 

between the Turnbull Mountains and the Indian reservation boundary 

herds of some hundreds of horses struggle for a livelihood. Ranchers 

in other parts of the region raise a few horses for their own use.

Agriculture is practiced along Arivaipa Creek and to a moderate 

extent elsewhere, but mostly as an adjunct to other interests. Insufficient food is raised to support the population, and considerable 

quantities, both canned and fresh, are shipped in from Willcox and 

from towns on Gila River. A considerable part of the grain and 

hay needed for stock must also be shipped in from the irrigated farms 

along Gila River.

Mining is of more potential than actual importance. Much prospecting and considerable haphazard development work has been done. 

The total shipments of ore and concentrates from all properties in 

the Aravaipa district regarding which information could be obtained 

amount to only about 6,000 tons, of which much the greater part 

came from the Grand Reef mine. In addition it is probable that 

a few carloads of ore have been shipped by lessees and prospectors 

regarding which no data were obtained. The data so far gathered 

as to production in the Stanley district are so fragmentary that
6 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

figures can not be given, but the total is certainly much less than that 

for the Aravaipa district, because there is n^ single mine in the 

Stanley district whose production can compare with that of the 

Grand Reef. There are in the Aravaipa district 56 patented and 

137 unpatented claims whose approximate positions are known and 

a number of unpatented claims for which data are lacking. The 

total number of claims in the Stanley district is undoubtedly greater 

than this, as there are several mines, notably the Copper Reef and 

Princess Pat, that have large groups of claims. The only patented 

ground in this district is the Starlight group of 12 claims.

From the facts above stated it is obvious that although the districts have been known for 50 years, they are still in the prospecting 

stage of development. There is no mine in either district which has 

yet been put on a firm foundation of successful production. On the 

other hand, it has by no means been proved that an adequate amount 

of correctly planned and directed development would not accomplish such a result.

CLIMATE

The region lies near the southern border of the mountain province 

of Arizona and has the climate characteristic of this province. It 

is so mild that outdoor work can be continued throughout the year 

with little difficulty or discomfort. During the greater part of the 

year the weather is most pleasant and healthful.

The temperature ranges from 20° F. up to somewhat over 100° F. 

The coolest weather comes in the first two months of the year, and 

June and July are usually the hottest months. The temperature 

does not soar to such heights as are characteristic for the southwestern part of the State. Even in midsummer oppressively hot 

days are rare.

A Weather Bureau station for recording the rainfall was maintained at Klondyke during the four or five years prior to 1919, 

but complete annual records are available for 1915 and 1916 only. 

These indicate that the annual rainfall at this place is about 19 

inches. There are usually less than 60 days in a year in which 0.1 

inch or more of precipitation takes place. These are concentrated 

into two rainy seasons. About half the annual precipitation occurs 

in July and August, and the greater part of the remainder falls 

in January and February. The annual snowfall is usually less 

than a foot, and in some years there is very little snow.

,THE MAP

The topographic map was prepared by me by means of a planetable survey. Section corners in the surveyed portion of Arivaipa 

Valley were utilized as known points from which to start the trian-
INTRODUCTION 7

gulation net. Any discrepancy between the assumed and actual positions of the section corners chosen is evidently within the allowable 

error for a map on the scale of 1:125,000, as the triangulation based 

on them proved to be consistent throughout. Thus the control is 

believed to be fairly good, so that the different parts of the area are 

mapped nearly in their proper relations. The topography as shown, 

however, is correct only in a general way. It was sketched from numerous points whose positions had been determined by triangulation. 

Every effort was made to sketch as accurately as possible, but errors 

of detail have undoubtedly been made. Altitudes were determined 

by means of an aneroid barometer, supplemented by vertical-angle 

measurements on the more prominent peaks with a Gale telescopic 

alidade. The data thus obtained were later adjusted so as to be consistent with themselves and with points of known altitude in the 

region mapped and in the Christmas quadrangle, adjoining it on the

west, which has been accurately mapped by the United States Geological Survey. The determination of altitudes by such methods is 

subject to unavoidable errors, but the resulting inaccuracies are 

principally in matters of detail, and the map is an essentially correct 

representation of the topography of the region. A contour interval 

of 100 feet was adopted in order to show adequately differences in 

topographic form, even though the measurements of altitude are not 

strictly accurate or complete enough for this interval.

The latitude and longitude of Mount Turnbull, in the northe'astern part of the Turnbull Mountains, have been accurately determined by the United States Geological Survey. This peak was 

carefully tied in to the triangulation net, and the latitude land longitude of the region were determined from it. The determinations 

thus made check closely with the position of the east boundary of 

the Christmas quadrangle as found by triangulation in the field.

The township net in the Aravaipa district is based on the plats of 

the General Land Office adjusted to the positions of a number of section corners determined in the field. The boundary of the Crook 

National Forest is based on the Forest Service's map of 1921, adjusted by means of several boundary markers tied in the triangulation net in the field. The boundary between Final and Graham 

counties is drawn on the basis of one boundary monument found in 

the field 'and the position of the boundary shown on the General 

Land Office's map of Arizona, 1921. It accords closely with the 

location of the boundary as indicated by several persons familiar 

with the region.

The geology was mapped simultaneously with the topography. 

Positions on or near geologic boundaries were determined by means 

of plane-table intersections, and the geologic features were sketched 

in the same manner as the topographic features. Thus the delinea-
8 ABAVAIPA AND STANLEY MINING DISTRICTS, AR1Z.

tion of the geology is as accurate as that of the topography but is 

similarly generalized. No attempt has been made to show dikes and 

other siriall masses of intrusive rock. In areas of complicated normal faulting, like that near Arivaipa village, it was necessary to 

generalize, as some of the blocks into which the rocks have been 

broken are too small to be shown.

TOPOGRAPHY

The Aravaipa-Stanley region is made up of small mountain 

ranges such as are characteristic of southern Arizona. In the 

eastern part are the Turnbull and Santa Teresa mountains, separated by the rocky valley of Black Rock Wash. On the north 

side is the detritus-floored valley of Gila Eiver. The hilly and 

mountainous country in the Stanley district is drained by a series 

of rather closely spaced and sharply incised gulches that lead 

northward into Gila River. On the west side of the Stanley district is the valley of Deer Creek, surrounded near its 'head by 

a horseshoe-shaped rampart of narrow ridges. This stream, which 

drains westward into Gila River, must not be confused with Old 

Deer Creek, on the boundary between the Aravaipa and Stanley 

districts. In the northwestern portion of the region are the mountains that form the southeast end of the Mescal Range. The valley of Arivaipa Creek forms the west end of the Aravaipa district. This stream is the largest in the area mapped and has water 

flowing at the surface in the portion of its valley known as the box 

canyon during the greater part of the year.

TURNBULL MOUNTAINS

The Turnbull Mountains form the largest mountain mass in the region. The northeastern part of this range was not reached during 

the present investigation. In plan, the range as a whole has the shape 

of a quadrilateral, roughly approximating a square 7 miles on a side, 

with several ridges projecting beyond the flanks of the main mass. 

(See PI. II.) The component ridges on the west side trend about 

N. 35° W., parallel to the west side of the range 'as a whole, but most 

of the larger ridges in the center of the mass trend almost at right 

angles to this. The range as a whole is a less compact unit than many 

others in southern Arizona. It has the appearance of a group of 

connected, serrate ridges, rather than a single dissected block. A 

number of the peaks in the area mapped reach altitudes of 7,000 feet 

above sea level, and Mount Turnbull itself may be almost 1,000 feet 

higher. The mountains rise 2,000 feet above the more open country 

to the west and south and even higher above Gila River, which encircles the range on the east and north. The maximum relief in the
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE I

II Of 3D1

V,

Cobre Gran<3e 

 -- -.Mtn .''

Gua conglomerate (firmly cemented grav

el, sand, and tuff, in part at least of

Pliocene age) overlain in

Andesite, rhyolite, rnyoute, anda latite, lauwithn minor i 

nts of tuff, sandstone, and

glomerate of fluviatile origin

Lava and volcanic breccia (principally andesitic) interbedded, especially m lower

shale, and coal beds containing fossils

y^ti-TWJ/ ^L«m«««e! J-^'T^S / 11" : " vs^r7x<a^ ^" .^

Pinnacle Ridge .....r,

ive quartzite, in part cross-bedded

and with some pebbly layers; in places

Final schist and associated igneous rocks

Granite of main batholith

goctaxe, microperthite, microWine-pink granite

(Coante granite, containing quartz, orthoclase 

microperthite, and biotite)

I IO°3O' R.I9 E. R.20 E.

GEOLOGIC SKETCH MAP OF THE ARAVAIPA-STANLEY REGION, GRAHAM COUNTY.

Scale ISCooo i ^ ^ o . l 2 3 4 5

Contour interval 100 feet

Datum* is mean sea level

1924,

ARIZ. Geology and topography 

by Clyde P. Ross, 1922

Section alon^ line B~B' Section alon^ line C~C 

1.

Section alon^S line D~D
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE I

IIO°3D'

33°

TOPOGRAPHIC SKETCH MAP OF THE ARAVA1PA-STANLEY REGION,GRAHAM COUNTY, ARIZ.

Scale 125,000 i 2

Contour interval 100 feet 

Datum is mean sea level

1924
TOPOGRAPHY . . 9

area mapped is about 4,000 feet. The slopes, are very steep, and most 

of the divides are sharp. The soil cover is thin, and rock projects 

through it in numerous places. The stream beds in general consist 

of bare rock, and there are many cliffs and rocky pinnacles. Large 

areas of the ridge slopes, however, are covered with a heavy growth 

of manzanita, scrub oak, and other brush. In places there are cedar, 

oak, and pine trees, some of which grow to considerable size. On the 

east flank of Cobre Grande Mountain and elsewhere in the eastern 

portion of the range are pine forests. Mescal and other agaves are 

rather generally distributed, especially on the lower slopes, cucumber 

cactus and other small rounded forms are common, and cholla and 

prickly pear are also found. The topography of this range is very 

rough. The trails follow the ridges for the most part, as the canyon 

bottoms are so encumbered with boulders and dry' waterfalls that 

a mounted man can not follow them for any distance. Even on the 

ridges traveling is precarious.

The Turnbull Mountains are surrounded by gently sloping plains 

into which numerous streams have cut gulches. (See PI. III.) 

All these streams are ephemeral, but near the heads of many of 

them water stands in pools and pockets or flows for°short stretches 

during a large part of the year..

On the slopes of some of the gulches in the northern part of the 

region are a few giant cacti, or sahuaros, not present elsewhere. 

The mountains rise above these dissected plains with striking abruptness. A surface whose grade is so slight as to be almost imperceptible to the casual observer may lie at the foot of a slope so steep that 

a horse can scarcely maintain his footing on it.

Stanley Butte is an impressive outlier of the Turnbull Mountains 

connected with the main range only by the narrow divide at the head 

of Garden Gulch. (See PI. III.) It appears to be exceeded in 

height among the peaks of the range only by Cobre Grande Mountain 

and Mount Turnbull. Copper Reef Mountain and the ridges north 

of it form connecting links of rugged heights between the Turnbull 

Mountains and the east end of Mescal Range.

The streamways across the mesa lands about the mountains are 

very sharply incised into them. The steep walls of the V-shaped 

canyons break off abruptly from the nearly level surface above. So 

sharp is the change in grade that to an observer on the surface of 

the mesa canyons at a little distance appear more like gentle swales 

than the deep gulches they are. An example of this is shown in 

Plate II, A. Between the observer and Stanley Butte is a precipitous-sided canyon, but only the rounded edges of the cut are 

visible in the picture. As the view also shows, the vegetation on these 

uplands is sparse. There are a few small cedars here and there, 

acacias and other bushes on the canyon slopes, low, inconspicuous
10 ABAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

rounded cacti in spots, a few agaves and cholla, and a scanty cover 

of bunch grasses everywhere.

MESCAL RANGE AND DEER CHEEK BASIN

The Mescal Eange ends in the northwest corner of the region in 

the rugged mass of Eawhide Mountain.2 The mountain rises 2,000 

feet above Hawk Canyon in a series of irregular scarps. This impressive northeast front, in which the frayed edges of the strata 

show in parallel bands of color, is pictured in Plate IV, A. On the 

southwest the slopes are smoother, have less diversified coloring, and 

rise only 1,000 feet above the base.

The basin at the head of Deer Creek southwest of Eawhide 

Mountain is one of the striking features of the region. It is a 

roughly rectangular area of rolling land into which the headwaters 

of Deer Creek are gnawing their way in a set of steep-walled, 

branching gulches. On three sides the basin is inclosed by a line 

of hills that form a continuous rampart except where streams have 

cut notches in them. The average width of the hills is less 

than a quarter of a mile, and their height is in most places little 

over 200 feet above the base. The slopes of these little hills 

are so steep as to be generally almost unclimbable by a mounted 

man. Many of the streams intersecting them on the south side have 

small but steep waterfalls in the gaps between the hills, adding to 

the effectiveness of the barrier. The rampart of hills is broader and 

less distinctly marked at the east end of the basin than at the sides. 

Beyond the hills at this end is the head of Hawk Canyon, in which 

the stream bed is more than 200 feet lower than the Deer Creek 

basin, at the foot of the hills. Outside the narrow rampart is an 

outer border of larger and more irregular elevations, of which 

Eawhide Mountain, already described, is the most prominent. Lookout Mountain, on the south side, is reported to have been so named 

because sentinels were stationed there by the coal prospectors to warn 

them of movements of troops from San Carlos in their direction. 

This was at the time when the coal fields were included in the 

Indian reservation, and mining was prohibited. South of Lookout 

Mountain, in the unmapped area, the country slopes off gradually 

into dissected uplands that broadly resemble Lone Cedar Mesa and 

the area around it.

SANTA TERESA MOUNTAINS

The Santa Teresa Mountains form a somewhat more compact unit 

than the Turnbull Mountains. In plan the shape of the range is 

that of a roughly equilateral triangle, approximately 7 miles on a

2 Name adopted by the United States Geographic Board, December 1922; also known 

locally as Hobson Mountain and Spion Kop.
U. S. GEOLOGICAL SURVEY BULLETIN 703 PLATE III

A. STANLEY BUTTE AND THE DISSECTED UPLAND SURFACE AT ITS 

BASE, FROM LONE CEDAR MESA

B. STANLEY AND LITTLK STANLEY BUTTES AND THE DISSECTED 

UPLAND AT THEIR BASE, FROM THE NORTH
U. S. GEOLOGICAL SURVEY 7JULLETIN "IB PLATE IV

A. RAWHIDE MOUNTAIN, KHOM THE SOUTHEAST

B. THE SUMMIT OF RAWHIDE MOUNTAIN, FROM A POINT ON ITS 

NORTHEAST FACE
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE V

NORTH SIDE OF THE SANTA TERESA MOUNTAINS, FROM FISHER 

PROSPECT

B. NORTHEAST FLANKS OF THE SANTA TERESA MOUNTAINS, FROM 

COBRE GRANDE MOUNTAIN
tT. S. GEOLOGICAL SURVEY

A. CLIFF OF TUFF AND SANDSTONE OF 

THE GILA FORMATION ON THE EAST 

SIDE OF TURKEY CREEK

BULLETIN 763 PLATE VI

B. CLIFF OF CONGLOMERATE OF THE 

GILA FORMATION IN ARIVAIPA BOX, 

NEAR T RAIL RANCH
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE VII

A. THE SOUTH SIDE OF THE SANTA TERESA MOUNTAINS AND THE 

PLAIN AT ITS BASE

The plain is cut in quartz monzonite; the mountain at the left side of the picture is 

Buford Hill, formed of metamorphic rocks; in the center is Pinnacle Ridge, carved 

from granite

B. CAMBRIAN QUARTZITE IN ARIZONA CANYON NEAR ARIVAIPA
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE VIII

iiLTED MIOCENE (?) CONGLOMERATE SOUTH OF THE SAFFORD ROAD

B. TILTED CROSS-BEDDED SANDSTONE WITH LAVA BELOW, BOTH OF 

MIOCENE (?) AGE, IN ARIZONA CANYON JUST ISELOW THE CLARIDGE 

RANCH
TOPOGRAPHY 11

side. (See PL II.) The apex is formed by Buford Hill, on the 

south side, and the base on the north trends nearly east. The main 

portion of the range, exclusive of Buford Hill and its attendant 

outliers, is a narrow irregular but continuous ridge, concave on the 

north side. The altitude of the summits increases from about 6,300 

feet in the west to about 7,000 feet in the east. The western half 

of this ridge, especially on the north, is rugged in the extreme. Soil 

is scanty everywhere in this portion of the mountains, and in most 

places it is almost completely absent. Eocky pinnacles, rough cliffs, 

and narrow canyons abound. Such vegetation as exists finds precarious footholds in crevices in the rocks and in canyon bottoms. 

In the eastern portion of the range there is a considerable area on 

the top of the main ridge which is comparatively flat and covered 

with pines and other vegetation. On the north side are impressive 

cliffs, as can be seen in Plate V, A. On the south the slopes are 

steep but less intricately carved than those farther west.

West of the Santa Teresa Mountains is a dissected plain like that 

west of the Turnbull Mountains, forming the upper slopes of the 

east side of this portion of the valley of Arivaipa Creek. Corresponding level areas, dissected, especially on their edges, by steepwalled gulches, are present on the west side of the valley.

South of the Santa Teresa Mountains is a broad, slightly rolling 

plain, separating them from the Graham Mountains. (See PI. VII, 

A.) Tributaries of Arivaipa Creek have bitten deeply into the 

periphery of this plain, but several square miles of almost featureless surface still remains. The comparatively level areas described 

above and the gulches between them support a scattered vegetation 

of bunch grasses, manzanita, laurel, mesquite, and other bushes, 

various cacti, mostly small, and several species of agave. The 

. bushes are more abundant on the gulch walls and the grasses on the 

level uplands.

North of the Santa Teresa Mountains is Black Eock Wash. Except at the head of this stream, where erosion has not yet accomplished so much, little suggestion of level surfaces remains. On 

the contrary, this side of the mountains is rugged and desolate in 

the extreme. Steep, branching canyons are so closely spaced that 

no room is left for gentle slopes. Everywhere are cliffs and pinnacles, whose fantastic shapes have been carved from bare granite. 

The scene has a grim, forbidding beauty all its own. (See PI.

v,#.)

ABIVAIPA CREEK

Arivaipa Creek flows through a broad valley west of the Santa 

Teresa Mountains. Its slopes, above the box canyon, are smooth, 

steep, and terraced, with occasional small bluffs, especially in the
12 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

southern part. The average width of the valley is about 6 miles. 

The stream has. cut below the level of the upland plains at the base 

of the mountains to a depth of some 1,500 feet. The divide between 

Arivaipa Valley and Sulphur Spring Valley, on the south, is so 

low and smooth that a traveler might well pass from one valley 

to the other without realizing it. Along Arivaipa Creek is a flood 

plain more than a mile in width over which are dotted numerous 

ranch houses with small irrigated patches near them. There are 

groves of cottonwoods and other trees in the upper part of the 

valley, and mesquite and acacia thickets below.

About 3 miles below Klondyke the topography of the valley 

changes. Here the stream enters a precipitous-walled gorge carved 

out of Gila conglomerate. This is the upstream end of Arivaipa 

Box. which farther west is cut in resistant beds of Tertiary volcanic 

rocks that form the north end of the Galiuro Mountains. The walls 

in many places are nearly vertical. (See PI. VI. One of these 

views was taken in the tributary Turkey Creek, but it is characteristic of large parts of the main canyon also.) Water flows at the 

surface throughout the year in Arivaipa Box. It is confined between 

banks some 3 feet high on the average, and the streamway is notably 

narrower than that in the more open valley above. The presence 

of flowing water has produced verdure which makes this canyon a 

place of unusual beauty in this semiarid land. There are green 

grass, bushes of various sorts, and stately cottonwood trees. A 

number of the level patches of ground have been utilized for irrigated crops, principally forage.

The divide west of Stanley Butte, between the drainage basins 

of Arivaipa Creek and Hawk Canyon, is almost as unobtrusive as 

the divide on the south already mentioned. The stream valleys in 

the upper part of the Hawk Canyon drainage basin are steep-sided 

gulches cut in an originally almost level plain. Farther north, 

Hawk Canyon passes for a few miles between narrow ridges, outliers of the Turnbull Mountains, on the east, and the steep and 

rough east end of the Mescal Range, on the west. Near the northwest corner of the area mapped it swings west and eventually finds 

its way into Gila River.

STRATIGRAPHY AND PETROLOGY

MAJOR FEATURES

The basement of pre-Cambrian metamorphic rocks underlying 

southern Arizona crops out in several places in the Aravaipa-Stanley 

region. The Paleozoic strata are well represented in the northern 

part of the region, and there are fragments of them to the south. 

In several particulars the Paleozoic section does not correspond
METAMORPHIC BOCKS (PRE-CAMBRIAN) 13

with those in neighboring regions. The Apache group, at the 

base of the section, regarded as chiefly if not wholly of Cambrian 

age, is represented only by quartzite of variable thickness, lithologically resembling the Troy quartzite, and minor amounts of 

other kinds of rock. Above this is the Devonian Martin limestone, 

but it is nowhere prominent and in places appears to be absent. 

The Carboniferous Tornado limestone is typically developed. The 

character of some poorly preserved and scanty fossils from this 

limestone near Arivaipa suggests the possibility that beds of upper 

Mississippian age, apparently absent in the Tornado limestone 

farther west, are present here. Above the Tornado are volcanic 

and sedimentary beds of shallow marine origin containing fossils 

of Colorado age, thus shifting the known extent of the inland 

Cretaceous sea farther -south and west. Batholithic masses of 

granite and quartz monzonite, probably intruded near the beginning 

of Tertiary time, occupy a large part of the region. There are 

extensive exposures of Tertiary volcanic strata and Tertiary and 

Quaternary alluvium.

METAMORPHIC ROCKS (PRE-CAMBRIAN) 

FINAL SCHIST

Definition and distribution. All the metamorphic rocks in the 

region, except those of intrusive igneous origin, are included under 

the term Final schist, which has been adopted by Eansome 3 for 

similar rocks in the Final Eange and elsewhere in Arizona. The 

resemblance in stratigraphic relations, metamorphism, and most of 

the petrologic characters is so striking as to leave no doubt of the 

validity of the correlation.

Schist crops out in a number of places in this region but on 

Plate I has not been separated from the metamorphosed igneous 

rocks. One of the largest areas of schist is on the south and southwest borders of the Santa Teresa Mountains, where it covers several square miles, including Buford Hill and most of the adjacent 

heights. There is another large area at the south end of the Turnbull Mountains, where a large part of Cobre Grand Mountain is 

composed of this formation. Some schist occurs in the metamorphic 

igneous complex on the north side of the Turnbull Mountains, and 

small strips of similar rocks are found on the south side of the 

headwater basin of Deer Creek and north of Copper Reef Mountain.

Character. In the area about Buford Hill the schist is of two 

general types. On Buford Hill itself and on Quartz Hill, north of

3 Ransome, F. L., Geology of the Globe copper district, Ariz.: U. S. Geol. Survey Prof. 

Paper 12, p. 23, 1903.
14 ABAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

it, the rock is largely hard quartzitic schist. In some outcrops 

bedding can be distinctly seen. The schistosity strikes nearly parallel to the bedding and dips in the same direction but at steeper 

angles. The rock is composed essentially of quartz and muscovite. 

It is white with a silvery sheen on the schist planes, caused by the 

mica. It is harder than the rocks around it and therefore forms 

ridges, but, like many schists, it is friable, and its outcrops tend to 

weather into masses of small fragments. The contrast between the 

topography of Buford Hill, formed largely of quartzitic schist, and 

that of Pinnacle Ridge, formed of granite, can be seen by a glance 

at Plate VII, A.

The other type of schist in this area is a rather soft greenish-gray 

rock, intensely sheared and thoroughly recrystallized, with a dull 

satin sheen on schist planes composed essentially of quartz, alkali 

feldspar, sericite, and chlorite. In some specimens there is a faint 

banding which may be bedding. This rock is similar in appearance, 

composition, and degree of metamorphism to much of the typical 

Pinal schist of the Pinal Eange. It covers most of the area mapped 

as pre-Cambrian along the southern border of the Santa Teresa 

Mountains and extends eastward beyond the area mapped. The 

rocks of intrusive origin described below are of subordinate areal 

extent.

The quartzitic schist was noted only in the two localities already 

mentioned. It is interbedded with the fine-grained schist. The 

lenticular masses of quartzitic schist strike approximately parallel 

to the average strike of the schistosity. The fine schist weathers 

down even more readily than the quartzitic variety. Few outcrops 

project notably above the surrounding surfaces, and the characteristic topographic forms are smooth and, considering the location, 

not steep. A number of small dikes of metamorphosed dioritic and 

diabasic rocks cut the schist in places.

From the data summarized above, it is evident that the two varieties of Pinal schist in the Buford Hill area are derived by 

metamorphism from stratified rocks, probably of sedimentary origin. 

The quartzitic variety was probably derived from a rather pure 

quartz sandstone, and the fine variety doubtless came from a mudstone.

The other large area of schist is on Cobre Grande Mountain. The 

most abundant rock here, 'although thoroughly metamorphosed, is 

less markedly schistose than that just described. It is composed 

largely of quartz with subordinate sericite and breaks up readily 

.into small angular blocks bounded by joint planes. In some places 

there is fairly well marked schistosity, which has an average strike 

of N. 40° E. and a nearly vertical dip. The rock is nearly white on 

fresh surfaces but in most outcrops is stained yellow or brown by
METAMOEPHIC BOCKS (PRE-CAMBRIAN) 15

limonite. It is probably ji much metamorphosed sedimentary rock. 

It is cut by numerous felsitic dikes, mostly light-colored rhyolite. 

These dikes in their bleached and weathered outcrops can not alw&ya 

be readily distinguished from the schist, and not only have they 

been omitted in mapping, but the actually irregular contact of the 

schist with the rhyolite to the west has been generalized. This is 

probably in part a fault and in part 'an intrusive contact. Similar 

schist crops out on the north side of the Turnbull Mountains but 

has not been separated in mapping from the metamorphosed igneous 

complex.

North of the Copper Reef mine is a narrow strip of metamorphic 

rock exposed in a gulch on the west slope of the ridge. It is overlain on the south by Cambrian quartzite and 'adjoined on the north 

by wine-pink granite. The rock is a gritty schistose quartzite with 

numerous scattered pebbles, most of which are quartz. It is distinguished from the younger quartzite above it by the greater metamorphism and by the lack of well-marked bedding. A wedgelike 

mass of schist resembling that on the southwest side of the Santa 

Teresa Mountains lies on the south side of the basin of Deer Creek. 

The depression south of the limestone rampart here is carved in 

such rock.

Age. The rocks described above are all similarly metamorphosed. 

They are by far the most thoroughly metamorphosed rocks of sedimentary origin in the region, if local alteration due to mineralization is excluded, and are older than any of the other formations. 

The oldest nonschistose rock in the region is of Cambrian age. From 

these facts it seems evident that the schistose rocks here, as in neighboring parts of Arizona, are pre-Cambrian. Possibly, as Ransome * 

has suggested for the same formation in the Ray-Globe region, their 

age may be somewhat more closely given as Archean.

GRANITIC GNEISS

The rock described under the name granitic gneiss is the metamorphosed rock of granitic composition on the south side of the Santa 

Teresa Mountains. It is readily distinguished from the other granite 

in this vicinity by its much greater metmorphism. This rock forms 

most of the southern slopes of the line of ridges between Buford Hill 

and Cottonwood Wash and may occur farther east.

The rock is medium grained and predominantly pinkish gray 

mottled by greenish-brown biotite spangles which are grouped in 

thin, roughly parallel bands, giving it a distinctly gneissic appearance. It is composed essentially of quartz, orthoclase, andesine, and 

biotite. The gneissic texture is due partly to a segregation of coarse

* Ransome, F. L., Copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey Prof. 

Paper 115, p. 32, 1919.
16 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

and fine grains of quartz and feldspar in^ bands and partly to the 

parallel arrangement of the biotite shreds. The biotite is somewhat 

chloritized, but the feldspar is little altered less so, in fact, than 

much of that in the younger granite in the vicinity. The texture is 

clearly that of <a medium-grained intrusive rock that has been subjected to much compressive stress. Quartz is abundant, and the 

plagioclase is subordinate in amount to the alkali feldspar, so that 

the rock is evidently a^ granite rendered gneissoid by metamorphism. 

This rock is very probably intrusive into the Final schist, which 

surrounds it, and is therefore younger than that formation. Like 

the schist, however, it has been subjected to strong metamorphism 

and is therefore assigned to the pre-Cambrian.

METAMORPHIC IGNEOUS COMPLEX

The rocks on the north side of the Turnbull Mountains mapped as 

pre-Cambrian on Plate I are, with the exception of a number of 

small dikes, all metamorphosed, and most of them are of igneous 

origin. They may therefore be grouped under the term " metamorphic igneous complex." They occupy more than 8 square miles 

in the northwest end of the Turnbull Mountains and are almost completely circumscribed by granite and the related rhyolite.

This part of the region received only a somewhat cursory examination. There are no mines and no prospects of consequence in it, and 

the ruggedness of the country and the thick cover of brush and trees, 

coupled with the scarcity of satisfactory outcrops in many places, 

made an adequate study of what is obviously somewhat complicated 

geology too time-consuming to be practicable. Four general types 

of rock were noted chloritic schist; a coarse-grained, foliated igneous rock akin to diorite; quartzitic schist; and dikes of later, 

unmetamorphosed felsite.

The chloritic schist is evidently a metamorphosed trap. It is 

widely distributed in the southern part of the metamorphic area. 

Its relations to the other rocks are not clear, but it seems to form 

irregular masses of considerable size and is believed to be a finegrained subsilicic intrusive igneous rock that has suffered strong 

metamorphism. Quartzitic schist like that of Cobre Grande Mountain was noted near the chloritic rock on some of the high ridges. 

Farther north, on the south side of Kelly Gulch, some of the ridges 

are composed of a rather coarse-grained intrusive rock which seems 

to be a diorite, although some phases of it may be more silicic. This 

rock is less metamorphosed than those mentioned above, but most 

outcrops show distinct foliation. The later dikes in this area are 

mostly quartz porphyry related to the granite batholith.

The chloritic and quartzitic schists are so metamorphosed that 

they can scarcely be other than pre-Cambrian, and the quartzitic
STRATIFIED ROCKS 17

variety doubtless belongs to the Final schist. The dioritic rock 

is less altered, but its texture is distinctly foliated, a feature which 

seems to indicate more intense pressure than affected the Paleozoic 

rocks. It is therefore also considered pre-Cambrian, although probably much later than the Final schist. Slightly metamorphosed 

granitic rock has been referred to the pre-Cambrian in the CliftonMorenci B and other districts in Arizona.

STRATIFIED BOCKS 

CAMBRIAN QUARTZITE

Definition and distribution. The lowest formation of the Paleozoic section is here termed simply the Cambrian quartzite. The 

lack of the other formations of the Apache group makes positive 

correlation with the section worked out by Ransome 6 in the RayGlobe region difficult. Consequently a noncommittal name has been 

adopted, but the evidence for correlation is discussed below, in the 

paragraph on age.

The Cambrian quartzite is scattered in small areas throughout 

the region. Although doubtless once continuous over the whole 

region it has since been shattered by faulting, carved by erosion, 

and covered by later deposits, until comparatively little of it is 

now exposed. Strips of this formation occur in the northern part 

of the region in several places; the largest one is on Copper Reef 

Mountain and in the band that stretches from Quartzite Mountain 

to the northeast flank of Limestone Mountain. There are blocks 

of it on the south side of the Deer Creek basin, in the vicinity of 

Arivaipa, and on the northwest end of Cobre Grande Mountain. 

There seems to be a notable thickness of quartzite in the east end 

of the Santa Teresa Mountains, but this part of the range was not 

visited during the present investigation. The quartzite shown on 

Plate I as occurring at the east end of the range was mapped on the 

basis of long-distance observation supplemented by information 

furnished by Frank Landsman, who has prospected in that part of 

the region. The cliffs formed on the thick resistant beds of this rock 

and the contrast between the topography developed on them and 

that on the granite which forms the western part of the range are 

shown in Plate V, A. Loose quartzite blocks and a small amount of 

conglomerate in place were found near the La Clede mine, east of 

Klondyke.

Character. The quartzite is white to buff on fresh surfaces, though 

in places stained yellow or red by iron oxides. Quartz pebbles

e Llndgren, Waldemar, Copper deposits of the Ollfton-Morend district, Arlz.: U. S. 

Geol. Survey Prof. Paper 43, pp. 66-58, 1905.

6 Ransome, P. !>., Copper deposits of Bay and Miami, Ariz.: TJ. S. Geol. Survey Prof. 

Paper 115, pp. 30-31, 1919.
18 ABAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

scattered through or arranged in narrow bands in the fine to medium grained quartzite were seen in a number of outcrops. The 

beds are from 1 foot to several feet thick, with considerable smallscale cross-bedding.

On the hill east of Arivaipa, sometimes called Quartz Hill, the 

quartzite is underlain by several score feet of banded greenish-gray 

shale, which crumbles readily. The contact between the shale and 

the quartzite is even and sharp, with no indication of unconformity 

except the abrupt change in the character of the sediments. The 

lower part of the shale rests against a fault block of Tornado limestone. Similar shale was noted on the slopes of Cobre Grande 

Mountain, but it was not observed in the Stanley district.

The thickness of the formation is variable, and the prevalence of 

normal faults makes measurements somewhat unreliable. In the 

vicinity of Arivaipa the total thickness of quartzite and underlying 

shale can not much exceed 200 feet. In the Stanley district the 

thickness of the quartzite is more than 400 feet, and in the vicinity 

of Quartzite and Limestone mountains it seems1 to be over 500 feet. 

Walcott 7 estimated 1,000 feet of quartzite north of Rawhide Mountain, but this estimate is probably too large. As seen from a distance, 

the thickness of quartzitic beds in the east end of the Santa Teresa 

Mountains seems to be great. It is easily as much as 1,000 feet 

and may well be more. The quartzite here is reported to be underlain by granite.

Between Quartz Hill and the border of the Gila conglomerate a 

number of blocks of nonschisto°se quartzite and quartzitic conglomerate were noted lying loose on the surface of the ground. The 

only known outcrop of rock of this sort in place in this part of the region is in the gulch where the La Clede mine is situated, a few hundred feet upstream from the mine. These loose blocks vary somewhat 

in lithologic character, but all bear a resemblance to members of 

the Apache group of Ransome.8 Some are light-colored quartzite, 

with or without cross-bedding, which might belong to either the 

Troy or the Dripping Spring quartzite. Some are conglomerate 

with quartzose pebbles resembling the Barnes conglomerate. These 

blocks are so numerous and have outlines so angular that they can 

not have been transported far from the place where they were 

formed, yet no such rock is" known in place here. The conglomerate 

in place near the La Clede mine resembles lithologically the Scanlan 

conglomerate of the Ray-Globe region. It is composed of fairly 

well rounded but poorly sorted pebbles of quartz, schist, and decomposed granitic rock in a coarse arkosic matrix. It is a hard, thor7 Walcott, C. D., and Bannon, M., Deer Creek coal field, White Mountain Indian Reservation, Ariz.: 48th Cong., 2d sess., S. Ex. Doc. 20, p. 7, 1885.

