Geology of the 

Christmas Copper 

Mine, Gila County 

Arizona

By NELS P. PETERSON and ROGER W. SWANSON

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGICAL SURVEY BULLETIN 1027-H

An exploration of the ore deposits, in 

mine workings and by diamond drilling

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

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

F«r sale by the Superintendent of Docunients, U^ S. Government Printing Office 

Washington 25, D. C.
CONTENTS

Page

______..___-___-_____-_-_-___-_-__---_--_---_-__---__---_ 351

Introduction-___--__-_________-_---_-__--____..__-___-_-___--__-_.._ 352

Acknowledgments _________________________________________________ 353

Previous work.___l____________________-__-__-__-________-_____-._ 354

History.... _._____________....___________.______--__ 354

Production ____________________________________^_ _.____.____ 355

Description of the mine workings-___________________________________ 356

Geology-_-_____-___-__-__________----_--_-_-_-_-__________-______ 357

Rocks and stratigraphy..._____-________.__,.__._______._____.__ 357

Structure...______--..__-..-____..-___.._________ 360

Mineral deposits.__-_-._-____-_--__-_-_---_______--____-_____-'_ 363

Geologic controls of the mineralization__-__-_____-______..___ 363

^ Ore bodies in the Naco limestone__-__-_-____._______._______ 365

Ore bodies in the Escabrosa and Martin limestones.___________ 368

Oxidation and enrichment-... ____________________________ 370

Literature cited___________________________________________________ 371

Index._._._..______________________________L 373

ILLUSTEATIONS

[Plates 33 43 in pocket]

Plate 33. Geologic map of the Christmas area.

34. Composite map of Christmas mine.

35. Geologic map of 300 level.

36. Geologic map of 400 level.

37. Geologic map of 800 level.

38. Stratigraphic section of Tornado Peak.

39. Stratigraphic section of Naco limestone.

40. Section B-B' through No. 4 shaft.

41. Sections through the Christmas mine.

42. Correlation chart of ore-bearing beds in the Naco limestone.

43. Section A-A' through south-side stopes.

Figure 50. Index map of Arizona showing location of Christmas area___ 352 

51. Relation of periods of operation to the price of copper...._ 355

HI

A CONTRIBUTION TO ECONOMIC GEOLOGY

GEOLOGY OF THE CHRISTMAS COPPER MINE 

GILA COUNTY, ARIZONA

By NEJLS P. PETEKSON and EOGER W. SWANSON

ABSTRACT

The Christmas copper mine is in the Banner mining district, Gila County, 

Arizona. It is 8 miles north of Winkelman and 22 miles south of Globe. The 

mine was opened in 1905; to the end of 1943 it had produced about 55,340,000 

pounds of copper. In 1946 it was operated under lease. The ore is high-lime 

fluxing ore, required by the smelter at Hayden. The ore produced during 1942 

averaged 2.16 percent copper, but it contained no other metals paid for by the 

smelter.

The mineral deposits are in a thick series of gently dipping Paleozoic limestones that range in age from Devonian to Permian(?). Overlying the limestones with only slight discordance is a thick sequence of Cretaceous (?) volcanic 

rocks, mainly andesitic tuffs, breccias, and flows. A small quartz diorite Stock 

has been intruded into the limestones and volcanic rocks. The Christmas fault 

cuts northwestward through the limestones, lavas, and the quartz diorite intrusive. The eastern part of the area has been depressed, bringing the lavas in 

contact with the limestones, which crop out west of the fault.

The mineral deposits are of the contact metaniorphic or pyrometasomatic type. 

Chalcopyrite is the most abundant ore mineral, but variable amounts of bornite, 

chalcocite, and oxidized copper minerals are generally present. The gangue is 

chiefly garnet, quartz, magnetite, and unreplaced limestone. The factors that 

controlled the localization of the ore minerals are: (1) proximity to the limestone-quartz diorite contact, (2) favorable character of certain limestone beds, 

( 3) -garnetization of the limestone, and (4) postgarnetization fracturing.

The past production of the mine came mainly from ore bodies in the Naco 

limestone of Pennsylvania and Permian (?) age. A few small ore bodies have 

been mined from the Escabrosa limestone of Mississippian age. Other deposits 

of ore grade have been discovered by a drilling project carried on by the Bureau 

of Mines. Deep drilling below the .bottom level (770-foot level) of the mine alsa 

disclosed mineralized limestone in the lower part of the Martin limestone of 

Devonian age. The ore in the Naco occurs in flat tabular bodies which are replacements of certain favorable limestone beds close to their contact with the 

quartz diorite. The ore is confined to 11 distinct beds, which are consistently 

mineralized wherever they occur in favorable relationship to the contact. They 

constitute a zone about 425 feet thick of interbedded limestones and shale. The 

deposits in the Escabrosa are thick irregular bodies that lie against the contact.

,351
352 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The deposits in the Martin limestone are known only from drill holes, and little 

can be determined concerning their size or shape.

INTRODUCTION

The Christmas copper mine is in the Banner mining district, Gila 

County, Ariz. It is 8 miles north of Winkelman and about 22 miles 

south of Globe (fig. 50) and is accessible from either town via State

E 5O. Index map of Arizona showing location of the C&ristmas area,

Highway 77, a graded gravel road. A branch line of tll6 Pacific K. K. has its terminus a mile east of the camp and gives easy

access to the American Smelting and Refining Co. smelter at HaydfiD, 

9 miles by fail from the loading station.

The Christmas area is a part of the Christmas 15-minute quadrangle, 

which was mapped by the U. S. Geological Survey in 1915. The mine
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 353

is a mile west of the Gila River, in a steep-walled tributary gulch at 

the southeastern end of the Dripping Spring Mountains. The topography is rugged; altitudes range from 2,100 feet above sea level at the 

river to 4,200 feet on the crest of canyon walls within a distance of 2 

miles. The collar of the main shaft is at 3,040 feet.

In normal times about 40,000 gallons of water per day is pumped 

from the mine workings, but during wet seasons it is commonly necessary to pump twice this amount in order to keep pace with the inflow. 

At the present time all water for domestic and mining purposes is 

obtained from the mine. When a concentrator was in operation, 

water for metallurgical use was pumped from shallow wells near the 

Gila River. Electric power is supplied by the San Carlos Irrigation 

Project from a 66,000-volt transmission line, which crosses the property near the main shaft.

The exploration project at Christmas was carried on cooperatively 

by the Geological Survey and U. S. Bureau of Mines. Mr. 0. M. 

Bishop, Engineer for the Bureau of Mines, examined-the property and 

in his report of June 6, 1942 recommended that six holes be drilled 

from the 800 level of the mine. The Bureau of Mines began drilling 

in September 1942, and the Survey investigations began a month 

later. Since any ore bodies discovered below the 800 level would be 

inaccessible until a deeper level could be developed, the Bureau and 

Survey decided to explore from higher levels where resulting benefits could be more quickly realized. Drilling from the upper levels 

was begun early in 1943.

The field work for this report was completed by the end of June 

1943. R. W. Swanson remained until the completion of the Bureau 

of Mines project in January 1944.

