GEOLOGICAL SURVEY CIRCULAR 334

URANIUM-BEARING COPPER 

DEPOSITS IN THE COYOTE 

DISTRICT, MORA COUNTY, 

NEW MEXICO

This report concerns work done on 

behalf of the U. S. Atomic Energy 

Commission and is published with 

the permission of the Commission.
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEJLOGICAL SURVEY CIRCULAR 334

URANIUM-BEARING COPPER DEPOSITS IN THE COYOTE DISTRICT

MORA COUNTY, NEW MEXICO

By Howard D. Zeller and Elmer H. Baltz, Jr.

This report concerns work done on behalf of the 

U. S. Atomic Energy Commission and is published 

with the permission of the Commission.

Washington, D. C., 1964

Free on application to the Geological Survey, Washington 25, D. C.
109° 

37°-rl ,

32°

SANTA FE

Las Vegas

0 Albuquerque

N EW

MEXICO

r

log37"

.-J432- 

103°

LAS VEGAS

30 Miles

Figure 1. Index map showing Coyote district, Moro County, N. Mex.

ii
URANIUM-BEARING COPPER DEPOSITS IN THE COYOTE DISTRICT

MORA COUNTY, NEW MEXICO

By Howard D. Zeller and Elmer H. Baltz, Jr.

CONTENTS

Page

Abstract. ..................................... 1

Introduction................................... 1

Location and accessibility ................. 1

Geography............................... 2

Previous work ........................... 2

Purpose and methods of examination........ 2

Acknowledgments. ........................ 2

Geology ...................................... 2

Stratigraphy ............................. 2

Sangre de Cristo formation........... 3

Structure................................ 4

Mineral deposits .............................. 4

Occ urrence.............................. 5

Deposits in shale .................... 5

Deposits in sandstone ................ 5

Page

Mineral deposits Continued 

Occurrence Continued

Deposits in limestone ................ 6

Finely disseminated copper minerals... 6 

Mineralogy .............................. 6

Origin of deposits ........................ 6

Evidence of syngenetic origin......... 6

Evidence of diagenetic

concentration ..................... 7

Original source of copper and

uranium.......................... 8

Literature cited............................... 8

Unpublished reports ............................ 8

Radioactivity determinations and chemical

analyses of samples ......................... 9

ILLUSTRATIONS

Page

Plate 1.

Figure 1. 

2.

Geologic map showing uranium-bearing copper deposits in the Coyote district,

Mora County, N. Mex ......................................................... Inside back cover

Index map of the Coyote district, Mora. County. ................................................. ii

_A, Looking north from south end of the Coyote district. 13, Typical (locality 5) prospect

showing mineralized zone................................................................... 4

A, Photomicrograph of part of a copper sulfide nodule. 13, Chalcocite and vitrain along margin

of a copper sulfide nodule. C_, Graphic association of bornite and chalcocite in a copper sulfide

nodule............................................................................'........ 7

ABSTRACT

Uranium-bearing copper deposits occur in steeply 

dipping beds of the Sangre de Cristo formation of Pennsylvanian and Permian( ?) age south of Coyote, Mora 

County, N. Mex. Mapping and sampling of these deposits 

indicate that they are found in lenticular carbonaceous 

zones in shales and arkosic sandstones. Samples from 

these zones contain as much as 0.067 percent uranium 

and aver age 3 percent copper. Metatyuyamunite is disseminated in some of the arkosic sandstone beds, and 

uraninite is present in some of the copper sulfide nodules 

occurring in the shale. These sulfide nodules are composed principally of chalcocite but include some bornite, 

covellite, pyrite, and malachite. Most of the samples 

were collected near the surface from the weathered zone.

The copper and uranium were probably deposited 

with the sediments and concentrated into zones during 

compaction and lithification. Carbonaceous material in 

the Sangre de Cristo formation provided the environment 

that precipitated uranium and copper from mineralcharged connate waters forced from the clayey sediments.

INTRODUCTION 

Location and accessibility

The Coyote district in the west-central part of 

Mora County, N. Mex. (fig. 1) is about 10 miles 

northeast from Mora, the county seat of Mora. County, 

and about 34 miles north from Las Vegas, N. Mex., 

the nearest railroad shipping point. Uraniumbearing copper deposits of the district are in the 

narrow belt of outcrop that extends from the village 

of Coyote about 6 miles south along the west side 

of Coyote Creek.