8 Ransome, F. L., Copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey Prof. 

Paper 115, p. 50, 1919.
STRATIFIED BOOKS 19

oughly cemented rock but not in the least schistose. It is clearly 

younger than the Final schist, on which it lies. The outcrop is so 

small that it is not distinguished from the schist on the geologic map.

Age. The stratigraphic relations and general lithology of the 

quartzite and accompanying shale indicate that they are broadly 

equivalent to some portion of the Apache group. Lithologically the 

quartzite resembles more closely the Troy quartzite than any other 

formation of that group. Kansome 9 states that the pebbly character is " a useful means of distinguishing isolated exposures of the 

Troy quartzite from the pebble-free Dripping Spring quartzite." 

The quartzite in the Aravaipa-Stanley region contains pebbles in 

places, although nowhere abundantly. It is also, like the Troy 

quartzite, cross-bedded. The stratigraphic relations of the formation can be seen on Packwood Peak, in the northern part of the 

region. Here the quartzite overlies a complex of pre-Cambrian 

rocks and later dikes. The contact is irregular, and doubtless there 

is an unconformity, although the pinching out of the quartzite to 

the south, shown on Plate I, may be due to structural disturbance. 

The Paleozoic beds here are offset by several small faults. The 

quartzite beds parallel those of the dark limestone above, and, so 

far as could be determined, the limestone, which is believed to be 

part of the Martin limestone, rests conformably on the quartzite, 

just as the Martin limestone of the Ray-Globe region rests on the 

Troy quartzite. The relations are similar north of the Copper Reef 

mine, except that here the Martin limestone was not identified and 

it appears that the Tornado limestone rests directly on the quartzite. Thus it seems probable that the quartzite of the AravaipaStanley region is equivalent to the Troy quartzite of the Ray-Globe 

region, but the evidence of exact equivalency seems insufficient to 

justify the application of that formation name. The Cambrian 

quartzite of the Aravaipa-Stanley region has some points of lithologic similarity with the Coronado quartzite of the Clifton-Morenci 

district,10 which is probably of Cambrian age. Ransome u has suggested that the Coronado quartzite may be equivalent to the Bolsa 

quartzite of Bisbee, and further that the Bolsa may be equivalent 

to the Dripping Spring quartzite or to that quartzite and all the 

Apache group below it. Unless the formations can be adequately 

traced from one region to another uncertainties in correlation are 

likely to remain.

The proper correlation of the shale that in places appears at the 

base of the quartzite and has been mapped with it is even more

8 Op. clt., p. 44.

10 Lindgren, Waldemar, The copper deposits of the Clifton-Morenci district, Ariz.: U. S. 

Geol. Survey Prof. Paper 43, pp. 59-60, 1905.

11 Ransome, F. L., Some Paleozoic sections in Arizona and their correlation: U. S. 

Geol. Survey Prof. Paper 98, p. ^64, 1916.
20 ARAVAIPA .AND STANLEY MINING DISTRICTS, ARIZ.

puzzling. Doubtless it belongs somewhere in the Apache group, but 

whether it is equivalent to shaly beds in the Dripping Spring quartzite or to part of the Pioneer shale or is the time equivalent of some 

lithologically different rock is not known.

If, as'suggested above, the quartzite is equivalent to the upper part 

of the Apache group, then it is probably of Upper Cambrian age.18

MARTIN LIMESTONE (DEVONIAN)

Definition and distribution. The Martin limestone is defined by 

Kansome 13 as the thin-bedded limestone, chiefly if not wholly of Devonian age, which is stratigraphically between the Troy quartzite 

and the Tornado limestone. Beds correlated with this formation are 

present in the Aravaipa-Stanley region, but the area covered by 

rock known to be of this age is so small that it has been included in 

mapping with the overlying Tornado limestone. Rock believed to 

belong to this formation is present near the summit of Packwood 

Peak. It has not been identified elsewhere in the region during the 

present investigation. Walcott 14 found limestone of this age somewhere in the vicinity of the coal prospects on Deer Creek, apparently 

on the south side. His description is not sufficiently clear to make 

it possible to determine the exact locality. The limestone observed 

during the present investigation south of the " upper coal field " is 

lithologically similar to characteristic Tornado limestone, but a small 

exposure of Martin limestone might have been overlooked in the 

course of the necessarily hasty examination. If any Martin limestone 

is present between the Cambrian quartzite and Tornado limestone on 

the ridges north of Copper Reef Mountain it is either a narrow band 

or else so similar lithologically to the Tornado as to be mistaken for 

that rock.

Character. The formation lying between the Tornado limestone 

and Cambrian quartzite on Packwood Peak is in part black, rather 

soft shale, in part black dense limestone. This is the only place 

where rock differing in this way from the formation above and below was observed in this stratigraphic position. The shale and limestone together have a thickness estimated as of the order of 100 

feet. Walcott 14 gives the thickness of the Devonian limestone he 

found as 50 feet, but one side is bounded by a fault, so that the total 

thickness may not be present. The Devonian is evidently not thick 

anywhere in this region and is apparently absent in places.

12 Ransome, F. L., Copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey Prof. 

Paper 115, p. 31, 1919. Ross, C. P., Ore deposits of the Saddle Mountain and Banner 

mining districts, Ariz.: U. S. Geol. Survey Bull. 771 (in preparation).

18 Ransome, F. L., Some Paleozoic sections in Arizona and their correlation: U. S. 

Geol. Survey Prof. Paper 98, p. 141, 1916.

14 Walcott, C. D., and Bannon, M., Deer Creek coal field, White Mountain Indian Reservation, Ariz.; 48th Cong., 2d sess., S. Ex. Doc. 20, p. 7, 1885.
STRATIFIED ROCKS 21

Age. As no fossils were found in the dark limestone on Packwood Peak the age can not be fixed from data gained in this investigation closer than somewhere between the Cambrian and the 

Mississippian. Walcott,15 however, found the following fossils of 

Devonian age in limestone near the " upper coal field ":

Stromatopora sp.?

Michelina sp. undet.

Heliolites sp.?

Alveolites sp.?

Cladopora sp.?

Aulopora, 2 sp.

Acervularla pentagona Goldfuss.

Phillipsastrea verneuili Milne-Edwards.

Diphyphyllum simcoense Billings.

Walcott's collection in the National Museum was kindly reexamined by Edwin Kirk for the present report. Possibly the fossils 

in this collection came from a slightly different locality from those 

in the above list, but the label with the collection states that they 

came from a point 13 miles south of the San Carlos Agency, which 

is the distance of the coal field from the agency according to Walcott, 

so they are probably from nearly the same place as those he listed. 

Mr. Kirk's list, given below, is so similar to that of Walcott that 

there can be no doubt of the similarity of the faunas, if they are not 

actually identical.

Aulopora spl 

Stromatopora sp. 

Pachyphyllum sp. 

Cladopora sp. 

Alveolites sp. 

Acervularia sp. 

Syringopora sp.

In regard to this collection Mr. Kirk states:

No specific determinations of these corals have been given, as they could 

be of little value. Little attention has been paid to the Devonian corals for 

many years, and accurate comparison of western forms with eastern species 

is at present out of the question. The fauna is doubtless the same as that 

of the Martin limestone, the age of which has been discussed by Williams in 

Professional Paper 21. The age is late Middle Devonian, and the resemblance 

to the Upper Devonian of New York is perhaps less striking than suggested 

by Williams.

E. M. Kindle 16 has shown that the Martin limestone also includes 

rocks of Upper Devonian age.

The paleontologic data above set forth are sufficient to establish the 

presence of the Martin limestone in the Aravaipa-Stanley region. 

On account of their stratigraphic position and lithology, the beds on 

Packwood Peak, described above, are believed to belong to it, and 

closer study would doubtless reveal other outcrops.

16 Op. cit., p. 7.

>" U. S, Geol. Survey Prof. Paper 98, p. 142, 1917.
22 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ. 

TORNADO LIMESTONE (CARBONIFEROUS)

Definition and distribution. The Tornado limestone as defined by 

Kansome 18 in the Ray-Globe region is the Carboniferous limestone 

overlyitig the Martin limestone. As will be shown below, the 

equivalency of the principal limestone formation in the AravaipaStanley region to the Tornado limestone has been clearly established.

The Tornado limestone is found in a number of fault blocks of 

varying size in the vicinity of Arivaipa and around Cobre Grande 

Mountain. Like those of the Cambrian quartzite, the exposures 

here are more cut up by faults than could be indicated on the map 

(PI. I). The most prominent and continuous exposure of the formation in the region is that which stretches from Packwood Peak 

through Stanley and Copper Reef Mountain and extends to the 

northwest beyond the limits of the area mapped. The rampart of 

hills around the headwater basin of Deer Creek, described in some 

detail in the sections on topography and structure, is composed of 

this formation.

Character. The Tornado limestone is a massive formation built 

up of beds from 1 foot to several feet thick. The color of fresh surfaces varies from rather light gray to almost black with a bluish 

cast. Weathered surfaces have a lighter color, resembling that of 

Portland cement. Irregular siliceous concretions, usually small, are 

present in many beds. The formation contains little argillaceous 

material and is resistant to weathering, forming cliffs in many places. 

Where cliffs have not been formed elevations underlain by the limestone commonly ascend in a series of steps composed of resistant 

beds. It does not form soil readily and stands up in prominent bare 

outcrops, on most of which the scanty vegetation finds foothold only 

in cracks and crevices. A characteristic outcrop is shown in Plate 

IX, A.

The full thickness of the Tornado limestone is nowhere exposed in 

the Aravaipa district unless it is on Liine Hill, northwest of Cobre 

Grande Mountain, where, allowance being made for faulting near the 

base, about 1,000 feet of limestone is estimated to be present. The 

section measured by Tolman 19 on the claims of the Royal Tinto 

group contained only 500 feet of limestone, and the exposed thickness 

in some of the fault blocks is much less than this. Northwest of 

Copper Reef Mountain, in the Stanley district, where the formation 

is better exposed, the thickness is about 1,200 feet, and on Limestone 

Mountain it is probably equally great. Walcott 20 gives 1,200 feet as

»* Ransome, F. L., Some Paleozoic sections in Arizona and their correlation: U. S. Geol. 

Survey Prof. Paper 98, p. 142, 1916.

1B Tolmari, C. F., unpublished report on the property of the Royal Tinto Mining & 

Smelting Co., Dec. 3, 1910.

20 Walcott, C. D., and Bannon, M., op. cit., pp. 5-7.
STRATIFIED ROCKS 23

the thickness of Carboniferous limestone on the north side of the 

headwater basin of Deer Creek but adds that north of this locality 

there is a mass of Carboniferous limestone 2,500 to 3,000 feet thick. 

No such thickness as that exists in the Aravaipa-Stanley region. 

The average thickness in the Stanley district is about 1,200 feet, and 

the maximum does not exceed this by more than 200 feet. This is 

slightly greater than the average thickness of the Tornado limestone 

in the Eay-Globe region as at present exposed.

Age. The limestone north of Deer Creek is an extension of that 

in the Mescal Range and can be traced in practically continuous 

outcrop along that range from the head of Deer Creek into the Eay 

quadrangle, where it has been mapped by Ransome 21 as Tornado 

limestone. The correlation based on continuity along the strike and 

similarity in lithology and stratigraphic position is strengthened by 

the paleontologic evidence. Traces of organisms were found in many 

outcrops of the limestone, but they were for the most part broken 

and poorly preserved. All the fossils obtained from the limestone are 

considered by G. H. Girty to be of Mississippian age. The forms, 

however, differ from those he identified in collections made by 

Ransome 22 in the Ray quadrangle. The collections from the Aravaipa-Stanley region came from fault blocks in the area between 

Arivaipa and Lime Hill. They doubtless all came from beds in the 

lower part of the formation. There can be little doubt that the 

Pennsylvanian is represented in the upper part of the Tornado 

limestone in the Aravaipa-Stanley region, as it is in the Ray quadrangle and elsewhere in Arizona. The fossils are listed below.

Lot 4202:

Hydreionocrinus aff. H. acauthophorus.

Derbya? sp.

Productus aff. P. altonensls.

Productus aff. P. setiger.

Spirifer aff. S. pellensis.

Spiriferina sp.

Griffithides sp. 

Lot 4202-a:

Productus ovatus.

Productus sp.

Productella? sp.

Pustula aff. P. punctata.

Spirifer aff. S. pellensis.

Spiriferina sp.

Composita sp. 

Lot 4205:

Lithostrotlon aff. L. basaltlforme.

21 Ransome, F. L., U. S. Geol. Survey Geol. Atlas, Ray folio (No. 217), 1924.

22 Ransome, F. L., The copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey 

Prof. Paper 115, p. 47, 1919.
24 ABAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

Mr. Girty, in his report on these collections and others from the 

vicinity of Christmas, Ariz., submitted to him at the same time and 

to be discussed in a forthcoming paper, makes the following comments :

The material from the Aravaipa district is exceptionally poor and unsatisfactory, so that no reliable conclusions can be drawn from it. Furthermore, 

It does not fit in well with the faunas from the Christmas district, as one 

would naturally expect Lots 4202 and 4202-a were collected at about the 

same locality, but the faunas are by no means identical. They are clearly 

unlike any of the Pennsylvanian faunas from the Christmas district, nor do 

they present any of the well-known aspects of the lower Mississippian faunas. 

These two facts, if they imply that the faunas are neither lower Mississippian 

nor Pennsylvanian, suggest that the horizon is upper Mississippian, and such 

may actually be its age, though no upper Mississippian is as yet known in the 

region. An upper Mississippian age is also suggested by the Lithostrotion 

found in lot 4205, for this type of coral is very common in rocks of upper 

Mississippian age in both the East and the West, especially the East. In the 

West, however, it seems to occur also in the Pennsylvanian, real refinement 

in specific or even in generic distinctions not having been made in this group.

Thus the paleontologic evidence, while confirming the Carboniferous age of the limestone, suggests the interesting possibility that 

the upper Mississippian, hitherto unknown in this part of Arizona, 

may be present in the Aravaipa district.

Paleontologic data as to the presence of Pennsylvanian beds in 

this formation are available to supplement the evidence of field relations. Walcott 23 collected fossils in the upper part of the limestone north of the " upper coal field," which are, according to G. H. 

Girty,24 clearly of Pennsylvanian age. The list of fossils as determined by Walcott follows:

Fusulina cylindrica. 

Crinoid stems. 

Zaphrentis. 

Syringopora.

Productus semireticulatus. 

Spirifera camerata. 

Spirifera rockymontana. 

Spiriferina cristata. 

Eetzia radialis. 

Athyris subtilita.

Thus, on lithologic, stratigraphic, and paleontologic grounds and 

on the evidence of field relations to previously known outcrops of 

the formation, the thick series of limestone beds in the AravaipaStanley region may be confidently correlated with the Tornado limestone. As already explained, in some places in the region a small 

thickness of beds at the base of the limestone as mapped belongs to 

the Martin limestone.

z» Walcott, C. D., and Bannon, M., op. cit., p. 7. 

24 Personal communication.
STRATIFIED, BOCKS. 25 

CRETACEOUS ROCKS

Definition and distribution. The rocks lying stratigraphically 

above the Tornado limestone are here termed simply the Cretaceous 

rocks. Their age has been determined on fossil evidence, but the 

available data do not seem to warrant assigning a formation name. 

The sedimentary part of the assemblage may, as explained below, be 

equivalent to the Pinkard formation of the Clifton-Morenci district. 

This name might have been tentatively used were it not for the 

large amount of volcanic rock present in the Cretaceous of the Aravaipa-Stanley district. No volcanic rocks are present in the Pinkard 

formation in the Clifton-Morenci district, and the extension of the 

formation name to include them is not warranted on present information. On the other hand, the equivalence of part of the Cretaceous 

rocks in the Aravaipa-Stanley region to the Pinkard formation is 

sufficiently probable to make a new name seem inadvisable.

The Cretaceous rocks form a band extending from the northwest 

corner of the area mapped up Hawk Canyon to Garden Gulch, passing around the northeast side of Stanley Butte, and reaching the 

ridge crests on the south side of Old Deer Creek. Another mass 

forms the floor of the headwater basin of Deer Creek inside the line 

of limestone hills.

Character. The Cretaceous rocks in this region are of two general types sedimentary and volcanic. The rocks of these two types 

are so interbedded, both here and in the Christmas quadrangle, to 

the west, that it was impracticable to separate them in mapping. 

In a broad way, the lower strata are predominantly of sedimentary 

origin and those above of volcanic origin. Lava is, however, found 

near the base of the series, and sedimentary strata occur well up 

among the volcanic beds.

The sedimentary beds consist of sandstone, shale, and conglomerate. The sandstone is hard and somewhat calcareous. It is distinctly though in places irregularly bedded. Weathered surfaces 

are rather light yellow, but in some beds fresh fracture surfaces 

are darker and in places almost black. Fragments of fossil wood 

are plentiful in some sandstone beds. The shale is soft and easily 

crumbled. It varies in color from greenish yellow to black according to the amount of carbonaceous matter which it contains. In 

places beds of coal are associated with the sandstone and shale. (See 

pp. 114-117.) Conglomerate is not as abundant in the AravaipaStanley region as it is in the Christmas quadrangle, most of the sedimentary beds being finer grained. Conglomerate containing pebbles 

of white to yellow sandstone, 3 to 6 inches in greatest diameter, crops 

out east of Stanley Butte. The pebbles were doubtless derived from 

underlying Cretaceous sandstone, and the beds therefore indicate
26 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

contemporaneous erosion during the deposition of the formation. 

Elsewhere the conglomerate beds contain pebbles of the Paleozoic 

limestone and quartzite, metamorphosed granitic rocks, quartz, and 

other rocks derived from the underlying formations. These are especially prominent in the Christmas quadrangle, where thick beds, some 

of them full of large cobbles, are found. The greater part of the sedimentary rock is sandstone. Next in amount is the shale, which is 

widely distributed in beds a few inches to a few feet thick. Conglomerate, especially in the Aravaipa-Stanley region, is a subordinate part of the formation. In the basin northeast of Little Stanley 

Butte, above the Friend mine, there is reported to be red sandstone 

containing scattered flakes of native copper. The outcrop was 

covered with recent wash and not visible at the time of visit.

The volcanic rocks are in part lava, in part pyroclastic rocks 

of several kinds, the latter probably predominating. They are 

colored various shades of purple, green, gray, and red. All the 

colors are dull, and the outlines of crystal grains and included 

fragments are hazy and indistinct, owing to widespread alteration 

of the rocks after their deposition. Such alteration is rather common in volcanic rocks of this sort. The various strata differ somewhat in composition, but all are of intermediate types, and most of 

them are andesites. Those examined microscopically contain sodalime plagioclase and chlorite, epidote, and other alteration products 

of ferromagnesian minerals. A little unaltered biotite is present in 

some specimens, and hornblende occurs in others.

The thickness of the Cretaceous beds is somewhat variable and 

is difficult to measure accurately because of the numerous minor 

structural disturbances of the strata. There are many small faults 

whose cumulative effect on the apparent thickness in some places may 

be large but can not be ascertained without detailed investigation. There are also minor crenulations or small folds which, as 

Campbell 25 has suggested, may have a large effect on the apparent 

thickness but one that is difficult to evaluate. The numerous dikes 

p»robably also tend to increase the width of outcrop. On the northeast side of Stanley Butte there is about 1,000 feet of Cretaceous 

rock, of which one-third or more is sedimentary. On the northeast side of Rawhide Mountain the width of the outcrop as mapped 

indicates a thickness of about 1,400 feet, of which mor6 than half 

is of sedimentary origin, but there may be some duplication by 

faulting. Campbell 26 estimates the thickness of sandstone and 

shale below the volcanic beds on the north side1 of the basin of 

Deer Creek as 400 to 500 feet and shows that the thickness varies

28 Campbell, M. R., The Deer Creek coal field, Ariz.: U. S. Geol. Survey Bull. 225, p. 246, 

1904. 

26 Campbell, M. R., op. cit, p. 246.
STKATIFIED BOCKS 27

markedly in different localities. Walcott 27 gives a much greater 

thickness for the formation, but, as Campbell has indicated, his estimate is probably in error. Probably the average thickness of the 

whole is of the order of 1,000 to 1,500 feet, of which 500 feet or 

more is of sedimentary origin and the rest of volcanic origin. Most 

of the sedimentary beds are in the lower part of the formation in 

all exposures, but the amount of volcanic strata interbedded with 

them varies.

Age. The age of the sedimentary beds is definitely established 

as Upper Cretaceous by means of fossils collected from a calcareous 

bed in Garden Gulch at Abe Eeed's ranch house. The bed is only 

a few tens of feet above the base of the series. Similar fossils can 

be found at the same horizon for a considerable distance on both 

sides of the place where the collection was made but were not observed elsewhere. The list of fossils as kindly determined by T. W. 

Stantoii, together with his comment, is given below:

Exogyra sp. related to E. laeviuscula Roemer. Identical with the Utah

form described by White under this name.

Trigonarca sp. related to and possibly identical with T. depressa (White). 

Callista (Dosiniopsis?) n. sp. 

Glauconia coalvillensis (Meek). 

Turritella sp. 

Undetermined gastropods belonging to one or two other genera.

These fossils belong to an Upper Cretaceous fauna of Colorado group age 

found in the lower part of the Mancos shale in northwestern New Mexico and 

southeastern Utah. Arizona collections representing about the same horizon 

have been received from the vicinity of Morenci, from Cottonwood Creek 

above White River Agency, from a locality 2 miles south of Showlow, and 

from a coal field south of Holbrook.

The sedimentary rocks wherever observed are so similar that they 

can all be assigned to the same age with little hesitancy, and they are 

so intimately interbedded with the volcanic strata that the latter 

must be also essentially of the same age. This fact is even more 

convincingly shown in the Christmas quadrangle than it is in the 

Aravaipa-Stanley region.

Fossil wood was found south of Copper Reef Mountain and on the 

north side of the headwater basin of Deer Creek. All the specimens 

observed are broken pieces, mostly square-ended, from a few inches 

to about 3 feet in length. Some of the trunks are more than a foot 

in diameter. Some are embedded in the rock; others lie loose on the 

surface. Probably all the fossil wood observed is driftwood that 

was buried in the rocks and later silicified by circulating solutions, 

which removed the woody matter and deposited silica in its place. 

The original woody structure is well preserved and, according to

27 Walcott, C. D., and Bannon, M., op. cit., p. 7. 

106914 25 3
28 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

F. H. Knowlton, shows beyond question that the trees were dicotyledons. He states that wood of this type is rare in strata as old as 

Upper Cretaceous, most of the wood preserved in such rocks being 

coniferous. He considers that the presence of such wood precludes 

the possibility that the beds containing it are older than Upper 

Cretaceous. Specimens of the fossil wood have been examined by 

I. W. Bailey, of the Bussey Institution for Kesearch in Applied 

Biology. He named the species Paraphyllanthoxylon arizonense and 

describes it in an as yet unpublished manuscript.

The lower part of this series of sedimentary and volcanic rocks is 

thus equivalent in age to part of the Colorado group, in the lower 

part of the Upper Cretaceous. As no fossils have been found in the 

upper beds, it is impossible to determine the length of time occupied 

by the deposition of the series. The upper beds, principally of 

volcanic origin, are obviously younger than the beds that have yielded 

fossils, but the time occupied in piling up a thickness of 1,000 feet 

of such rocks as these is not necessarily great measured in terms of 

geologic chronology, and the whole may be safely referred to the 

Upper Cretaceous. This conclusion is in accord with the opinions 

expressed by Walcott 28 and Campbell,29 both of whom found poorly 

preserved plant remains that were doubtfully referred to the Cretaceous. Campbell also collected imperfect specimens of Ostrea and 

Exogyra, and the latter, according to Stanton, indicates that'the 

formation is of Cretaceous age.

The part of the Cretaceous rocks of the Stanley-Aravaip a region 

which is of sedimentary origin bears some resemblance to the Pinkard 

formation of the Clifton-Morenci district, over 50 miles to the northeast, described by Lindgren.30 This formation consists of several 

hundred feet of sandstone and shale containing fossils some of which, 

according to Stanton, belong to the Colorado group fauna and are 

known elsewhere only in the upper part of the Benton formation 

and its equivalents, thus indicating a close similarity in age between 

these beds and those in the Aravaipa-Stanley region. Lindgren 

states that the formation consists of black shale in the lower part 

with alternating shale and yellowish-gray sandstone, in places calcareous, in the upper part. He found no volcanic strata associated 

with these beds. In view of the great distance of the AravaipaStanley region from known outcrops of the Pinkard formation, the 

large amount of volcanic material in the beds of this region, and 

other lithologic differences, it seems best not to refer these beds definitely to the Pinkard formation at this time.

» Walcott, C. D., and Bannon, M., op. cit> p. 7. j

29 Campbell, M. R., The Deer Creek coal field, Ariz.: TJ. S. Geol. Surey Bull. 225, p.

245, 1904.

"? Lindgren, Waldemar, The copper deposits of the Clifton-Morenci district, Ariz.: TJ. S.

Geol. Survey Prof. Paper 43, pp. 73-74, 1905.
STRATIFIED ROCKS 29 

MIOCENE ( V) STRATA

Definition and distribution. The comparatively unmetamorphosed beds above the Cretaceous strata and below the Gila conglomerate will be described under the name Miocene (?) strata. The 

largest mass of such rock mapped extends from a point near the 

northwest corner of the area through Rawhide Mountain and Stanley Butte to Old Deer Creek and connects southeast of Rawhide 

Mountain with a mass that swings around the upper end of Deer 

Creek and reaches northward into the Galiuro Mountains, just off the 

area shown on Plate I. As seen from a distance, these mountains appear to be built up largely of Tertiary lava. Similar rock forms the 

backbone of the hills west of the valley containing the Dowdle. 

ranches. Remnants of it still remain visible on the east side of Arivaipa Valley. Small patches of it were noted in the fault complex in 

the general vicinity of Arivaipa. Only one of these is shown on the 

map, and the size of this is exaggerated somewhat to make it visible.

Character. The Miocene (?) beds are composed predominantly of 

lava and tuff, but in a number of places sedimentary strata are interbedded with the volcanic rocks.

Rhyolite is one of the most widespread types of Tertiary lava in 

this region, but less silicic flows make up a large part of the whole 

in most places. These include rhyolite, quartz latite, latite, and 

latitic and rhyolitic flow breccia. Obsidian, rhyolitic tuff, and 

tuffaceous conglomerate are also found. These rocks are of various 

colors. Many are of different shades of purple and heliotrope. Some 

nre wine-pink, resembling somewhat the intrusive rhyolite associated 

with the batholith that forms a large part of the Turnbull and Santa 

Teresa mountains. Some beds are nearly white, and others are 

yellow, buff, salmon-pink, and gray. All the lavas are fine grained, 

and many have a glassy or cryptocrystalline groimdmass. Most 

of them are porphyritic, but in many the phenocrysts are inconspicuous. Some of the glassy rocks are markedly spherulitic. In 

general, the rocks are composed essentially of quartz, orthoclase, sodic 

plagioclase, and biotite in various proportions. Many contain finely 

divided iron oxides. They are fairly fresh for the most part, but in 

some the feldspar is clouded with alteration products. Views of the 

Miocene (?) beds are given in Plate VIII.

The sedimentary rocks associated with the lavas are apparently 

of alluvial origin and are derived in part from the lavas and in 

part from the older rocks. Some are conglomerates composed of 

rather poorly sorted subangular to angular pebbles. Others are 

coarse, highly cross-bedded sandstones. Although not as hard or as 

much altered as the Paleozoic sedimentary strata, they are firm,
30 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

well-consolidated rocks that stand up in prominent outcrops, as can 

be seen by a glance at Plate VIII.

Age. The Miocene (?) rocks in and near Rawhide Mountain and 

Stanley Butte lie nearly parallel to the underlying Cretaceous strata, 

but there is a marked difference in degree of metamorphism of the 

two formations, and in places there appears to be an angular discordance. The Gila conglomerate, which is the next v succeeding 

formation and is believed to be of upper Pliocene age, is separated 

from the Miocene (?) strata by an angular unconformity. Faulting 

took place after the eruption of the lava a^d before the deposition of 

tlje Gila formation. Such structural disturbances, however, do not 

necessarily occupy a long period of geologic time, and, especially as 

the tuff in the formation shows that volcanism was active during the 

deposition of the Gila, it may be that the time interval represented 

'by the unconformity was short. Perhaps it is equivalent to the part 

of the Pliocene epoch preceding the deposition of the Gila formation. 

The age of similar volcanic formations as determined by various 

authors in numerous localities in the Southwest ranges all the wa)> 

ffoin Eocene to Pleistocene, but a large part of the lava in localities 

where the period in which the volcanism took place was determined 

'is considered to be Miocene. In the absence of fossils it is impossible 

to fix the age of these Tertiary strata in the Aravaipa-Stanley region 

with, assurance, but consideration of the several lines of evidence 

leads to the opinion that the major part of the volcanism took place 

in 'the Miocene epoch.

: . GIJLA CONGLOMERATE

Tlie Gila conglomerate,, originally described by Gilbert,31 is a thick 

depos.it of fairly well consolidated alluvial material in valleys in 

southern Arizona. Deposits which it is believed should be correlated 

with this formation underlie a large part of the Aravaipa-Stanley 

. region. They extend in a broad belt southward from a point below 

I4ttle Stanley Butte to and beyond the southern limit of the area 

, mapped and also crop out in the northern part of the region on the 

upper slopes of the valley of Gila River.

.A large part of the formation as exposed in this region is conglomerate of various grades of coarseness. In most beds the pebbles 

.are .subangular and poorly assorted. All the older formations are 

represented among the pebbles in different parts of the region. In 

some beds the pebbles have probably been transported a considerable 

..distance from the outcrops whence they came, but in many the pebare obviously derived from near-by hard-rock formations. The

' ' a Gilbert, G. K., U. S. Geog. .and. Geol. Surveys W. lOOtli Mer. Kept., vol. 3, pp. 54O-541, 

1875.
STRATIFIED' ROCKS 3L.

conglomerate beds are sufficiently indurated to stand up in steep 

slopes and bluffs, but they are by no means hard rocks. (See.'3Rl. 

VI, B.} Firmly cemented, generally coarse sand is interbedded. with 

the conglomerate in many places. In the Arivaipa box cany on. the 

greater portion of the formation is tuff and tuffaceous conglomerate, 

which has been sorted more or less by the action of water. (See PL 

VI, A.} The tuff is composed of fragments of glass, quartz, feldspar, 

biotite, and various alteration products. . - The Gila formation rests in angular unconformity on the Miocene ( ?) strata just described and is in turn unconformably overlain 

by unconsolidated alluvium. No fossils have been found either in 

the Gila formation or in the rocks iabove or below it in this region, 

so that from the local evidence its age can only be surmised., .Although a gap in geologic mapping still exists between the formation 

here termed Gila and the corresponding deposit in the Winkelman, 

Christmas, and Eay quadrangles, enough is known regarding the 

intervening country to warrant the belief that the correlation will 

eventually be established by actual mapping.. Bryan 82 has found 

that the beds in the San Pedro Valley, in the Winkelman quadrangle, 

from which he and Gidley collected numerous fossils are, in his 

opinion, equivalent to the Gila conglomerate of the Ray and Christmas quadrangles, and Gidley 33 has shown that the fossils from two 

localities are of Pliocene age and probably belong to a late stage of 

the Pliocene. On the basis Qf this determination, which is in accord with the field evidence in the Aravaipa-Stanley region, the Gila 

conglomerate in this report is considered Pliocene, at least in part.

QUATERNARY ALLUVIUM

All the unconsolidated or slightly consolidated alluvial material 

in the region is termed Quaternary alluvium. This includes the 

deposits in the present stream channels, the flood-plain deposits 

along the larger streams, such as those in Arivaipa Valley and Hawk 

Canyon,, and the detritus on the terrace tops and mountain pediments. Representatives of the Quaternary alluvium are thus distributed generally over the region. In nearly all the areas mapped on 

Plate I as underlain by Gila conglomerate there are also deposits of 

later alluvium. On parts of the pediments cut on rock older than the 

Gila there is a more or less continuous cover of detritus, in most places 

scarcely more than one pebble or boulder thick. The stream channels contain shifting deposits of gravel and sand. Because of the 

shifting character of the deposits, the thinness of some, and the

32 Bryan, Kirk, and Smith, G. E. P., Geology and water resources of the San Pedro 

Valley, Ariz.: U. S. Geol. Survey Water-Supply Paper (in preparation).

33 Gidley, J. W., Preliminary report on, fossil vertebrates of the San Pedro Valley, 

Ariz.: U. S. Geol. Survey Prof. Paper 131, pp. 120-121, 1922.
32 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

small areal extent of many, no attempt was made to differentiate 

them in mapping. It would be quite impracticable to show many 

of them on a map such as Plate I, which is intended primarily to 

indicate the distribution of the bedrock formations. The most extensive and also the thickest deposits of Quaternary alluvium rest on 

the Gila conglomerate, and in places they can scarcely be distinguished from disintegration products of that rock.

The alluvial material ranges from coarse fan conglomerate containing large boulders in the mountains to fine silt in parts of the 

flood plains. Some of it is composed of angular blocks of diverse 

sizes derived from near-by outcrops, and some is composed of sorted 

and rounded grains which have in the course of many years been 

carried far from their sources in the swift torrents that fill the 

stream ways in prompt response to rainfall. It is the rather heterogeneous, irregularly bedded material characteristic of the more re- x 

cent deposits in southern Arizona. The thickness of the deposits is 

variable. In few places does it much exceed 20 feet, and in many it 

is only a few inches, but in parts of the valley of Arivaipa Creek it is 

probably a few score feet. There are wells in the valley as much as 

40 feet deep which are probably all in unconsolidated alluvium.

The alluvial deposits just described are all younger than the 

Gila conglomerate, which can hardly be older than Pliocene, and 

some of them are in process of formation at present. Thus some 

may be as old as Pleistocene and some are Recent, but all have been 

deposited in the Quaternary period. The stages in the formation of 

the Quaternary alluvium are discussed in the section on physiography (pp. 54-57).