A supplementary diamond drilling project to explore for new ore 

bodies below the 800 level of the mine was begun by the Bureau of 

Mines in September 1945 .and completed in January 1947.

ACKNOWLEDGMENTS

The base maps of the underground workings used in this report 

were supplied by the operators. Sam Knight, lessee, and Frank P. 

Knight, mine superintendent, gave the writers every possible assistance and made available all existing records, maps, and engineering 

data pertaining to the property. Unfortunately many maps and 

records had been lost in a fire that destroyed the engineering office in 

1931. We are also indebted to Mr. L. C. Marshall and Mr. Stanton 

L. Tainter, project engineers for the Bureau of Mines.

All except the most recent underground workings were mapped by 

Guy N. Bjorge, Harrison Schmitt, S. H. Sherman, and others. The 

writers made full use of all previous work and remapped the geology 

of all workings and stopes that are still accessible.
354 CONTRIBUTIONS TO ECONOMIC GEOLOGY

PREVIOUS WORK

The only published work on the Christmas area is by C. P. Ross, 

entitled "Ore deposits of the Saddle Mountain and Banner mining 

districts, Ariz." (U. S. Greol. Survey Bull. 771), published in 1925.

HISTORY

The original mineral claims that include the Christmas deposit 

were located about 1880 by Dennis O'Brien and William Tweed,, who 

sold or optioned them to Phelps-Dodge Co. The locations proved to 

be on the San Carlos Indian Reservation and were declared invalid. 

In December 1902, the portion .of the reservation that includes the 

deposits was restored to the public domain by Executive Order, and 

the claims were relocated on Christmas Eve by G. B. Chittenden.

Phelps-Dodge Co. filed suit to recover the property without success, 

and the Saddle Mountain Mining Co. was organized to hold and 

operate the claims. A small copper smelter, erected in 1905, was 

operated until the spring of 1907, when the company failed. The 

Gila Copper Sulphide Co. was organized in 1909 to take over the

 assets of the -old company. Capital necessary to resume operation 

could not be raised .until April 1915, when a contract was made with 

American Smelting and Refining Co. under which that company 

assumed .management and advanced funds to develop the propert}^. 

Production of copper ore began in February 1916; and by the end of 

the year, the loan had been repaid. American Smelting and Refining Co. continued to operate the property until January 1919. In 

the meantime, certain bonds fell due and were defaulted. A receiver 

was, appointed, who operated the mine until it was shut down in 

April 1921.

In 1925, Mineral Products Co,, a corporation controlled by the 

Iron Cap Copper Co., bought a controlling interest in the Gila Copper 

Sulphide Co. which was then reorganized as the Christmas Copper

Co. The mine was reopened, and in 1925 a 500-ton concentrator was

moved from the Iron Cap mine in the Globe-Miami district and

erected at Christmas. To 1932 about 321,000 tons of ore had been

treated by flotation. The Christmas Copper Co. became bankrupt

and was reorganized as the Christmas Copper Corp. in 1026. The

mine was reopened in 1937 but was closed again in March of the

following year owing to the low price of copper.

Mining was resumed in 1939, and the property has been operated 

under lease since that date by the Sam Knight Mining Lease, inc.,

producing high-lime fluxing ore. Shipments have been limited to the amount of flux required by the Hayden smeiter ±0* treating the

-copper concentrate from the mine at Eay. The ore shipped during 

1942 averaged 2.16 percent copper and about 30 percent lime. No 

other metals were paid for by the smelter. The operation has been
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 355

economically possible only because of low transportation costs and 

because the premium paid for lime more than offsets the treatment

charge.

PRODUCTION

The Christmas mine has produced mainly copper, though records 

covering the period 1905 to 1933 also show production of $160,000 

in gold and $150,000 m silver (Elsing and Heineman, 1936, p. 92). 

Since the mine was reopened in 1937 the smelter has not paid for 

gold and silver. The copper production of the Christmas mine to 

the end of 1943 is shown in the accompanying table.

Copper production of the Christmas mine, 1905-^8

Year

1905-33 -._ . 

1937. ... 

1938.. . . 

1939.. _. - - -- 

1940.. - . - -

1942.. 

1943.. . 

Total 

Ore (tons)

1, 079, 855

29, 692

6,098

24,790

25, 871

35, 791

39, 837

27, 030

1, 268, 964

Copper 

(pounds)

i 48, 300, 000

2 1, 225, 982

275, 303

889, 698

1, 030, 381

1, 308, 156

1, 400, 852

906, 926

55, 337, 298

Value

i $8, 990, 000

148, 344

26, 980

92, 529

116, 433

1 14 W>

169, 503

$9, 816, 051

1 Elsing, M. J., andHeineman, R. E. S., Arizona metal production: Ariz. Bur. Mines Bull. 140, p. 92,1936.

2 Pounds of copper paid for by the smelter. Production figures from 1937 to 1943 furnished by lessee. 

Published with permission.

The relation of the periods during which the mine was operated 

to the average yearly price of copper is illustrated in figure 51.

FIGURE 51. Relation of periods of operation of the Christmas mine to the price of copper. 

353102 56 2
356 CONTRIBUTIONS TO ECONOMIC GEOLOGY

DESCRIPTION OF THE MINE WORKINGS

The Christmas mine was developed from 5 shafts, of which only 

No. 3 and parts of the Christmas shaft are now accessible. No. 3, 

which is the main working shaft, is vertical and has 3 compartments; 

two are equipped with cages, and the third serves as manway and pipe 

compartment. This shaft begins in diorite near the west end of 

the main mass, and at 635 feet below the collar it crosses the south contact and continues in limestone to the bottom, which is at 908 feet. The 

main levels are at 95, 200, 275, 375, 500, 635, and 770 feet below the 

collar and are generally referred to as the 100, 200, 300, 400, 500, 

600, and 800 levels respectively. The mine is drained to the 800 level, 

which is about 280 feet above the bed of the Gila River a mile to the 

east. The composite level map (pi. 34) shows the arrangement of 

the levels and stopes around the borders of the diorite intrusive.

The 100 level is no longer accessible from No. 3 shaft, but the parts 

of the level that are still open can be reached through stopes which 

connect with the surface. The level was originally developed from 

No. 1 shaft and later connected with No. 3.

The 200 level is developed only on the south side of the diorite 

where it extends for 1,800 feet along the south contact. Only a small 

part of the level that lies west of the shaft is now accessible.

The 300 level (pi. 35) is extensively developed on both sides of the 

intrusive. The north-side workings can be entered either from the 

shaft or by an adit in the old Hackberry workings, which connects 

with the surface in the gulch at the northwest edge of the settlement.

The east end of the south-side workings connects with the surface by 

way of the Track tunnel, which is an adit in the Old Christmas workings about 10 feet above the level. Nearly all the stoping along the

north contact was on or above the 300 level; only a few stopes are 

below the level, and these are in the lower part of the Las Novias 

beds.1 The south-side workings extend for 2,000 feet along the contact where limestone beds above and below the level have been extensively mined. Practically all the drifts and crosscuts under the 

stoped area on the south side are now caved.

The 400 level (pi. 36) has about the same extent as the level above. 