The Coyote district may be reached from Las 

Vegas by State Highway 3 north for 24 miles to 

La Cueva, then 5 miles north of State Highway 21 

across Coyote Creek, and 3 miles west on a dirt 

road to Lucero. The south end of the area is 2 miles 

north from Lucero by dirt road. The district may 

also be reached from Mora, N. Mex., by State Highway 

38 north for about 9 miles, then east about 2 miles 

on a dirt road.
Geography

The altitudes in the Coyote district range from 

about 7, 240 to 8,000 feet. In the mapped area the 

south-trending valley of Coyote Creek approximates 

the eastern boundary of the Southern Rocky Mountains 

and the western boundary of the Raton section of the 

Great Plains province.

Immediately west of Coyote Creek is a belt of 

hogback ridges. West of the hogback belt is a broad, 

generally south-trending alluvial valley that separates 

the belt from the Rincon Range, the easternmost ridge 

of the Sangre de Cristo Mountains. The main mass of 

the Rincon Range in this vicinity rises to altitudes 

above 10, 000 feet.

East of Coyote Creek, a broad, gently sloping, 

relatively little dissected plateau is underlain by massive sandstone to the south and by extensive remnants 

of basaltic lava flows to the north. Altitudes on this 

plateau, range from 7, 700 feet south of Coyote to 

almost 9, 000 feet north of Coyote.

The only permanent stream in the area is Coyote 

Creek. This creek flows south to Lucero where it cuts 

eastward through the hogbacks and drains into the Mora 

River to the southeast.

The hogback ridg'es and the Rincon Range west of 

Coyote Creek support heavy growths of scrub oak, pinon 

pine, and juniper on the lower slopes and fir and western yellow pine on the higher slopes. The northern 

part of the plateau east of Coyote Creek also has a 

heavy growth of timber that gradually gives way to 

grassy plains to the south. The lower valleys are 

grassy and have clumps of cottonwood and willow along 

the streams.

No temperature or precipitation figures are available for this area but the summers are pleasingly cool 

and subfreezing temperatures are common during the 

winter. At Chacon, about 10 miles northeast from 

Coyote and about 900 feet higher than Coyote, the precipitation is 20. 88 inches per year (Harley, 1940, 

table 1, p. 13).

Nearly all the inhabitants are of Spanish or Mexican 

descent and many of the older people speak little or no 

English. Farming in the irrigated Coyote valley is the 

principal occupation, but lumbering and grazing of 

cattle and sheep are also important means of livelihood. 

The graded roads in the area are passable in dry weather 

but become slick and rutted in rainy weather and may 

be impassable after heavy snowfalls.

Previous work

Copper deposits of the Coyote district have been 

known since the latter part of the 19th century. Lindgren, 

Graton, and Gordon (1910, p. 109) mention these deposits 

briefly. The district has also been mentioned by Lasky 

and Wooton (1933, p. 84) and examined and described 

by Harley (1940, p. 42-43).

Read, Sample, and Shelton (1944) examined the 

deposits and briefly described them in a short unpublished 

report. Bachman and Read (1952) reexamined the deposits and found traces of radioactivity. The present

writers made a preliminary report (Zeller and Baltz, 

1952) on the results of examination of the deposits.

Purpose and methods of examination

This report is the result of a geologic study of 

the Coyote district recommended by Bachman and 

Read (1952). The purpose of the study was to determine 

whether sufficient quantities of uranium were present 

to justify a program of exploration and evaluation of 

the deposits by the Geological Survey.

About 2 months were spent in mapping topography 

and geology with plane table and alidade, tracing mineralized zones, and examining and describing individual 

prospects. Many field Geiger-counter readings were 

taken and 29 samples were collected for copper and 

uranium analysis and polished-section study. A table 

containing results of the analyses is shown at the end 

of this report.

Acknowledgments

The writers were assisted for the first week of 

field work by C. B. Read, G. O. Bachman, and 

R. B. O'Sullivan. Radioactivity measurements, chemical analyses, and mlneralogical determinations were 

made by the Geological Survey Denver laboratory. 

This work is part of a program of exploration for radioactive materials undertaken by the U. S. Geological 

Survey on behalf of the'U. S. Atomic Energy Commission.

GEOLOGY 

Stratigraphy

Rocks of Pennsylvanian and Permian age are 

exposed in the valley of Coyote Creek within the area 

of this report. West of Coyote Creek the highest hogback ridges are composed of limestone, gray to buff 

sandstone, and interbedded dark-gray shale of the undifferentiated Magdalena group of Pennsylvanian age. 