INTRUSIVE ROCKS 

GRANITE OF THE MAIN BATHOLITH

The- main granite .batholith of the Aravaipa-Stanley region is 

that which forms the major part of the Santa Teresa and Turnbull 

mountains and floors the valley between these ranges. The total area 

is not known, as its eastern border has not been mapped, but it is 

evidently over 50 square miles. It extends in a direction a little 

west of north for nearly 20 miles from the southern border of the 

Santa Teresa Mountains. The width is probably everywhere less 

than half the length. A small outlier composed of similar rock crops 

out on the northeast flank of Quartzite Mountain. Two masses of red 

granitic rock that are probably genetically related to the main 

batholith are described separately below. The masses of rhyolite 

on the west side of the batholith are also genetically related to it. 

Granitic dikes, in some of which the rock is indistinguishable from
INTRUSIVE ROCKS 33

that of the main batholith, cut the rhyolite and other rocks near it, 

but these are all so small that they have not been mapped.

The granite is everywhere rather coarse grained and in nearly all 

exposures is porphyritic. Feldspar phenocrysts over an inch long 

are common in some outcrops. Most of the rock is flesh colored, but 

in some outcrops, especially near the head of Black Eock Wash, the 

rock is dark greenish gray mottled with white and pink feldspars, 

some of which are large.

The essential minerals of the rock are quartz, albite, oligoclase, microperthite, microcline, micropegmatite, and biotite. A 

little hornblende is present in some of the specimens, and small 

grains of black iron ore and titanite were also noted in a few thin 

sections. Most of the feldspars are somewhat clouded with alteration products, and the biotite shows incipient alteration to chlorite. 

Secondary epidote was noted in places. The iron ore in some sections has partly altered to leucoxene, showing that it contains 

titanium. The texture of the groundmass is in general allotriomorphic, but the feldspars in some specimens exhibit approximations to 

crystal form. The proportions of the several feldspars listed above 

vary in different specimens. Micropegmatite was noted in only a 

few and is not characteristic of the main mass of the batholith. 

Microperthite is abundant in all the specimens studied, and microcline is present in most of them. As a rule the other feldspars are 

subordinate. Quartz is plentiful in all specimens. The only ferromagnesian. mineral present in any considerable amount is biotite, 

and even this is not abundant. Some of the biotite flakes have 

crystal form, but many are ragged. The rock is thus a granite, 

but the relative abundance of the albite molecule in the feldspars 

indicates that the sodium content is higher than in normal granite. 

In places near the head of Black Kock Wash the rock is less silicic 

than the avera'ge and approaches a quartz monzonite in composition. 

A characteristic exposure is shown in Plate IX, B.

The batholith is intrusive into strata of Colorado age near the 

head of Old Deer Creek and is therefore younger than these rocks. 

Beds of older Tertiary flow breccia rest on the rhyolite associated 

with the granite a short distance northwest of the Grand Beef mine 

in what appears to be depositional contact, and the Gila conglomerate has clearly been laid down on the eroded surface of the rhyolite 

along a line 10 miles long on the west side of the batholith. Hence 

the intrusion can not have taken place before the last of the Cretaceous period and must have happened sufficiently long before the 

time of Tertiary volcanism tb allow the intrusive mass to be deeply 

eroded. It probably occurred early in Tertiary time, perhaps in 

the Eocene.
34 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

QUARTZ MONZONITE

Microscopic examination of a typical specimen of the granitic rock 

on the plain south of the Santa Teresa Mountains shows that it is a 

quartz monzonite, and the mass is therefore so denominated. The 

pediment that extends from the mountains south to the Safford road 

is floored with this rock. About 10 square miles has been mapped, 

and it extends eastward an undetermined distance.

The quartz monzonite is a dark wine-colored rock dotted with numerous rounded lead-gray quartz grains. It is medium to coarse 

grained and has abundant feldspar phenocrysts, some of them l*/2 

inches long.

The essential minerals of the rock are quartz, oligoclase, orthoclase, biotite, and perhaps microperthite. Small flakes of hematite 

are scattered throughout, and a little apatite is present. Most of the 

feldspar is clouded with alteration products. Quartz is very abundant, both in rounded phenocrysts, some of which show strain shadows, and in small grains inclosed in the feldspar. Most of the feldspar has roughly rectangular outlines. Oligoclase is more abundant 

than orthoclase. Some of the feldspar seems to be microperthite, but 

it is so altered as to make identification uncertain. The biotite is in 

irregular green, pleochrodc flakes and is not abundant. From these 

data it is evident that the rock is a quartz monzonite.

The field relations of the quartz monzonite do not furnish evidence 

by which its age can be closely fixed. It is evidently younger than 

the pre-Cambrian rocks in the vicinity and older than the Tertiary 

beds, but there is a tremendous interval between the dates of formation of these two. Its petrologic character differs somewhat from 

that of the granite of the main batholith, yet there are several points 

of similarity. The extent and character of alteration in the monzonite are similar to those in the granite. The two rocks are so similar 

that they may well be related to each other and have been intruded 

during the same period of igneous activity. The quartz monzonite 

may therefore be tentatively considered, like the granite, of early 

Tertiary age, but proof of this inference is lacking.

WINE-PINK GRANITE

The granite of Squaw Creek and its vicinity is here called the 

"wine-pink granite," because its color corresponds to that designated "vinaceous pink" in Bidgway's "Color standards." This 

designation is considered sufficient to differentiate it from the granite of the main batholith, which it resembles petrographically. This 

granite is exposed north of Copper Keef and Quartzite mountains. 

Only about 2 square miles of it is shown on the map (PI. I), but
INTRUSIVE ROCKS 35

outcrops of it can be found in the bottoms of gulches cut in the Gila 

conglomerate over a larger area. If, these exposures are taken into 

account, the granite covers fully 5 square miles south of the Indian 

reservation boundary and extends an unknown distance north of 

the boundary.

The general tone of a fresh surface of this rock is wine-pink mottled with small sage-green areas. Closer inspection reveals numerous light lavender-gray spots. It has a medium to coarse granitic 

texture, with some tendency to the development of feldspar phenocrysts. The essential minerals are quartz, orthoclase, andesine, 

microperthite, and biotite. The rock is fairly fresh, but the feldspars are clouded with alteration, and the biotite is somewhat chloritized. Quartz is very abundant in large rounded grains, most of 

which show strain shadows. It also forms intergrowths with alkali 

feldspar that resemble micropegmatite. Andesine is much less 

abundant than the more alkalic feldspars. Biotite is more abundant than in the typical granite of the main batholith but is decidedly subordinate in amount to the quartz and feldspar. The 

rock is clearly a granite, probably with a fairly high sodium content.

This granite cuts the pre-Cambrian rocks near it and probably the 

Cambrian quartzite also and is cut by dikes resembling the rock of 

the main granite batholith. Consequently it was produced before 

the end of the period of intrusion in which the main batholith was 

formed and is probably post-Cambrian. The petrologic characters 

of the two granites differ sufficiently to be recognized in the field, 

yet they are so similar as to suggest that the granites may be closely 

related to each other. In the absence of more definite evidence the 

wine-pink granite may be tentatively regarded as slightly older than 

the granite of the main batholith but as formed in the same general 

period of intrusion and therefore also of early Tertiary age.

INTRUSIVE RHYOLITE

The rock of rhyolitic composition that rims the main granite 

batholith on the west side is termed intrusive rhyolite to distinguish 

it from Tertiary lava of somewhat similar composition. Such rock 

borders the main batholith along its west side but is either absent or 

shows only as a comparatively narrow and ill-defined band where 

the batholith cuts pre-Cambrian metamorphic rocks. The only place 

where the rhyolite has been mapped in contact with metamorphic 

rock is east of Crystal Peak, in the northern part of the Turnbull 

Mountains. Most of the rock mapped as rhyolite at this locality is 

coarser grained than the average rhyolite and merges so gradually 

into granite that the boundary drawn between the two is of necessity 

arbitrary. In the vicinity of Arivaipa the area mapped as intrusive 

106914 25 4
36 ARAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

rhyolite contains also numerous dikes probably related to the Tertiary lava. The rocks are so much altered by mineralization and 

weathering as to make discrimination between these two similar types 

of igneous rock difficult. In places there may also be patches of 

Tertiary lava not differentiated in mapping.

The intrusive rhyolite is characterized in most exposures by a 

grayish heliotrope color. The groundmass of the rock is in general 

fine grained and in some exposures shows flow banding. The rock 

is everywhere porphyritic and in most exposures is dotted with 

numerous small rectangular phenocrysts of white feldspar and less 

conspicuous rounded gray phenocrysts of quartz. Small biotite 

spangles are also visible in some specimens. Gradations between 

this typical texture and that of the granite already described are 

found in a number of places.

The essential minerals are quartz, orthoclase, albite, oligoclase, 

micropegmatite, microcline, and biotite. Finely divided hematite and 

grains of black iron ore are also present. The feldspar is clouded 

with alteration products, and small amounts of chlorite are present 

in some specimens. In some thin sections there are large corroded 

quartz phenocrysts, many of which are surrounded with quartz reaction rims; in others the quartz is less prominent, but in all it is 

fairly abundant. Peculiar rosettes of quartz are present in a number 

of specimens. The proportions of the feldspars vary, and the 

alteration in them is sufficient to make precise identification difficult, 

but they are all alkalic. Apparently none are more calcic than 

oligoclase. Biotite is rather generally distributed but everywhere 

in small amounts. Many specimens contain so little that it can 

be discerned only at high magnifications. It is the only original 

ferromagnesian mineral present. All gradations in texture from 

that of a very fine grained porphyritic felsite to that of granite can 

be found. In most specimens the minerals of the groundmass are 

without crystal form and the grain is fine, but most of the phenocrysts, except the corroded quartz, exhibit approximations to crystal 

outlines. These data show clearly that the rock is in general similar 

in composition to the granite of the main batholith. The average 

composition and texture correspond to those of a rhyolite rather rich 

in sodium, but in some places sufficient soda-lime feldspar is present 

to make the rock a quartz latite.

The fact that in places the intrusive rhyolite and the granite 

grade into each other and that everywhere they are intimately associated shows that they are genetically related. The similarity in 

composition of the two rocks is corroborative evidence. The 

interpretation of the mode of origin and structural relations presented in the section on structure (pp. 41-42) indicates that the main 

bodies of rhyolite are slightly older than the granite, but they both
INTRUSIVE ROCKS 37

belong to the same period of intrusion and are of essentially the same 

geologic age that is, probably early Tertiary.

GRANITIC DIKES

The dikes composed of rock essentially similar to that of the 

main batholith are termed granitic dikes. Such dikes are abundant 

in the intrusive rhyolite from the vicinity of the Grand Eeef mine 

north to Imperial. Hill. Some of them occur on and near Cobre 

Grande Mountain. Similar dikes cut the wine-pink granite near 

the northwest end of the Turnbull Mountains.

These dikes range from a few feet to over 20 feet in width and 

can be traced in places for several hundred feet on the surface. 

Irregular granitic intrusions were noted' on Cobre Grande Mountain. 

There is some tendency to diminution in the coarseness of texture 

near the contacts, but in many dikes this is not a marked feature. 

The rock is of the same color and general appearance as that of 

the main batholith and of variable texture. Nearly all of it is noticeably porphyritic, and some contains numerous large phenocrysts.

The essential minerals of the dikes, as of the main granite mass, 

are quartz, microperthite, micropegmatite, albite, oligoclase, microcline, and biotite, and the accessory minerals and alteration products 

are also like those in the rock of the batholith. In outcrops on 

Cobre Grande Mountain the rock contains more micropegmatite than 

was noted in the. granite of the main mass, but this is not characteristic of most of the dikes.

These dikes are offshoots of the main granite mass. Both the 

field relations and the close similarity in the character of the rocks 

show the close genetic relations between them. Therefore the dikes, 

like the parent batholith, are regarded as of early Tertiary age.

FEL6ITE

The fine-grained porphyritic dike rocks of silicic composition may 

be included under the term felsite. Dikes of such rocks cutting the 

pre-Cambrian metamorphic rocks and strata of Paleozoic and Cretaceous age are numerous in and near the northern part of the Turnbull Mountains and on the southwest side of Cobre Grande Mountain. Dikes of this kind cut Paleozoic beds in the vicinity-of Arivaipa. Similar rocks, though mostly somewhat coarser grained, cut 

the granite east of Imperial Hill. Such dikes were also noted on the 

northeast flank of Cobre Grande Mountain. In general they crop 

out around the outer edges of the batholith and cut Cretaceous and 

older rocks.

Fine-grained dikes of aplitic composition were found in the 

vicinity of the Fisher prospect, in the southern part of the Turnbull
38 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

Mountains. None of the dikes are large enough to be shown on the 

map.

The rock of most of the dikes has a fine-grained groundmass 

crowded with small phenocrysts of quartz and feldspar. Many have 

a gray-heliotrope color closely resembling that of the intrusive rhyolite described above, but some are nearly white, apparently as a result 

of bleaching during alteration. They all contain abundant quartz 

in corroded phenocrysts, irregular grains, and some rosettes. Some 

of the phenocrysts are rimmed with later quartz. The feldspars are 

microcline and soda plagioclase; most of the plagioclase is near 

albite in composition. Micropegmatite is abundant in the aplite near 

the; Fisher prospect (see p. 103) and in similar but coarser rocks 

 east of Imperial Hill. Biotite is present in small amount in most 

of the dikes, but in many it is bleached and inconspicuous. Some 

of the micropegmatite-bearing dikes near Imperial Hill contain a 

little hornblende. Some of the rocks in the northern and western 

parts of the Turnbull Mountains contain muscovite. In general the 

rocks are fairly fresh, but most of them contain some chlorite or other 

alteration products. Near the Starlight mine is a mass of chloritized 

and otherwise intensely altered rock, originally a felsite. (See p. 

114.) Most of the felsitic dikes have the composition of rhyolite with 

:a rather high soda content. Some of them are sufficiently rich in 

spda plagioclase to be considered quartz latites.

Most of the rocks of this group are petrographically similar to the 

intrusive rhyolite, and many of them may be offshoots of the rhyolite 

and are probably therefore, like it, of early Tertiary age. It is possible that some of the dikes included in this group, particularly those 

characterized by muscovite, are related to the Tertiary lavas and are 

thus younger than the intrusive rhyolite. At one place on Stanley 

Butte a felsite dike of appearance similar to those just described cuts 

Tertiary lava.

TRAP

The fine-grained porphyritic dikes and irregular intrusions, principally of intermediate composition, which are common in parts of 

the region, may be grouped under the name trap. Such rocks are 

present in a number of places in the northern part of the region, 

cutting the Tertiary lavas and older formations. They are common 

in the vicinity of Arivaipa, where they cut Paleozoic beds and where 

some of them are of considerable size. Rocks of this group were 

noted in the area southwest of Cobre Grande Mountain. Dikes in 

Tertiary and older rocks crop out on the southwest side of the Santa 

Teresa Mountains. Trap rocks are probably also exposed in other 

parts of the region. None of these rocks have been shown on Plate I.
STRUCTURE 39

The rocks included in this group are all fine grained. Most of 

them are porphyritic, but many have few visible phenocrysts. In the 

vicinity of Arivaipa, however, are a number of dikes that contain 

numerous plates of white feldspar, many of which are over threequarters of an inch long. Some of the rocks of the group contain 

cavities lined with green crystals of epidote. All the rocks are dark 

colored. 

The rocks of this group that have been examined petrographically 

have the composition of andesite and basalt. The feldspar in different specimens ranges from oligoclase to labradorite. , Altered 

olivine was found in a basalt from the vicinity of Arivaipa. The 

ferromagnesian minerals have been so generally altered that positive identifications could not be made, but it is probable that some of 

the rocks originally contained hornblende and others augite.... The 

feldspars, most of which are lath-shaped, are clouded with hematite 

dust but have not on the average been much altered.

In spite of a considerable range in composition, most of the rocks 

here grouped together are closely related in mode of origin and age. 

Some of them cut Tertiary strata east of JOondyke and also in -the 

northern part of the region, and some north of Arivaipa cut felsitel 

It is believed that most of the dikes are genetically related to the 

Tertiary lava and therefore of essentially the same age. In average 

composition the dikes are more calcic than most of the flows, but 

lava fully as calcic and of the same age is present in the northwestern part of the region and is abundant in places in the Christmas quadrangle, to the west. Some of these dikes may be genetically 

related to the Cretaceous volcanic rocks. The composition is similar 

but there is less alteration in the intrusive rocks.

The stratified rocks of this region are tilted, fractured, and bent 

in various ways, showing that they have been subjected to powerful 

forces since their deposition. In general, the forces that have acted 

here are not complex nor difficult to understand. Erosion and the 

covering up of some formations by later ones have removed or concealed some of the evidence, but enough is known to determine the 

major features of the structure, and many more details could be 

learned by longer and more thorough examination than it was possible to make during the present investigation.

PRE-CAMBRIAN FOLDING ,

The pre-Cambrian record is scanty and throws little, light on 

the structure then produced. Igneous activity occurred on a large 

scale, and the rocks were subjected to powerful and long-coritmuetl 

.compressive stresses, more so than any of the later formations,.and in
40 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

consequence suffered notable textural and chemical changes. The 

compressive forces doubtless also bent the stratified rocks into close 

folds. In the small areas of sedimentary pre-Cambrian rock exposed the original bedding planes are now greatly obscured. In 

intrusive rocks, such as make up a large part of the pre-Cambrian 

complex, there are no bedding planes, so that the effects of structural forces on them are less easily discerned. 'The ancient rocks 

have of course been affected by all the geologic forces that have been 

at work in their vicinity since their formation, and it is difficult to 

determine to what extent their present attitude is due to pre-Cambrian folding rather than to later earth movements. The general 

accord in strike of the schistosity in widely separated areas suggests, 

however, that in a broad way the attitude of the pre-Cambrian rocks 

has not been greatly modified by later movements. Faulting has 

doubtless lifted some blocks and depressed others relatively, but 

there has been comparatively little twisting or folding of the highly 

compressed ancient rocks since the dawn of the Paleozoic era.

The metamorphism of the rocks bears striking evidence to the 

action of mountain-building forces in pre-Cambrian time. These 

forces acted in a general northwest-southeast direction the direction taken by mountain-building forces of similar age elsewhere in 

this part of Arizona.34 The average strike of the schistosity produced in the rocks by the compression is about N. 40° E.

The pre-Cambrian intrusive rocks differ somewhat among themselves in character and in degree of metamorphism. They may well 

have been intruded at different times, and there was perhaps more 

than one period of structural disturbance in the pre-Cambrian. Indeed, it is highly probable that during that long time there were 

many geologic events of which the evidence is no longer legible.

There is no evidence of sharp structural disturbance in this region 

from the end of pre-Cambrian time nearly to the end of the Mesozoic. During these hundreds of millions of years1 there were oscillations of level of the land and perhaps broad-scale warpings of 

the strata, but apparently no folding, faulting, or intrusion of large 

igneous masses.

After the deposition of the Cretaceous strata came earth movements, followed or accompanied by batholithic intrusion. The general arrangement of the rocks as they exist to-day was in large 

measure produced at this time, but disturbances resulting in further 

changes in the attitude of the rocks have continued intermittently up

 <! - : 

84 Ransome, F. L., The copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey 

Prof. Paper 115, p. 85, 1919.
STRUCTURE 41

.to geologically recent time. Obviously forces that affected rocks of 

a certain age must have been active at a time later than that in which 

the rocks were originally formed. For this reason it is evident that 

the earth movements continued at least into Pliocene time and probably later, as is more fully stated below.

IGNEOUS INTRUSIONS

The only intrusion after pre-Cambrian time on a sufficiently large 

scale to be of structural importance was that of the granitic masses 

from which the largest parts of the present Turnbull and Santa 

Teresa mountains and the smaller similar masses near by have been 

carved. The granite magma that formed the main body surged up 

from great depths within the earth, in part tearing through the preexisting rocks, in part shoving them aside and bowing them up. The 

roots of the mass probably lie buried far below any depths to which 

erosion is likely to reach. Its sides, in general, are evidently steep, 

but they are irregular, and tongues of granite or related rock reach 

out from them into the inclosing formations. Such an intrusive mass 

is called a batholith. Over an area of many square miles the cover 

has been stripped from it and a considerable part of the granite itself 

has been removed by erosion. The thickness of the fine-grained outer 

layer of the intrusive mass which still remains in places indicates 

that the magma was rapidly chilled. This conclusion, coupled with 

the fact that the granite reached well up into the Cretaceous strata, 

suggests that at the point where the intrusion spent its force and 

stopped the blanket of older rocks above it was not very thick. There 

are no quantitative data available by which the thickness of this 

blanket can be measured, but it is perhaps to be regarded as of the 

order of hundreds rather than of many thousands of feet. Both the 

upper surface of the intrusive mass and the surface of the ground 

above it were irregular, so that the amount of cover must have differed greatly at different places. This variation is reflected in the 

variations in the thickness of the fine-grained coating of the batholith the rock here described as intrusive rhyolite.

The similarity in composition and the intimacy of the relations of 

the intrusive rhyolite and the granite leave no doubt that they came 

from the same parent magma and were formed during the same 

period of intrusion. The main rhyolitic masses are interpreted as 

portions of the magma that were injected into the comparatively cool 

older rocks and rapidly chilled. In so doing they of necessity 

heated the rocks into which they had forced their way. Partly because of this rise in temperature in the surrounding rocks and partly 

because of the effective insulation provided by the consolidated but 

still hot rhyolite, the magma following closely behind the leading 

masses was enabled to cool more slowly and thus crystallized with
42 ARAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

a coarser, granitic texture. The process was not a simple one.,, 

Conditions of temperature, pressure, and composition of the magma 

changed from place to place and from time to time during the course 

of the intrusion, and the .products bear evidence to these changes. 

In some places rhyolite grades into granite with no perceptible 

break. Elsewhere there is a sharp boundary between the two. In 

Laurel Canyon just above the Grand Reef mine the contact between 

fine and coarse grained rock is sharp, and the latter is clearly intrusive into and includes blocks of the former. Evidently at this place 

the first of the magma to be injected cooled into a firm fine-grained 

rock before a later incursion of magma took place. In numerous 

localities dikes of granite cut the rhyolite. The magma that formed 

them did not chill into fine-grained masses, like the similar magma 

from which the rhyolite was derived, because the rhyolite was still 

hot. Thus it appears that the rhyolite and the granite were formed 

in the same period of intrusion and consolidated from magma of 

similar composition. The variations in texture are principally results of variations in the physical conditions affecting the different 

masses of magma at the time they consolidated.

The smaller masses of wine-pink granite and quartz monzonite 

were intruded in a manner similar to that of the main batholithi 

They may have come from the same magmatic reservoir and may 

still be connected at depth with the main batholith.

FLEXUBES

The stratified rocks in general dip away from the granite all 

along its western front. The mass of Tornado limestone composing 

Lime Hill is an exception to this rule, and there are probably others. 

On the southeast the thick mass of Paleozoic strata forming the 

summits of the east end of the Santa Teresa Mountains appears 

to dip gently southward away from the batholith. The east and 

north sides have not been mapped geologically. This attitude of 

the strata may in part be attributed to the upward thrust of 

the granite during intrusion, but, as rocks younger than the granite 

are involved, part of it is clearly later, resulting from a subsequent 

relative uplift of the mountain masses. Whatever the cause or 

the date of the flexure, the result is an arrangement of the formations on the west side of the Turnbull Mountains in parallel bands, 

the oldest on the east, as can be seen from the geologic map and 

structure sections A-A' and B-B'', Plate I. The dip is westward 

and is in general steeper in the older formations and at higher 

altitudes. The strike is generally northwest but swings somewhat 

more toward the west in the northern part of the region mapped. 

This swing is even more pronounced in the continuation of tho
STEUCTTJEE 43

same formations in the Christmas quadrangle,35 to the west. There 

are numerous exceptions to the general arrangement outlined above, 

but they are principally the result of faulting and will be considered in the next section. Some tendency to a similar arrangement of the formations can be discerned west of the Santa Teresa 

Mountains and the south end of the Turnbull Mountains, but here 

the Paleozoic strata are less conspicuous and continuous partly because of faulting and partly because of the extensive cover of later 

Gila conglomerate. Similar forces were nevertheless active here 

also, at least in the later stages, for even the Gila conglomerate 

dips away from the mountains, as shown in structure sections C-Cr 

and D-D'', Plate I. The Paleozoic beds and perhaps also the later 

formations doubtless originally arched over the mountains, but 

they have now been almost completely removed by erosion except 

on the borders of the ranges.

In the northeastern part of the region mapped there are other 

flexures which may be related in time of origin to the one just described. Structure sectionM.-A', Plate I, shows one interpretation of 

the conditions in this area. Such sections are of necessity somewhat 

diagrammatic, and the actual structure may be somewhat more 

complicated than that indicated in the drawing. Rawhide Mountain 

is a syncline whose east flank is a part of the structure described in 

the preceding paragraph. The west flank is the shorter and steeper 

side of the synclinal trough. Just west of this downwarp of the 

strata there may once have existed an anticline, but this has been 

broken by faults. Around the head of Deer Creek the Cretaceous 

strata dip gently valleyward, forming a syncline. The combination 

of folding and faulting about this basin has resulted in a peculiar 

distribution of the rocks. The gently sloping Cretaceous beds in 

the basin itself are surrounded by an almost continuous wall of 

highly inclined Tornado limestone. On the south side there are 

also areas of Cambrian and pre-Cambrian rocks. Encircling the 

whole upper end of the basin and everywhere dipping away from 

it are Tertiary beds, principally of volcanic origin. Part of the 

bending now visible in the strata was doubtless caused by the 

faulting, and part of it is to be attributed to earlier folding, but the 

effects of the two periods of disturbance can not be definitely distinguished. They may have been separated by a long time interval, 

or the first of the faulting may have followed the folding closely. 

Wherever the relations can be observed the Tertiary strata rest on 

the Cretaceous beds with only a small angular unconformity, but 

in this particular place the discordance may be greater than usual. 

If so, it is possible that the Tertiary beds originally arched over the

BB Barton, N. H., U. S. Geol. Survey Geol. Atlas, Christmas folio (in preparation).
44 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

location of Deer Creek in a broad anticline. If the Tertiary and 

Cretaceous beds were essentially conformable here, then the deformation by faulting was very marked. On either assumption, 

the curved outcrop of the limestone is difficult to account for by 

faulting alone. It is probably the result of a syncline with its axis 

plunging to the west formed before the fracturing. A number of 

small faults exist that have not been plotted, and those which are 

shown are groups of fractures rather than breaks on single planes as 

drawn. It is possible that faulting has occurred on the north side 

of the limestone ridge south of the basin and that consequently the 

limestone below the surface is broken instead of forming so smooth 

a curve as is represented in structure section A-A', Plate I.

NORMAL FAULTS

The minor intricacies of the structure are principally results 

of faulting. Nearly a score of faults are shown on Plate I, and 

many others exist. A number of faults too small to plot were 

observed in the course of the field work, and there are doubtless 

others which escaped detection. In the vicinity of Arivaipa, in 

particular, faults are so numerous that it was necessary to generalize in mapping, and a comparatively small part of the total 

number are shown. To present adequately the intricate checkerwork of faults here would require a map of much larger scale 

and much more detailed field study. Most of the fault lines plotted 

probably represent groups of breaks whose composite trend approximates that shown. Most of the faults are of the normal type 

that is, the hanging wall is depressed relative to ,the footwall, as 

if it had slipped down the inclined fault plane.

There are at least three systems of faults. One of these strikes 

about N. 20°-30° W.; a second set, probably closely related to 

the first, strikes N. 70°-80° E.; and a third set, developed particularly in the northwestern part of the region, strikes about N. 

60°-70° W. The dips of the fault planes are steep, probably of 

the order of 70° to 90°, though few quantitative data are available. The fracturing probably started early in the Tertiary period, 

after the batholithic intrusion. The Tertiary volcanic rocks are extensively faulted, so that it is probable that notable fracturing 

continued into the Miocene. The Gila conglomerate, which is no 

older than Pliocene, is faulted in places, but apparently the disturbance that affected it was less powerful than the preceding ones. 

The conditions of unstable equilibrium set up in the earth's crust, 

in part, perhaps, as results of the granite intrusion and later volcanic 

extrusions, were) gradually being adjusted by the beginning of 

Pleistocene time, although complete equilibrium has not even yet
STRUCTURE 45

been established, as is shown by the minor earth tremors that are 

still occasionally reported in this part of Arizona.

Most of the faults formed at these different times can not be assigned to one or another period. In general, a fault may be assumed to be younger than the youngest rocks that are clearly involved in the movement, but where only ancient rocks are present, as, 

for example, along Squaw Creek in the northern part of the region, 

this assumption leaves a wide range of possibilities. As has been 

suggested, faulting was apparently recurrent over a long time, and 

it may be that in each period of stress movement was renewed on the 

old fault planes, in addition to forming new ones.

Some of the faults around the basin at the head of Deer Creek 

have a vertical throw of the order of 1,000 feet, as shown in structure section A-A', Plate I, and there may be others of the same 

magnitude. The largest fault, or rather group of faults, in which 

the Gila formation is known to have been involved lies along the 

east front of the line of hills that cuts across T. 6 S., R. 19 E. Its 

best exposure is in the box canyon in Arizona Creek at the Claridge 

ranch. The resultant vertical throw on the group of fault planes 

visible here is probably almost 200 feet. Farther south, near the 

Dowdle ranch, the throw may be even greater. The fault that displaces the quartzite on the upper part of Squaw Creek has a horizontal shift of about three-quarters of a mile, perhaps the resultant 

of several related breaks. Horizontal shifts of hundreds of feet 

were noted in several places but are not adequately represented on 

the map.

OVERTHRUSTS

Like the normal faults just described, overthrusts result from fracturing of rocks with subsequent relative movement of the blocks on 

opposite sides of the fracture plane with respect to each other. In 

normal faults the effect is that which would result from the slipping down of a block of rock under gravitational force along a surface that is inclined toward the relatively downthrown block. The 

angle made with the horizon by such fault surfaces is usually large. 

Overthrust blocks, on the other hand, override the adjacent rocks, 

usually along surfaces inclined at low angles. Many normal faults 

are produced by a passive settling or readjustment of inadequately 

supported blocks of rock, but overthrusts seem to imply the work of 

more active shearing forces.

Only one overthrust of any magnitude has been found in this 

region, although evidence of the play of similar forces was observed 

elsewhere, as, for example, at the Starlight mine. (See p. 113.) The 

thrust mentioned is along the lower course of Garden Gulch between 

Stanley and Hawk Canyon. (See PL I.) Here a block of Tornado
46 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

limestone has been thrust over the surface of Cretaceous sandstone 

beds. In structure section B-B'', Plate I, it is drawn as accurately 

as possible from the data available, and a view of a portion of it is 

given in Plate IX, A. The limestone block, which has a maximum 

residual thickness of over 300 feet, has overridden the younger beds 

for a distance of more than a mile. Wherever the thrust surface can 

be observed it is essentially horizontal, as can be seen in Plate IX, A. 

As plotted, the thrust surface dips gently westward, away from the 

main mass of Tornado limestone, but this may be the result of inaccuracies in the topographic sketching. Probably this surface is in 

general flat-lying, although there may be irregularities in it. Some 

brecciation has occurred locally along the contact, but it is nowhere 

great and in places is insignificant. The thrust that pushed the mass 

of Carboniferous rock nearly horizontally for more than a mile came 

from the east, the direction of the batholith. The movement certainly took place after the Cretaceous deposition and probably after 

the strata had been tilted up around the batholith. Perhaps the 

tilting had not been completed, and the thrusting was merely one 

phase of the crustal disturbance that followed the igneous intrusion. 

If so, the thrust surface would have shared in any tilting movement 

after its formation, and this would account for the fact that, unlike 

many thrust surfaces in other regions, it is not inclined upward 

away from the place of origin. The thrust evidently took place in 

the Tertiary period, but its date can not be fixed more closely.

GEOLOGIC HISTORY

The geologic history of this region may be inferred from the 

geologic facts and hypotheses set forth in the preceding sections. 

The events whose combined effect is seen in the present form and 

constitution of the rock masses of the region are fitted as well as 

may be into their proper places in the geologic time scale. The 

fossil remains of plants and animals that lived in past ages, if sufficiently abundant and well preserved, furnish the most positive clues 

as to the age of the rocks that contain them. Where fossils are 

lacking, the relative age of the different rock masses may often 

be determined by study of their relations to one another and of 

the degree and character of the changes that have affected them, 

but doubt may well arise as to the proper place in the time scale 

which should be assigned to the formation of the rocks and to 

the events that have occurred since their formation. In this region 

sufficient fossil evidence is available to warrant the assignment 

of most of the rock formations at least approximately to their 

proper places, but in the wide time gaps between the dates of 

some of these formations many events must have occurred re-
GEOLOGIC HISTORY 47

garding which uncertainty necessarily arises. Many of the events 

of geologic time in this region are known, and more will be 

inferred as facts regarding this and neighboring regions accumulate, but parts of the record will doubtless always remain buried in 

mystery.

PRE-CAMBRIAN TIME

The earliest records available are in the pre-Cambrian rocks. Of 

the events that occurred before the deposition of these rocks, only 

remnants of which are now exposed, all trace is now lost. These 

pre-Cambrian rocks have passed through so many vicissitudes that 

their original character can be deciphered only with difficulty. Most 

of them are granular igneous rocks that are clearly of intrusive 

origin, but there are considerable masses of fine-grained Final 

schist probably derived from marine sediments. The metamorphosed igneous rocks in the southwestern part of the Santa Teresa 

Mountains intrude and are therefore younger than the schist. The 

ancient igneous rocks in the Turnbull Mountains may well be of 

the same age as those farther south. Thus at the earliest time of 

which we have any knowledge this part of Arizona was buried 

beneath the waters of an extensive sea.

In the long ages that elapsed between the laying down of the 

mud and sand in the pre-Cambrian sea and the deposition of the 

first of the Paleozoic strata there were earth movements on a grand 

scale, resulting in compression, plication, shearing, and chemical 

alteration of the rocks. During this time there were one or more 

periods of igneous activity, in which great masses of granitic and 

dioritic rocks and dikes of diabase and other rocks were intruded 

into the sedimentary strata. The heat and pressure resulting from 

these intrusions doubtless contributed to the metamorphism of the 

neighboring formations. Comparatively volatile material was given 

off during their cooling. This doubtless resulted in chemical changes 

of various kinds in the rocks penetrated. The igneous rocks bear evidence of having been subjected to regional metamorphism, showing 

that erogenic forces were active after their intrusion. Much the 

greater part of the profound alteration in the pre-Cambrian rocks 

took place before the deposition of the oldest Paleozoic beds, for 

these beds have not been metamorphosed to a comparable degree. 

The time interval represented by the unconformity between the preCambrian and Paleozoic rocks is certainly very long, probably the 

longest in all the stratigraphic record of the region. The intrusions 

and earth movements mentioned above may have been phases in the 

building of mountain ranges. The uplift was, at all events, sufficient to raise the land above sea level and subject it to active erosion.
48 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

PALEOZOIC TIME

In the Cambrian period the sea once more invaded this region. 