North of the shaft the level is near the top of a thick diorite sill. One 

drift, No. 410, follows close to the north contact as far as the Christmas fault. South of the intrusive the beds along the contact have

been extensively mined above the level; some of the lower stopes are

a few feet below it. This level serves as the main haulageway for the

mine. All the ore no>T being mined is either hoisted or transf©rracl

through raises to the 400 level and trammed out of the mine through 

an adit at the east end.

1 Local names applied to beds in the mining area are given on plate 42.
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 357

The station at the 500 level is caved and bulkheaded so that workings cannot be entered from the shaft. North of the shaft the 

development was mainly in diorite, and the workings are entirely 

inaccessible except for a short section of drift at the bottom of raise 

501 A. The level south of the shaft has been abandoned and is in 

poor condition and partly flooded. The only means of entry is 

through raise 512 A near the east end of the level.

The 600 (635-foot) level consists of about 1,200 feet of drifting 

which cuts across several fingers of diorite at the west end of the 

main mass. The ground is heavy, the timbering is in poor repair, and 

much of the level is unsafe. The south contact cuts through the 

shaft at the level, and about 400 feet of drift is in the limestone south 

of the contact.

The 800 (770-foot) or bottom level was also developed mainly at the 

west end of the intrusive, where the diorite splits into a number of 

dikelike fingers (pi. 37). The diorite dikes and the limestone between them are fractured and contain much clay gouge which makes 

the ground very heavy, especially before it is thoroughly drained 

and dried out. The stopes on the 800 level were heavy and required 

square-set timber support.

GEOLOGY

The Christmas mine is in the southwestern part of the Christmas 

quadrangle about one-half mile east of the western boundary. The 

areal geology of the part of the Banner mining district that lies within 

the Christmas quadrangle was mapped by C. P. Ross (1925, pi. 1) 

of the U. S. Geological Survey in 1922 and that of the adjacent Ray 

quadrangle, which includes the remainder of the Banner district, was 

mapped by F. L. Ransome (1923) in 1910 and 1911. A more detailed 

geologic map of the mine area is shown on plate 33.

The mineral deposits are in a thick series of Paleozoic limestones 

that dip gently toward the southeast. Overlying the limestones with 

only slight discordance is a thick sequence of volcanic rocks that are 

mainly andesitic tuffs, breccias, and flows. A small quartz diorite 

stock has been intruded into the limestones and volcanic rocks. The 

Christmas fault cuts northwestward through the limestones, lavas, and 

the quartz diorite intrusive. The eastern part of the area has been 

depressed, bringing the lavas in contact with the limestones that crop 

out west of the fault. The ore bodies are replacements of certain 

favorable limestone beds by copper minerals and occur close to the 

limestone-quartz diorite contact. All the known ore bodies are in the 

higher block, west of the Christmas fault.

BOCKS AND STRATIGRAPHY

The sedimentary formations of the Christmas area are well exposed 

on Tornado Peak (pi. 38) about 2% miles west of the mine, and in a
358 r ; ; > CONTRIBUTIONS TO ECONOMIC GEOLOGY

section a mile north of the mine (pi. 39). At Tornado Peak, the Troy 

quartzite of Cambrian age is the oldest rock exposed. It is overlain 

by 185 feet of fine-grained argillaceous quartzite containing a few 

thin beds of coarser grained iron-stained quartzite. These quartzitesare probably also of Cambrian age and equivalent to the Santa Catalina formation of Stoyanow (1936, p. 476).

The Devonian system is represented by 340 feet of Martin limestone. 

There is a thin quartzite member at the bottom, which is overlain by 

about 30 feet of dolomitic limestone that is thin-bedded and shaly in 

the lower part. This member is mineralized in the vicinity of Tornado 

Peak and in the Christmas mine and is known locally as the O'Carroll 

bed. The middle part of the Martin at Tornado Peak is thin- to 

medium-bedded limestone about 180 feet thick. Many of the thicker 

beds are marble and are in part dolomitic. The upper part of the 

Martin is a bed of olive-gray argillite 65 feet thick overlain by soft 

thin-bedded shaly limestone. The argillite is the metamorphosed 

equivalent of the fissile calcareous shale that is commonly the top

member of the Martin limestone.

The thick series of Carboniferous limestones that overlie the Martin 

was named Tornado limestone by Ransome (1919, p. 47). In the 

Bisbee quadrangle, Ransome (1904, p. 42-44) subdivided the Carboniferous formations into the Escabrosa limestone of Mississippian 

age and the Naco limestone of Pennsylvanian and Permian ages. The 

use of these names has been extended to designate limestones of similar 

ages throughout southeastern Arizona.

The Escabrosa on Tornado Peak is 550 feet thick and consists 

largely of pure crystalline limestone | some beds are composed almost

entirely of crinoid fragments, a few beds are dolomitic, and some contain abundant nodules of chert. 

The upper 380 feet of the Tornado Peak section is Naco limestone.

It is separated from the Escabrosa by a thin bed of chert conglomerate 

and shale. The Naco is made up of thin to medium beds of nearly 

pure gray limestone, separated by thin layers of calcareous shale.

A section of younger beds, which, appears to be a continuation of

part of the Tornado Peak section, is exposed one mile north of the

mine (pi. 39). The middle part of this section contains about 300

feet of alternating thin beds of limestone and shale, which is the only

part Of the Section that is comparable with the most extensively mineralized beds in the upper levels of the Christmas mine. M. L. 

Thompson (personal communication) states that fusulinids collected

from the uppermost teds of this section are characteristic of the transition zone between rocks of Pennsylyanian and Permian ages. An 

abundant fauna of dwarf gastropods also suggests that the beds at 

the top of this section are possibly of Permian age. Beds containing
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 359

similar fusulinids and gastropods crop out just under the lavas west 

of No. 3 shaft; therefore the Naco limestone is considered to be of 

Peiinsylvanian and Permian (?) ages in the Christmas mine area.

The total thickness of Naco limestone represented in these two sections is probably a little more than 1,000 feet, and the total thickness 

of Carboniferous rocks is about 1,550 feet. Thus, if the productive 

ore bodies of the Christmas mine are in the upper third quarter of 

the Naco limestone, as appears to be the case, the top of the Escabrosa 

is approximately at the bottom level of the mine (800 level), and 550 

feet of Escabrosa and 300 feet of Martin limestone could be expected 

below that level. Deep drilling below the 800 level has roughly confirmed this estimate; however, the formation members that can be 

identified in drill cores appear to be considerably thinner than in the 

measured section on Tornado Peak. The thinning may be partly the 

result of shrinkage attending the metamorphism of the rocks, but 

the Martin limestone and its various members are known to differ 

greatly in thickness from place to place. Furthermore, owing to the 

intense alteration of the limestones and the limited exposures in the 

mine workings, the top of the Escabrosa cannot be determined 

accurately.

Only the upper part of the Naco limestone crops out in the vicinity 

of the mine. In general, the exposures are poor, and the limestone 

i? so completely altered by recrystallization and garnetization that 

beds cannot be correlated from one place to another.

The Paleozoic limestones are overlain by a thick sequence of volcanic 

rocks mainly andesitic tuffs, flow breccias, and flows which form 

the high ridges north, south, and west of the camp. These volcanic 

rocks are brown, brownish black, or dark gray and are generally fine 

grained. Eoss (1925, p. 11-14) regards them to be of Cretaceous age. 