Rocks of the westernmost Magdalena are in fault contact 

with pre-Cambrian quartzites that make up the bulk of 

the Rincon Range and a considerable amount of the 

lower Magdalena probably is cut out by the faulting.

Conformably above and geographically east of the 

rocks of the Magdalena group is the thick series of 

variegated shale, and interbedded conglomeratic arkosic 

sandstone and limestone of the Sangre de Cristo formation of Pennsylvanian and Permian(?) age. In the 

mapped area, the valley of Coyote Creek is underlain 

by the Sangre de Cristo formation. West of Coyote 

Creek the lower beds of the Sangre de Cristo formation 

form-hogbacks. East of Coyote Creek, the beds flatten 

progressively and pass under the high plateau with low 

eastward dips.

The high plateau east of Coyote Creek is capped 

by the massive buff-colored Glorieta sandstone member 

of the San Andres formation of Permian age that conformably overlies the Sangre de Cristo formation and 

probably intertongues with it. Above the eroded top 

of the Glorieta sandstone member are remnants of 

basaltic lava flows, either late Tertiary or Quaternary 

in age.
Sediments of the Magdalena group and Sangre de 

Cristo formation were deposited in a deep subsiding 

trough which has been called the Rowe-Mora basin by 

Read and Wood (1947, p. 227). . This basin was flanked 

on the east and west by highlands that served as source 

areas for much of the detrital material in the basin. 

The presence during Paleozoic time of these highlands 

composed of pre-Cambrian crystalline rocks has been 

well demonstrated in mapped areas to'the southeast, 

south, -and southwest of the Coyote area (Read and Wood, 

1947; Northrop, and others, 1946; Read and Andrews; 

1944).

Sangre de Cristo formation

All the mineral deposits described in this paper 

occur in the Sangre de Cristo formation. Lasky and 

Wooton (1933, p. 84) state that the copper deposits of 

the Coyote district are in carbonaceous shale of Cretaceous age. According to Harley (1940, p. 42) the 

deposits occur in beds of the Dockum group of Triassic 

age. Apparently in both papers, the Glorieta. sandstone 

member on the plateau east of Coyote Creek was miscorrelated with the Dakota sandstone to which it bears 

some resemblance. Bachman and Read (1952), on the 

basis of regional investigations recognized the red beds 

on Coyote Creek to be in the Sangre de Cristo formation. 

The present writers found carbonized plant remains of 

the Permian conifer Lebachia in the Sangre de Cristo 

formation at locality 1, shown on plate 1. Exposures 

east of Lucero, south of the mapped area, show normal 

succession of Triassic, Jurassic, and Cretaceous beds 

above and to the east of the Glorieta sandstone member.

The Sangre de Cristo formation is composed of 

a series of interbedded thick conglomeratic arkosic 

sandstone; variegated clay shale, sandy shale, and siltstone; and dense gray bedded and nodular limestone. 

Sandstone beds are thin to massive and the thicker beds 

generally form persistent ledges. The sandstone is 

fine- to very coarse grained; sorting is characteristically poor. Many beds contain conspicuous quantities 

of pebbles and cobbles of granite gneiss, schist, and 

quartzite. The most common mineral in the sandstone 

is quartz, but all the sandstone beds contain notable 

amounts of freshly to slightly weathered angular potash 

feldspar fragments that give the beds their typical 

salmon-pink color. Some of the sandstone contains as 

much as 50 percent feldspar having unweathered cleavage 

fragments as large as three-fourths of an inch in diameter. Sericite, muscovite, and biotite are present in 

some beds. The principal cementing agent is calcite but 

kaolin, silica, and iron oxide are also present. Crossbedding and cross lamination are prominent and in many 

places both are marked by thin layers of magnetite 

sand. Sandstone beds form a.bout 35 percent of the 

Sangre de Cristo formation.

The thicker shaly intervals form small valleys 

and flats between ridges of arkose. These shaly intervals are persistent for considerable distances (fig. 2A) 

although individual shale beds appear to be lenticular. 

The shales are laminated clays, commonly sandy or 

silty, containing interbedded siltstone and shaly finegrained sandstone. Lateral and-vertical gradation between beds of all types is common. Many of the less 

permeable clay beds are light green to gray, whereas 

the beds of more permeable silty and sandy shale are 

reddish or brown. In some of the prospect pits the

red oxidized beds'appear to die out with depth. This" 

may indicate that the distinctive red beds color of parts 

of the Sangre de Cristo formation is the result of recent 

oxidation near the surface rather than an original depositional color of the sediments. About 60 percent 

of the Sangre de Cristo formation is composed of shale.