The surface which it covered was not an even one. So far as can 

be judged from the available evidence there were hills and valleys, 

but probably no mountains. Mud, sand, and gravel were laid down 

on the sea floor, but much the greater part of the material deposited 

was clean, siliceous sand, now altered into quartzite. The irregular 

distribution and variations in thickness of this formation as at present exposed are in part due to later structural disturbances, but they 

are certainly in part due to original differences in deposition 

resulting from variations in the shape of the sea bottom and in the 

supply of sediment. There is evidence here and in neighboring areas 

that the Cambrian sea was not deep and that land was probably 

rear at hand throughout the deposition of the formation. The position and shape of the shore and of possible islands doubtless changed 

progressively during the marine invasion, perhaps with fluctuations. 

Deposition approximately kept pace with subsidence of the land, as 

is shown by the absence of deep-water deposits of Cambrian age.

Above the Cambrian strata there is another long gap in the record. No rocks of Ordovician or Silurian age are known anywhere 

in this region. If rocks were formed during these periods, they 

appear to have been since removed by erosion, yet evidence has nowhere been found of erosion of the upper surface of the Cambrian 

rocks. It seems probable that no large amount of Ordovician or 

Silurian rock ever existed here. Probably the region was out of 

water during at least a portion of Ordovician and Silurian time.

The existing deposits of Devonian limestone and shale are discontinuous and nowhere very thick, and the fossils they contain represent animals that must have lived in a shallow sea. It may well be 

that the beds were originally more continuous than might be inferred from the few exposures that have been recognized, but it is 

unlikely that they were ever very thick, and perhaps in some places 

they were not deposited at all.

Deposition of marine limestone continued in the Mississippian 

and Pennsylvania!! epochs of the Carboniferous. Although no break 

in sedimentation has been detected, it is not certain that deposition 

was continuous, as beds of upper Mississippian age have not been 

certainly identified. At all events, the sea covered southeastern 

Arizona during a large part of Mississippi and Pennsylvanian time. 

There is no evidence of Permian deposition, and the region may 

have been above sea level during that epoch.

One of the striking things about the Paleozoic stratigraphlc 

record is the lack of angular unconformities. The different formations are known to have been deposited at widely separated in-
GEOLOGIC HISTORY 49

tervals of time, yet the beds are all essentially parallel. The strata 

were originally deposited in approximately horizontally attitude 

on the sea bottom, and they appear to have remained in that attitude during the whole of the Paleozoic era. There must have 

been oscillations in the earth's crust at intervals during this tremendously long time, but none of these movements tilted or flexed 

the beds already deposited so much that later beds, laid down horizontally, made noticeable angles with them. In this region there 

is no evidence of igneous activity or of mountain building in 

Paleozoic or early Mesozoic time. It was essentially an era of 

quiescence, during the greater part of which the land was covered 

by sea water.

MESOZOIC TIME

The beds stratigraphically above the Carboniferous limestone are 

of Colorado (Upper Cretaceous) age. No representatives of the 

Permian or of the earlier Mesozoic systems have been found in 

this region, and there is no evidence that either igneous or sedimentary rocks of those periods ever existed here. It appears that 

the Cretaceous beds were laid down on an approximately level surface of the Carboniferous Tornado limestome, and that the limestone had suffered little disturbance since its deposition, except for 

a relative uplift of the whole mass with respect to sea level. In 

most places where the contact has been observed the Cretaceous and 

Carboniferous strata are nearly parallel, in spite of the many millions of years that elapsed between these two periods. No angular 

discordance of any material amount between the bedding planes of 

the two formations was observed in the region mapped. This 

essential parallelism continues in the outcrops farther west, but in 

the " middle coal field " there is a visible unconformity.36

Some of the conglomerate beds in the lower part of the Cretaceous 

formation contain pebbles of Paleozoic rocks, proving that these 

rocks were being eroded to some extent at the time the deposition of 

the Cretaceous beds began. The small variations noted in places in 

the thickness of the Tornado limestone .may in part have resulted 

from erosion, but there is no known evidence to indicate any large 

amount of pre-Cretaceous erosion of the limestone. The explanation appears to be that in this region during the greater part of the 

Mesozoic era there was no mountain building, no igneous activity, 

and little or no deposition of sediments. It is hardly likely that the 

region remained absolutely quiescent during so long a time, but no 

evidence as to the events which may have occurred has yet been 

found.

80 Campbell, M. R., The Deer Creek coal field, Ariz.: U. S. Geol. Survey Bull. 225, p. 

245, 1904.
50 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

Much igneous intrusion and faulting is reported to have occurred 

in the Ray quadrangle,37 west of this region, in tne Mesozoic beds. 

These events are supposed to have taken place before Upper Cretaceous time and thus appear to mark a period of disturbance of 

which there seems to be no evidence in the region here considered.

The character of the Upper Cretaceous sedimentary rocks indicate that they were formed in shallow water along a seacoast. It 

has long been known that marine conditions prevailed over a broad 

strip of territory east of this region in Upper Cretaceous time. The 

sea extended from Mexico and Texas northward through the Great 

Plains and Rocky Mountain regions into Canada and; perhaps 

reached the Arctic Ocean.38 Marine deposits of Upper Cretaceous 

age occur near Pinedale, Holbrook, White River Agency, and Morenci, in northeastern Arizona (p. 27), showing that the sea covered 

this part of the State.

The near-shore deposits of Colorado age (Upper Cretaceous) in 

the Stanley district mark the location of a part of the western shore 

of this ancient sea at one stage in its development. There were fluctuations in the exact position of the shore at different times during the deposition of these sediments, as is shown by the variation in 

their character and by the extent of the area covered by them. Sedimentary rocks belonging to this formation are known to extend 20 

miles west of Stanley, but this seems to mark the western limit of the 

Colorado sea. The part of Arizona west of this was apparently dry 

land in Colorado time, and most of it has remained so ever since. It 

is interesting to note that in Lower Cretaceous or Comanche time a 

sea extended up from Mexico into southern Arizona. Marine deposits of Comanche age are known on both sides of the southern part 

of Sulphur Spring Valley 39 and in various places in the general 

vicinity of Tucson.40 No sedimentary rocks of Comanche age are 

known in the Stanley and Aravaipa districts, and there is no evidence that any ever existed. It appears that the northern shore of 

the Comanche sea in this region lay somewhere between the present 

north end of Sulphur Spring Valley and the vicinity of Bisbee.

The sea withdrew from this region in Colorado time and has not 

returned since. Before it finally left the Stanley district and the

37 Ransome, P. L., Copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey Prof. 

Paper 115, p. 87, 1919.

88 Stanton, T. W., Succession and distribution of later Mesozoic invertebrate faunas in 

North America: Jour. Geology, vol. 17, No. 5, p. 419, 1909. Grabau, A. W., Textbook 

of geology, pt. 2, fig. 1704, 1921.

39 Ransome, F. L., Geology and ore deposits of the Bisbee quadrangle, Ariz.: U. S. 

Geol. Survey Prof. Paper 21, p. 57, 1904. Meinzer, O. E., Geology and water resources 

of Sulphur Spring Valley, Ariz.: TJ. S. Geol. Survey Water-Supply Paper 320, p. 46, 1913.

40 Schrader, F. C., Mineral deposits of the Santa Rita and Patagonia mountains, Ariz.: 

U. S. Geol. Survey Bull. 582, pp. 51-53, 1915. Bryan, Kirk, Erosion and sedimentation 

in the Papago country, Ariz.: U. S. Geol. Survey Bull. 730, p. 24, 1922.
GEOLOGIC HISTORY 51

area immediately to the west volcanism on a grand scale broke out, 

and probably it continued until after the sea had retreated from the 

region. It is impossible to be sure what part of the hundreds of 

feet of volcanic strata were formed under water, but probably most 

of them were laid down on dry land. The large amount of fragmental material formed indicates explosive violence in many of the 

eruptions, but there are also numerous lava flows produced by quieter 

effusion. Campbell 41 has suggested that the eruptions came through 

extensive fissures rather than from craters. This explanation accords with such facts as are yet available, but the presence of so 

great quantities of pyroclastic material suggests that some craters 

probably existed, even though no trace of them has yet been found. 

The Cretaceous strata are cut by innumerable dikes of a variety of 

types, and some of these may fill former conduits through which 

certain of the flows found their way to the surface.

INTRUSIVE ACTIVITY

After the volcanism had ceased, probably in late Cretaceous or 

early Tertiary time, came a period of earth movement and batholithic 

intrusion. The age of the granite masses that cover large areas in 

the Santa Teresa and Turnbull mountains has not been fixed with 

precision, but such evidence as is available in this and adjoining 

regions indicates that the intrusions took place at about this time. 

The greatest structural disturbances since the pre-Cambrian appear 

also to have occurred during this period. Most of the folding and 

fracturing that determined the present attitude of the rocks took 

place after the deposition of the Cretaceous beds, and the major 

movements were probably earlier than the Tertiary volcanism. The 

igneous and tectonic activity of this period initiated the formation 

of many of the ore deposits. Indeed, it is probable that all the ore 

deposits in the Stanley and Aravaipa districts that have yet attained 

any commercial importance date from this time.

TERTIARY AND QUATERNARY TIME

The manifold geologic activities that began near the end of the 

Mesozoic era continued to some not yet determined time in the 

Tertiary. There was probably a lull in the disturbances at some 

time before the end of the Miocene, perhaps starting in the Oligocene 

or even earlier. The land had been elevated well above sea level, 

and a somewhat rugged topography had probably been developed. 

Very little evidence regarding the events of early Tertiary time has 

been found, and the lack of fossils makes it impossible to date

41 Campbell, M. R., The Deer Creek coal field, Ariz.: U. S. Geol. Survey Bull. 225, p. 

246, 1904.
52 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

accurately such facts as are known. Probably, in a broad way, the 

appearance of the land bore an approximate resemblance to that of 

to-day. There were numerous differences in topographic detail, but 

some of the major features of the topography were probably already 

in existence, and the climatic conditions may well have been similar 

to those of the present. There have been marked changes in topographic forms and probably fluctuations in climate, but the general 

characteristics of both have probably not changed greatly.

In the Miocene, or perhaps earlier, there was a renewal of 

igneous activity. Sheets of rhyolite and other types of lava were 

poured out, and rhyolitic tuff was formed. The maximum thickness 

of volcanic material erupted at this time in the Stanley district may 

have exceeded the maximum thickness of the Cretaceous volcanic 

deposits, and the Tertiary flows evidently covered a much larger area 

in southern Arizona than the earlier flows. Veins in the vicinity 

of Stanley Butte cut lava of this age. These veins and some others 

are clearly genetically related to the Tertiary volcanism and are 

the youngest mineral deposits in the region. The character of the 

sedimentary deposits associated with the lavas shows that erosional 

processes similar to those of the present time were active then.

A certain amount of crustal disturbance doubtless accompanied the 

volcanism and resulted in fracturing of the rocks or renewed movement on old fractures. Faulting continued in the Pliocene and 

Pleistocene epochs, breaking and shifting 'about blocks of the 

Tertiary lava. Earth movements of diminished violence have continued until geologically recent time. Some features of the present 

topography are direct reflections of these Tertiary and Quaternary 

faults. There is some evidence of the production of a partial peneplain in the Tertiary, probably before part of the faulting. Valleys

formed in this surface, in part as the result of faulting, were filled 

with the sandstone and conglomerate of the Gila formation, which 

is now regarded as in part at least of Pliocene age. The presence 

of tuff in this formation in Arivaipa Box proves that volcanism continued at least into the Pliocene, but no lava of that age has been 

identified.

The physiographic record shows that there have been several more 

or less complete cycles of erosion between the beginning of the 

Pliocene epoch and the present time. The causes of these cycles are 

not yet clear. There may have been changes in local base-level, due 

to earth movements, or fluctuations in climate. Probably both of 

these factors had their effect. If the tentative interpretation of 

the physiography here adopted is correct, erosion after the deposition of the Gila conglomerate continued long enough to form extensive, coalescing pediments, essentially a partial peneplain. After 

this came three or four other periods of deposition of gravel, each
PHYSIOGRAPHY 53

followed by a period of erosion. The erosion in each succeeding 

period of which evidence remains appears to have been less than in 

the previous one.

PHYSIOGRAPHY

The present topographic features of this region are the results of 

a complicated series of events. Only incidental attention to the 

numerous physiographic problems could be given in- the present investigation, but when the data obtained are compared with the 

available information regarding neighboring parts of Arizona it is 

possible to give a tentative summary of the salient physiographic 

events. Most^of the events considered in the following discussion 

took place after the extrusion of the Tertiary lava flows. Even 

before that time the blocking out of some of the broad features 

of the present topography had probably begun, but there is little 

definite information available as to the early Tertiary topography.

PHYSIOGRAPHIC PROCESSES

Surface forms are changed by both mechanical and chemical processes, but chemical changes have had a comparatively minor effect 

in the production of the topography of this region. The mechanical 

effects of running water, wind, and fluctuations of temperature are 

more marked. The end product of the combination of effects produced by these various agents would be a nearly level surface, called 

a peneplain. Such a result is seldom attained before some change 

in conditions causes an interruption. Occasionally the process is interrupted so soon that it has gone only far enough for comparatively 

small level areas to be produced in the valley bottoms. Later the 

streams may be rejuvenated and enabled to cut down into1 the level 

areas, forming terraces. The particular type of partial peneplain 

formed under arid conditions at the base of mountain ranges has 

been called " mountain pediment" by Bryan.42 Pediments formed in 

earlier erosion cycles are of course subjected to erosion in later 

cycles and may eventually be entirely obliterated. In this region 

there are a number of partly completed pediments and terraces at 

varying elevations, and it is largely from a study of these features 

and of the deposits on them that the physiographic history of the 

region is to be learned.

Many of the features of surface forms, especially the broader features, are related to structural disturbances of the crust, but most of 

the details of earth sculpture are produced by weathering and erosion 

acting on rocks of varying resistance. The differences in size and appearance of most of the mountains in the region are due in large 

measure to differences in the character of the rocks composing them

42 Bryan, Kirk, Erosion, and sedimentation in the Papago country, Arlz.: U. S. Geol. 

Survey Bull. 730, pp. 52-54, 1922.
54 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

and to the relation of their positions to the drainage system developed in response to a complicated series of interrelated processes. 

Some isolated mountains may be principally the direct results of 

structural uplifts of geologically recent date. Even these have fallen 

under the dominating influence of superficial agencies, which exert 

themselves as -soon as a rock mass is brought, by any process, within 

their sphere of action.

As oxidation and enrichment in ore deposits are results of 

weathering and of the circulation of ground water, it is obvious that 

a comprehension of the effects of these processes in any district depends on an understanding of the physiography of that district. The 

effects of enrichment may remain in a deposit long after the processes 

that operated to produce it have changed. The data presented in 

this chapter are general rather than specific, but they form a basis on 

which the detailed study of the physiography of specific ore deposits 

in which secondary processes are suspected may be founded.

PEDIMENTS AND TERRACES

Some of the high peaks and ridges in the Turnbull Mountains 

and perhaps also the Santa Teresa Mountains are capped by small 

level areas in striking contrast to the steep slopes below them. These 

may be remnants, isolated by later erosion, of one or more ancient 

peneplains, the oldest that have left any trace in this region. The 

so-called mesa lands surrounding the mountains are other and 

better-defined surfaces of erosion. They occur about both mountain 

groups but are somewhat more extensive and better preserved about 

the Turnbull Mountains. If the material that has been removed 

from them by the many ephemeral streams that issue from these

mountains could be replaced in the gulches whence it came, the 

result would be a set of coalescing plains, which would together 

form, in a broad way, a truncated cone whose sides would slope at 

very low angles. The Turnbull Mountains rest on the upper base 

of this truncated cone as on a pedestal. The sides of the cone, so 

gently sloping as to appear almost flat to the casual observer, are 

formed in part on hard Tertiary and older rocks, in part on alluvium, most of which is somewhat consolidated, tilted, and in places 

broken by faults. At least some of the portion of the plains underlain by this older alluvium has a thin veneer of more recent, unconsolidated alluvium, which is composed mainly of boulders and coarse 

gravel derived from the near-by mountains, whose rugged slopes 

rise abruptly from the plains. In brief, the plains that form the 

sides of this theoretical cone are moderately dissected coalescing 

mountain pediments, in the sense of the term as defined by Bryan.43

" Bryan, Kirk, Erosion and sedimentation In the Papago country, Ariz.: U. S. Geol. 

Survey Bull. 730, pp. 52-54, 1922.
PHYSIOGEAPHY 55

The Santa Teresa Mountains are surrounded by dissected coalescing pediments similar to those around the Turnbull Mountains. 

The east end of the range was not visited. On the north Black Kock 

Wash and its tributaries have removed most of the evidence of the 

pediment which presumably once existed there. On the northwest 

nearly level remnants of pediments are plainly visible to the most 

casual observer, and on the southwest similar plains, cut by numerous gulches, can easily be traced. On the southeast there is a broad, 

rolling plain cut on granite and as yet but little dissected (PL 

VII, A). The altitude of these pediments ranges from about 4,600 

feet above sea level around the Turnbull Mountains to slightly more 

than 5,000 feet south of the Santa Teresa Mountains.

Below the pediments just described no extensive plains have yet 

been carved by erosion, but there is evidence that the process of making such plains has been started several times, only to be interrupted 

by some change in conditions. Most of the mountain streams in the 

region flow in comparatively narrow inner gorges cut in more gently 

sloping valleys. Such changes in slope in valley walls show that 

at some stage in the history of the valley the stream that formed it 

gained increased erosive power and cut down more rapidly than it 

was able to do before the change. These inner gorges in the mountains are doubtless genetically related to terraces farther downstream. 

As streams grow in length by headward erosion, the tributaries 

and upper parts of streams that are not completely graded are 

always more recently formed and consequently have produced less 

mature topographic fo,rms than those along the lower reaches 

In this region erosion along some of the larger streams, such as 

Arivaipa Creek, proceeded far enough in the erosion cycle 

succeeding that in which the mountain pediments were cut to 

produce flood plains. Consequently when this cycle was interrupted 

by increased erosion, terraces were produced along these streams, 

while in those valleys where flood plains did not yet exist the effect 

was to produce inner gorges. The topographic forms in Arivaipa 

Valley indicate that such an interruption of the erosion cycle and renewed cutting has taken place three times since the stream started to 

cut below the level of the pediments around the mountains. This is 

shown by the two imperfectly preserved sets of terraces and the cut 

banks of the present stream channel, where a third set is being made. 

The terraces have been considerably dissected by later erosion and 

are not now continuous throughout the length of the valley. West of 

Klondyke and in several places on the east side of the tributary valley 

in which the Dowdle ranches are situated the terraces are conspicuous 

features of the landscape, and they can also be discerned at other 

points. East of the Dowdle ranches the upper terrace is 200 feet and
56 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

the lower one a few score feet above the floor of the valley. These 

heights become progressively less as the head of Arivaipa Creek is 

approached. The present channel has banks only a foot or two high 

in most places in the main valley. No unquestionably stream-cut terrace was recognized in the steep-walled canyon known as Arivaipa 

Box, but there are in places benches which may be remnants of terraces. (See PI. VI, B) . Some of these benches, however, are doubtless due to fortuitous spalling off of blocks of the wall rocks.

There are gravel deposits of several different ages in this region, 

corresponding to the different partial erosion cycles indicated by the 

topographic forms described above. The extensive pediments around 

the mountains truncate the edges of tilted blocks of alluvial material 

of at least two ages. On the surface of the dissected pediments, 

especially near the outer edges of the present remnants, is a thin 

veneer of gravel. Thin accumulations of loose gravel occur on each 

of the two terraces in Arivaipa Valley. The flood plain below them 

is floored with an undetermined thickness of alluvium, which is later 

than the terraces. The stream channels are filled with gravel and 

sand brought down by the floods of the present day. Part of the 

gravel on the terraces and pediments may have merely weathered out 

of the Gila conglomerate, on which these forms are cut, but on the 

pediments certainly, and on the terraces probably, there is streamlaid gravel later than the erosion surface on which it rests. In places 

on the pediments gravel deposits of two ages lie above the eroded Gila 

conglomerate.

From the data above set forth it is evident that since the mountains 

of the region were uplifted and exposed to erosion early in the 

Tertiary period they have been subjected to fluctuating conditions, 

a-part of the effects of which can still be seen in the topographic 

forms produced. Doubtless there are events in the physiographic 

history of the region of which no record has yet been found. The 

closer spacing of the more recent events, as here sketched, may mean 

not that alternation in conditions was actually more rapid than in 

earlier ages but that the record is more completely preserved.

No fossils have yet been found in the Tertiary or later rocks in this 

region, and there is little by which the events suggested above can 

be dated. In the valley of San Pedro River, to which Arivaipa Creek 

is tributary, numerous fossils have been found in the Gila conglomerate, and the physiographic history of the valley since the 

deposition of that formation has been worked out in detail by 

Bryan,44 who has given names to several of the groups of erosion 

surfaces found in San Pedro Valley. He called the most extensive

44 Bryan, Kirk, and Smith, G. E. P., Geology and water resources of the San Pedro 

Valley, Ariz.: U. S. Geol. Survey Water-Supply Paper (in preparation).
PHYSIOGRAPHY 57

group of pediments the Tombstone. This group can be traced almost 

continuously through the Winkleman and Christmas quadrangles 

into the pediments south of the Mescal Kange and west of the Turnbull Mountains in the Stanley district. In both regions these pediments are cut on Gila conglomerate, lava, and older rocks, and it is 

believed that they are to be correlated. The physiographic events in 

the Stanley and Aravaipa districts inferred from the data given 

above are summarized below, and tentative correlations with similar 

events in San Pedro Valley are given.

The events that led to the formation of the old peneplains, of which 

only remnants are left in the high mountains, and to the deposition 

of the Gila formation took place in the Tertiary period and perhaps 

extended into earliest Pleistocene time. The first Quaternary event 

of which a record remains is the formation of the extensive pediments 

that correspond to the Tombstone p'ediments of San Pedro Valley. 

On these was deposited gravel to a thickness of some tens of feet. Renewed denudation resulted in the production of a broad flood plain 

in Arivaipa Valley but stopped short of the development of pediments such as those of the corresponding Whetstone stage in San 

Pedro Valley. Deposition was resumed but was soon interrupted 

by erosion, which cut some scores of feet into the Whetstone flood 

plain, producing a narrower one below it. This appears to correspond to the Arivaipa stage in San Pedro Valley. A small amount 

of deposition ensued, followed by the erosion that resulted in the 

surface on which the present flood-plain deposits lie. After the formation of these deposits a channel 1 foot to several feet deep was 

cut in them. If this is to be correlated with the similar channel 

of San Pedro Eiver, it is very recent, because, according to Bryan, 

the San Pedro channel was produced in the eighties. The Arivaipa 

channel is floored with a thin deposit of sand and gravel, which 

shifts with every flood.

MOUNTAIN SCULPTURE

The area occupied by the Turnbull and Santa Teresa mountains 

was elevated as a result of crustal disturbance related to the batholithic intrusion, but the present mountains bear only the broadest 

relations to th'at uplift. The cover of stratified rocks has been 

largely stripped off, and erosion has bitten deeply into the massive 

granite beneath. A great body of gently inclined Paleozoic strata 

still remains in the east end of the Santa Teresa Mountains, producing the nearly flat top and cliffed slopes of that p'art of the range. 

Elsewhere in the high mountains the irregularly jointed granite has 

been attacked by the agents of denudation, and the resulting topographic forms lack regularity of shape and system. The forks of
58 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

Good win Wash and their tributaries h'ave cut into the very core of 

the Turnbull Mountains and may some day work their way through 

and split the range up into more or -less isolated ridges. On the 

flanks of both ranges areas of rocks other than granite still linger, 

and here the topography characteristic of e'ach of the rdck types 

is developed. The mountains carved on pre-Cambrian rocks, 

although steep, have in general smoother, more regular slopes with 

more soil than those carved on granite. Mountains formed of 

tilted str'ata are asymmetric. The sides sloping in the direction of 

dip of the beds tend to have smooth, flowing profiles. Those whose 

slopes are opposed to the dip of the beds are characteristically 

steeper and marked by cliffs. Good examples are Eawhide Mountain, in the Mescal Range, and Quartzite and Limestone mountains, 

in the Turnbull Eange. A few elevations, notably those which rim 

the west side of the Valley in which the Dowdle ranches lie, north of 

Klondyke, originated by faulting at the end of the Tertiary or in 

the Pleistocene, and their position and general shape result from 

the structural movement, modified in detail by later erosion.

ORE DEPOSITS

TYPES

In the Aravaipa-Stanley region there are deposits of metallic 

minerals of six general types and also beds of coal. The type of 

greatest areal extent is represented by the Grand Reef and associated lodes. This group might be further subdivided on the basis 

of variations in both mineral composition and character of deposition. Replacement deposits in limestone constitute a second type 

of widespread occurrence. There is some overlap between this and 

the first group, because some of the replacement deposits on fissures 

in limestone partake of characteristics of both. A third type is 

represented by the veins with calcite gangue on and near Little 

Stanley Butte. The shear zones in andesite and the adjoining disseminated deposits south of Stanley Butte are thought to be related 

to this type. The veins in which barite is a prominent constituent 

exemplify a fourth type. The copper deposits of Fisher's prospect constitute the only known representatives of a fifth type. The 

sixth type comprises the gold-bearing veins of the Santa Teresa 

Mountains. Available knowledge of the coal beds in the valley of 

Deer Creek is summarized on pages 114-117. All the ore deposits 

have been subjected to the processes of oxidation, and there has 

been some enrichment. The effects of these processes are considered 

in a separate section (pp. 72-76).
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE IX

A. NORTH SIDE OK GARDKN GULCH BELOW TIIK I'MII'.iM) MINE

The white rock above is the Tornado limestone, of Carboniferous age. The thin-bedded 

rock below is Upper Cretaceous sandstone. They were brought into reversed relations 

by an overthrust

B. GRANITE NEAR FISHER PROSPECT, IN THE SOUTHEASTERN PART OF 

THE TURNBULL MOUNTAINS
U. S. GEOLOGICAL SURVEY BULLETIN 763 PLATE X

A. GRAND REEF OUTCROP, FROM THE RIDGE ON THE NORTH SIDE 

OF LAUREL CANYON

The dismantled mill is in the right foreground

B. EDGE VIEW OF THE GRAND REEF OUTCROP, ON THE NORTH SIDE 

OF LAUREL CANYON, FROM THE MILL

Dumps from the upper workings are visible at the left
U. S. GEOLOGICAL SURVEY BULLETIN 703 PLATE XI

COBRE *

GRANDE

MINE

f/SHER PROSPECT 

3 MILES DUE EAST 

OF THIS POINT

* LACLEDE MINE

CLAIM MAP OF THE ARAVAIPA MINING DISTRICT

Compiled by C. P. Ross from mops supplied by C. A. Firth, Frank Landsman, Aravaipa Leasing Co., and E. H. Bachman and from data obtained in the field. Some claims on which little development work has been done are not shown, and the positions of some groups are indicated only by their names, for lack of information

Aravaipa Leasing Co.

1 Varick

2 Junction (patented) 

3 Conundrum 

4 Blank (patented)

5 Silver Cable 

6 Dog Water (patented)

7 Boston

8 New York

9 Chicago

10 St. Louis

11 Kansas City

12 Laurel 

13 Mountain Spring (patented) 

14 El Paso

15 Los Angeles

16 Liberty Loan 

17 South Point (patented) 

18 New Independence 

19 Grand Reef No. 2 

20 Gulch

21 Grand Reef (patented) 

22 Grand Reef No. 1 

23 New Liberty 

24 Bleviu (^ owned by T. 

Finnegan) 

25 Aravaipa (patented)

James Quinn group

26 New Year's Gift 

27 Copper Prince 

28 Homestako

29 Ten Strike

T. Finnegan group

30 Oronoco

31 Guard No. 1

32 Xraas Gift

33 Guard No. 2

Bullis group

34 Anna 

35 Josie

36 Maggie 

37 Lone Jack

38 Anita

39 Crcston

40 Good Luck

41 Little Johnie

42 Black Oak (patented)

43 Imperial (patented) 

44 Keynote

45 Nogi

46 Acorn (patented) 

47 Western (patented)

48 Winsor (patented) 

49 Apex (patented) 

50 Blue Oak 

51 While Oak

52 San Antonio 

53 Lular (patented) 

54 May Tustin 

55 Copper Queen 

56 Red Oak 

57 St. Louis 

58 Flying Dutchman

59 Octavia

60 Teko (patented) 

61 Iron King (patented) 

Bullis-Landsman group

62 Vulture

63 Lookout

64 Aleman 

65 Lead King

66 Red Queen

67 Red Ruby

68 Ben Hur No. 2

69 Ben Hur No. 1 

70 Iron Cross

Aravaipa Mining Co.

71 Sand Carbonate 

72 Panama

73 Nina

74 Number 1

75 Number 2

76 Standish

77 Orejana

78 Wiutlirop 

79 Silver Bell (patented)

80 Mammoth Chief (patented) 

81 Connection (patented)

82 Keedy (patented) 

83 Thanksgiving (patented) 

04 Arizona (patented) 

85 David (patented)

86 Glory (patented) 

87 Maxwell (patented) 

88 Gordon (patented) 

89 Iron Cap (patented) 

90 Irontou (patented) 

91 Ionia (patented) 

92 Grand Central (patented)

93 Head Center ^ateuted)

94 Forest 

Tolman-Babcock group 

95 Extension

96 Tolman

97 Babcock

98 Triangle 

99 Ramon Coro

100 La Sorrilla

//. T. Firth's claim

101 Curtis 

Norton group 

102 Box Canyon

103 Norton 

104 Number 12

105 Number 11 

//. T. & C. A. Firth group

106 Lead One

] 07 Lead Two

108 Lead Three 

109 Lead Four

110 Lead Five

111 Lead Six

C. A. Firth group

112 Woodrow Wilson 

113 Tinker

114 Wedge 

115 Joe Bush

Moltke group

116 Moltke No. 2 ' 

117 Copper Coin 

118 Moltke

119 Buffalo

Royal T into Mining & Smelting Co.

120 Oak Grove

121 Florida (patented)

122 Frances

123 Maine (patented) 

124 New Jersey (patented)

125 Constitution

126 Iron Jacket (patented)

127 New York (patented)

128 Sandy (patented) 

129 Tinto (patented) 

130 Sam Jones (patented) 

131 Charlie Boy (patented)

132 Stranger 

133 Rainbow (patented)

134 Anaconda

135 Clansman (patented)

136 Annex (patented)

137 New State

138 Roosevelt

139 Copper Bar (patented) 

140 Baldwin (patented)

141 Limelight (patented)

142 Sidney (patented) 

143 Pinchot

144 Rosa 

145 Newark (patented) 

146 Norton (patented) 

147 Carrie (patented)

148 Jerome 

149 Copper Spar (patented) 

150 Cora (patented) 

151 Clara (patented) 

Landsman group 

152 Little Eagle No. 6

153 Little Eagle No. 7

15<L Little Eagle No. 5 

155 Little Eagle No. 4 

156 Little Eagle No. 3 

157 Fluoride No. 4

158 Fluoride No. 3

159 Fluoride No. 2

160 Fluoride No. 1 

161 Little Eagle No. 2

162 Little Eagle No. 1

163 Iron Reef No. 1

164 Iron Reef No. 4

165 Iron Reef No. 7 

166 Iron Reef No. 11 

167 Iron Reef No. 14 

168 Iron Reef No. 17

169 Alpine 

170 Iron Reef No. 2

171 Iron Reef No. 5

172 Iron Reef No. 8.

173 Iron Reef No. 12

174 Iron Reef No. 15

175 Iron Reef No. 18

176 Tip Top No. 1 

177 Iron Hat No. 2

178 Iron Hat No. 1

179 Iron Reef No. 9 

180 Iron Reef No. 13

181 Iron Reef No. 16 

182 Iron Reef No. 19 

183 Iron Reef No. 20 

184 Tip Top No. 2

185 Iron Reef No. 6 

186 Iron Reef No. 3 

187 Iron Reef No. 10 

188 Ruetia

Silver Coin mine 

189 Silver Certificate

190 Silver Coin

191 Legal Tender 

192 Hard Case 

193 Anna 

194 Ted

 * * ** * /* 

 !*! *. .* . * 1 *** 
ORE DEPOSITS 59 

AGE

All the ore deposits in the region appear to have been formed 

after the intrusion of the batholith. Some, such as those of the 

Fisher prospect, were closely related in time to that event. Others 

were not formed until after the extrusion of the Miocene (?) lava. 

There is evidence of two periods of mineralization in veins near 

Arivaipa. Probably there were recurrent periods of minerali/-itio:i 

extending from the Eocene into Miocene or even later time.

GRAND BEEP LODE SYSTEM

On the west side of the Santa Teresa Mountains there is a group 

of lodes which, although differing in details, have sufficient characteristics in common to indicate that they are genetically related. 

The principal mineralization in all of them took place during the 

same period and under similar conditions. They thus form a single 

lode system. The largest of the lodes and the one on which most 

development work has been done is known as the Grand Reef, 

and the group as a whole may for convenience be designated the 

Grand Reef system.

The system extends from a point west of Buford Hill through 

Imperial Hill to Old Deer Creek, a distance of more than 11 miles 

in a straight line. The claim map (PI. XI) serves to bring out 

the trend of the deposits in a general way, as the longer sides of many 

of the claims are approximately parallel to the strike of the lodes in 

them. The larger groups of claims, however, have been laid out so 

as to cover a number of adjoining lodes, and the claims do not necessarily bear any relation to the strike. The Landsman claims cover 

contact-metamorphic deposits of irregular extent, which do not form 

part of the Grand Reef system. The deposits on the other claims 

shown on Plate XI probably all belong to this system. The strike of 

the system as a whole is about 1ST. 20° W. Most of the lodes strike 

somewhat west of north, but there is a considerable variation, especially near the ends of the system, and a few strike nearly east. 

Most of the lodes dip steeply west, and many are nearly vertical. 

A few dip east. The width ranges from a few inches to 200 feet. 

The lodes clearly extend much deeper than development work hats 

yet gone. Comparison with deposits of similar origin in other 

regions leads to the supposition that they may in places continue 

hundreds or even thousands of feet below the lowest points yet 

reached in the mines. Mineralized outcrops are by no means continuous throughout the 11 miles of extent of the system. It is 

probably not possible to trace any lode in the district continuously 

106914 25 5
60 ABAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

on the surface for much" over a mile, and most exposures are far 

shorter than this. Underground the deposits would probably be 

found to be more continuous. It seems that at the Grand Reef mine 

and for several miles north of it the zone in which mineralization 

took place is narrow, although some of the individual lodes here 

are wider than any known in other parts of the system. In Imperial Hill several lodes are recognized. Beyond it the lode system spreads out. To the northeast are the lodes on the Royal 

Tinto and adjoining properties. To the northwest are those of the 

Aravaipa Mining Co. and the apparently less continuous deposits 

to. the east of them. South of the Grand Reef a number of lodes 

are also known. The Dog Water and Silver Cable mines are clearly 

on separate lodes. East of these are still other lodes whose strikes 

diverge widely from that of the Grand Reef. Farther south are 

the La Clede and Silver Coin lodes, which are parallel to each 

ather and strike approximately east. It may be noted that the 

.portion of the Grand Reef system in which the zone of mineralization is narrow is entirely in the intrusive fhyolite near its contact 

with the granite of the main batholith. North and south of this 

locality, where there is a larger number of lodes and greater divergence in strike, other rocks either form the wall rocks of the deposits or are near at hand. Perhaps the differences in strike of 

the fracture zones that contain the deposits bear some relation to 

the differences in the effects of pressure exerted on rocks of different types and powers of resistance.