The lower part of the volcanic series contains gray hornblende porphyry which may be either flows or intruded sills. Other bodies of 

similar hornblende porphyry form sills within the uppermost limestones near their contact with the andesitic rocks.

The volcanic rocks are so poorly bedded and so widely covered by 

talus that a satisfactory section cannot be measured, but, judging from 

the development in No. 4 shaft (pi. 40), their thickness must be at 

least 2,000 feet. They appear to be nearly conformable with the limestone strata. In places contact metamorphism has affected the andesites, causing the formation of abundant epidote and small amounts 

of pyrite; but they are not known to be ore bearing in the Christmas 

area.

Several varieties of dioritic intrusive rock occur in the Christmas 

area, all of which are assumed to be f acies of the same magma. The 

most common type, which constitutes the main intrusive mass, is a
360 CONTRIBUTIONS TO ECONOMIC GEOLOGY

quartz-mica diorite porphyry containing phenocrysts of quartz, feldspar, and biotite in a fine-grained gray groundmass. Other facies 

are not porphyritic and show wide variation in grain size. The 

coarser varieties are usually light colored, whereas the fine-grained 

rocks are dark. The petrographic character of the rocks has been 

adequately described by Ross (1925, p. 20-21) and Ransome (1919, 

p. 64-66). Some of the sills and smaller dikes contain hornblende 

with or without biotite.

Several narrow dikes of fine-grained brownish-black andesite or 

basalt are exposed in the mine workings. They cut at random 

through the ore bodies, altered limestone, and other rocks with no 

apparent alteration or change in character. They are younger than 

the quartz diorite and the mineralization. Some dikes trend northeast, others nearly north. One particularly persistent dike, 2 to 4 

feet wide, follows the limestone-quartz diorite contact on the north 

side of the main intrusive (pis. 35 and 36).

Most of the area surrounding the mine is underlain by thick deposits 

of talus and alluvium that accumulated in the bottom of the main 

gulch. Much of this detrital material is partly consolidated and was 

designated by Ross (1925, p. 18) as older alluvium. It is a poorly 

sorted aggregate of coarse gravel and subangular to rounded boulders 

of the older rocks, more or less firmly cemented by caliche. The more 

recent alluvium is unconsolidated slope wash and talus derived mainly 

from the andesitic rocks and older alluvium. The two types of alluvium are not differentiated on plate 33.

STBUCTURE

The limestone strata in the vicinity of the mine have a general 

southeastward dip of about 1.0°, but local dips may vary considerably

from the general trend, particularly near igneous contacts. The

Cretaceous (?) volcanic rocks are too poorly bedded to show their true

attitude, but they appear to be nearly conformable with the underlying

limestone,

The limestones and. volcanic rocks in the mine area have been

intruded by a small stock of quartz diorite. The outcrop of the

Stock is largely obscxired by alluvium and talus, hence its boundaries

at the surface can be only approximately determined, The west end

and part Of the south contact are well exposed in the mine workings.

in plan, the stock is roughly elliptical with its long axis trending 

about N. 60° E. Its dimensions are about 1,000 by 3,000 feet. xhe

Christmas fault cuts northwestward across the central part of the

Stock, and the block east of the fault has been relatively depressed, 

which brings the volcanic rocks against the limestones west of the 

fault.
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 361

At the west end, the quartz diorite mass fringes out into a number 

of narrow dikes that dip steeply toward the north (pis. 35 and 36). 

The same is true of the east end, where several dikes extend into the 

volcanic rocks beyond the main mass. This dike structure at the 

ends of the body suggests that the quartz diorite was intruded along a 

system of east-striking fractures, probably at their intersection with 

the Christmas fault. The fact that the outcrop of the quartz diorite 

shows very little lateral offset at the fault suggests that some, if not 

most, of the displacement occurred before the intrusion. It is uncertain that any appreciable displacement occurred along the eaststriking fractures. The location of the base of the Martin limestone, 

as determined by drill holes 23D and 24B (pi. 41) on opposite sides 

of the quartz diorite body, indicates a smaller angle of dip than the 

assumed regional dip, but the difference is not large enough to justify 

any estimate of possible displacement. The bedding in the narrow 

blocks between the dikes shows little if any change from the normal 

attitude of the limestone strata.

Between the surface and the 500 level of the mine, the south contact 

is fairly regular with only a few major apophyses, mostly on or 

below the 400 level. It strikes about N. 75° W. and dips 45°-75° 

NE. The contact is generally sharp and is marked by clay gouge and 

minor slip planes; but in a few places it is serrated by many small, 

discontinuous sills pushed out between the limestone beds. These 

sills are especially prominent in. sections having a large proportion 

of interbedded shale which the magma has partly or wholly assimilated. Local flexures and minor thrust faults are common. The beds 

are commonly bent downward against the quartz diorite and show 

small rolls or wrinkles parallel to the contact; but in 512A stope on 

the 500 level, they are bent sharply upward against the contact.

Fractures and sheeted zones, either in the limestone or quartz diorite 

or both, are generally parallel to the contact. Cross fractures, many 

of which are mineralized, probably served as feeder channels for the 

copper-bearing solutions. Sills pushed out between the bedding 

planes caused displacement on certain fractures by lifting the overlying beds. Where this occurred, the sills end abruptly against 

vertical or steeply dipping faults. Many of the minor diplacements 

of the beds are believed to have been caused in this way.

Except for a few short workings from the old Hackberry shaft, 

which are now caved, the Christmas mine is entirely within the 

upthrown or footwall block west of the Christmas fault. The only 

exploration of any consequence in the down-thrown block was by 

means of No. 4 shaft which was sunk in the volcanic rocks about 1,600 

feet northeast of the Christmas fault. The purpose of this shaft, 

according to report, was at least partly to explore for the limestone
362 CONTRIBUTIONS TO ECONOMIC GEOLOGY

below the volcanic rocks. From a level 500 feet below the collar 

of the shaft (pi. 40), a vertical drill hole was put down 1,085 feet. 

According to the available records, the shaft and drill hole cut 1,585 

feet of andesite and quartz diorite. The drill hole passed out of 

andesite into quartz diorite at 1,375 feet below the shaft collar, but 

undoubtedly this point does not represent the lower limit of the 

volcanic rocks.

Ross (1925, p. 22) regards the Christmas fault as a segment of 

a major fault zone that can be traced northwestward and southeastward from the mine for a total distance of 7y2 miles. The displacement took place along a system of nearly parallel breaks which 

in places forms a zone more than 100 feet wide. This zone can be 

seen underground in the Hackberry workings on the north contact 

(pis. 35 and 41, sec. E-E'), where the mineralized beds are cut off 

by the fault, and also at the extreme northeast end of the 400 level 

(pi. 36). That at least part of the displacement was later than the 

intrusion and the copper mineralization is shown by blocks of quartz 

diorite and ore that occur in the fault zone where it is crossed by the 

300 level adit. The total displacement on the Christmas fault cannot 

be determined, but from the evidence depicted on section C-C' (pi. 