The country rock at nearly all exposures has been brecciated and in 

many places has been intensely shattered. The deposits formed in 

.the fracture zones have a composite character. They are made up 

in.part of mineral matter introduced from without, in part of fractured and highly altered country rock which has been incorporated 

in them. They are termed lodes to distinguish them from veins 

formed essentially by the deposition of mineral matter as filling in 

fissures, with or without alteration of the wall rocks. The country 

rock of the lodes in the different parts of the Grand Reef system varies markedly in chemical composition and other characteristics, yet 

the chemical composition of all the lodes is in general similar, though 

local variations have been noted. The chemical composition of the 

lode matter also differs markedly from that of the unaltered country 

rock. For these reasons it seems clear that a large part of the mineral matter in the lodes has been introduced from some outside 

source. On the basis of the mass of evidence accumulated by the 

study of similar deposits in other regions by many geologists it 

can be affirmed with confidence that deposits exhibiting such mineral 

associations as those found in these lodes have derived part of the 

material composing them from igneous rock. It is highly probable
ORE DEPOSITS 61

that in this region the magma which formed the granite batholith 

was the source of mineralization. The contact-metamorphic deposits 

and the copper deposits of the Fisher prospect, which are even more 

intimately related to the intrusion, show conclusively that the valuable metals and most of the nonmetallic constituents of the lodes here 

described were present in the magma from which the granite consolidated. The processes by which the lodes were produced are outlined 

below. The molten mass that was intruded into the rocks of the 

crust to form the batholith contained besides the material that 

consolidated into granite considerable material that did not become 

solid under the conditions existing when the minerals of the granite 

crystallized. These volatile constituents were squeezed out of the 

granite mass as it solidified and were forced into the surroundingrocks. The process was gradual, continuing throughout the period of 

consolidation of the batholith, which probably occupied a long time 

measured in terms of human experience. Part of the volatile constituents went to form the contact-metamorphic deposits and those represented by the Fisher prospect, both of which are described below 

(pp. 63-70). Part of them got farther from their sources and 

under the lower temperature and pressure there encountered became 

liquid solutions. The fracture zones on the west side of the Santa 

Teresa Mountains afforded convenient paths for the ascending SO!UT 

tions, and the deposits were consequently localized along these zones. 

The fractures may originally have been opened in the course of adjustments in the rocks brought about by the intrusion of the batholith. Movement recurred along them during the mineralization, as 

is abundantly shown by the brecciation and sheeting in the deposits. 

Emanations and solutions thus genetically related to igneous rocks 

are termed hypogene to distinguish them from descending waters 

containing matter dissolved out of rocks near the surface by processes 

of weathering, which are termed supergene. These terms are also 

applied to the deposits thus formed. The material of which the 

hypogene minerals in these lodes consist came in large part from the 

ascending solutions, but pait of it came from the brecciated rock 

through which the solutions circulated and which they attacked 

chemically. The differences in mineral composition in the lodes in 

the various parts of the system result in part from differences in 

the composition of the rocks traversed by the solutions. The process 

of hypogene mineralization probably occupied a considerable time 

and appears to have been divided into several stages. With the possible exception of some of the minerals in the lodes in limestone the 

minerals are such as do not require very high temperature for their 

formation.

In most of the lodes of the Grand Reef system the gangue is quartz 

and fluorite. In lodes in and near the Tornado limestone chlorite,
62 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

epidote, actinolite, and small amounts of specularite and calcite have 

also been found. The hypogene sulphides found are galena, sphalerite, pyrite, chalcopyrite, and argentite. Products of oxidation and 

secondary deposition from surficial water were noted in most of the 

deposits.

The dominant alteration in the country rock is silicification. The 

brecciated rock incorporated in the lodes is largely replaced by 

quartz and cut by numerous later stringers of the same mineral. 

Rock at some distance from the lodes is similarly affected but to a 

less degree. The feldspar of the igneous rocks near the lodes, especially the rhyolite and quartz latite in the vicinity of the Grand 

Reef and neighboring lodes, is sericitized, but in general sericite is 

not much more abundant in rock near the lodes than in similar rock 

at a distance. It is noteworthy that primary ferromagnesian minerals are almost completely absent in the igneous rocks close to the 

lodes. They have broken down into chlorite and other alteration 

products.

Quartz is present in irregular masses and distinct veins in the lodes 

as well as in the replacement deposits already mentioned. The texture displayed by it is various. In the stopes above the adit in the 

Grand Reef mine gray chert is present in the breccia. On the 

100-foot level are irregular masses of white and pink glassy quartz. 

In several places on this level and above there is medium-grained 

thin-banded quartz with narrow drusy cavities. Clear quartz forms 

only a small proportion of the parts of the Grand Reef lode seen 

during the present investigation, but in most of the other lodes it is 

more abundant. In some mines and prospects the deposits are essentially quartz veins. The wall rocks are altered and fractured, but 

fragments of them do not enter into the composition of the vein 

itself. The veins exposed in the Arizona and Orejana tunnels, near 

Arivaipa, are examples. In most such veins the quartz is thin 

banded and contains druses. The banding approximately parallels 

the sides of the vein and appears to have resulted from shearing of 

the quartz after deposition. The drusy openings common in the 

(quartz appear to indicate that the pressure existing at the time of 

formation was moderate, as deposits formed under great pressure do 

not contain open cavities. This inference is also in accord with the 

probable depth of the parts of the lodes now exposed at the time 

mineralization commenced.

Fluorite is widespread in the Grand Reef mine. It has also been 

noted in some of the others and may be present in a number of places 

where it was not detected, as it is most inconspicuous. Clear, 

roughly cubical grains, visible only under the microscope, were found 

in quartz from the Grand Reef. In the breccia of this reef there are 

in places numerous small fragments composed of fine-grained fluorite
OKE DEPOSITS 63

that looks more like chert than like typical fluorite. A veinlet over 

half an inch wide of similar white fine-grained fluorite cuts galena 

in one of the Mountain Spring prospect tunnels. The fluorite is cut 

by tiny stringers of quartz. The veinlet is indistinctly banded by 

shearing, and the sides of the veinlet and sheared surfaces in it are 

coated by a thin film of some micaceous mineral.

Galena is as a rule the most abundant of the sulphides. It is of 

variable texture. .Most specimens from the Grand Reef and neighboring lodes show considerable crushing. Specimens of galena from 

this and a number of other deposits when polished, etched with acid, 

and examined under the microscope are found to contain blebs of a 

mineral which appears to be argentite, the sulphide of silver. Probably most of the silver found by assay in the galena ore is in this 

form, and it is likely that most of the galena in the deposits of the 

Aravaipa-Stanley region contains argentite. Where exposed in the 

deposits on Imperial Hill and north of it the galena is coarse and 

shows little evidence of having been crushed. Sphalerite is associated with the galena in most places but in small amount. Only in 

the deposits on the north flank of Imperial Hill is it conspicuous. 

Pyrite is nowhere abundant and in many specimens is absent. Chalcopyrite is of irregular distribution. It is present as microscopic 

blebs in some sphalerite grains and has also been noted in irregular 

masses and veinlets cutting galena. The records of the Aravaipa 

Leasing Co. indicate an apparent increase with depth in the copper 

content of the ore in the Grand Reef mine.

CONTACT-METAMORPHIC DEPOSITS

There are mineral deposits in nearly all the masses of Tornado 

limestone scattered over the region. Most of them have the characteristics of contact-metamorphic deposits and will be described in 

this section. These include the deposits on the Landsman property, 

at the Cobre Grande mine, and on Satisfaction, Packwood, Limestone, and Copper Reef mountains. Some deposits in limestone form 

parts of the Grand Reef lode system, already described. Even these 

have characteristics in common with the contact-metamorphic deposits and form connecting links between them and the lodes. A fCAV 

deposits, such as those of the Starlight mine and southwest of Rawhide Mountain, are not known to contain contact-metamorphic minerals and are too greatly separated from the lodes of the Grand Reef 

system to be assigned to that system. When more is learned regarding these deposits it will probably be found that their mode of formation is similar to that of the lode system or the contact-metamorphic 

deposits. There are certain features of the Starlight mine, however, 

which suggest that there may be material differences between the
64 AKAVAIPA AND STANLEY MINING DISTRICTS,, ARIZ.

.method of formation of the deposits here and that of any of the 

others in the region. In the lack of fuller knowledge these deposits 

are discussed in the present section.

Contact metamorphism is a process of alteration by which changes 

are produced in rocks as a result of the intrusion of igneous magma 

into them. The changes are in part produced by the mechanical 

disturbance and heating of the rocks, but of much greater importance 

in connection with ore deposits are the chemical changes produced by 

the injection of hot fluids, probably largely gaseous, from the cooling 

magma. Calcareous rocks are affected to a much greater degree by 

such emanations than others, and ore deposits formed in this way are 

therefore more likely to be found in such rocks. The name contact 

metamorphism was given to the process because as a rule the rocks 

near the contact of the igneous mass that supplies the agents of 

metamorphism are most intensely altered by it. In many places, 

however, rocks at considerable distances from known masses of 

igneous rock show contact-metamorphic changes. It appears that 

under favorable conditions emanations from the magma can penetrate 

long distances into the surrounding rocks. The deposits typical of 

contact metamorphism are produced by rearrangement of the substances present and the introduction of others, forming a new set of 

minerals in rock already existing, rather than by the deposition of 

bodies of foreign mineral matter from solution along channels opened 

in the rocks, as in the vein deposits. The silicate minerals, such as 

garnet, epidote, and actinolite, are characteristic of contact-metamorphic deposits, although rare in mineral deposits of most other 

types. The iron oxide minerals magnetite and specularite, the crystalline form of hematite, are frequently found. Pyrite and chalcopyrite are among the common sulphides in such deposits. The 

texture of most of the deposits is coarse, and some minerals exhibit 

crystal form. The shape of the deposits depends partly on the ease 

with which the different rocks that came within the influence of the 

emanations were attacked by them, and partly on the freedom of 

access from the igneous rock that was the source of supply. Slight 

differences in original composition may cause marked differences in 

the amount of metamorphism. In some deposits the shape can be 

seen to have resulted from selective replacement along beds of favorable composition. Other deposits have formed where fractures offered convenient paths for the emanations, and such deposits may be 

intermediate in character between those typical of contact metamorphism and veins.

The following general description and the accounts of individual 

deposits show that all the deposits in limestone, with such exceptions 

as have already been rioted, are in form, texture, arid mineral associations characteristic of contact-metamorphic deposits. They re-
ORE DEPOSITS 65

semble in many respects the contact-metamorphic ore bodies of the 

Clifton-Morenci district 45 and are of about the same age. Some of 

them, like those at the Copper Reef mine, are at a distance from outcrops of granitic rock, but all of these are near f elsitic porphyry dikes 

that may have contributed to their formation. Near some dikes 

there is notable contact metamorphism, and the dike rock itself is 

partly replaced, but near others there is little alteration in the adjacent limestone. There may be granite below the surface which is 

nearer to some of these deposits than can be determined from the outcrops of such rock.

Mineralized deposits

PIGDEB 1. Diagram showing contact-metamorphic deposits in limestone

The forms assumed by these deposits are various. Some representative ones are shown diagrammatically in Figure 1. In many 

deposits the replacement has been guided by the bedding planes in 

the limestone, and the original sedimentary structure is preserved 

in the metamorphic rock. Replacement may occur in a number of 

contiguous strata or may be approximately confined to a single bed. 

Locally fractures in the rock have furnished channels along which 

replacement has occurred. Replacement along fissures appears to 

have produced more irregular, smaller, and less continuous deposits

<B Lindgren, Waldemar, The copper deposits of the Clifton-Morenci district, Ariz.: U. S. 

Geol. Survey Prof. Paper 43, 1905.
66 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

than that along the bedding, but there may well be exceptions to 

this rule. Some of the deposits are most irregular in shape and are 

independent both of the bedding and of visible fractures. The 

larger deposits can be traced in places hundreds of feet laterally 

along the limestone beds. The transition into unaltered limestone is 

generally rather abrupt, although more gradual transitions were also 

noted. In places the major part of the limestone exposed over a 

considerable area has been altered, and there is a progressive decrease 

in the amount of limestone so affected at increasing distances from 

this area, although the replacement in the rock that has been affected 

may be as complete in one place as in the other. These deposits are 

so irregular in shape and have boundaries so indefinite that it is not 

safe to predict the continuation of a given deposit far in advance 

of actual exposures.

The minerals noted in the deposits are quartz, garnet, actinolite, 

chlorite, epidote, fluorite, barite, calcite, specularite, magnetite, 

pyrite, chalcopyrite, sphalerite, galena, stibnite, and various oxidized 

minerals and secondary sulphides. Most of the galena contains tiny 

blebs that are probably argentite. The proportions of the minerals 

differ in different places, and in no single deposit have all the minerals listed above been found. Quartz is abundant in a number of 

exposures, but in some it is inconspicuous. It is clearry of two generations, both later than most of the metallic minerals. There are 

in a number of places drusy cavities lined with well-formed quartz 

crystals. The garnet resembles andradite, but its exact composition 

has not been determined. It occurs in massive form and in crystals 

projecting into cavities. The quantity of garnet in most of the ore 

deposits is small, and in many none was found. In the contactmetamorphic rock of Crystal Peak garnet is abundant. Actinolite 

is locally prominent in masses composed of groups of needles radiating in all directions from common centers. Chlorite is found in 

masses of flakes of various sizes but is not a conspicuous constituent 

in much of the ore. Epidote forms small groups of crystals but is 

nowhere very abundant. It is associated with garnet in most specimens in which it has been identified. Fluorite was found in the deposits on the Landsman property. Crystals of it nestle among 

the quartz prisms in druses, and it was also noted in massive quartz 

veinlets. Calcite is present in many of the deposits but everywhere 

in small amount. Barite was noted only in specimens from the 

Copper Reef mine.

Specularite and magnetite occur in all the deposits seen. In most 

specimens the former is the more abundant. The relations of these 

two minerals to each other are complicated and present many features of interest. Each may replace the other, and it is evident that 

this reversible chemical process has taken place in both directions in
U. S. GEOLOGICAL SUKVEY BULLETIN 763 PLATE XII

» jfrv

 A

c

MAGNETITE IN PROCESS OF REPIACEMENT BY SPECULARITE
ORE DEPOSITS 67

the deposits of this region. In specimens from the Landsman property magnetite that was formed early in the process of mineralization has been extensively replaced by specularite. Small rounded 

grains of magnetite penetrated along octahedral partings by specularite and surrounded by that mineral can still be found. (See PL 

XII.) Such relations clearly indicate that the specularite has 

formed at the expense of the magnetite. The specularite inclosing 

such residual magnetite grains is irregular in outline, but crystal 

plates of the mineral project from it into the quartz gangue,in which 

numerous well-formed specularite plates are embedded. The long 

axes of the plates have a subparallel arrangement strongly suggestive of flowage. It seems that the specularite formed from the magnetite had so strong a tendency to crystallize that it assumed the 

plate form characteristic of the mineral. Evidently, this took place 

before complete consolidation of the quartz in which the iron minerals are embedded, for the plates could not have been rearranged 

along lines of flowage if they had been inclosed in solid material. 

However, the specularite tends to segregate along lines around quartz 

grains, proving that part of the quartz had already crystallized before the specularite assumed its present arrangement. These plates 

are themselves embedded in quartz, which crystallized after they 

did. Some of the specularite may have originally crystallized as 

such instead of being derived from magnetite.

Some specimens from the Cobre Grande mine show entirely different conditions. Here there are grains that are composed of magnetite but have the crystal form of specularite. These are clearly 

pseudomorphs produced by the conversion of original specularite into 

magnetite. In specimens from the same deposit there are foils of 

micaceous specularite containing small amounts of magnetite. All 

the specimens of black iron ore from various parts of the region that 

have been tested contain both specularite and magnetite, but the 

visible crystal forms in all of them are those of specularite.

Pyrite is abundant in many specimens of ore. It was one of the 

first sulphides to form and crystallized in more or less cubical grains, 

which were later broken apart, shattered, and embedded in gangue 

minerals or chalcopyrite that subsequently consolidated. Only small 

quantities of chalcopyrite were noted in any of the deposits except at 

the Cobre Grande mine. In some of the specimens from this mine 

the mineral is abundant in structureless masses inclosing pyrite 

grains. Some specimens contain a few small grains that appear to 

be sphalerite and galena, but both these minerals are rare in all the 

contact-metamorphic deposits visited. A few small crystals of stibnite were found in ore specimens from the Cold Spring prospect, 

but the mineral was not observed elsewhere, and tests on ore specimens from other deposits failed to reveal any antimony. 

106914 25 6
68' ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

The distribution of the different minerals within the contactmetamorphic deposits is variable? In places one of the nonvaluable 

minerals is the most abundant constituent, in others another. Parts 

of some deposits contain so high a percentage of magnetite and specularite as to 'constitute iron ore, which might be utilized if it were 

found in sufficient quantity and if a suitable market for such material 

were sufficiently convenient. Under present conditions iron ore in 

this region is of little value. The metallic sulphides are of particularly irregular distribution and make up only a small part of the 

axposed contact-metamorphic deposits. This is strikingly shown on 

Crystal Peak, where thousands of tons of intensely contact-metamorphosed limestone is exposed. The only prospect known here is 

at Cold Spring, on the edge of the contact-metamorphosed mass, and 

the development work at this prospect appears to have discovered 

little of value. Elsewhere on Crystal Peak no sulphides or evidences 

of their former presence appear to have been found. The distribution of minerals in such deposits and the shape and size of the 

deposits themselves are so diverse that prospecting in them presents 

even more uncertainties than in veins, but valuable ore bodies occur 

in otherv regions under conditions similar to those which exist here, 

and small amounts of copper ore have been found in contact-metamorphic deposits in so many places in this region as to encourage the 

hope that deposits of sufficient size and grade to be commercially 

valuable may be present in the Aravaipa-Stanley region.

As has been mentioned, the Starlight mine presents some features 

of interest. The rocks in the vicinity of the mine comprise the 

Tornado limestone, Cambrian quartzite, pre-Cambrian schist, and an 

altered intrusive rock. The Paleozoic strata are fractured, tilted, 

and even in part overturned. Schist is exposed under these rocks in

Godless Gulch. Just east of the mine is the altered igneous rock, a 

dark-green fine-grained rock having the composition of an altered 

soda-rich granodiorite or soda granite that originally consisted of 

micrographic intergrowths of quartz, alkali feldspar, and plagioclase, and also presumably ferromagnesian minerals, although none 

now remain. The alteration of this rock produced chlorite, epidote, calcite, and secondary quartz and was probably effected under the influence of moderately heated solutions that seeped up 

through the rock from below. Some of the original minerals broke 

down and formed new combinations, and some water, carbon dioxide, 

arid perhaps other things were added. Although the appearance and 

mineral composition have changed notably, the chemical composition 

may not be much different from that of the original rock. Such 

alteration differs markedly from that produced by contact metamorphism. This fact, coupled with the apparent lack of contactmetamorphic minerals in the ore, makes it appear that the deposits
ORE DEPOSITS 69

of the Starlight mine may differ in origin from most of the ore 

deposits in limestone in the region.

COPPEB DEPOSITS IN THE GRANITE OF THE MAIN BATHOLITH

A curious type of copper deposit in the granite of the main batholith is known only in the Fisher prospect, in the southeastern part of 

the Turnbull Mountains. The rock here and for 2 miles or more 

in every direction is granite. Near the prospect are some narrow 

dikelets of aplite containing abundant micropegmatite. The metallic 

minerals are irregularly disseminated in the granite. The limits of 

each deposit are indefinite, but there appear to be a number of disconnected, elongate zones of mineralization. Indefinitely marked slips 

occur in the mineralized granite in places, but there is no suggestion 

of the filling of fissures by vein matter or of any definite walls. 

Chalcopyrite, the only original sulphide found, has crystallized in 

the granite with only a minor development of gangue -minerals foreign to that rock. These are epidote, titanite, apatite, and chlorite, 

or a similar alteration product. The minerals of the granite are. 

almost perfectly fresh, but some of those near ore minerals are 

somewhat shattered. There has been some oxidation and a little 

enrichment.

The striking features of these deposits are the paucity of nonmetallic minerals connected with the metallization, the lack of alteration in the granite, the intimate relations .of the chalcopyrite to 

the minerals of the granite, and the lack of definite form or bounds 

to the deposits. Clearly the mineralization resulted in impregnation 

of the granite, not in the formation of veins. The slips mentioned 

may well have been merely openings along joints formed by contraction during the cooling of the granitic magma. They may have 

furnished paths of access to the mineralizing agents and thus served 

to localize the deposits to a certain extent. The mineralization is 

evidently closely related to the intrusion of the granite. It probably took place during the cooling of the rock, when joints were beginning to form but while the temperature was still high. At this 

stage in the consolidation of an igneous rock most of the minerals 

constituting the main mass of the intrusion have crystallized, but 

some of the most volatile constituents of the original magma have 

not yet consolidated. Some of these volatile constituents, presumably 

gaseous, squeezed out from below by the formation of the rock minerals, seeped upward until a favorable combination of conditions 

of temperature, pressure, and concentration was encountered. Here 

the emanations attacked the minerals of the granite, replaced them, 

and deposited chalcopyrite in their stead. Epidote crystallized out 

later to fill the spaces between, the chalcopyrite grains. Thus the
70 AEAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

deposits appear to fall in the class which Graton and McLaughlin 46 

propose to call pneumotectic that is, they were formed after the 

strictly magmatic phase of intrusion of molten rock and before the 

pneumatolytic stage marked by the presence of abundant miner - 

alizers. They were intimately related to the intrusion of the granite 

magma but were probably formed shortly after the major part of the 

consolidation of the main mass had taken place. Although formed 

under the influence of gaseous constituents by replacement of the 

granite, they can not be called pneumatolytic in the sense in which 

that term has been restricted by Graton and McLaughlin, for there 

is little evidence of destructive pneumatolytic action, and none of the 

characteristic pneumatolytic minerals were found. Each of the nonmetallic minerals formed during the original mineralization is much 

less abundant than the chalcopyrite. The few prisms of apatite 

noted are almost negligible, especially as similar tiny crystals were 

found in thin sections of specimens from distant parts of the batholith. The epidote is thought to have formed in the pneumotectic 

stage after the deposition of the chalcopyrite, but possibly, as Tolman 

and Rogers 47 have suggested, it is a result of later hydrothermal 

alteration. The titanite was probably formed under essentially the 

same conditions as the epidote. The chlorite is distinctly a later 

hydrothermal alteration product. It is to be noted that the Fisher 

prospect is in granite, whereas most of the sulphide deposits in other 

regions so closely related to magmatic processes are in subsilicic 

rocks.48

The copper minerals present other than the chalcopyrite are all 

much later in origin. They were formed by processes of oxidation 

and enrichment similar to those which produced similar minerals in 

deposits elsewhere in the region.

CALCITE VEINS

There are several veins in the vicinity of Stanley Butte in which 

c*alcite is a prominent gangue mineral. This mineral is inconspicuous or absent in the other veins of the region, except where a 

vein cuts limestone and has derived calcite from it. The mechanism 

of formation of these veins is similar in some respects to that of the 

formation of the Grand Reef lode system, already described, but 

the mineral composition is markedly different. Some of the veins 

of this type cut Miocene (?) lava, showing clearly that they are at 

least as young as the lava, and therefore more recent than the major 

mineralization in the Grand Reef system.

*a Graton, L. C., and McLaughlin, D. H., Further remarks on the ores of Engels, Calif.: 

Econ. Geology, vol. 13, p. 85, March, 1918.

47 Tolman, C. F., and Rogers, A. F., A study of the magmatic sulfld ores: Leland Stanford Junior Univ. Pub., Univ. series, p. 17, 1916.

"Idem, p. 70.
ORE DEPOSITS 71

The veins in the Tertiary lava are composed very largely of massive, coarsely crystalline calcite containing manganese oxide. A 

little cherty quartz is present in places, and films of gypsum coat 

cleavage cracks in the calcite. In chert-lined cavities are tiny crystals of a mineral resembling anatase. Such veins were found in 

prospect holes on Stanley and Little Stanley buttes. The copper 

veins of the Friend mine and the zinc and copper veins and shear 

zones of the Princess Pat mine and its vicinity contain calcite as a 

prominent constituent of the g'angue. These deposits are in. volcanic strata believed to be Cretaceous, but Miocene (?) lava overlies the Cretaceous beds a short distance above the deposits, so that 

possibly the veins originally extended up into the Tertiary (Miocene?) lava before the lava was eroded. The deposits at both localities are therefore tentatively grouped with the Miocene (?) calcitebearing veins. The veins that the tunnel of the Stanley mine 

was driven to develop and the veins on Rawhide Mountain regarding which little is known may belong in this group.

The deposits of this group are in part clear-cut veins with definite 

and regular walls, in part zones of brecciation and shearing. They 

contain c'alcite, quartz, chalcopyrite, sphalerite, pyrite, galena, and 

other metallic minerals produced by oxidation and supergene deposition. The bornite reported from the Friend mine may have been an 

original constituent of the ore.

BARITE LODES

Near the summit of Stanley Butte on the east side, at the Silver 

Spar prospect, there are seams in the fractured lava filled with 

vein matter in which barite is a prominent constituent. These 

seams may represent a different phase of the mineralization tluit 

produced the calcite veins just described, or they may be older or 

younger than those veins. They are obviously not older than tho 

Miocene (?) lava containing them.' Veins containing barite also 

exist in the complex of pre-Cambrian metamorphic rocks and later 

intrusive rocks in the vicinity of Kelly Canyon, in the northern 

part of the Turnbull Mountains. The mineral was also noted in 

the replacement deposits in limestone at the Copper Reef mine.

At the Silver Spar prospect there are sharply defined but discontinuous seams a few inches wide containing plates of barite and 

cubes of fluorite in a mosaic of quartz grains. In the vein nidtier 

there are irregular aggregates of small black grains of an unidentified silver-lead mineral, and a copper mineral which is probably 

bornite.

GOLD VEINS

In and near the Santa Teresa Mountains there are a number of 

quartz veins, some of which contain gold. Prospecting and a little
72 ARAVAIPA AND STANLEY MINING DISTRICTS,, ARIZ.

mining for gold have been undertaken in such veins, but none of 

the mines are reported to be active at present, and, so far as known, 

all are outside the region mapped in the present investigation. 

As none of these mines or prospects were visited, no accounts of 

them can be given in the descriptions of the mining districts. Gush 

veins filled with massive white quartz were observed in the quartz 

monzonite on the south side of the Santa Teresa Mountain?. All 

those seen were short lenticular masses, with outcrops only a fev. 

feet long. It is probably in such veins that the pockets of goid 

lit) ve been found.

OXIDATION AND ENRICHMENT

The processes of oxidation and enrichment have played a part in 

the production of most of the mineral deposits of the region, as1 will 

be seen from the descriptions of the mines and prospects given 

below. The conditions believed to have affected the operation of

Oxidation products Secondary sulphides Primary sulphides

FIGURE 2. Diagram to illustrate oxidation and enrichment. A, under favorable conditions; B, under accelerated erosion

these processes in this region and inferences drawn from the scanty 

available data as to what may be expected at depth will next be 

presented.

The oxidation of mineral deposits is merely a phase of the weathering process that attacks all rocks as soon as they come within its 

influence. As mineral deposits contain substances that are chemi- 

<cally more active and powerful than those commonly present in 

rocks, the effects of weathering on such deposits are more rapid 

and intense. Oxidation starts in a mineral deposit as soon as water 

percolating downward from the surface and carrying dissolved 

oxygen and other substances derived from the air and surficial 

formations comes into contact with it. (See fig. 2.) A great diversity of chemical reactions may take place, the particular reactions 

depending on the particular set of chemical and physical conditions 

(existing. The results in general are that part of the substances in 

the deposit are taken into solution and removed, part are converted 

by solution, precipitation, and chemical interchange into new min-
ORE DEPOSITS 73

erals, and part are attacked so slowly as to remain in their original 

form for a long time. The probable behavior of the common hypogene metallic minerals present in a region may be summarized as 

follows. The iron oxides, magnetite and specularite, are attacked 

slowly and remain essentially unaltered in most outcrops. Galena 

is readily protected by coatings of its difficultly soluble oxidation 

products and may remain near the surface after considerable oxidation. A large part of the lead that is dissolved is likely to be 

reprecipitated promptly as cerusite, anglesite, or some other oxidized mineral. Pyrite and chalcopyrite are both attacked rather 

readily and would not be expected to crop out where there has 

been any notable amount of oxidation. Hydrated iron oxides such 

as limonite are formed as decomposition products of both pyrite and 

chalcopyrite. Malachite, azurite, chrysocolla, and various copper 

oxides are formed from chalcopyrite. Lack of visible copper minerals in an oxidized deposit is not, however, proof that none formerly 

existed, as they may be dissolved and almost completely removed 

by long-continued oxidation. Sphalerite is readily attacked and is 

soluble under oxidizing conditions, so that zinc minerals' in any 

quantity are not to be expected close to the surface where there 

has been much oxidation.

Oxidation may continue to any depth at which the circulatingground water retains any free oxygen. It is usually assumed to cease 

near the average position of the water table, or ground-water level, 

and this assumption is probably in general an approximation to the 

truth. (See fig. 2, A.) The position of the water table is, however, 

constantly shifting with seasonal fluctuations in precipitation and 

changes in climatic and physiographic conditions. Oxidation, on the 

contrary, is persistent but slow. The actual lower limits of oxidation in a given deposit are irregular and dependent on a number of 

factors. In the Aravaipa-Stanley region it seems to have penetrated 

to comparatively shallow depths in most deposits, as at present exposed, and many deposits are not greatly affected by it even at the 

surface.

The water that percolates below the zone of oxidation has lost its 

power to oxidize but has gained a load of metallic salts. A largepart of it usually continues downward in the deposit, coming into 

contact with the as yet unaltered minerals below. Here the greater 

part of the dissolved metals may be precipitated as supergene 

sulphides as a result of direct or indirect chemical reaction between 

the hypogene sulphides and the salts in the water. The primary 

sulphides involved in this process will be in part chemically changed 

and replaced, and some substances will go into solution in exchange 

for those precipitated, but the net result is a gain in the content of 

valuable metals in this portion of the deposit, which is therefore
74 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

termed the zone of enrichment. (See fig. 2, A.) The process seems 

to be more efficient with copper than with the other metals, and 

valuable deposits of enriched copper ore are known in many regions. 

Similar deposits of silver minerals have been found at numerous 

places, but the process seems to have been in general less effective in 

enriching silver deposits. Supergene sulphides of lead and zinc are 

known, but deposits of commercial importance are rare. In the 

Aravaipa-Stanley region supergene copper sulphides have been found 

in a number of deposits, but supergene sulphides of other metals 

have not been proved to be present.

The contacts between oxidized material and supergene sulphides 

and between these sulphides and the unchanged minerals below are 

usually irregular. They may be sharp or gradational, according to 

the existing conditions. In most deposits some supergene sulphides 

and smaller amounts of hypogene sulphides are found in the oxidized 

zone, and oxidation products find their way into the enriched zone. 

Hypogene sulphides are usually found in places in the zone of enrichment, and supergene sulphides may extend in places well below 

the lower limits of the zone characterized by such minerals. Figure 

2, A, shows the relations of the three zones to one another, though 

the zones as drawn are more sharply defined and regular than they 

are in most actual deposits.

Oxidation in the exposed parts of the deposits in the AravaipaStanley region is irregular. Most of the deposits show some oxidation on the outcrop, but in a large number original sulphides can 

be found at the surface, and it is exceptional to find evidence of 

extensive leaching and removal of metallic constituents from the 

zone of oxidation. In several places, however, oxidized metallic 

minerals have been found in such quantity that they have been 

mined. The ore containing wulfenite, the molybdate of lead, stoped 

in the Silver Cable and near-by mines is an example. Some of the 

ore mined at the Grand Reef was partly oxidized to anglesite, cerusite, and other lead minerals, with malachite and chrysocolla in 

places, but most of this ore contained some unoxidized sulphides, 

and a large part of the ore in this mine is essentially unaffected by 

oxidation. The presence of unaltered sphalerite, the sulphide of 

zinc, only a short distance below the surface shows that oxidation 

has not been very effective here. On the contrary, strongly oxidized 

ore, containing, however, some residual sulphides, was encountered 

on the 300-foot level, the greatest depth to which development has 

been carried, well below the present water level. It is probable that 

this oxidation so far below the depth to which the ore body in general has been oxidized has resulted from some circumstance particularly favorable to it, such as the seeping down of oxygen-bearing 

water from the surface along some fracture that served to facilitate
QBE DEPOSITS 75

its rapid descent. Partly oxidized ore has been mined at the Tenstrike and other prospects near it and on Imperial Hill. Essentially 

unoxidized sulphides, including sphalerite, have been found near 

the surface on the northern flank of Imperial Hill.

In the shaft on No. 1 claim and at several other places near Arivaipa high-grade bodies of cerusite, the carbonate of lead, have been 

mined. These were produced by concentration within the zone of 

oxidation, by the deposition in favorable places of lead carbonate 

from water that had obtained it from oxidized galena ore. Some of 

these cerusite masses contain so little gangue that the lead content is 

much higher than that of the original ore. They are, however, small 

and discontinuous, and there is no means of predicting their location 

or extent in advance of development.

Oxidized copper ore has been mined at the Copper Reef and Friend 

mines and elsewhere. The copper minerals in it are principally the 

carbonates malachite and azurite and the silicate .chrysocolla. Limonite and earthy red hematite are present. In partly oxidized copper 

ore the so-called copper-pitch ore develops around residual cores of 

chalcopyrite. The copper-pitch ore in this region appears to be an 

intimate mixture of the black oxide of copper, tenorite, with limonite 

and the supergene copper sulphide chalcocite. The copper-pitch ore 

of the contact-metamorphic deposits contains manganese oxide, but 

the material of similar appearance in the deposits in granite at the 

Fisher prospect does not appear to contain any manganese.

The supergene copper sulphides chalcocite and covellite have been 

found in most of the deposits in which copper is present in the unoxidized ore, but at no place in the region are commercially valuable 

deposits of such sulphides known. Development in most deposits is 

insufficient to establish the absence of such bodies of sulphides. The 

chalcocite in the ore of the Fisher prospect and in some of the 

contact-metamorphic deposits is probably sufficient to raise the copper content appreciably. In those mines in which considerable bodies 

of original hypogene sulphides have been developed the amount of 

supergene sulphide present is so small as to be almost negligible.

Supergene silver minerals are present in places. Horn silver is 

found in the oxidized parts of several deposits. Native silver and 

supergene silver sulphides are reported from the La Clede mine, but 

no specimens of such ore were seen during the present investigation. 

At the Silver Spar prospect there is argentite, but whether it is a 

product of original deposition or is secondary is uncertain.

The physiography of the region shows that there have been a 

number of renewals of erosive activity since Pliocene time. During 

at least the more recent of these the upper parts of the ore deposits 

have been exposed to attack and portions of them have been removed.
76 ABAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

The irregularity and scantiness of the oxidation products in the 

deposits as now exposed seem to indicate that in geologically recent 

time erosion has been more active than oxidation. The oxidation 

products were in most places stripped rapidly away, and the original 

ore and such supergene sulphides as had formed were exposed to 

attack. Part of the oxidized copper minerals now present in the 

deposits have been derived by reoxidation of the copper in supergene 

sulphides. Figure 2, B, illustrates the effect of accelerated erosion 

on the oxidized and enriched deposits shown in Figure 2, A. In 

most of the deposits of this region the process has gone even farther 

than is shown in the figure, or else iihe physiographic conditions have 

been so unstable that no such definite zones as are indicated in Figure 2, A, were ever formed. It must be remembered that few deposits in which copper sulphides and pyrite were abundant as hypogene minerals have yet been developed to any depth by mining in 

this region. It is possible that such deposits may be found so favorably situated that they include zones of supergene copper enrichment. In deposits in which notable amounts of hypogene sulphides 

are encountered before bodies of supergene sulphides are found it is 

unlikely that masses of enriched ore of commercial importance exist 

at greater depths.

ABAVAIPA MINING DISTRICT

GENERAL FEATURES

Location and extent. The Aravaipa mining district is in Tps. 5, 

6, and 7 S., Rs. 19, 20, and 21 E., only parts of which are surveyed. 

It lies near the middle of the west border of Graham County and 

has somewhat irregular and indefinite boundaries. It is bounded on 

the north by Old Deer Creek, on the west by Arivaipa Creek, and 

on the south by the valley between the Santa Teresa and Graham 

mountains. The eastern boundary appears to lie approximately 

along the divide between streams tributary to Arivaipa Creek and 

those which flow directly into Gila River. The Cobre Grande mine, 

on the northeast flank of the mountain of the same name, is considered to be in the Aravaipa district, and John Fisher's prospects, 

in the southeast end of the Turnbull Mountains, are in the Black 

Rock mining district. Fisher's prospects are the only ones in theBlack Rock district reached during the present investigation, and 

they are described in the present chapter.

Population. Klondyke, which consists of a store and post office, 

a school, a church, and a dwelling house, is the distributing point 

for the district. A number of small ranches lie in Arivaipa Valley 

in the vicinity of Klondyke. Most of those north of Klondyke are 

shown on the map (PI. I), but some of those south of it are omitted.
ARAVAIPA DISTRICT 77

Arivaipa, about 10 miles from Klondyke, is the center of population 

for the northern part of the district. It consists of a post office and 

several buildings, one of which is occupied. When the Aravaipa 

Mining Co. was operating, there were as many as 60 people here. 

According to the census of 1920, Klondyke precinct had a population 

of 461. In 1910 the population was 334.

Roads. Klondyke is accessible from Willcox, on the main line of 

the Southern Pacific Kailroad, by a wagon road about 60 miles long, 

and from Glenbar, on the Arizona Eastern Railroad, by a road about 

36 miles long. Safford, the largest town in that part of the valley 

of Gila River, is about 10 miles southeast of Glenbar. Both roads 

are good " natural" roads and passable for automobiles. The 

Willcox road has fewer and lower grades than that to Glenbar but 

gives some trouble from mud in wet weather. There is at present 

no road connecting the Aravaipa and Stanley districts, but the gap 

of about 3 miles between Arivaipa and the Princess Pat mine could 

easily be closed, the only obstacle of any moment being the canyon 

of Old Deer Creek. There is talk of the construction of a road by 

Graham County to connect with one to be built by Final County 

which would pass from Klondyke either through Arivaipa, across 

Lone Cedar Mesa into Hawk Canyon, and thence over the divide 

westward into the head of the valley of Deer Creek, or else through 

Arivaipa Box. Such a road would aid greatly in the development 

of the district, but its growth will continue to be handicapped until 

better railroad facilities are available. It would not be difficult to 

construct a railroad line between Willcox and Klondyke, but the 

present production of the district is not sufficient to warrant the 

necessary outlay. This lack of adequate transportation has hampered the district from the outset and is one of the principal reasons 

for a total production of less than 35,000 tons of ore in more than 

4.0 years of mining. The hope for future growth of the district 

seems to lie in its mining rather than in its other industries, important though they will be as aids. This hope can be realized only if 

some company, backed by adequate capital, should be successful in 

proving the presence of such large ore bodies of workable grade 

somewhere in the district as to induce it or others to provide modern 

transportation. As will be seen from the descriptions of the several 

properties given below, there are a number of mineral deposits 

whose appearance warrants hope of the presence of good-sized bodies of ore, but on few has there been any systematic attempt at development, and on none has development been carried far enough 

to establish the presence or absence of really large ore bodies.

The ranches along Arivaipa Creek and the principal mines of the 

district are all connected with Klondyke by " natural" roads that 

present few difficulties to wagons. Some of those leading to mines
78 ARAVAIPA AND STANLEY MINING DISTRICT'S, ARIZ.

where little work has been done of late years are scarcely passablefor automobiles but could be made so with little work. One road 

leads from Klondyke 3 miles east to the Silver Coin mine, with a. 

branch to the La Clede mine. Another leads southwest up Fourmile Creek. Another trends northwest, with a branch leading to the 

Grand Keef mine about 4 miles from Klondyke and short branches, 

to ranches in the valley. At the head of the box canyon the road 

splits, one branch going down the canyon and the other into the 

side valley where the Dowdle ranches are. About 5 miles below this 

fork the road down the canyon forks again, one branch continuing 

a short distance farther down the main canyon, the other leading' 

to a goat ranch on Turkey Creek. The road up the side valley has 

branches leading to the Tenstrike mine, the Bullis property, and the 

several ranches, and, after climbing out of the valley, to the Royal 

Tinto property, and ends at Arivaipa, nearly 11 miles from Klondyke.. 

It formerly extended .somewhat less than a mile farther, to the 

Arizona mine. From this mine to the end of the road from San 

Carlos at the Princess Pat mine the distance is only a little over 2: 

miles. If this short gap were closed by building a road, communication between the Aravaipa and Stanley districts, by vehicle would 

become possible and the Aravaipa district would have another outlet to the railroad.

Plan of descriptions of deposits. The descriptions of the mines 

and prospects in both the Aravaipa and Stanley districts are grouped 

in accordance with the mode of origin and location. In several of 

the groups there are deposits on which more development work has 

been done, and these are described first. The groups are described in 

order from south to north in each district. General notes on the types 

of deposits and modes of origin have already been given. In this 

part of the report the known facts regarding the individual deposits 

are stated. Plate XI shows all the mining claims whose positions are 

known, including all the patented claims and most of the unpatented 

ones. For some of the claims no data by which they could be plotted 

are available, and only the approximate position of the prospects 

could be shown. A few groups of claims, for lack of information,, 

could not be shown at all, but these are all groups on which little 

work has been done.

MINES AND PROSPECTS 

ARAVAIPA LEASING CO.

Property. The Aravaipa Leasing Co., of Boston, Mass., owns the 

Grand Eeef mine, the principal producer of lead-silver ore in the 

Aravaipa district, and several smaller mines and prospects. The mill 

and principal workings of this company are in Laurel Canyon, on 

the west flank of the Santa Teresa Mountains, about 3y2 miles from
ARAVATPA DISTRICT 79

Klondyke, the supply point for the vicinity. The property comprises 

seven patented and eighteen unpatented claims stretching north and 

south frjom the main camp. Their location is shown on Plate XI. 

There are also two mill-site claims in Laurel Canyon, and 160 acres

 of land in Arivaipa Valley. Thomas Finnegan has one-third interest 

in one of the unpatented claims. In Laurel Canyon there are a small 

ore-dressing mill, now partly dismantled, a blacksmith shop, an engine house, a boarding house, a school, and other buildings. In Silver 

Cable Canyon, half a mile to the south, there are also small buildings. 

The deposits have been prospected by means of a number of tunnels, pits, and small shafts. The principal workings are in the Grand 

Reef claim, in Laurel Canyon, the Dogwater and Silver Cable claims, 

in Silver Cable Canyon^ and the Aravaipa claim, \y2 miles north of 

the main camp. The Grand Eeef workings consist of 'an adit some 

1,400 feet long, with crosscuts off it and stopes above it, a winze extending 300 feet below the adit level, and levels leading off from the 

winze at intervals of 100 feet below the adit, making a total of over 

4,000 feet. The principal workings are shown in Figure 3. On the 

top of the ridge on the north side of Laurel Canyon is a shallow shaft, 

known as No. 4 shaft, not shown in the sketches. On the Mountain 

Spring claim there are two short tunnels. On the Silver Cable claim 

is a tunnel a few hundred feet long with stopes above. On the Dogwater claim is a tunnel about 140 feet long, a little over 100 feet from 

the mouth is a stope that extends up to the surface, and just beyond 

is a short winze off which a little work has been done. (See fig. 4.) 

On the Aravaipa claim is a shaft somewhat less than 100 feet deep 

off which about 500 feet of drifting and some stoping has been done. 

These workings are shown in Figure 5. They connect underground 

with workings on the Tenstrike group, and such data as are available 

regarding the mineralization at the Aravaipa mine are given in the

 description of the Tenstrike mine.

History.49 The principal claims of. the group were purchased by 

John W. Mackay from the locators in the nineties. He carried development at the Grand Reef to a depth of 300 feet, did considerable 

other work on the property, and planned extensive exploration. 

Avhich was terminated by his death in 1902. No further work was

 clone until 1915, when a lease was obtained by local people, who 

erected a small mill and shipped most of the ore and concentrates 

that had been produced from the property. After about four years 

of activity their operations ceased because of litigation, in June, 

1919. At this time the property was taken over by the Aravaipa 

Leasing Co., first under lease and later by purchase. In 1919 and 

1920 this company unwatered the Grand Reef mine, sampled it, did

46 Most of this section is based on. notes by C. E. Minor, who was superintendent in 

1020 and 1921 at the Grand Reef for the Aravaipa Leasing Co.
80 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

considerable exploration/work on this and on other properties in 

the district, and mined, concentrated, and shipped some ore. The 

major efforts of the company during this period were directed 

rather to exploration than to mining ore; consequently the total of 

the shipments, as shown in the table below, was not large.

N. S.

55-FOOT LEVEL

/OO-FOOT LEVEL

20O-FOOT LEVEL

50 100 ISO FEET

300-FOOT LEVEL

FIGUIJE 3. Section through principal workings at the Grand Reef mine. From sketch 

furnished toy Aravaipa Leasing Co.

The company suspended operations late in 1920, and the mines 

were closed down and left in charge of a watchman early in 1921. 

The shutdown was the result of general business conditions in the 

United States, which, in the opinion of the company's officials, made 

it inadvisable to continue work. It is expected that operations will 

be resumed when conditions become more favorable.
ABAVAIPA DISTRICT 81

Production. If any ore shipments were made prior to 1915, no 

records of them are now available. Below is given a table showing the 

amount of ore and concentrates shipped from the several mines of the 

group from 1915 to 1920. The table 

is compiled from data assembled 

by C. E. Minor from the records of 

the Aravaipa Leasing Co. It has 

been estimated that the total ore 

mined is about 30,000 tons.50 This 

small tonnage by no means represents the capacity of the mine, for 

no systematic campaign of development and mining backed by adequate capital has yet been undertaken. It is to be hoped that as 

soon as favorable business conditions return the present owners will 

continue their development of the property and give the mine 

a thorough test. 

Ore and concentrates shipped from the Grand Reef group, 1915-1920, in dry tons

0 50 100 FEET

FIGURE 4. Section through Dogwater 

mine. From sketch furnished by Aravaipa Leasing Co.

Year

1916... ---.- 

1916.... 

1917... _.... -

1918... ........ ........ .. . - 

1919... 

1920--. 

Ore

from

Grand 

Reef 

mine

61 

247 

423

242 

75

1,389

Mixed

Grand

Beef, Aravaipa, and Dogwater

mines

117 

117

(

Grand 

Reef 

mine

110 

392 

841 &<t^

385 

2,613

3oncentrat

Aravaipa 

mine

89 

89

e

Dogwater 

mine

160 

160

Total ore, 1,506 tons; total concentrate, 2,862 tons.

Character of the deposits -The, Grand Reef mine takes its name 

from the remarkable outcrop of the lode. In Laurel Canyon, where 

the reef is most prominently exposed, it is indeed a grand and impressive sight. It is a great mass of iron-stained rock composed of 

brecciated and silicified igneous rock and vein material cemented 

with quartz and other vein minerals. Plate X gives some idea of 

the way in which it towers above the softer rocks on either side of 

it. The exposure of the reef along the stream bed in Laurel Canyon 

is 200 feet wide. This is about the maximum width, but the outcrop 

is over 100 feet wide for a considerable distance on either side of the 

stream. The average strike is approximately N. 12° W., and the dip

Weed, W. H., Mines Handbook, vol. 15, p. 197, 1022.
82 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

ranges from about 70° W. to vertical. To the south the reef splits 

up into several smaller and less conspicuous lodes. The Mountain 

Spring, Silver Cable, and DogAvater mines and prospects are on such 

extensions of the main reef. Southeast of these there is a group of 

four claims on similar deposits. The country rock of the Grand 

Reef and the deposits near it belongs for the most part to what has 

been here termed the intrusive rhyolite. Some of it has the composition of quartz latite and is very fine grained. The rock near the 

lodes, especially west of the main reef, is sufficiently altered to 

make accurate determination of its original characteristics difficult. 

Just east of the Grand Reef is the granite of the main batholith, 

which here clearly intrudes the rhyolite porphyry. The porphyry 

east of the reef seems coarser and is somewhat darker than that west 

of it, but this difference is thought to have resulted from differences 

in hydrothermal alteration. On the 300-foot level of the Grand Reef

FIGURE 0. Section through Aravaipa mine. From sketch furnished by 

Aravaipa Leasing Co.

mine just east of the footwall of the lode diabase is reported 51 to 

have been encountered. A short distance farther east the diabase is 

in contact with granite. The contact strikes approximately parallel 

to the vein and dips 70° W.

The adit level, parts of the stopes above it, the first 100 feet of 

the winze, and part of the 100-foot level were the only portions of 

the Grand Reef mine accessible at the time of visit. Water stood 

in the winze 30 or 40 feet below the 100-foot level, but at most 

seasons the water is reported to stand above that level.

The following data regarding the ore shoots are abstracted from 

records furnished by H. A. Wentworth, the president of the Aravaipa 

 Leasing Co. The principal known ore shoot is the one in which 

the winze is sunk. Stoping has been done on this shoot from the 

adit level up into the portion of the reef that projects above the 

surface of the ground (fig. 3), and ore has been found vertically

61 Wentworth, H. A., letter of Feb. 2, 1923.
AEAVAIPA DISTRICT 83

below tliese stopes as far as development has gone. On the adit 

level the ore shoot has a stope length of more than 120 feet and a 

width ranging from 15 feet to considerably more than 30 feet.

Besides the principal ore shoot described above, several smaller 

ones have been found. West of the principal shoot and separated 

from it by about 10 feet of barren material is the hanging-wall or 

No. 3 ore shoot. It has been stoped and back-filled from the adit 

level down about 30 feet and up nearly to the surface; the stope 

length is about 60 feet and the width of the shoot about 3 feet. The 

outcrop above this stope shows mineralization. No. 4 shoot is developed by a shallow shaft on the top of the ridge 600 feet north of 

the Dey stope, and what is believed by company officials to be the 

same shoot has been encountered at the adit level vertically below 

this shaft. Ore is also reported to have been found in the adit north 

of this shoot. On the 200-foot level a body of soft ore was encountered south of the main ore shoot.

Most of the ore mined in the Grand Keef mine has come from the 

stopes in the principal ore shoot and the hanging-wall shoot above 

the adit level, so that the table below showing the average content 

of the crude ore shipped will serve to give an idea of the character 

of the ore of shipping grade found in the upper 200 feet of these 

shoots.

Assays of crude ore shipped from Grand Reef mine, 1915-1920

Year

1915 

1916... _ ...........

1917. _ .............

1918. 

1919 ,.. 

1920.......... .......

Ore 

(dry 

tons)

61

247

423

341

242

75

1,389

Gold- 

(ounce 

per 

ton)

0.01

.01

.01

.01

.01

Silver 

(ounces 

per 

ton)

17.3

19.2

23.9

21.9

13.4

15.4

20.0

Lead 

(per 

cent)

52.9

46.1

40.4

40.3

34.8

37.0

40.9

Copper 

(per 

cent)

2.06

2.12

3.21

2.85

3.56

1.15

2.83

Insoluble 

(per 

cent)

20.3

21.3

37.4

32.0

36.9

33.9

32.3

Iron 

(per 

cent)

' 1.2

2.8

3.0

1.9

2.2

1.8

2.4

Lime 0 

(per 

cent)

4.7

3.5

2.2

4.5

3.0

.9

3.1

Zinc" 

(per 

cent)

1.7

1.9

1.8

1.2

.9

.6

1.4

Sulphur 

(per 

cent)

6.5

5.8

7.4

6.6

5.5

4.3

6. 4

0 Not reported in all assays.

A large part of the ore is of sufficiently low grade to require concentration before shipping. The company estimates that it has 

90,000 tons of ore reserves.52 The computations of the company's 

engineers 53 indicate that the ore in No. 1 shoot between the adit and 

100-foot levels, estimated to be 43,000 tons, averages 7.0 ounces of 

silver to the ton, 1.5 per cent of copper, and 8.8 per cent of lead; this 

gives an idea of the tenor of the average ore in the mine.

It has already been stated that the country rock on the hangingwall side of the lode is hydrothermally altered. In places on the

M Weed, W. H., Mines Handbook, vol. 15, p. 197, 1922. 

53 Wentwortn, H. A., letter of Feb. 2, 1923.
84 ARAVAIPA AND STANLEY MINING DISTRICTS, ABIZ.

%

hanging wall there is reported to be a distinct gouge. No gouge has 

been found on the footwall, and on that side on the 300-foot level 

both the diabase and the granite beyond it are iron stained and contain pyrite and a little chalcopyrite.

Most of the deposit is a breccia composed of angular fragments 

many of which are less than an inch in greatest dimension. The 

fragments are in part silicified and otherwise altered wall rock, in 

part vein minerals. A large number of the light-colored fragments 

abundant in parts of the deposits are fine-grained fluorite. Many of 

the fluorite fragments are white; others have pinkish or violet casts. 

Some of them show distinct banding. Their appearance more closely resembles that of chert than of the commonly observed forms of 

fluorite. The matrix of the breccia in most places is a dark-purplish 

mass composed principally of fine-grained quartz in which comparatively large clear grains of fluorite are embedded. In places 

tiny flakes of chlorite are scattered through the matrix. Some of 

the fragments are green with chlorite, and a few are entirely composed of that mineral.

Quartz is the most abundant of the gangue minerals and occurs in 

various forms. The fine-grained quartzose matrix of the breccia has 

already been mentioned. Brecciated ore from the large stope above 

the adit is cut by irregular bands of light-gray chert which have 

themselves been fractured. Here and in the small opening at the 

55-foot level are narrow quartz veinlets with comb structure and 

drusy cavities, which were apparently the latest products of hypogene mineralization. On the 100-foot level the ore in places is 

sheeted and banded rather than brecciated, and there is considerable 

clear massive quartz which is in part white, in part pink and vitreous. Adjoining such banded ore is breccia like that elsewhere, containing little sulphide.

Galena is the most abundant sulphide. It is of variable texture. 

In places it occurs in irregular curved bands, but in probably most 

of the ore it shows marked evidence of having been brecciated. 

Argentite in tiny blebs is present in much of the galena. Veinlets 

and-small irregular masses of chalcopyrite are prominent income 

specimens. Sphalerite is associated with the galena but in subordinate amount. A little pyrite was noted, but it is nowhere 

abundant. In the flbor of the main adit near the north end there is 

reported to have been found a hard black mineral resembling 

tetrahedrite. C. E. Minor states that a specimen of this ore given 

to him was found to assay 7 ounces of silver to the ton and 5.1 per 

cent of copper.

Films of the supergene copper sulphide covellite were noted on 

chalcopyrite in specimens from the large stope above the adit and 

from the 55-foot level. No chalcocite was found.
ARAVATPA DISTRICT 85

The ore in the large stope above the adit and that visible on the 

55 and 100 foot levels showed no evidence of oxidation except superficially. Within 50 feet or less of the surface in the upper stopes 

there is unaltered galena, and chalcopyrite is reported to occur also, 

but much of the ore in these stopes is oxidized. Cerusite, anglesite, 

and probably other sulphates of lead are present. The copper carbonates, malachite and azurite, and the silicate, chrysocolla, are also 

found. Limonite occurs in places in the ore and stains the outcrops 

of the reef but is nowhere present in great .quantity. On the 300-foot 

level there is reported to be a mass of highly oxidized ore.

The short tunnels on the Mountain Spring claim penetrate an outcrop of breccia similar to and in line with the Grand Eeef but much 

smaller. A small amount of ore has been found here.

The tunnel on the Silver Cable claim is in shattered igneous rock,

most of which is altered beyond recognition. It is thoroughly 

silicified, and the feldsp'ars that remain are clouded with alteration products. No ferromagnesian minerals were noted in it. Near 

the tunnel mouth there are several slips. Most of the tunnel follows 

a fairly well defined lead that strikes about N. 30° W. 'and dips 

steeply to the east. It is composed of sheared and altered rock and 

, ribbon-banded and drusy quartz. The stope 'above is reported 84 to 

have been opened in mining oxidized ore supposed to contain lead 

vanadate, for a mill test in 1915 or 1916. The so-called vanadate 

was probably the molybdate wulfenite, such as occurs at the Dogwater &nd Silver Coin mines.

The lode in the Dogwater tunnel is doubtless similar to that in the 

Silver Cable. The only place where ore was noted was in the face 

of the tunnel, that in the back having been stoped out. At the 

face there is a mineralized zone 2 or 3 feet wide which contains 

wulfenite and some galena. The ore mined is reported 55 to have 

contained cerusite, galena, wulfenite, and a small amount of argentite. There was considerable fluorspar in the gangue. The galena 

was found to contain silver, which was doubtless in the form of invisible blebs of argentite. The ore from this mine carried considerable silver and lead. High-grade ore is reported to have been found 

in the shallow shaft in the gulch below the Dogwater tunnel.

Little development work has be'en done on the claims in the southcast end of the group owned by the Aravaipa Leasing Co. On the 

Junction and Varick claims is a reef similar to and almost as impressive as that at the Grand Keef mine. In places on this reef 

ore containing galena and ass'aying well in lead and silver is reported 

to crop out. On the west side the wall rock is rhyolitic porphyry. 

On the east a large part of the wall is pre-Cambrian schist, although

M Wentworth, H. A., letter of Dec. 1, 1922.

10 Minor, C. E., notes furnished by H. A. Wentworth.
86 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

porphyry is also present, and the granite is close at hand. The 

Blank and Conundrum claims were not examined during the present 

investigation but 'are reported by Mr. Minor to follow the outcrops 

of a lode striking approximately east.

PROSPECTS SOUTH OF THE ABAVAIPA LEASING CO.'S PROPERTY

From the Aravaipa Leasing Co.'s property south to the Tertiary 

beds near the Safford road a considerable number of claims have 

been staked, but on many of them no work has ever been done.58 

Some shallow workings were noted during the present investigation, 

but no prospects of any consequence were found here except the 

La Clede and Silver Coin mines, described below. Most of such 

deposits as exist in this part of the district are probably of the same 

general type as those just described. In the vicinity of Oak Canyon 

there is in places considerable micaceous specularite along partings 

in the schist. This indicates a concentration of iron by hydrothermal processes but may have no relation to the formation ,of ore 

deposits.

LA CLEDE MINE

The La Clede mine, owned by James Quinn, of Klondyke, is in a 

narrow gulch southwest of the Santa Teresa Mountains and about 

2,1/2 miles east of Klondyke, with which it is connected by a road. 

The property comprises about five unpatented claims. There is a 

shallow shaft in the side of the gulch and a tunnel entering near 

stream level. Mr. Quinn states that he has shipped about three carloads of ore in 12 years of operation.

The country rock is a bluish-purple fine-grained porphyry, which 

has been fractured, silicified, and altered even at some distance from 

the vein. The rock is highly silicified but contains microcline and 

sodic plagioclase, which are probably hypogene. Some of the quartz 

may also be hypogene. The rock may have been a latite, but whether 

it is related to the intrusive rhyolite or to the later volcanic rocks is 

conjectural. Sparingly disseminated through it are tiny black 

grains, which are in part specularite. Small areas of later albite 

have formed by replacement of the rock.

The vein strikes nearly east and stands almost vertical. Assessment work was in progress when the mine was visited, but most of 

the workings were inaccessible. Near the surface there appears to 

be considerable oxidation in the vein and its wall rocks, with the development of limonite, some malachite, and other oxidation products. The owner reports that native silver has been found here and 

that some of the ore assays very high in silver.

58 Koch, A. W., letter of Jan. 24, 1923.
ARAVAIPA DISTRICT 87

PLAN

W.

SECTION

SILVEE COIN MINE

The Silver Coin mine is in the gulch immediately south of the 

one in which the La Clede mine is situated, about 3 miles east of 

Klondyke, with which it is connected by a road. The property comprises five unpatented claims owned by Ted Quinn, who resides on it 

with his family. The position of the group is only approximately 

shown on Plate XL ' but the A/

relations of the claims to one 

another are essentially as there 

shown.

The developments consist 

of a tunnel 180 feet long with 

short crosscuts off it, a winze 

about 50 feet deep at the end 

of the tunnel, and a shaft 

more than 200 feet deep which 

passes at one side of the 

Avinze and is connected with it. 

Part of this work was done 

by the Aravaipa Leasing Co. 

Avhen it had the property 

under lease. The workings 

are shown in Figure 6 as they 

were in July, 1919, when the 

Aravaipa Leasing Co. ceased 

work. The winze and probably also the shaft have been 

deepened since then. Small 

lots of ore have been shipped 

at different times.

The country rock is a highly <j>____sp_____190 FEET

altered and weathered light- FIGURE 6. Workings of Silver Coin Mine. From

colored igneous rock, which sketch furnished by Aravalpa Leasing Co" 

may have been a fine-grained granite. It contained some original 

quartz and alkali feldspar, a few flakes of bleached biotite and 

chlorite, and much secondary quartz both in veinlets and as finegrained aggregates replacing original minerals. The lode is made 

up of brecciated rock of this character and quartz. The average 

strike is nearly east, and the dip is steep to the north. Wulfenite 

and other oxidized minerals are present in the lode and also in the 

altered igneous rock at some distance from the lode, but the most 

valuable ore is that containing unoxidized galena. The distribution 

of the galena is irregular, but in places it is reported to have been 

found in sufficient abundance to make ore with a good content of 

silver and lead.
88 ARAVAIPA-AND STANLEY MINING DISTRICTS, AEIZ.

TENSTEIKE GROUP

The four unpatented claims comprising the Tenstrike groupy 

owned by James Quinn, of Klondyke, stretch between the north end 

of the main group of claims owned by the Aravaipa Leasing Co. 

and the Aravaipa claim of the same company. (See PL XI.) The 

property was formerly connected with Klondyke by a wagon road 

forking off the main road a short distance above the upstream end 

of the Arivaipa box canyon. This road has been out of use so long 

that repairs are needed to make it available for vehicles. There is a 

cabin on the Tenstrike claim, and considerable underground development work has been done on this and the other claims of the 

group. A tunnel on the Tenstrike extends north into the Aravaipa 

claim. Ore has been stoped from this and other workings on the 

property, and probably a few carloads have been shipped.

These claims are evidently on a northward extension of the 

Grand Eeef vein, and the deposits in them, like those of the Grand 

Reef mine, are in brecciated and mineralized rhyolite. The rock is 

silicified and shot through with numerous narrow quartz stringers, 

most of them distinctly banded. There are small druses with welldeveloped quartz crystals. Narrow seams of calcite were noted, but 

these may be of supergene origin. The hypogene metallic minerals 

are galena, pyrite, sphalerite, and chalcopyrite, of which the galena 

is much the most abundant. The galena occurs in coarsely crystalline masses; the other sulphides.in small individual grains irregularly disseminated in the quartz. Supergene chalcocite is a prominent constituent of some specimens. Galena has oxidized to anglesite and cerusite. There is a small amount of linarite, a basic sulphate of lead and copper, but, except for occasional slight stains, 

other oxidized copper minerals were not noted.

FINNEGAN GROUP

Thomas Finnegan, of Klondyke, owns four unpatented claims 

just south of the Bullis property and a third of the Blevin claim, 

at the north end of the Grand Reef group. These are on the northern part of the Grand Reef vein and have outcrops of iron-stained, 

silicified, brecciated rhyolite like that at the Grand Reef mine, but 

smaller. The deposits have been prospected by means of tunnels.

BULLIS GROUP

Property. The Bullis group consists of 9 patented and 19 unpatented claims on Imperial Hill, shown on Plate XI. The northern part of the group is little more than a mile southeast of Arivaipa. 

but the intervention of the steep-walled Tule Canyon makes it inaccessible from that side. The property is reached from the south-
ARAVAIPA DISTRICT 89

west by a road from the valley containing the Dowdle ranches. The 

two shacks on the south side of Imperial Hill, the only buildings 

on the property, are nearly 9 miles from Klondyke by this road. 

A considerable amount of miscellaneous development work has 

been done in various places on this property, principally in the 

course of annual assessment work. There has been more systematic 

work done in the Windsor workings, shown in Figure 7, than elsewhere. These workings, which aggregate over 1,100 feet, consist 

of an inclined shaft and drifts and crosscuts at the 60 and 200 foot 

levels connecting with the surface by an adit at the lower level. The 

shaft reaches a depth of 190 feet vertically below the collar. Besides 

the Windsor workings there is a shaft farther down the hill to the 

east and tunnels, cuts, pits, and small shafts scattered over the 

property.

zoorzcr no TUNNEL MOUTH

FIGURE 7. Composite level map of Windsor mine. From sketch furnished by 

Aravaipa Leasing Co.

History. The deposits on Imperial Hill are reported to have 

been found in the early seventies, but little work appears to have 

been done on them until 20 years later, when Gen. J. L. Bullis began 

to acquire the group of claims now owned by his estate. Under his 

direction all parts of the property were prospected, but little development work was done, and little or no ore was shipped. At the 

time of his death, about 10 years ago, he is reported to have been 

planning more intensive development. For some years after his 

death little was done. The Aravaipa Leasing Co. had a lease on 

the property in 1918 and 1919 and did some development work on 

the Windsor and on several other claims. Since this company's operations ceased nothing beyond annual assessment work has been 

done, except that in 1922 the Windsor workings were sampled by 

E. H. Bachman, of Globe, Ariz. He and his associates hope to develop this part of the property under lease and to erect a cyanide 

mill of some 20 to 30 tons daily capacity to treat the ore mined.
90 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

Character of the deposits. The greater part of Imperial Hill is 

composed of intrusive rhyolite. The contact between it and the 

granite to the east is gradational, and numerous dikes and irregular 

masses of granite cut the rhyolite. On the northeast flank of the 

hill are blocks of Paleozoic limestone and quartzite inclosed in the 

rhyolite. The presence of these rocks is indicated diagrammatically 

on Plate I, but the strata are actually more broken and scattered 

about in smaller blocks than it was possible to show on the map. 

Less limestone than quartzite is exposed.

Several lodes crop out on the property. According to Thomas 

Finnegan, who has charge of the annual assessment work, there are 

four principal lodes. The exposures of mineralized rock have not 

been mapped, but in a broad way it may be said that there is a 

group of veins and zones of mineralization outcropping over a broad 

area oni the east side of Imperial Hill. The strikes measured at 

different exposures range from N. 40° W. to almost 1ST. 40° E., but 

the average is somewhat west of north. The lodes cut representatives of all the rocks mentioned in the last paragraph. The quartzite, rhyolite, and granite are cut by quartz stringers, brecciated, and 

somewhat altered and replaced. The limestone has locally been permeated with mineralizing solutions, and small portions of it have 

been thoroughly altered. The igneous rocks in the vicinity of the 

deposits are somewhat chloritized and fractured, but the feldspars 

in them seem as fresh as in similar rocks that have not been exposed 

to mineralization. In some exposures the brecciated quartzite 01 

rhyolite is permeated irregularly with quartz. Elsewhere there are 

distinct veins of quartz, which in places are'sheeted. The quartz in 

most exposures has drusy cavities lined with well-developed quartz 

crystals. The deposits contain lead, copper, and silver both as sulphides and in oxidized minerals. The exposures seen during the 

present investigation showed only small amounts of metallic minerals. Samples taken by E. H. Bachman, of Globe, at 5-foot intervals down the Windsor shaft contained, according to Mr. Bachman, 

both lead and silver. One of these samples assayed slightly over 

100 ounces in silver, but the average of the assays is less than 15 

ounces. The lead content of the samples ranged from a few tenths 

of 1 per cent to more than 9 per cent. The distribution of both lead 

and silver is irregular and appears to bear no relation to depth. 

Assays from the 60 and 200 foot levels also show some lead and 

.silver, but the average amount is small. A composite sample from 

the shaft contained 0.14 per cent of copper. Copper is present in 

spots on the 200-foot level, one assay of 1.5 per cent and several of 

less amounts being reported, but the average amount is small, and 

in places, notably in the crosscut where the ore carrying the most
ARAVAIPA DISTRICT 91

silver found on the level is exposed, no copper is present. The drift 

on the lower level south of the adit is in brecciated quartzite that 

shows a little mineralization. Mr. Bachman's assays show from 

0.94 to 2.42 ounces of silver to the ton in this part of the mine. A 

short distance north of the adit there is broken ground and the drift 

has caved in. According to the map prepared by the Aravaipa Leasing Co.'s engineers there is a fault here which shifts the lode westward about 40 feet, as indicated in Figure 7. A green fine-grained 

rock collected at the point where the drift is caved proved on examination to be quartzite containing a little feldspar and partly replaced 

by calcite and chlorite. The map just referred to shows limestone 

in this drift beyond the caved portion, and the calcite in the altered 

quartzite may be derived from this rock. The same map indicates 

that rhyolite forms the hanging wall south of the adit and that there 

is porphyry in the north end of the mine' beyond the limestone.