40) the vertical throw along the fault zone can safely be assumed 

as at least 1,770 feet.

The outcrops east of the fault are so poor that little can be determined concerning the underlying structure except that the andesitequartz diorite contact is very irregular. The interfingered quartz 

diorite and andesite cut by the shaft and tributary workings are badly 

faulted and fractured, and the ground is said to be so heavy that mine 

openings are difficult to maintain.

Below the 500 level, the quartz diorite mass seems to expand laterally; its contact with the limestone becomes very irregular, particularly below the 800 level, There are many irregular, dikelike

apophyses and countless large and small discontinuous sills that 

extend out into the adjacent limestone. Development on the 600 and

800 levels indicates the presence of a thick, probably very irregular,

sill-like body that extends for some distance along the south contact. 

It is probably the counterpart of this sill that forms the floor of the

limestone in the broad, bay on the northwest side of the stock (pis.

35, 36, and 41). Drill holes sunk to explore the south contact below

tne 800 level skow many alternating intersections of quartz clients

and altered limestone, and no definite location for the contact could

be determined. On the north side of the intrusive, drilling showed

such complex relationships as to defy attempts to interpret the struo

ture or to correlate from one hole to another with any reasonable 

degree of certainty. There are some blocks of limestone that appear 

to be completely engulfed by the quartz diorite. These complex
GEOLOGY OF THE-CHRISTMAS COPPER IVfllNE, GILA COUNTY 363

intrusive relationships appear to coincide roughly with the zone in 

which the quartz diorite intrudes the thick pure crystalline limestone 

beds of the Escabrosa.

MINERAL DEPOSITS

The mineral deposits of the Christmas area are all of the contact 

metamorphic or pyrometasomatic type. The ore bodies are replacements of limestone around the borders of the quartz diorite stock 

(pis. 3^-87,41).

The scope of this investigation did not permit a detailed mineralogical study of the ore, and the following discussion of the minerals 

is based on a rather superficial megascopic examination of the ore and 

gangue. A few of the gangue minerals were identified by microscopic 

examination of oil immersions. The principal metallic minerals of 

the primary ore are pyrite, chalcopyrite, bornite, magnetite, and 

specular hematite. Small amounts of sphalerite and galena are commonly present, and molybdenite occurs in a few places, mainly on 

the upper levels. At the time the mill was operated, the ore was 

not assayed for molybdenum. Pyrite and magnetite are abundant 

close to the contacts and in the ore in the narrow blocks of limestone between the quartz diorite dikes at the west end of the 

intrusive body. Magnetite becomes increasingly abundant with 

depth, and much of the ore found on the 800 level and below contains 

so much magnetite that it completely masks the primary copper 

minerals. Practically all the ore that has been mined above the 800 

level is partly oxidized and contains more or less chalcocite, covellite, 

cuprite, native copper, and copper carbonates.

The gangue of the ore is mainly green and brown garnet, idocrase, 

epidote, quartz, unreplaced limestone, and generally some clay and 

chlorite. Diopside and tremolite are prominent gangue minerals 

in the ore that replaced the dolomitic limestone in the lower part of 

the Martin. A little anhydrite occurs in some of the ore from the 

deeper levels. Chert bands and nodules in the limestone are replaced 

by wollastonite in the altered zone. In recent years the ore has carried 

from 23 to 31 percent CaO, which makes a desirable flux for smelting 

copper concentrates.

A typical analysis of the ore is as follows:

Gold _ _ 0.005 oz. per ton. Alumina______. 1.7 percent.

Silver 0.23 oz. per ton. Sulfur_______. 3.6 percent.

Copper ____ 2.04 percent. Iron_________. 12.8 percent.

Silica ____ 33.2 percent. Lime __.___. 28.2 percent.

GEOLOGIC CONTROLS OP THE MINERALIZATION

There are four prerequisites for the localization of ore bodies in the 

Christmas mine. The first and most important of these is proximity
364 CONTRIBUTIONS TO ECONOMIC GEOLOGY

to the limestone-quartz diorite contact; the second is the favorable 

character of certain limestone beds; the third is garnetization of the 

favorable beds; and the fourth is faulting and fracturing that followed garnetization.

The main channels of the mineralizing solutions appear to have 

been along the contacts between the limestone and the quartz diorite, 

and most of the ore bodies are in the limestone close to the borders 

of the main quartz diorite mass or along the walls of dikes that 

extend outward from the main mass. In some places, particularly 

in the large bay of limestone at the west end of the intrusive shown 

on plate 35, the mineralizing solutions followed minor faults and 

fractures and replaced beds that are a considerable distance from 

the contact. The distance to which metallization extends depends

largely on the extent of garnetization and the presence of postgarnetization fractures. In some places, especially along the walls 

of dikes, ore may lie directly against the quartz diorite, but along 

the main contacts there is generally a zone of low-grade material 

between the ore bodies and the quartz diorite. Since the contact is 

not usually exposed in the stopes, the width of this zone is uncertain, 

but probably it rarely exceeds 25 feet.

Precisely what characteristic of the limestone beds determines the 

difference in susceptibility to replacement is not clear, but the selection 

of certain definite beds by the mineralizing solutions is very consistent. Originally, most of the ore-bearing beds were relatively 

pure limestone, but many of the unmineralized beds are pure also. 

A few of the consistently mineralized beds are impure and cherty, 

but generally the ore in them is not as good as that in the purer beds.

The outstanding characteristic of the ore beds is that they are relatively thin units which, occur in a series of alternating shale and 

limestone.

Garnetization Of the limestone is an important prerequisite of 

metallization. Garnetized beds are not always ore bearing, but beds 

that have not been garnetized are nowhere sufficiently metallized to 

constitute ore. The ore bodies occur only where the contact alteration 

was sufficiently intense to produce abundant garnet in the limestone 

beds, and the size of the ore bodies is limited by the width of the 

altered zone.

The width of the garnet zone differs considerably from place to

place. Its extent was influenced by faults and fractures that preceded or accompanied the intrusion of the quartz dlOrite. WheT6

fracturing occurred, the solutions or gases that caused the alteration

were able to permeate to greater distances from the contact. The 

fractures that preceded the garnetization have been largely obscured 

and healed by alteration and recrystallization of the limestone but in 

places can still be recognized.
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 365

Fracturing that followed garnetization had a far greater influence 

on the localization of ore bodies than the earlier fractures. In some 

places, garnetized rock has been mineralized where no fracturing is 

apparent, but in most stopes it is quite apparent that the shape of the 

ore bodies was governed by the fracture pattern. Irregularities in 

the outlines of the stopes occur as the result of fractures that have permitted mineralizing solutions to permeate farther into the garnetized 

limestone than elsewhere. Similar irregularities may have been 

caused, however, by the garnetization pattern, which in turn was 

governed by the pregarnetization fractures. The ore does not extend 

beyond the limits of the garnet rock regardless of the pattern of 

subsequent fracturing. The effect of fracturing on the thickness of 

the ore is not so marked, because most of the ore bodies are bounded 

top and bottom by shale beds which appear to have been nearly 

impermeable to the copper-bearing solutions.