The quartzite at the mouth of the Windsor shaft contains small 

amounts of horn silver, malachite, copper pitch, covellite, and chalcocite. The two sulphides occur together in small black blebs. They 

carry silver,, perhaps in solid solution as sulphide.

The shaft east of and down the hill from the Windsor is in coarse 

porphyritic granite, which has been somewhat crushed. The biotite 

in it is chloritized, and quartz has been introduced since the formation 

of the rock. Ore containing 4 or 5 per cent of copper is reported to 

have been found in the shaft, and a number of pieces containing 

malachite and azurite were noted on the dump. If any considerable 

quantity of ore Avas taken out, it has since been removed.

BULLIS-LANDSMAN GROUP

There are nine unpatented claims which adjoin the Bullis property 

on the northwest and the Norton group on the south. (See PI, XI.) 

These may be called the Bullis-Landsman group, as Mrs. J. L. Bullis 

and Frank Landsman hold them in common. They are developed 

by several branching tunnels. Part of the work was done by the 

Aravaipa Leasing Co. when it leased the claims in 1919.

The country rock is largely intrusive rhyolite, but there is also a 

little limestone which is cut by dikes of the rhyolitic rock and of 

a dark trap. Streaks of copper sulphide are reported to have been 

found in dike rock of both these types. On these claims there are 

several lodes, which in general strike west of north and have a 

nearly vertical dip. In the rhyolite there are iron-stained outcrops 

which resemble the Grand Reef in miniature. Underground stringers 

of sulphides and specularite are found on small slips in the brecciated rock. Galena, pyrite, and chalcopyrite are found, but if 

sphalerite is present it is in small amount. The galena here, as else106914 25 7
92 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

where, doubtless contains argentite. In the limestone, which is 

brecciated and partly silicified, the ore is in irregular stringers and 

small masses. The gangue minerals are quartz, actinolite, specularite, 

calcite, and chlorite. The only sulphides noted are galena and 

sphalerite. The quartz, which is the most abundant gangue mineral, 

varies in texture from cherty. rims around sulphide grains to rather 

coarsely crystalline masses, with drusy cavities. The actinolite 

masses are made up of small bunches of radiating needles. Specularite, which is not 'abundant, is in scattered flakes and finegrained aggregates. There is only a little calcite. The sulphides are 

in part in fine-grained aggregates, in part in scattered grains, some of 

which are an inch wide. They show almost no oxidation.

ROYAL TINTO MINING & SMELTING CO.

Property.- The property of the. Royal Tinto Mining & Smelting 

Go., .of New York, consists of 22 patented and 10 unpatented claims 

on Tule and Copper Bar gulches 2 .miles east of Arivaipa. (See 

PI. XI.) Except for a shaft house on the Copper Bar claim, there 

are no buildings on the .property.

The principal underground workings are the Sam Jones and Copper Bar tunnels, named, from the claims in which they start. They 

are shown in Figure 8. There is also a shaft near the mouth of the 

Copper Bar tunnel, reported to be 100 feet deep; other shafts on the 

Tinto claim, one of which is reported to have been 100 feet deep; 

and .several excavations, mostly small and shallow, on the other 

claims. At the time of visit it was possible to get underground only 

in the two tunnels.

History.^ The ore deposits of this group have been known for at 

least 20 years. In 1902 Frank Landsman had a lease on the New 

York claim and shipped 15 tons of carefully picked chalcocite ore 

reported to have assayed 29.7 per cent of copper and several dollars' 

worth of gold and silver to the ton. This seems to be the only ore 

that has been shipped from the property. In 1905 the Royal Tinto 

Mining & Smelting Co., the present owner, was organized under the 

laws of New Jersey. Most of the work was done in 1906 and 1907, 

and, except for annual assessment work, little has been done since 

then.

Character of the, deposits. The deposits lie in a complex of fault 

blocks of pre-Cambrian schist and Paleozoic sedimentary strata, 

bordered on the south and east by the granite batholith and cut by 

rhyolitic apophyses of the granite. There are numerous faults, most 

of them small. Many strike northwest, but some trend in other directions. An idea of the extent to which the rocks have been shatw From H. W. Darling's report on the property of the Royal Tinto Mining & Smelting 

Co., supplemented by information furnished by Charles Firth, of Ariyaipa.
ABAVAIPA DISTRICT 93

tered and broken into small blocks can be gained from Figure 8. This 

sketch, showing the geologic features exposed in the two tunnels, is 

copied from a report on the property made for the company by C. F. 

Tolman, from which some of the facts given below are taken. The

^Fault 

^Quartz-hematite

breccia 

vFault

COPPER BAR 

TUNNEL

Bn=cciated porphyry 

aric^copper 'stain

. ;-\ \v \

rfQuartziteV *^ \

N \ 

Synclin^-Brecciatech Faults

, \Massive hematite

~ replaces the limestone

'' Q uartzits, brecciated 

" ' and iron stained

FIGURE 8. Geologic sketch map of Sam Jones and Copper Bar tunnels. 

After C. F. Tolman. Scale, 1 inch=200 feet

deposits are on fracture zones that cut altered rhyolitic facies of the 

granite along the contact and extend northward beyond the igneous 

rock into the quartzite and limestone. The zones fork and pinch out 

in irregular fashion, but the resultant trend of the group of zones 

is to the northeast. The mineralized outcrops are in most places in-
94 AKAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

conspicuous features on the brush-covered hillsides, but in some 

places, notably at the mouth of the Copper Bar tunnel, there are 

prominent exposures of iron-stained siliceous breccia. Mineralization can be traced on the surface for an air-line distance of over a 

mile on the property, and according to Tolman the outcrops of the 

zones range in width from about 8 feet on the New York claim to 

300 feet on the Copper Spar claim.

The rock along the zones has been sheared, brecciated, and replaced by chlorite, hematite, quartz, pyrite, chalcopyrite, and products of oxidation and supergene deposition. In some places the 

original rocks have been completely replaced; elsewhere there has 

been sufficient alteration to make it difficult to recognize the rock. 

The wall rocks were altered to some distance beyond the fracture 

zones in places, but this alteration is irregular, and so far as can be 

judged from the exposures in the two tunnels the amount of metallic 

minerals deposited is small, with the exception of some small irregular bodies in limestone. No primary copper minerals were observed 

during the present investigation, but chalcopyrite is reported to have 

been found in the bottom of the shaft' at the mouth of the Copper 

Bar tunnel, and Tolman noted small quantities of the mineral in some 

of the surface cuts. Copper oxidation products and supergene sulphides exist in a number of places, proving the original presence of 

hypogene copper minerals in the deposits. The amount of copper 

originally formed in parts of the deposits was negligible, but it may 

well be that in places ore shoots containing considerable copper 

were produced. Chlorite is one of the most abundant minerals in 

the deposits exposed in the Copper Bar tunnel. Intimately mixed 

with it are seams and aggregates of quartz, hematite in fine disseminated flakes and aggregates, and pyrite in streaks and irregular 

groups of small cubes disseminated in the masses of chlorite and 

hematite. Elsewhere chlorite is not so abundantly exposed. In places 

reticulating veinlets of hematite are the only evidence of hypogene 

mineralization.

The outcrops of the mineralized rocks all show weathering, but 

the oxidation is neither intense nor deep. Limonite occurs only in 

superficial stains and small masses. Malachite, azurite, cuprite, and 

copper pitch are found on the Tinto and New York claims and have 

also been reported on the Newark, but the amount at all exposures is 

small. In the Copper Bar tunnel the pyrite has been tarnished and 

loosened by leaching and there is an efflorescence of hydrous iron 

sulphate on the walls. The end of this tunnel is about 100 feet below the surface, which is the greatest depth at which the deposits 

are now exposed. From this it appears that incipient oxidation 

 reached depths as great as 100 feet, but that its effects were slight. 

The supergene sulphides, chalcocite and covellite, are present in vary-
ARAVAIPA DISTRICT 95

ing amount in many of the exposures of mineralized rock, although 

in some the amount is so small that it can not be seen. A little massive chalcocite can still be found on the Tinto dump. It evidently 

formed veinlets and irregular masses in the altered and brecciated 

rock. Chalcocite ore is also reported to have been found in the shaft 

at the mouth of the Copper Bar tunnel. For the first 25'feet this 

shaft is reported to be in mineralized rock like that exposed in the 

tunnel except that considerable chalcocite was noted. Below this 

the rock penetrated is reported to be barren except at the bottom, at 

a depth of about 100 feet, where chalcopyrite was found. The small 

amount of copper found by chemical tests in specimens from the 

Copper Bar tunnel is probably present as films of chalcocite and 

perhaps also covellite on the pyrite. Specks of covellite were noted by 

Tolman on the New York claim, and it is probably also present elsewhere. H. W. Darling, in the course of an examination of the property, for its owners in 1918, took several grab samples for assay, and 

the results show that copper is present in a number of places. Part 

of the copper is in the form of carbonates and oxides, and a little 

may be in hypogene chalcopyrite, but much of it is probably in supergene sulphides. In some of the places where he sampled such sulphides are visible. In others there is no visible copper mineral, and 

the copper is probably in films of supergene sulphides, a form in 

which it is less conspicuous than in either hypogene sulphides or oxidation products,

C. A. FIRTH GROUP

Charles A. Firth has four unpatented claims adjoining the property of the Royal Tinto Mining & Smelting Co. As is shown on 

Plate XI, two of these claims are south of that property, and the 

other two are northwest of it. Only a little development work 

has been done on these claims. Presumably the deposits here are 

similar to those on the Royal Tinto ground.

ARAVAIPA MINING CO.

Property, The property of the Aravaipa Mining Co., of New 

York, consists of 19 patented and 5 unpatented claims. These claims, 

on which mining for lead-silver and copper ores has been carried 

on intermittently for many years, extend from Arivaipa north to 

Deer Creek. They are shown on Plate XI. There is an engine house 

at the Arizona shaft and about eight buildings at Arivaipa, including the residence of H. T. Firth, superintendent, the post office, the 

houses used by the workmen when the mines were running, and 

outbuildings.

 The principal workings of this company are on the Arizona, No. 1, 

and Orejana claims. No maps of these workings are available, and
96 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

considerable parts of them are now inaccessible, so that only approximate data can be given.

At the Arizona mine there is a shaft about 580 feet deep. The 

lower part of this shaft is now full of water, and the whole was 

inaccessible at the time of visit. The deposit is also developed by 

means of a tunnel entering farther down the hillside, which encountered the vein about 200 feet from its mouth. The tunnel was continued about 500 feet farther without cutting any more veins. From 

the point where the vein was cut drifts were run on it about 400 

feet in a southerly and 700 feet in a northerly direction. The north 

end of the north drift is close to the shaft, at a depth estimated by 

Mr. Firth as 125 feet below the collar.

On the Orejana claim a tunnel about 700 feet long follows another vein. On the No. 1 there is a shaft a few hundred feet deep 

and a short tunnel connected with it. There has been some stoping 

and a little drifting off this shaft, which was inaccessible at the time 

of visit. Other workings on the company's claims include a tunnel 

several hundred feet long on the Gordon, irregular tunnels on the 

Grand Central and Head Center, and tunnels and pits on the Iron 

Cap and elsewhere.

History. The principal deposits have been known for nearly 50 

years. Among«the early locators were W. C. Bridwell, Charles 

Cunningham, the Dunlap brothers, John Harr, and Charles McGeary. Col. W. C. Bridwell had a smelter near Arivaipa in the 

late seventies in which he treated ore from these deposits. In 1889 

the deposits were acquired by a group of men who formed the 

present Aravaipa Mining Co. At one time this organization was 

known as the Aravaipa Leasing Co., a name that has since been 

adopted by the company which owns the Grand Reef group. The

Aravaipa Mining Co. operated from 1890 to 1895 and is reported to 

have shipped two cars of ore obtained from different places on the 

property for the purpose of a mill test. In 1916 John Gleason and 

T. C. Parker leased the No. 1 claim and are reported to have shipped 

lead carbonate ore of a gross value of about $90,000. No other work 

except the annual assessment work on the unpatented claims has been 

done on the property.

Character of the deposits. The rocks that crop out on the Aravaipa Mining Co.'s property comprise fault blocks of Paleozoic 

quartzite and limestone cut by a number of dikes and irregular intrusive masses of felsite, andesite, and basalt. Several veins crop 

6ut on the property but are probably all parts of the same vein system. One group of mineralized outcrops extends northward from 

Arivaipa through the Arizona claim to Gordon Canyon and beyond, 

on Abe Reed's claims, as far as Old Deer Creek. Another line of 

outcrops lies to the west on the Standish, Orejana, and Winthrop
AKAVAIPA DISTRICT ' 97

claims. These two groups are principally in quartzite and felsite 

with limestone in the vicinity of Arivaipa. To the east, on the 

Grand Central and neighboring claims, there are deposits in limestone. The line of claims from Imperial Hill through Arivaipa to 

Old Deer Creek is over 3 miles long. The principal workings of 

the Aravaipa Mining Co. are in this group, and most of the claims 

are held by the company. Mineralized outcrops are found at short 

intervals on these claims, but the exposures are by no means continuous. It is probable that there is a zone of mineralization made 

up of a series of genetically related lodes, which may be connected 

with one another at depth. The deposits on the Orejana group are 

similar and related to the deposits of this zone but lie somewhat to 

the west. The deposits in quartzite are veins with definite walls 

and approximately constant strikes which range from north to about 

N. 20° W., but those in limestone are more irregular, and the strikes 

of the mineralized fractures vary widely.

The vein exposed in the drift oft' the tunnel at the Arizona mine 

is in an altered fine-gr'ained porphyry. It strikes about-N. 20° W. 

and dips steeply west. The maximum exposed width is over 10 

feet. The vein filling is banded quartz with quartz crystals on 

partings and in vugs. Galena is present in the quartz at the north 

end of'the drift. Cerusite is irregularly distributed along the vein 

in streaks and bunches. The quartz is impregnated with manganese 

oxide in places. Mr. Firth states that the ore in the drift has an 

average content of 12 to 15 ounces of silver to the ton, 10 to 15 per 

cent of lead, and a little gold. The shaft is said to have passed through 

broken ground containing fragments of limestone between depths of 

450 and 500 feet. On the dump is sulphide ore reported to h'ave 

come from a depth of 560 feet. This ore contains galena, argentite, 

sphalerite, pyrite, chalcopyrite, quartz, and calcite. Other specimens on the dump consist largely of calcite and quartz stained dark 

red with hematite. In this fine-grained mass are small aggregates 

of pyrite and grains of sphalerite speckled with chalcopyrite. The 

rock is reticulated with tiny branching veinlets and irregular masses 

of earthy hematite. It is probable that these specimens represent 

silicified and mineralized limestone and therefore that the vein intersects a fault block of limestone at a depth of about 560 feet. Mr. 

Firth is authority for the statement that no ore was encountered 

in the shaft until this depth was attained 'and that all the mineralized rock on the shaft dump came from this depth. This is the 

greatest depth so far reached by mine workings in the Aravaipa 

district, and the presence of products of oxidation in rock found 

near the bottom of the shaft is interesting as indicating the depth 

to which oxidation has extended. Water was encountered in this 

shaft at a depth of 500 feet in sufficient quantity to be a handicap in
98 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

sinking the shaft deeper. Work finally ceased in May, 1895, when 

the shaft Was down about 580 feet.

The ore found on the No. 1 claim is cerusite, whiqh was found in 

irregular masses in the limestone. Most of it so far discovered is 

reported to have been stoped out, but other bodies may well be found 

if development work is carried farther. No sulphides appear to 

have been encountered. Near by the limestone is silicified and replaced by actinolite in places.

The tunnel on the Orejana claim is in quartzite with a dike of 

altered trap shoAving near the mouth. The tunnel follows a vein 

striking approximately N. 15° W. and ranging in width from a few 

inches to 2 feet. The vein filling is ribbon-banded quartz, in places 

with coarse galena. The galena is altering to angiesite and cerusite. 

Both the chloride and the bromide of silver are reported to have 

been found. The highest silver assays are obtained from narrow 

streaks of soft material on the vein Avails. Small amounts of ore 

containing as much as 300 ounces of silver to the ton are reported 

to have been shipped.

The other workings on the claims of the Ar.avaipa Mining Co. 

do not appear to have developed ore bodies of commercial importance. On the Grand Central and Head Center sulphides occur 

along irregular slips in limestone exposed in short tunnels and pits. 

The Iron Cap and adjoining claims were not visited, but the development work on them is reported to be small. The limestone is 

somewhat mineralized, but valuable ore bodies have not been discovered. A long tunnel on the Gordon claim disclosed nothing of 

value.

MOLTKE GROUP'

- The Moltke group consists of four unpatented claims owned by 

Mrs. H. T. Firth and Frank Landsman. It is on the road between 

Arivaipa and Tule Spring, about a mile from Arivaipa. There are 

some short tunnels on the property on slips in the altered rock. 

Most of the rock in this vicinity appears to be related to the intrusive 

rhyolite, but pre-Cambrian schistose rocks are also present.

NORTON GROUP

. The Norton group consists of four unpatented claims owned by 

Mrs. H. T. Firth, and C. A. Firth. They border the south end of 

the Aravaipa Mining Co.'s property on the east, near Arivaipa, and 

contain principally Paleozoic sedimentary strata that show brecciation and some mineralization. The development work on these 

claims is small.

There is an unpatented claim north of this group which appears 

to belong to H. T. Firth.
ARAVAIPA DISTEICT ' 99 

H. T. AND C. A. FIRTH GROUP

A group of six unpatented claims belonging to H. T. and C. A. 

Firth lies north of Arivaipa, bordering the principal group of claims 

belonging to the Aravaipa Mining Co. on the west. Little work has 

 been done on these claims.

TOLMAN-BABCOCK GROUP

The six unpatented claims that constitute the Tolman-Babcock 

group lie east of the Arizona mine and about a mile north of Arivaipa. They are owned by Mrs. H. T. Firth, of Arivaipa. Two or 

three cars of cerusite ore have been shipped from this property. 

There is a short tunnel and a 75-foot winze on the Babcock claim, 

a shallow shaft on the La Sorilla claim from which 55 tons of cerusite ore has been sloped, and other workings elsewhere.

The workings on the Babcock and La Sorilla claims of this group 

were the only ones examined. At the Babcock there is a zone about' 

S1/^ to 5 feet Avide without definite Avails composed of brecciated arid 

altered fine-grained porphyry. It' strikes nortliAvest and dips about 

60° W. The ore is reported to assay about 10 per cent of lead and 5 

ounces of silver to the ton. The rock of the brecciated zone contains 

somewhat crushed and altered phenocrysts of alkali feldspar, quartz, 

and chloritized biotite in a groundmass so fine that it can not be 

satisfactorily resolved even under the microscope. It is cut by 

stringers of vein quartz. The rock is too much altered and too fine 

grained for exact determination. In the hand specimen it is of a 

dirty heliotrope color clotted with white specks of feldspar and 

green chlorite patches. In the field it was thought to be an altered 

variety of the intrusive rhyolite, but the composition appears to be 

too calcic. It might be related to either the Miocene (?) or the Cre- 

. taceous A7olcanism.

At the La Sorilla claim there is glassy vein quartz in a brecciated 

and altered porphyry, which in the hand specimen resembles intrusive rhyolite. A basalt dike cuts the brecciated porphyry and the 

vein matter. There Avas reneAved brecciation and deposition after 

the basalt intrusion. The zones along which both the original and 

the postbasalt fracturing and mineralization took place strike in 

about the same direction, someAvhat Avest of north. The lode noAv 

consists of fragments of porphyry, quartz vein matter, and basalt. 

The basalt has been markedly altered, the original augite and olivine 

being almost completely converted to chlorite, epidote, and ironoxide dust. The groundmass is composed of feldspar microliths with 

floAv structure. About 55 tons of cerusite ore has been mined from a 

pocket in this lode. 

106914 25 S
100 ARAVAIPA AND STANLEY MINING DISTRICTS, ABIZ. 

BRYCE-MERRILL PROSPECT

E. W. Bryce and W. P. Merrill have some unpatented claims in 

Williamson Canyon east of the Arizona mine and about a mile north 

of Arivaipa, A shaft about 50 feet deep has been sunk on one 

of the veins belonging to the zone of mineralization that extends 

through this part of the district.

SINN FEIN PROSPECT

The Sinn Fein prospect is owned by James Quinn and Thomas 

Finnegan, of Klondyke. It is on the north side of Williamson 

Canyon, west of the Head Center claim of the Aravaipa Mining 

Co. and somewhat over a mile northeast of Arivaipa. It is developed 

by an irregular tunnel that begins a short distance above the level 

of the stream bed. This prospect was formerly owned by H-. T. 

Firth, of Arivaipa, who shipped one carload of ore. The present 

owners have shipped two carloads. About half a mile east of 

this prospect, on the west slope of Satisfaction Mountain, are some 

pits and shallow cuts. These are reported to be on claims belonging to the owners of the Sinn Fein.

The Sinn Fein tunnel is in Tornado limestone and follows a 

mineralized shear zone that strikes north and dips 60°-70° E. The 

ore contains galena and sphalerite in good-sized crystals and some 

cerusite.

The pits on Satisfaction Mountain are also in Tornado limestone. They are sunk on irregular masses of rather coarsely crystalline calcite and quartz impregnated with iron and manganese oxides. 

A little copper stain was noted, and specularite is present in small 

flakes.

BAWHIDE GROUP

Between the north end of the Aravaipa Mining Co.'s property 

and Old Deer Creek are four unpatented claims known as the 

Eawhide group and owned by Abe Keed, of Stanley. On this group 

there is reported to be a tunnel about 300 feet long and another 

about 50 feet long which expose a vein carrying lead and silver 

in Paleozoic strata.

WARM SPRING PROSPECT

Warm Spring is in the bed of Old Deer Creek on the trail between Arivaipa and Stanley 2 miles north of Arivaipa. There are 

corrals and a cabin here and a fenced pasture near by. The Old 

Rawhide Development Co. owns one or more unpatented mining 

claims at this locality. There is a short tunnel on the north side 

of the stream just below the spring.

A small block of Tornado limestone is inclosed in the rhyolitic 

rock. The tunnel follows slips in the limestone. It has caved
ABAVAIPA DISTRICT 101

and been partly reopened. Little evidence of mineralization could 

be seen in the part now accessible.

LANDSMAN GROUP

Property. The compact group of 37 unpatented claims which lie 

on the slopes southwest of Cobre Grande Mountain has for a number 

of years been controlled by Frank Landsman and may be termed the 

Landsman group. He has from time to time shared his interest in 

them with different partners. The location of the claims is shown 

on Plate XI. The only buildings on the property are the tent house 

and cabin at Lawrence Spring where Mr. Landsman lives.

There are a considerable number of shallow holes on the claims, 

also several short tunnels, most of which were caved and inaccessible 

at the time of visit. No developments beyond the required annual 

assessment work have been attempted, and the excavations serve 

principally to give fresh exposures of the rocks that crop out at the 

surface. No ore has been shipped.

Character of the deposits. Most of the mineralization on the 

Landsman group is in the Tornado limestone, which is cut by a 

number of rhyolite dikes that are in places themselves mineralized. 

These dikes are similar to the rhyolite associated with the main 

granite batholith and are probably related to it. There is also some 

mineralization in the schist. The mineralization in the limestone in 

part conforms to the bedding, in part forms irregular masses of indefinite extent, and in part follows lines of fracturing transverse to 

the bedding, most of which strike west of north and dip west. In 

several places rhyolitic dikes cut the replacement bodies and have 

been shattered and partly replaced, but not so completely as the limestone. The metamorphic rocks also are less thoroughly replaced 

than the limestone. Replacement in limestone is conspicuous over 

hundreds of square feet of the lower slopes of Lime Hill. In places 

the ore minerals have been almost completely substituted for those 

of the original rock over a considerable area of outcrop. In many 

of the irregular replacement deposits specularite predominates, but 

in those that accord with the bedding silicate minerals are more 

abundant.

The minerals formed .by hypogene deposition are specularite, 

magnetite, pyrite, chalcopyrite, quartz, fluorite, actinolite, epidote, 

and garnet. Oxidation has produced copper pitch, cuprite, malachite, and manganese and iron oxides. The supergene sulphides, 

chalcocite and covellite, are also present, principally in association 

with the oxidized copper minerals'. In many outcrops specularite 

is one of the most abundant minerals. It occurs in the limestone in aggregates of shining plates, intermingled in places with 

silicate minerals, and in the other rocks in fine-grained intersecting
102 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

stringers. There are cavities in rhyolite in which thin bands of 

specularite cover the walls and into which crystals of quartz and 

fluorite project from the specularite. A small quantity of magnetite 

is almost invariably found associated with the specularite. Sulphides are not abundant in any of the exposures. They are most 

conspicuous where there are veinlets or irregular masses of quartz. 

Actinolite is abundant in places, parts of some limestone beds being 

almost completely replaced by this mineral, but it is less widespread 

than specularite. Garnet and epidote were noted in a number of 

places, but they are not abundant in most exposures. The oxidized 

minerals are irregularly and rather widely distributed but are nowhere abundant. Assays as high as 1 per cent of copper and a 

little gold are reported to have been obtained from specimens' of 

specularite containing no visible copper minerals. Microscopic 

examination of such a specimen revealed small quantities of chalcocite. This mineral associated with copper pitch ore and a little 

covellite is also found around residual cores of chalcopyrite, but 

in most specimens the quantity of chalcocite is so small that it can 

not be distinguished with the unaided eye.

COBRE GRANDE MINE

The Cobre Grande mine lies on the northeast slope of the mountain of the same name. It is 4 miles northeast of Arivaipa and 

6 miles southeast of Stanley, measured in straight lines, and is 

accessible only by steep trails. The camp of the miners consisted 

of several tent houses and cabins about half a mile south of the 

main workings, at a place where there was formerly a good spring. 

The camp has been uninhabited for several years. The Cowboy 

tunnel, in which most of the ore has been found, winds around in 

an irregular curve a few hundred feet long; short drifts lead off 

it, and near the end stopes have been opened above and a winze 

about 40 feet deep below. 'Another tunnel near by cut ore also. A 

short distance down the slope is a caved tunnel reported to have 

been over 600 feet long but to have encountered no ore. A few 

hundred yards to the west, on the other side of the mountain spur, 

is a shaft reported to have been 160 feet deep in which some ore 

was found. On the trail to the old camp is a partly caved tunnel 

reported to have been over TOO feet long. There are doubtless other 

excavations, but those enumerated are the principal ones.

The deposits appear to have been first located in 1905 by Julius 

Riser and W. A. Clark.68 In recent years the owners have been 

Messrs. Snell, Elliot, Fisk, and Alderman, of Globe, Ariz. Location

58 Historical data have been furnished by Prank Landsman, of Arivaipa, who acted as 

guide to this and other properties.
AEAVAIPA DISTKICT 103

notices of J. C. Sayers dated January 3, 1922, were posted on the 

property when it was visited. A carload of ore running about 8 per 

cent of copper is reported to have been shipped to the Old Dominion smelter at Globe some years ago. Most of this ore came from the 

Cowboy tunnel.

The Cowboy tunnel and the workings near it are all in the Tornado limestone. The accessible part of the tunnel on the trail to the 

camp is in an altered fine-grained igneous rock, but the face is reported to have been in limestone. In the Cowboy tunnel, which is the 

only one where ore in place was accessible at the time of visit, the 

ore' is in irregular bodies in the limestone. In general the replacement followed the bedding. The gangue minerals include quartz, 

calcite, chlorite, epidote, garnet, specularite, and magnetite. The 

hypogene sulphides are pyrite, chalcopyrite, and a little galena. A 

little chalcocite is also present. There is scant evidence of oxidation 

in any of the ore.

FISHER PROSPECT

Location. John Fisher's copper prospect is in a rugged canyon 

in the southeast end of the Turnbull Mountains, in the Black Rock 

mining district. It is about 25 miles from Fort Thomas, on the Arizona Eastern Railroad, but there are ranches along Black Rock Wash 

within a few miles of Fisher's cabin.

Ore. The prospect has been developed by means of a number of 

pits and short irregular tunnels. The outcrops and tunnels are scattered around near the head of a short canyon, principally on the west 

side. They are not connected but show the presence of several mineralized masses. The rocks here are almost free from soil, but the 

surface evidences of mineralization are small and rather inconspicuous. No large amount of ore has yet been developed, but the underground work done so far is small and scattered. A few tons of rock, 

some of which contains several per cent of copper, has been mined, 

but none has yet been shipped.

Character of the deposits. The prospect is in the midst of the 

granitic batholith, probably 2 miles or more from the nearest boundary of the intrusive mass as at present exposed. The east boundary 

of the batholith was not reached during the present investigation, 

but the characteristic erosion forms of the granite are clearly visible 

for a considerable distance beyond the area mapped. (See PL IX, 

B.) In the vicinity of the prospect are a number of aplitic dikes 

rich in micropegmatite. Many of them are less than a foot in width. 

Such dikes are rare in other parts of the batholith. The metallic 

minerals are irregularly disseminated in the granite. Indefinitely 

marked slips were noted in the mineralized granite in some of the 

tunnels. Much of the rock exposed by the tunnels is colored green by
104 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

chrysocolla. Some of the rock originally contained a considerable 

amount of chalcopyrite, but this appears to have been concentrated 

in small irregular bunches. The tunnels twist and branch, following 

the zones of mineralization. There seems to be somfe tendency for 

these zones to be elongated in form, but the limits are indefinite and 

irregular. There is no suggestion of vein filling or of any definite 

walls.

The only original sulphide that was found is chalcopyrite. Later 

processes have produced copper pitch ore, chalcocite, covellite, and 

chrysocolla. The only gangue minerals besides those of the original 

granite are epidote and minor amounts of titanite, apatite, and 

chlorite or a similar alteration product. Like most of the rock of this 

batholith, the granite contains quartz, orthoclase, microperthite, 

albite, oligoclase, microcline, and biotite. The rock shows less alteration than most of the specimens from other parts of the batholith. 

Thin sections cut from specimens of ore contain almost perfectly 

fresh feldspars, but some of them, especially near ore minerals, 

are somewhat shattered. In a section cut from a specimen free 

from sulphide the feldspars are slightly clouded with alteration 

products. The chalcopyrite, which is the original ore mineral, 

is so greatly altered by oxidation that its relations to the minerals 

of the granite are somewhat obscure, but there can be little doubt 

that it was formed by replacement of the rock minerals. Epidote 

occurs in grains nearly 2 millimeters in the greatest dimension, 

some of which have crystal form, and in finer granular aggregates. 

Some of the grains are clouded with alteration, and most of them 

show cracks produced by weathering. The epidote seems later than 

the chalcopyrite. The large crystals appear in places to be molded 

on chalcopyrite grains, and finer aggregates probably filled cracks 

in the sulphide. Here also the oxide minerals obscure the relations 

somewhat. It is rare to find epidote in actual contact with sulphide. 

Many of the grains are embedded in copper pitch. Probably most 

,of the epidote is in contact with feldspar, which it replaces, and 

not with any metallic mineral. All of it, however, is in the' vicinity 

of such minerals. None is found in the granite that was not impregnated with chalcopyrite. Titanite is not abundant. It occurs 

here and there in granular aggregates, certainly later than the feldspar and perhaps later than the epidote. It was not noted in the 

unaltered granite. A few tiny prisms of apatite were noted near 

the epidote grains. Similar prisms were found in small amounts 

in some of the thin sections of specimens from other parts of the 

batholith, and it is possible that the apatite is to be considered an 

original constituent of the granite, although its association with 

epidote in the ore leads to the suggestion that it may have been 

introduced during the mineralization.
STANLEY DISTRICT 105

The chalcopyrite grains have been in large part replaced by an 

assemblage of supergene minerals. These are copper pitch ore and 

chrysocolla formed by weathering' of the sulphides, with small 

amounts of the supergene sulphides chalcocite and covellite. The 

copper pitch in this ore is an indefinite mixture of hydrous oxides of 

copper and iron without manganese. The small cores which are all 

that remain of the chalcopyrite grains are embedded in the copper 

pitch. The latter has not wandered far from its place of origin, 

although, besides replacing chalcopyrite, it has reached out into the 

feldspar to some extent, especially along cracks. The chrysocolla is 

more widely diffused than the copper pitch ore. Much of it is so 

finely disseminated through the granite in the vicinity of the ore 

minerals that it can not be resolved even under the microscope, and 

its presence is determined only from the slightly bluish-green color 

which suffuses the rock. Here and there, however, along tiny cracks 

are knots of the mineral, some of them large enough to be seen with 

the unaided eye. Some of the chalcopyrite cores have narrow rims of 

chalcocite with a little associated covellite. The total quantity of 

such supergene sulphides visible even under high magnifications is 

small. They were formed by downward enrichment, apparently after 

the original chalcopyrite had been attacked by oxidation, with the 

formation of copper pitch ore.

STANLEY MINING DISTRICT 

GENERAL FEATURES

Location and extent. The Stanley mining district lies approximately in unsurveyed Tps. 4 and 5 S., Rs. 19 and 20 E., in Graham 

County just north of the middle of the west border of the county. 

It is bounded on the north by the south border of the San Carlos 

Indian Reservation, on the west by the Final County boundary, and 

on the south by Old Deer Creek. The eastern boundary, which is 

somewhat irregular and indefinite, corresponds in part with the west 

border of the Turnbull mining district and for the purposes of this 

report may be taken as a line along Kelly and Rustler Park gulches 

to the head of the latter and thence west and south along the ridge 

tops to the head of Old Deer Creek.

Population. The old settlement of Stanley is the center of population for the district. It is a collection of houses and shacks all but 

one of which are now abandoned. The sole remaining resident is 

J. Flaherty, a veteran prospector whose success in raising vegetables 

on the patches of soil in the rocky streamway that passes by Stanley 

has resulted in the streamway being known as Garden Gulch. The 

post office of Stanley has recently been moved to the assistant postmaster's house, about half a mile south of the old settlement. Ac-
106 ABAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

cording to the census of 1920 Stanley precinct, which doubtless comprises the whole of the district, has a population of 54. This is ma°de 

up of stockmen, prospectors, and miners scattered over the district, 

there being nowhere more than a single family or group of a few 

men at any one place. In 1910 the population, according to the 

census, was 139.

Roads. Stanley is over 15 miles by road from San Carlos, which 

is the supply point for the district. This road is in poor repair but 

is practicable for a wagon, and most of it can be traversed by an 

automobile. Beyond Stanley the road continues nearly 4 miles farther to the Princess Pat mine but has been little- traveled since that 

mine shut down in 1918. The whole of this road could be made 

passable for automobiles with a small amount of work, but unless 

considerable surfacing and grading were done it could hardly be 

made into a good automobile road. Another road extends from San 

Carlos to the Copper Reef mine, and a, branch of it goes up Hawk 

Canyon to the Webster ranch, near its head. The road to the mine is 

in fair shape, but that up Hawk Canyon is washed out in places and 

very rough. The other parts of the district are accessible only by 

trail.