ORE BODIES ty THE NACO LIMESTONE

Practically all the past production of the mine has been from ore 

bodies in the Naco limestone. On the north side of the quartz diorite 

body, the ore occurs in 9 distinct beds that constitute a zone about 

300 feet thick. These mineralized beds are known locally as the Las 

Novias, 250, 235, 220, 205, Johnny, 85, 50, and Upper Copper 

Knob named or numbered after the original stope in each bed (pi. 

42). The bottom of this zone is a little below the 300 level; the upper 

beds crop out in the canyon north of No. 3 shaft. Other beds higher 

in the section are mineralized along the south side of the intrusive 

body.

The Las Novias beds at the bottom of the zone are three or possibly 

four massive beds that behave more or less as a unit. This group of 

beds is 60 feet thick and is bounded at both top and bottom by persistent shale beds. Thin shale partings commonly occur between the 

beds in the lower part of the group, but as a rule they are not persistent 

and not always clear enough to be recognized. In places the entire 

group is mineralized, but generally only one or two beds are sufficiently rich in copper to constitute ore. Where adjacent beds are 

mineralized, they are mined as one stope, but usually the stopes are 

one above the other and are separated by floors of waste or low-grade 

material. The floor plans of a tier of stopes may show little or no similarity in size and shape.

The Las Novias beds on the north side of the quartz diorite are 

especially susceptible to replacement and are usually mineralized 

wherever they occur in favorable relationship to the contact. The ore 

is reported to have carried from 3 to 4 percent copper, which is considerably more than the average for the mine. Because bf the great
366 CONTRIBUTIONS TO ECONOMIC GEOLOGY

thickness of the beds, they have undoubtedly produced more ore than 

all the other north-side beds combined.

The remaining eight beds of the productive zone range from 6 to 

12 feet in thickness. They are separated by prominent shale partings 

that make up from one-third to one-half of the total section.

The 250 and 205 beds were the next most productive beds on the 

north side of the intrusive body. They are relatively pure limestones 

and, like the Las Novias, contained ore of superior grade.

The 220 and 235 beds are rather impure limestones, in part shaly 

and cherty. They are not consistently mineralized, but under favorable conditions they have been host to ore bodies which are generally below the average in copper content.

The Johnny bed is above the 205 bed and is separated from it by 

47 feet of interbedded shale and thin flaggy limestone. Generally 

only the lower 6 feet of the bed is ore, but in some places the upper 

part of the bed is sufficiently mineralized to make ore.

The stopes in the 85 and 50 beds on (the north side of the quartz 

diorite are not extensive, mainly because those parts of the beds that 

were within the limits of mineralization have been largely removed 

by erosion. The Johnny, 85, 50, and Upper Copper Knob beds 

crop out in the canyon north of No. 3 shaft. Little is known concerning the extent of the Upper Copper Knob ore because it was mined 

from an opencut that is now partly concealed by a dump. According 

to report, the ore averaged 2.8 percent copper. Erosion has removed, 

all the other favorable beds on the north side of the quartz diorite 

that were close enough to the contact to have been reached by the 

copper-bearing solutions.

The ore bodies conform with the bedding of the limestone and consist of a series of flat or gently dipping tabular bodies that extend 

outward from the margins of the quartz diorite stock (pi. 41). The

average Width Of all the stopes along the south contact is about 53 feet,

but mineralized rock of ore grade commonly extends as much as 150 

feet from, tka Kmestone-duartz diorite contact, The distance to which 

ore extends depends largely on the extent of garnetization and the 

presence of postgarnetization fractures. The formation of the lime 

silicates preceded the deposition of the metallic minerals and appears

to have been a prerequisite of metallization.

Because the ore bodies in the Naco limestone are confined to a

certain group of limestone beds, a method was sought whereby these

fclYOrable bedS COUld be identified throughout the mine, and particularly on the south side of the quartz diorite body. The individual

lifll6StOne fo6dS appeared to possess no unique characteristics by which

they could be recognized with any degree of certainty, especially 

where they 4iad been affected by such extreme and variable degrees
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 367

of alteration as prevail in those parts of the mine in which the beds 

are mineralized. However, regardless of the state of alteration, the 

shale partings can usually be distinguished from the limestone, and 

the pattern presented by the interbedded series of limestone and shale 

appeared to be distinctive enough to serve as a means of correlation. 

A section was first measured in 321A and 346A raises where the 

longest continuous sequence of beds is exposed (pi. 41, sec. D-D'). 

Then sections were measured in all the accessible raises on the north 

side of the quartz diorite body. In some of these sections, beds that

 could be traced laterally through the mine workings or that could be 

definitely identified served as markers. The measured sections were 

then plotted to a common scale and pieced together into a composite 

master section which extended from the 400 level to the highest stopes 

on the north side (pi. 42). No accessible raises could be found in 

which satisfactory sections could be measured below the 400 level. 

Comparison of sections that are known to be equivalent shows that 

the general pattern of the limestone and shale sequence is reasonably 

consistent within the limits of the mine area. Although some of the 

minor shale bands are not persistent, the more prominent shale beds 

carry through but commonly show considerable variation in thickness from place to place. The pattern is complicated by the presence 

of many quartz diorite sills, some of which have been intruded between the limestone strata, generally at the shale partings, whereas 

others appear to have formed by granitization of shale beds and grade 

laterally into shale. It is often difficult to distinguish between the 

highly metamorphosed shale beds and the fine-grained intruded sills. 

Some of the variations in .the measured sections may be due to this

 difficulty, but undoubtedly some are caused by different shrinkage of 

the beds resulting from different degrees of nietamorphism. Furthermore, not all limestone-shale contacts are sharp; some are gradational from shale to limy shale to limestone. Thus in highly altered 

beds some blending takes place, which may result in minor discrepancies in thickness measurements of individual beds. However, 

the comparison of equivalent sections in various parts of the mine 

has shown the degree of conformity that could be expected.

Sections were then measured in all accessible raises in the workings 

south of the diorite intrusive. Another section was compiled, partly 

from underground measurements and partly from surface mapping, 

of the Old Christmas workings at the extreme east end of the mine. 

When the north and south sections were compared, they presented 

.in part different patterns, but showed reasonably clear overlap between the lower part of the south sections and the upper part of 

the north sections. On the basis of this overlap, the 530A stope 

(pi. 43) is believed to be in the Johnny bed. The massive 39-foot J
368 CONTRIBUTIONS TO ECONOMIC GEOLOGY

bed along the south contact is believed to be the same as the UpperCopper Knob bed on the north side, and the ore-bearing series isincreased to 11 beds by the addition of the OX-14 and OX-15 beds. 

Other stratigraphically higher beds have been mined on the south sideof the quartz diorite, but, as in most of the underlying beds, the stopes 

are caved and no data concerning them can be obtained except from 

incomplete mine records. Thus the Johnny is the lowest bed inthi series to be consistently stoped south of the diorite, and therefore 

the 205, 220, 235, 250, and Las Novias series of beds lie below; that is, 

between the 400 and 600 levels. On the basis of this interpretation 

it appeared reasonable to assume that these beds were mineralized 

and probably contain ore bodies. Subsequent diamond drilling by 

the Bureau of Mines proved this assumption to be justified (pi. 43)-

ORE BODIES IN THE ESCABROSA AND MARTIN LIMESTONES

Several small ore bodies have been found by development on th& 

800 level, and others have been discovered by drilling below the level. 

The ore bodies replace the massive or thick-bedded Escabrosa limestone. In contrast with the flat, tabular deposits in the Naco limestone, those in the Escabrosa that have been mined or sufficiently developed to reveal their shape are thick, irregular bodies that lie like 

a shell against the contact. Others are replacements of narrow slivers. 

of limestone between dikes or small blocks that may be completely 

engulfed by the quartz diorite. Some bodies are known only from1 

drill-hole intersection, hence little can be discovered concerning their 

shape or size.

In order to explore the south contact, the Bureau of Mines selected 

a drilling site at the east end of 808 drift on the 800 level (pi. 37). 

The eastern part of the drift is in quartz diorite which was believed ix> 

be a thick sill. It was uncertain whether the main contact was to the 

llOrth OF to the south of the drilling site. A vertical hole (23A) drilled' 

by the Bureau of Mines showed qilftrtZ dlOIlte to a depth of 200 feet 

(pi. 41, Sec. F-F'). A hole (23B) inclined 45° from the horizontal 

was then drilled southward. It passed through quartz diorite for 323

feet, beyond Which it Showed alternating intersections of quartz dioritfr 

and garnetized limestone that contained f rom 0.5 to 2.5 percent Copper. 

Th6 laSt 15 feet Of the hole was in unmineralized white marble. Apparently the hole had passed through the sill-like body but was too far 

south of the main Contact to find mineralized limestone.

A third hole (23i>) was drilled at a steeper angle, 57° from the 

horizontal. It passed through 480 feet of quartz diorite into homfeis 

and altered limestone. The last 30 feet of the hole is in quartzite that 

apparently is the basal part of the Martin and probably includes some 

of the upper beds of the Cambrian system. The hornfels undoubt-
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 369

eclly represents the shale at the top of the Martin limestone. Directly 

below the quartz diorite, the hole intersected 110 feet of altered limestone probably in the lower part of the Escabrosa that averaged 

2.48 percent copper, and 133 feet of limestone a little above the quartzite that averaged 2.37 percent copper. The lower mineralized limestone contained abundant diopside and tremolite and is the metamorphosed equivalent of the dolomitic limestone in the lower part of 

the Martin.

The sill-like apophysis of quartz diorite appears to coincide roughly 

with "the position of the Escabrosa limestone, and it probably continues eastward along the contact to the Christmas fault. Its structure suggests that it splits up into thin sills that probably pinch out 

a few hundred feet to the south. If so, the limestone along the south 

edge is likely to be mineralized and may contain ore bodies. The 

thickness of the stratigraphic section indicates that the quartz dioritecomprising this projection stoped its way into the limestone and was 

not intruded between the beds.

The only available drilling site from which exploration of the north 

contact could be attempted was at the north end of the 817 drift on 

the 800 level (pi. 37). The last 125 feet of this drift is in quartz 

diorite which previous drilling had proved to be a thin sill. The 

intrusive relationships in this general locality are very complex, and 

there was no clue as to the direction in which the main contact might 

be found.

A vertical hole (24B) intersected a small body of altered limestone 

directly below the sill (pi. 41) and about 436 feet of quartz diorite. 

At a depth of 506 feet it passed from quartz diorite into Martin limestone, and at a depth of 650 feet into quartzite. Except for two thin 

sills of hornblende porphyry, it continued in quartzite for 130 feet toft total depth of 781 feet. The upper part of this quartzite probably 

is the basal-part of the Martin, but the remainder undoubtedly is of 

Cambrian age. The lower part of the limestone contains abundant 

diopside and tremolite as in drill hole 23D. It is slightly mineralized, 

and a segment of core 57 feet long averaged 1.54 percent copper.

Another hole (24E) drilled from the same site was directed N. 25° 

W. and inclined about 68° from horizontal. The drill passed through 

118 feet of well-mineralized limestone under the sill and 215 feet of 

quartz diorite. It entered limestone at 360 feet and quartzite at 652 

feet from the collar and penetrated about 50 feet of Escabrosa limestone and the entire section of Martin limestone. A segment of core 

41 feet long in the Escabrosa averaged 2.85 percent copper, and another 65 feet long in the lower part of the Martin averaged a little 

more than 2 percent copper.
370 CONTRIBUTIONS TO ECONOMIC GEOLOGY

A third drill hole (24D) in the same vertical plane as the other two 

hut inclined 30° from horizontal passed out of the main quartz diorite 

body into unmineralized white marble at 392 feet from the collar. All 

three drill holes apparently intersected the main north contact which, 

in the plane of the drill holes, dips southward 30° to 50°; however, 

it is uncertain that the plane is normal to the contact, and the dip may 

be considerably steeper. In the plane of the drill holes, the north 

contact on the 300 and 400 levels is about 250 feet south of its position 

in hole.24D, hence the north side of the stock also appears to have a 

bulge along the zone in which the quartz diorite intrudes the Escabrosa limestone.

Drill holes 24A, 24C, 24D, and 24E intersected ore of superior grade 

in what appears to be an inclusion of limestone just below the drilling 

site. Development work preparatory to its extraction,is under way.

The ore bodies tLat have been found on and below the 800 level prove

that the Escabrosa limestone is a favorable host rock. These ore 

bodies are much thicker than those in the Naco, but probably do not 

extend as far away from the contact. The known ore bodies are all 

either in the upper or lower part of the formation; the contact between 

the quartz diorite and the middle part is beyond the reach of the 

present mine workings and has not been explored.

The mineralized Escabrosa limestone is soft and granular and contains a large amount of clay. It is very incompetent, and mine workings in it are difficult to maintain, especially if the ground is wet.

The three drill holes that penetrated the Martin all found the thinbeclded, shaly, and clolomitio limestone in the lower part of the formation to be well mineralized. This zone is extensively mineralized and 

contained many small ore bodies on the London-Arizona and other

properties, 2 miles west of CKristmas where it is known as the 

O'Carroll ore bed.

The 800 level is developed only at the west end of the quartz diorite 

where the intrusive body breaks up into narrow .dikes. If, as on the 

upper levels of the mine, the contact-becomes more regular toward the 

 east, larger and more continuous ore bodies can reasonably be expected. 

At the east, the limestones are cut off by the Christmas fault; but because the faxilt dips northeast, the eastward extent of the contacts

increases with depth.

OXIDATION AND ENRICHMENT

ACCOrding tO report, Oxidation of sul fides was nearly complete in

some of the ore bodies mined above the 300 level, especially tllOSe that

cropped out. The ore now being mined, as well as that developed by 

Bureau of Mines drilling along- the south contact, is partly oxidized.
GEOLOGY OF THE CHRISTMAS COPPER MINE, GILA COUNTY 371

From 1928 to 1932, when the mill was in operation, most of the ore 

came from the south stopes and was partly oxidized, but satisfactory 

recovery was accomplished by flotation preceded by sulfide filming.