MINES AND PROSPECTS

PRINCESS PAT MINE

Property. The Princess Pat group consists of 44 unpatented 

claims, which were bonded to the Princess Pat Mining Co., of New 

York, by the Allison brothers. The claims are on Old Deer Creek 

just south of Stanley Butte, most of them on the north side of the 

stream. The company built a number of tent houses and shacks 

on a patch of level ground on Old Deer Creek and installed a compressor and other machinery at the tunnel mouth. The cabin of the 

late J. S. Allison is a short distance farther upstream. The camp is 

about 4 miles from Stanley by a road which, considering that it has 

not been repaired since 1918, is in fairly good condition.

The principal underground development work on the property is 

that done by the Princess Pat Mining Co., which opened a tunnel 

reported to be 870 feet long, with a trend of N. 10° W. There are 

two crosscuts on the west side, each about 120 feet long, and one on 

the east about TO feet long. Other workings of small extent resulting 

from annual assessment work are scattered over the property.

History. The presence of mineralized outcrops here has been 

known since the early days of prospecting in the region, and some 

work was done on them long ago. About the beginning of the present century the ground was located by members of the Allison 

family, and since then it has been held by Messrs. Grant, G. M., 

O. W., and J. S. Allison, the last two of whom are dead. Many of
STANLEY DISTRICT 107

the data given here were kindly furnished by G. M. Allison, who 

acted as guide in this part of the region. About a ton of oxidized 

copper ore was shipped by the Allisons from workings near the 

northwest corner of the property. In 1916 the property was bonded 

to the Princess Pat Mining Co., which gave the present name to the 

group. The claims had previously been known as the Butte & 

Arizona and Palo Alto groups. The company drove the tunnel and 

crosscuts already described but shipped no ore and in December, 

1918, suspended operations. Since then little has been done. The 

tunnel now contains considerable water and is beginning to cave.

Character of the deposits. The rocks on the property consist of 

Cretaceous and Miocene (?) beds and rhyolitic intrusive rock. The 

Cretaceous beds are principally andesite and andesitic breccia, but 

sandstone and shale, in part carbonaceous, are also present. The 

rocks strike about N. 45° W. and dip 30°-45° SW. They are cut by 

contemporaneous andesitic dikes. The Tertiary lava overlying the 

Cretaceous rocks on the west is principally glassy quartz latite.

The deposit which the tunnel was intended to open up shows on 

the slope above as a rusty and silicified shear zone in andesite. The 

only mineralized rock reported to have been found underground is 

in a zone about 7 feet wide in a crosscut to the west about 320 feet 

from the portal. Apparently this rock does not crop out. Specimens 

from this zone on the tunnel dump consist of light-green brecciated 

and chloritized andesite, softened by weathering. The most abundant 

metallic mineral is sphalerite. Pyrite in cubes and irregular grains, 

a little chalcopyrite, and probably some galena are also present. The 

rock is shot through with calcite, part of it in crystal form, and 

quartz has also been developed in it.

A few hundred feet west of the tunnel is a body of rhyolite which 

appears to be a continuation of the intrusive mass to the south, 

although differing somwhat from the typical intrusive rhyolite. It 

contains phenocrysts of quartz and alkali feldspar in a rather fine 

grained groundmass of alkali feldspar and quarts intimately intergrown somewhat after the manner of micropegmatite. This rock in 

places is altered, iron stained, and broken by small slips. The slips 

are more iron stained than the surrounding rock and show chrysocolla. 

and malachite in places. Some of the slip surfaces are coated with 

quartz. Casts of pyrite crystals partly filled with limonite are 

sparsely disseminated in the rhyolite. In shallow workings near 

the stream stringers of chalcocite are reported to have been found.

COPPER DIKE GROUP

The Copper Dike group consists of 14 unpatented claims on the 

south slope of Stanley Butte, adjoining the Princess Pat group on
108 ARAVAIPA AND STANLEY MINING DISTRICTS, AEIZ.

the north. Only a little shallow underground development work 

has been done on this property, to meet assessment requirements.

This group is a part of the Allison property which was retained 

when the Butte & Arizona and Palo Alto groups were bonded to 

the Princess Pat Copper Mining Co. The early history is given in 

the description of the Princess Pat mine. In recent years very little 

has been done on the Copper Dike group.

There are on these claims two shear zones in andesite breccia. 

The rock of these zones is silicified and rusty and in places contains azurite. The zones strike about N. 15° W. and appear to 

dip steeply east.

COLD SPRING PROSPECT

The Cold Spring prospect, owned by Martin Flaherty, of Stanley, 

is near the head of Garden Gulch, somewhat less than 3 miles southeast of Stanley. There is a tunnel opening a few feet above the 

stream bed from which issues the water that gives the place its 

name. The water, is piped into a trough in a small corral at the 

tunnel mouth, and the corral is closed with a gate. The place is now 

used for watering cattle, and no mining appears to have been done 

for some time.

The tunnel is in the Tornado limestone near the southwest border 

of the metamorphosed phase of that formation which forms Crystal 

Peak. Near the tunnel some beds are thoroughly altered, but some 

are little, affected by the metamorphism. Some of the limestone 

on the dump contains masses of recrystallized calcite with abundant 

cubical crystals and small amounts of stibnite, sphalerite, chalcopyrite, and perhaps supergene copper sulphides.

SOLDIER PROSPECT

The Soldier prospect is on the west slope of Limestone Mountain 

about a mile east of Stanley. It is owned by P. T. McCulley, assistant postmaster of Stanley. The development consists of an inclined shaft and a tunnel more than 1,000 feet long, starting a few 

hundred feet down the slope, which was intended to cut at depth the 

slip on which the inclined shaft was sunk.

The country rock of the workings is the Tornado limestone, which 

is cut by quartz porphyry dikes near by. Some of the limestone 

beds contain actinolite, garnet, specularite, and quartz, but most of 

them show little metamorphism of this type. On the slip at the shaft 

there is a little specularite and some copper stain. Near the mouth 

of the tunnel the rock is slightly mineralized, and at its face the 

limestone shows some replacement by garnet and similar minerals.
STANLEY DISTRICT 109 

COPPER BELLE MINE

The Copper Belle mine, owned by Martin Flaherty, is a short 

distance west of Stanley. It has been developed by several shafts, 

none of them deep. It was first located in 1883, and two-partial 

carloads of ore have been*shipped from it.

The deposits are in highly faulted Tornado limestone. The mineralized rock is in irregular seams and contains specularite, calcite. 

pyrite, and chalcopyrite.

SILVER SPAR PROSPECT

The Silver Spar prospect, owned by Joe Stewart, is on the west 

side of Stanley Butte near the summit. A short tunnel, a shallow 

shaft, and perhaps other cuts have been opened on the property. 

 The country rock is a dark latite or andesite breccia. The ore is 

in irregular seams and has a gangue of quartz, barite, and fluorite. 

The metallic minerals are in aggregates of tiny dark grains, on 

some of which there is a little malachite. Under the microscope 

three metallic minerals can be seen, but the quantity of each is so 

small that positive identification was not made. There are specks of 

some mineral that has the appearance of bornite. It is tentatively 

considered to be that mineral and to be the source of the malachite 

noted. A bright silvery mineral, very soft and sectile, is present in 

somewhat greater amount. The bright grains are rimmed with a 

soft gray material, evidently an alteration product. The microchemical reactions observed on these two minerals do not seem to accord with any of the minerals listed by Davy and Farnham.59 It 

was thought that the bright mineral might be a telluride, but chemical tests failed to confirm this conjecture. The material contains 

lead, silver, and probably antimony. Small quantities of a mineral 

resembling horn silver were noted in the specimens.

STANLEY MINE

The Stanley mine or prospect is on the northeast side of Little 

Stanley Butte, on a tributary of Garden Gulch a little over a mile in 

a straight line west of Stanley. It was worked by Martin Davis a 

few years ago. He lived in a house near the mouth of the tunnel, 

which is the principal underground working on the property. It is 

now caved but is reported to have been 1,200 feet long.

The tunnel is in red Cretaceous sandstone striking N. 15° W. and 

dipping 20° W. It is reported to have been driven to cut leads 

found on the slopes above but does not appear to have done so.

to Da.vy, W. M., and Farnham, C. M., Microscopic examination of the ore minerals. 

1920.
110 ABAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

FBIEND MINE

Property. The Friend mine comprises the principal development 

on the Copper Range group of claims, owned by the Stanley Peak 

Mining-Co. It is on the north side of Little Stanley Butte ll/% 

miles west of Stanley. The house where the miners live is near Garden Gulch, a short distance downhill from the mouth of the principal tunnel.

There are reported to be about 2,000 feet of underground workings on the property. The principal opening is a tunnel about 1,400 

feet long, now largely caved. Above this are some short tunnels and 

shafts.

History. The deposits were known in the early eighties and held 

for a time by a half-breed Indian named Bob Mclntosh, who took 

a negro and later a white man called James Stevens as partners. 

They sold the property to John Blake and Albert Warren in the 

nineties. Most of the development work is reported to have been 

done from 1870 to 1907. About three years ago the xpresent company was organized. Only one carload and a few small lots of 

ore have been shipped from the property. The carload was copper 

carbonate ore. At present the principal tunnel is being reopened. 

The company plans to clean it out and timber it to the point where 

the vein was intersected, about 1,100 feet from the tunnel mouth, 

and then to drift on the vein. The work is in charge of J. C. Anglin. He and Martin Flaherty, of Stanley, furnished the historical 

information here given.

Character of the deposits. The rocks on the property all belong 

to the Cretaceous system. Sandstone, shale, and andesite are exposed in the tunnel and crop out near by. The visible portions of 

the veins are in andesite, and the wall rock of the vein in the tunnel 

is reported to have been similar. At the top of a shaft on the hillside 

above the principal tunnel the intersection of two veins is exposed. 

These dip very steeply and at the intersection strike N. 20° W. 

and N". 20° E. The principal gangue'mineral in the portions of the 

veins visible in the upper workings is calcite. They contain aznrite, 

malachite, cuprite, and hematite, with some bornite, chalcocite, and 

chalcopyrite in places. Ore containing as much as 20 to 30 per cent 

of copper is reported to have been found in stopes in these upper 

workings and immediately below them, now for the most part inaccessible. The ore shipped came from these stopes. The vein cut 

in the principal tunnel is reported to be 4 feet wide and to contain 

chalcocite and bornite.

On Stanley and Little Stanley buttes there are small prospect 

tunnels and shafts belonging in part to the same company as the 

Friend mine. In one of these tunnels on the north end of the top
STANLEY DISTRICT 111

of Stanley Butte there is a zone from 2 to 3 feet wide of brecciated 

purple latite or andesite with calcite seams. This strikes N. 50° 

W. and dips 80° E. A little copper stain is visible. On the west 

side of Little Stanley Butte biotite latite is cut by a vein about 2 

feet wide of coarse calcite darkened with manganese, with a little 

yellowish chert. Thin seams of gypsum appear on cleavage surfaces of the calcite. Tiny crystals stud the cherty lining of cavities 

in the calcite and have been examined by W. T. Schaller and E. S. 

Larsen, who have furnished the following data., They are black as 

seen under the hand lens but deep blue by transmitted light under 

the microscope. The index of refraction is about 2.5. The mineral 

is soluble in acids. The properties suggest those of anatase, one of 

the minerals composed of titanium oxide, and the appearance gre'atly 

resembles that of some deep-blue to almost black vein anatase from 

Colorado. The mineral is therefore considered to be probably anatase, although positive proof was not obtained. The country rock 

of both veins is lava of Tertiary age.

J. C. Anglin, of the Friend mine, found a vein of calcite colored 

black with manganese oxide in Cretaceous sandstone near the mine.

COPPER REEF MINE

Property. The Copper Eeef mine is on the southwest slope of the 

mountain of the same name, about 3y2 miles northwest of Stanley 

and 12 miles by road from San Carlos, on the Arizona Eastern Railroad. The property comprises 125 unpatented mining claims and a 

600-acre 'mill site °° and is owned by the Copper Eeef Consolidated 

Mines. There is an engine house containing a compressor and other 

machinery, a blacksmith shop, and a storehouse at the portal of the 

principal tunnel, and buildings for the office, boarding house, and 

dwellings a short distance down the shope. In Hawk Canyon a 

low dam and pumping plant supply water for the mine.

The principal underground workings are the California tunnel 

and drift. The tunnel extends about 300 feet from its mouth in a 

N. 44° E. direction, then turns and continues an additional 1,100 

feet approximately N. 20° E. About 600 feet from the tunnel mouth 

there is a drift that extends about 1,000 feet with an average trend 

of about S. 40° E. Some winzes have been sunk and a little stoping 

done below this drift, principally near the southeast end. On the 

mountain some distance east of and several hundred feet higher than 

the tunnel mouth is the North Star shaft, reported to be 735 feet 

deep. There are several shallower shafts and other workings on 

the property.

History. The Copper Eeef Consolidated mine was incorporated 

in 1910 in Arizona, but the deposits were,known considerably earlier,

60 Weed, W. II., Mines Handbook, vol. 15, p. 258, 1922.
112 ARAVAIPA AND STANLEY MINING DISTKICTS, ABIZ.

and some work had been done. Operations were suspended in 1915 

but have been resumed several times since then. A small amount 

of lead ore obtained near the top of Copper Reef Mountain and 

small quantities of copper ore from other parts of the property are 

reported to have been shipped. At present the property is in charge 

of a caretaker, L. W. French, who furnished data as to underground 

development and other information. The company is now involved 

in litigation which hinders development of the property.

Character of tke deposits. The principal workings on the property are all in the Tornado limestone, which strikes about N. 50° W. 

and dips 25°-35° SW. The drift off the California tunnel exposes 

mineralized limestone along a large portion of it. The mineralized 

zone is from 1 foot to several feet wide, makes a small angle with 

the direction of bedding in the limestone, and dips steeply northeast. 

Workings below the level of the drift expose irregular mineralized 

bodies several feet wide containing oxidized copper ore making out 

along the bedding. On the slope above the tunnel mouth there are 

a number of irregular patches of oxidized ore exposed in shallow 

pits and cuts. In places the mineralization seems to have been confined to a given bed in the limestone, but in most exposures the outlines are irregular. The shafts that have been sunk in a number 

of places are reported to have run out of ore at depths of 20 to 40 

feet. Although several were driven hundreds of feet lower they 

are reported to have encountered almost no further evidence of mineralization. Apparently they were started on gash veins that 

pinched out at shallow depths.

The ore from the California workings contains quartz, calcite, 

barite, hematite, limonite, manganese oxide, chrysocolla, malachite, 

copper pitch> chalcocite, and remnants of chalcopyrite and pyrite.

Bornite and azurite are also reported to have been found but were not 

observed during the present investigation. The ore is reported 81 to 

average 5.4 per cent of copper and 68 per cent of silica, with some 

silver and gold. In surface exposures on and near Copper Reef 

Mountain beds of limestone are largely replaced by specularite with 

some actinolite.

PROSPECTS ON RAWHIDE MOUNTAIN 82

On the northeast face of Rawhide Mountain claims have been located on slips in the Tertiary lava. Silver ore is reported to have 

been found in these prospects. Southwest of the mountain in the 

Tornado limestone there is a short tunnel and probably other workings on slips showing some mineralization.

a Weed, W. H., op. cit.

82 Examination of this part of the region was facilitated by the guidance of Mark 

Claridge, of Hawk Canyon.
STANLEY DISTRICT 113 

STARLIGHT MINE

Property. The Starlight mine is owned by the Tribullion Smelting & Development Co., of New York, which also owns a copper 

mine at Kelly, N. Mex.' The property consists of 12 overlapping patented claims covering about 180 acres on Kelly Gulch, about 8 miles 

from San Carlos. Most of the property lies in the S-an Carlos Indian ^Reservation, the boundary fence passing through the south corner of the group of claims. The mine was formerly connected with 

San Carlos by a wagon road down Kelly Gulch. There are several 

buildings in the gulch opposite the mouth of the principal tunnel, 

but, having been abandoned for years, they are in poor repair.

In Kelly Gulch is a tunnel reported to be 1,900 feet long, now 

partly caved and inaccessible. In a short side canyon known as 

Godless Gulch there are a number of open cuts and caved tunnels. 

There are also several shafts on the property, two of which are of 

the order of 150 feet deep.

History. The deposits here were evidently worked by the Spaniards or Mexicans in very early days, as when the deposits were rediscovered in 1886 there were several glory holes in Godless Gulch 

and the remains of an adobe smelter near by. They were at that time 

inside the Indian reservation and therefore could not be worked. In 

1901 the land on which the deposits crop out was thrown open to location, although most of it was still within the reservation, and in 1903 

work was started. In 1905 ore valued at $6,876 is reported to have 

been shipped. In 1906 ore on which the smelter returns aggregated 

$15,900 was shipped. The claims were surveyed for patent in 1907. 

Apparently little work has been done since then, and the place has 

been deserted for about 12 years.

Character of the deposits. The deposits appear to be entirely in 

the Tornado limestone, but Cambrian quartzite and pre-Cambrian 

metamorphic rocks are also present. The Paleozoic rocks are fractured, tilted, and locally overturned. In Godless Gulch the limestone is much disturbed but appears to strike in general about N. 25° 

W. and to dip 60° E. Down the gulch to the east is Cambrian quartzite lying in about the same attitude, though dipping somewhat more 

steeply. The limestone thus.appears to dip under the older quartzite, and the formations are therefore overturned. Under the quartzite exposed in the stream bed is yellowish-brown schist, evidently 

belonging to the Final schist. The quartzite forms the sides of Godless Gulch from the limestone boundary east to the point where it 

enters Kelly Gulch, and forms both walls of Kelly Gulch for 

some distance on both sides of this point, cropping out on the west

03 Historical data principally from Stevens, H. J., Copper Handbook, vol. 6, pp. 984- 

985, 1906; vol. 10, p. 1696, 1911. More recent information supplied by Fritz Wolf, of 

Stanley, in whose company the mine was visited.
114 ARAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

side for over a mile above the junction. South of Godless Gulch 

both the quartzite and limestone dip west, assuming their normal 

stratigraphic relations. A narrow ravine entering Kelly Gulch 

from the east just above the mine buildings is walled with a finegrained dark-green rock that has the composition of an altered 

soda-rich granodiorite or soda granite. It consists largely of a 

micrographic intergrowth of quartz and feldspar and small hypidiomorphic feldspar laths, most of which have a composition approximating that of oligoclase-andesine. Orthoclase is present but is subordinate in amount to the plagioclase. A little apatite was noted. 

Quartz occurs in individual grains as well as in the intergrowths, 

but much of it appears to have been introduced by later hydrothermal processes. Ohlorite, epidote, and calcite were also produced in 

this later period, doubtless in part from the decomposition of origi- 

.nal ferromagnesian minerals, none of which appear to remain.

The mineralized rock in the upper part of Godless Gulch is in 

small irregular bodies that replace the fractured limestone. These 

are the only exposures of ore in place, that could be seen at the 

time of visit. Ore is reported to have been encountered in the 

long tunnel in Kelly Gulch at 1,400 or 1,500 feet from the portal. 

This tunnel passed through quartzite for the first 600 feet from 

the mouth and then entered limestone. There is little ore on the 

dump of the tunnel in Kelly Gulch, but some was found on dumps 

in Godless Gulch. This is a mixture of chrysocolla, malachite, 

azurite, anglesite, cerusite, hydrated iron oxide (largely limonite), 

quartz, calcite, and a little residual galena.

PARKS BROTHERS PROSPECT

On Kelly Canyon just upstream from the Starlight mine are some 

unpatented claims owned by the Parks brothers. The tunnel visited 

is in a somewhat chloritized felsite containing a little pyrite. Ore 

similar to that at the Starlight mine is reported to have been found 

elsewhere on these claims.

MITCHELL BARITE PROSPECT

Near Kelly Canyon, somewhat less than 2 miles southeast of the 

Starlight mine, is a vein containing barite, which has been prospected 

with a view to mining that mineral.

COAL FIELDS

GENERAL FEATURES

Location and extent. Just west of the Stanley mining district 

are three areas in which prospecting for coal has been undertaken. 

The easternmost is known locally as the " upper field." The " mid-
U. S. GEOLOGICAL SURVEY BULLETIN 753 PLATE XIII

I iff so'

Corrfour trrterva/ 2SO feet 

MAP OF THE COAL FIELDS IN THE ARAVAIPA-STANLEY REGION
COAL FIELDS 115

die " and " lower " fields are progressively farther west. The upper 

field, which comprises essentially the headwater basin of Deer Creek, 

is the only one included on Plate I, but all are shown on Plate XIII. 

The principal workings in the lower field, to which a brief visit 

was made in the course of work near Christmas, are in sees. 22 

and 23, T. 4 S., R. 17 E., in the Christmas quadrangle. The middle 

field lies roughly halfway between the other two.

, Accessibility. When work was in progress the coal fields could 

be reached by wagons. The road up Hawk Canyon already mentioned is reported to have been originally built to reach, the upper 

field. The traces of a road can still be seen leaving the canyon a 

short distance above the mouth of Garden Gulch, winding up a 

side gulch, and entering the basin of Deer Creek through a narrow 

pass at the northeast end. It is now so washed out that it would 

require reconstruction all the wa}' from Hawk Canyon to the basin 

to make it passable for a wagon.. The present trail from Hawk 

Canyon follows a somewhat different/route than that of the old road. 

The lower and middle fields were reached by a road from Dudleyville, south of the present town of Winkel'man, on Gila River 

west of the coal fields. The road originally extended only to what 

was then the camp of the Saddle Mountain Mining Co. on Ash 

Creek about 7 miles from Dudleyville, but in 1904 it was continued 

as far as the middle coal field. This road entered the valley of 

Peer Creek about iy2 miles northeast of the camp above referred 

to. The camp was at the place marked " Old Mill" on the topographic map of the Christmas quadrangle prepared by the United 

States Geological Survey. A branch of this road was built on the 

south side of the hills bordering Deer Creek and entered that stream 

just west of the lower end of Keed Basin. It is still possible to' 

traverse this branch road with a wagon, at least into the lower part 

of Reed Basin, but the road in Deer Creek below the basin has, 

been obliterated. Another road was started in 1907 up Deer Creek 

from its confluence with Gila River but never got farther upstream 

than the point where the road built in 1904 reached Deer Creek. 

This road was never- used to any extent and is now badly waslxed. 

out. If developments in the vicinity of the coal fields should warrant it, any of these roads could be put into passable shape without 

great expense.

History. The early history of the coal fields has already been 

described by Walcott and Bannon 64 and by Campbell 08 but for 

the sake of completeness is outlined here.60 The upper field was1

, °* Walcott, C. D., and Bannon, M., Deer Creek coal field. White Mountain Indian Reservation, Ariz, : 48th Cong., 2d sess., S. Ex. Doc. 20, pp. 2-3, 1885.

BB Campbell, M. R>., The Deer Creek coal field, Ariz.: U. S. Geoi. Survey Bull. 225, pp.. 

248-251, 1904.

08 Many of the data here jjiven wore supplied or confirmed by C. H. Mellor, of Winkelman, and Martin Flaherty, of Stanley.
116 ABAVAIPA AND STANLEY MINING DISTRICTS, ARIZ.

discovered in 1881 by David and Bob Anderson and other prospectors. The ground was then included in the San Carlos Indian 

Keservation, but in spite of warnings of the illegality of their actions from the Indian agent the prospectors carried on desultory 

development for several years. In 1883 they were removed by 

soldiers but are reported to have returned,. In 1896 the boundary 

of the Indian reservation was shifted north, and thereafter claims 

in this area could legally be acquired. For a time there was considerable activity in the upper field, small shipments of coal were 

made to Globe, and claims were staked in the middle and lower 

fields, but the difficulties were too great for the resources of the 

prospectors, and their plans for development had to be abandoned. 

Work seems to have been continued in the areas to the west after 

activity in the upper field ceased, but in 1907 all development was 

abandoned, and nothing has been done since then. A little prospecting for coal was also undertaken in the Stanley district, to the 

east, but apparently with negative results.

UPPER FIELD

The upper field was abandoned so long ago that most of the workings are almost obliterated, and it was nowhere possible to go underground. Dumps of shale and slaked coal can still be seen. According to the reports already cited and the statements of residents of the 

vicinity, a number of slopes, pits, and shafts were sunk, most of 

them small. A tunnel 110 feet long and shafts 200 and 150 feet deep 

are the most extensive workings reported.

The coal is in narrow beds in the sandstone and shale in the lower 

part of the Cretaceous strata. There are probably several beds of 

coal, but all are thin. The thickest measured by either Walcott 

or Campbell is only 10 inches thick. Two> samples were collected 

by Walcott and Bannon and analyzed by the United States Geological Survey. The results of the analyses show that the coal has about 

20 per cent of ash, 60 per cent of fixed carbon, 19 per cent of volatile matter, and 0.5 per cent of moisture. The coal is reported to 

be such as would make a fair grade of coke but is greatly crushed.

MIDDLE FIELD

The middle field was not visited during the present investigation, 

and the available data regarding it are meager. A number of openings have been made, but apparently the development here is less 

than in either the upper or the-lower field.

The coal beds here are similar to those in the upper field and 

may well be continuations of the same beds. No detailed data 

regarding them are available.
COAL FIELDS 117 

LOWER FIELD

The greatest development in the lower field is in the vicinity 

of the Lower Coal Field mine. (See PL III.) An inclined shaft, 

which at the time of Campbell's visit was 160 feet deep, was sunk 

at this point. Before this a slope 150 feet long had been driven 

into the coal-bearing rock 420 feet north of the location of the 

shaft. A coke oven was built near the shaft, probably about 1907, 

and a small amount of coke was made. A shaft about 100 feet 

deep, called the Crowe shaft, is reported by Campbell on the south 

side of the basin. According to him it is about a mile west of the 

old Manning ranch. This may be the place now known as Ming's 

ranch and, if so, would seem to be in the middle field, although included by Campbell in the lower field. The boundaries of the different fields are of course far from definite.

There are reported to be several other shafts and slopes in the 

lower field, but they are probably all smaller than those mentioned 

above. Prospecting by means of churn drills was undertaken about 

1907 in the lower field and perhaps also the middle field, but it is 

reported that the results were not altogether satisfactory.

The stratigraphic positions of the coal beds in the lower field are 

similar to those of the beds in the other two fields. Coal crops out 

on the south side of the basin as well as on the north, which is not 

true so far as known in the other fields, but as the structure of the 

Cretaceous strata is broadly synclinal this is not surprising.

The sections measured by Campbell indicate that the coal is in 

thicker beds here than in the upper field and also that some of it has 

escaped the crushing reported to be characteristic of that field. Near 

the mouth of the Eeed slope he measured 3 feet 1 inch of coal with 

3 inches of bone in the upper part, and in other places he found 

thicknesses of more than a foot. He expresses the opinion 67 that 

there are two coal beds underlying the greater part of the basin and 

that they range in thickness from 24 to 30 inches. He quotes four 

analyses of samples collected in the lower field, the most favorable 

of which is given below.

Analysis of lowest coal in Crowe shaft 

Moisture ______ _____________ 1. 76

Volatile combustible matter-_________________ 36. 65

Ash, light reddish_________________________ 34. 78 

Fixed carbon ____________________________ 26. 81

Sulphur_______________________________ 1. 91 

Silica in ash___. _______________________ 51. 5 

Coke, dull, not swollen, friable.

87 Campbell, M. R., op. ctt., p. 257.

INDEX

Acknowledgments for aid_.-_-_.- .-- 

Alluvium, Quaternary, nature and distribution of..-------------------------

Aravaipa Creek, course arid valley of -----

Aravaipa Leasing Co., minor workings of_ 

property of........ -----------....

developments on.__._ ..._------..

prospects south of.------------------

ore deposits on.. ___._...-.--.. 

production from..--____-..---- 

Aravaipa Mining Co.'s property, description and history of... L ......i.....

ore deposits on................ ........

Aravaipa mining district, claim map of .,. 

cxtent and population of.........-......-

roads-in...._............_.... ..-.

31-32 

11-12 

85-86

78-79

79-80 

86

81-86 

81

95-96

58

76-77

77-78

Barite lodes, occurrence of_................ 71

Brycc-Merrill prospect, description of..----. 100

Bullis group of claims, extent of--...-------- 88-89

history of...---.-----------..------.----- 89

ore deposits on.--.-.-------------------- 90-91

Bullis-Landsman group of claims, description of----.---------.----------- 91-92

Calcite veins, description of--...,:-......-.. 70-71

Cambrian quartzite, age of--..-..----------- 19-20

distribution of....----..-.-.........-.... 17

nature of.--...-. ..-.-..... ... 17-19

plate showing-...-.--.---..-.....--.--.-. 10

Climate of the region........................ 6

Coal fields of the region, accessibility of...... 315

development of.------.---------------- 115-116

location and extent of...-........-..-.- 114-115

map of--..-...----.------_.--.--.....- 114

Cohre Orande mine, description of-------- 102-103

Cold Spring prospect, description of..---.... 108

Cohtact-metamorphic deposits, features of. 63-66 

minerals in.-....---....--......._-.-.... 66-69

Copper in the main batholith, deposition of. 69-70 

Copper Belle mine, description of....------- 109

Copper Dike group of claims, description

Of . 107-108

Copper Reef mine, description and history

Of -,..... 111-112

ore deposits of. - . 112

Cretaceous rocks, ageof.- .__... .. 27-28 

distribution of. ------_. .... 25

nature of..----..----.----.-.---..-...... 25-27

Deer Creek basin, description of._..--..... 10

Development of natural resources of the area. 3-5

Dikes, granitic, features and age of.--------- 37

Faults, normal, magnitude and age of------- 44-45

Fclsite, features and age of..-.--..-.--...-... 37-38 

Finnegan group of claims, description of.-... 88 

Firth, C. A., group of claims, description of. 95

Page

Firth, H. T., and C. A., group of claims, description of......_ ..._ 99

Fisher prospect, location and development of. 103

ore deposits on.-..._ - 103-105

Flexures in the rocks, effects of.------------- 42-44

Friend mine, description of__..__.._ 110-111

Garden Gulch below Friend mine, plate

showing-_.___..._..._. 58 

Geologic sketch map of the region ------------ 8

Gila formation, conglomerate of, nature and

ageof.-----.------------------... 30-31

conglomerate of, plate showing.......... 10

tuff and sandstone of, plate showing..... 10 

Girty, G. H., cited.. 24

fossils determined by....... . . 23

Gneiss granitic, nature and age of --------- 15-16

Gold veins in the Santa Teresa mines, occurrence of..___.__*...._.... 71-72

Grand Reef, description of.......--._.__. 81-82

outcrop of, plates showing...._. --.... 58 

Grand Reef lode system, description of...... 59-61

minerals of...................._____ 61-63

Grand Reef mine, description of. . _. 82-85 

Granite, of the main batholith, nature and

ageof........-.-.-.-.---...-.-... 32-33

of the main batholith, plate showing_. 58

wine-pink, nature and age of------.--... 34-35

History, geologic.-- . 46-53

Igneous complex, metamorphic, nature, and

distribution of_ ... 16-17 

Industries of the region......... .......... 5-6

Intrusive masses, origin of 41-42, 51

Kirk, Edwin, fossils determined by. 21

La Cledemine, description of... ... 86 

Landsman group of claims, description of.. 101-102 

Little Stanley Butte and the upland at its

base, plate showing.............. 10

Location and extent of the region.........--- 2-3

Lower coal field, description of-.-- - 117

Magnetite partly replaced by specularite,

plate showing................... 66

Maps of the region, preparation of._....... 6-8

Martin limestone, age of...__.......__.. 21

nature and distribution of._........... 20

Mescal Range, features of.__.............. 10

Mesozoic time, events of...........___.... 49-51

Middle coal field, description of. ---. .. 116 

Miocene (?) conglomerate, plate showing-... 10 

Miocene (?) cross-bedded sandstone and lava,

plate showing................... 10

Miocene rocks, age of......._.._. __..._.. 30

distribution and nature of. _......_.. 29-30

Mitchell barite prospect, description of___ 114

119
120 INDEX

Page 

Moltke group of claims, description of....... 98

Mountains, sculpturing of. __...-....-. _. 57-58

Norton group of claims, description of..._. 98

Ore deposits, age of.....___......__..... 59

types of.-...---... . 58 

Overthrust on Garden Gulch, features of.... 45-46 

Oxidation and enrichment, course and results

of '- . 72^-76

Paleozoic time, events of_ _............. 48-49

Parks Brothers' prospect, description of..... 114

Pediments, construction of.. _.____.. 54-57 

Physiographic features, processes producing - 53-54 

Pinal schist, distribution of_________- 13

nature and age of.____........__.. 13-15

Pre-Cambrian time, events of......____. 47

structural changes produced in.... __ j 39-40 

Princess Pat mine, description of ___ 106-107 

Purpose of the report_______.____. 2

Quartz monzonite, nature and age of... _ 34 

Quaternary time, events of. .. ...... 52-53

Eawhide group of claims, description of..... 100 

Rawhide Mountain, plates showing...__. 10

prospects on_________.,.___. 112 

Bhyolite, intrusive, nature and age of..._. 35-37 

Royal Tinto Mining & Smelting Co.'s property, extent and history of___. 92

ore deposits on...____...__.._. 92-95

Santa Teresa Mountains, description of._. 10-11

plates showing...____._..____. 10

Scope of the report---....-. _....._... 2

Page

Silver coin mine, description of _._ 87 

Silver Spar.prospect, description of..__.... 109

Sinn Fein prospect, description of...__ 100 

Soldier prospect, description of...____ 108 

Stanley Butte and the upland at its base,

plates showing______.... 10

Stanley mine, description of._.____ 109 

Stanley mining district, population and physical features of.........____ 105-106

Stanton, T. W., fossils determined by....... 27

Starlight mine, description and history of.. 113

ore deposits of.____________. 113-114

Stratigraphy, major features of........... 12-13

Structure, changes produced in..____ 39-46 

Summary of the report._._..____ 1

Tenstrike group of claims, description of.. 88 

Terraces, construction of.. . ____ 54-57 

Tertiary time, events of...__.____... 51-53 

Tolman-Babcock group of claims, description of................____.. 99

Topography of the region______.___ 8-12

sketch map showing...... ...._._. 8

Tornado limestone, age of---------.-._._ 23-24

nature and distribution of---..__...... 22-23

Trap, features and age of---_.____... 38-39 

Turnbull Mountains, description of.. ___ 8-10

Upper coal field, description of---___.... 116 

Vegetation of the region.._________ 9-10,11

Walcott, C. D., fossils determined by__'.. 21,24 

Warm Spring prospect, description of__ 100-101 

Wood, fossil, occurrence and age of...___ 27-28

C