The structure and composition of the Christmas ore bodies are unfavorable for enrichment by supergene processes. The flat-lying ore 

bodies are relatively thin and are separated by barren limestone and. 

shale beds which are nearly impervious and prevent downward circulation of groimdwater except along fractures. In all the ore bodies 

which can now be observed, sufficient unreplaced limestone remains in 

the gangue to prevent the transportation of copper for more than a 

few feet. That some migration of copper did take place is shown by 

masses of chalcocite and native copper found in some stopes. Theenrichment accomplished was of no economic importance, as it took, 

place entirely within beds too thin to be mined selectively. Some 

oxidation has occurred at the deepest level reached by the drill holes,, 

but this is of no economic significance except insofar as it would affect, 

mill recovery by flotation.

LITERATURE CITED

Elsing, M. J., and Heineman, R. E. S., 1936, Arizona metal production: Ariz.

Bur. Mines Bull. 140, 112 p. 

Ransome, F. L., 1904, Geology and ore deposits of the Bisbee quadrangle,

Arizona: U. S. Geol. Survey Prof. Paper 21. 

 1919, The copper deposits of Ray and Miami, Ariz.: U. S. Geol. Survey

Prof. Paper 115. 

*" 1923, Description of the Ray quadrangle [Ariz.]: U. S. Geol. Survey

Geol. Atlas, folio 217.

Koss, C. P., 1925, Ore deposits of the Saddle Mountain and Banner mining districts, Arizona: U. S. Geol. Survey Bull. 771.

Stoyanow, A. A., 1936, Correlation of Arizona Paleozoic formations: Geol. Soc. 

America Bull., v. 47, p. 459-540.

INDEX

Page

 Abstract.........-....--...-.-...-..--.-.---.. 351

Accessibility...............--.-.------ --- 352

.Acknowledgments_.. .... . - 353

.Alluvium.....-..-..-.....--.....-----..---- 360

Analysis of ore -------------------------- 363

Auclesite-Quartz diorite contact.---..--------- 362

 Cambrian rocks.------------------------ 358,368

 Carboniferous rocks..------- ----- 358,359

Christmas Copper Co..---------- ......... 354

 Christmas Copper Corp...................... 354

 Christmas fault. .------- 356, 357, 360, 362, 369;

pis. 35, 36, 41

 Claims....-.---.. ---------------------- 354

 Contact metamorphism---... .._........ 359

Copper production, 1902-43-..-.-.---.- 355

Deep drilling, U. S. Bureau of Mines.. 359,361-363,

368-370; pis. 37, 41, 43

Devonian rocks.. _ _ _.._...- . ...._-. 358

Dikes, aiHlesitic..------.-.------------- 360

Diorite intrusive, relation to mine workings. 356-357 

Dioriticrdcks ---------------------------- 359

Displacement, Christmas fault.-.-..-..-... 362

Enrichment, supergene..._...._ ...-. .._ 371

Escabrosa limestone. ..... 358,359,363,368-369 

favorable host.-------------------------- 370

lithologic character. ___- ...._._ -..-.... 370

Electric power..........-.-.........-..-.-- 353

Exploratory drilling, north side...... ..... 369-370

soulli side......-.....------ 368-369;pis.37,41

Faults and fractures, channels of mineralization..-..-....------.----- ------ 364-365

Fractures, post-garnetlzation............... 365,366

Future development..... _........_--- - . 370

Ganguc minerals. - -.. --- . -- 363

Oarnetization...--------------------- 364,366

General geology....------. - .... - 357

Geologic controls of mineralization ---------- 363-365

Geologic map, Christmas area............... pi. 33

mine levels.... ..................... pis. 35-37

previous work.. 357

Gtla Copper Sulphide Co. ------------ 354

Gold production, 1905-33... ... 355

J-1'ayden smelter, relation with.. __ _- ....... 354

T-listory of the mine-. ..........-..- .. 354

'Las Novlas beds.- -- ---------------------- 356

orebodles....-- -- 365

Limestone, Paleozoic.-----....----- 357-359,360

Limestone beds, susceptibility to replacement- 364 

Location... -------------------- 352

'Martin lira.estone..... ... . 358,359,361,368-370 

mineralization..................------... 370

.Mine workings, composite map.......... 356; pi. 34

general description . .-. - 356-357

Mineralization......--------------- 363-371

channels.... 364

^Mineralized beds, Naco limestone. . 365-368 

50 bed.... . . - 365,366

85 bod........... -...........- .. 365,366

.205 bed.---.----.-------- 365,366,368

Mineralized beds Continued

220 bed----. --- ........... 365,366,368

235 bed. . 365,366,368

250 bed------.----------...-.. 365,366,368

LasNovias beds. ................ 365-366,368

J bed .-- - ._ - 367-368 

Johnny. .--._ __..__...... 365,367

OX-14 bed- ----.-.....-....-..--- 368

OX-15 bed... ......................... J .. 368

Upper Copper Knob....__...._ 365,366,368

Mississippian rocks_ _.... 358

Naco limestone_ 353,359

ore bodies in_........................ 365-368

Pennsylvanian-Permian age............ 358-359

No. 4 shaft exploration..................... 361^362

North contact..._.....______...___ 356

North-side workings....._____.__...... 356

O'Carroll bed......-.--..---.-------....-.. 358,370

Operation.................................... 354

relation to price of copper_............. 355

Ore, analysLs... ..............__._____ 363

Ore bodies, Escabrosa limestone............ 368-370

geologic relations-...................... 357,363

Naco limestone__._....__......_ 365-368

relation to dioritestock.......... 363-364; pi. 41

relation to garnetization................ 364-365

stratigraphic relations.. ___. ___. _ 359

Ore minerals-_.__...___....__...... 363

Ore-bearing beds, Naco limestone, correlation

267-268

Oxidation.,.. .-.------ ---. ..---- 370-371

Pennsylvanian-Permian rocks.-------_..... 358

Previous work_......____...__._.. 354

Production.------------------.-------.--.- 354,355

Quality of ore..________________ 354 

Quartz diorite stock___......._..-..---_ 357,

360,361,362,363,366,369,370 

relation to ore bodies.- .__.._... 363-364

Saddle Mountain Mining Co -_______ 354 

Sam Knight Mining Lease, Inc.._______ 354 

Sections, measured, comparison of. 367-368; pls.41-43 

Sedimentary rocks, Tornado Peak_....... 357-358;

pis. 38,39 

Silver production, 1905-33.....-.-.--....---.. 355

South contact . ._____.__.._ ..__ 361 

South-side workings.- ..-....-__... 356

Stratigraphy--.-.--------...--...-. 357-360

Structure...._____..-_....._........ 360-363

Tenor, 1942 shipments.._.__.__..._... 354 

ore in Escabrosa limestone......__.... 368,369

ore In Las Novias beds__--...--...--... 365 

Topography...--..--.-..-..------.-..-. 353,359

Tornado limestone, of Ransome............... 358

Tornado Peak, sedimentary rocks..... - 357-358;

pis. 38,39 

Troy quartzite.__._....___...__._ 358

U. S. Bureau of Mines, drilling-....... 353,361-363,

368-370; pis. 37,41,43

Volcanic rocks.....--..---..-.-.- 357,359,360 

Water supply-- - - -- ... ..--- 353

o

373