Thin-bedded and nodular limestone is interbedded 

with shale throughout the formation., Many of the limestone beds, particularly the nodular beds, apparently 

have been partly recrystallized. Limestone forms about 

5 percent of the formation.

Most of the limestones are probably of fresh water 

origin but some of the lower beds are undoubtedly marine. 

A sandy copper-bearing limestone exposed in the prospect at locality 22 (pi. 1), about 1,000 feet stratigraphically above the base of the Sangre de Cristo formation 

contains many small complete gastropod shells, crinoid 

columnals, and a few pelecypod valves. According to 

S. A. Northrop (personal communication, 1953) there 

are several genera of bellerophontid gastropods, but 

surface textures are too poor to permit specific 

identification. One well-preserved pelecypod valve 

was identified as Myalina sp. All the forms are definitely marine. The variety of gastropod genera and lack 

of broken or fragmental specimens indicate that these 

marine invertebrates are part of an indigenous fauna 

and do not represent reworked material. Field observations of the rocks which contain the fossils further 

substantiate this conclusion.

The lower contact of the Sangre de Cristo formation is generally placed at the top of the highest marine 

limestone of the underlying Magdalena group. However, 

in the Coyote area the contact as shown by Bachman and 

Read (1952) and Bachman (1953) is marked by a lithologic change from dark shale and light-colored quartz 

sandstone of the Magdalena. group to pink arkosic sandstone and variegated shale of the Sangre de Cristo 

formation. The fossiliferous marine limestone noted 

above is in the arkosic sandstone and variegated shale 

sequence. There is no lithologic basis for placing the 

contact higher stratigra.phica.lly as the thin fossiliferous 

limestone and enclosing shale and sandstone are similar 

to other unfossiliferous limestone-bearing sequences 

throughout the Sangre de Cristo formation. For this 

reason the writers have not changed the boundary to the 

position of the limestone and they consider the lower 

part of the Sangre de Cristo to be composed of both 

marine and nonmarine sediments.

Most of the shale beds contain at least small 

amounts of carbonaceous material and some of the beds 

are highly carbonaceous to coaly and contain many 

recognizable carbonized stems, twigs, and leaf impressions. Carbonaceous material ranging from microscopic fragments to large logs occurs in the coarser 

sediments but is not as common as in the shale beds. 

Nearly all the uranium-bearing copper deposits are in, 

or are associated with, these carbonaceous zones .

It was impossible to measure the thickness of the 

Sangre de Cristo formation accurately in the Coyote area 

because of thrust faulting in the western part 'of the area. 

According to G. O. Bachman (personal communication, 

1953) the formation is about 3,500 feet thick on Mora River, 

about 12 miles south of the Coyote area, and thickens considerably to the north. The writers estimate that the formation is at least 4,000 feet thick in the Coyote area.
Figure 2. ;A, looking north from south end of the Coyote district, showing prominent arkosic sandstone ledges and 

less resistant shale beds of the Sangre de Cristo formation. B, Typical prospect (locality 5) showing mineralized 

zone (m) in gray carbonaceous shale and siltstone between sandstone ledges.

Structure

Along the west side of Coyote Creek, beds of the 

Magdalena group and Sangre de Cristo formation are 

generally vertical or dip steeply to the east. In the 

northern part of the mapped area, beds are overturned 

and dip steeply to the west. The eastward dip of the 

beds is progressively less east of Coyote Creek and 

beds under the mesa dip only 7° to 10°.

Beds of the hogbacks were folded during uplift 

and ea.stwa.rd movement of large crustal blocks in the 

Sangre de Cristo Mountains. The folding occurred in 

front of large high-angle thrust faults that are the eastern boundaries of these crustal blocks.

The major belt of thrust-faulting is located in 

the valley west of the hogbacks outside the mapped 

area. Most of the thrust faults in the mapped area are 

essentially parallel to bedding planes but are discernible 

in areas where they cut across beds. These faults probably occur as "splinters" from the major faults in a 

marginal zone of deformation between the eastwardthrust Sangre de Cristo blocks and the relatively 

undeformed High Plains to the east.

MINERAL DEPOSITS

All the observed copper deposits including those 

that are uranium-bearing occur in the stratigraphic
sequence between 1, 000 and 2, 000 feet above the base 

of the Sangre de Cristo formation. Small amounts of 

copper and uranium are widely disseminated throughout this interval. The main deposits consist of localized concentrations of copper sulfides and carbonates, 

and uranium-bearing copper sulfides and carbonates 

in shale and sandstone beds. A small amount of copper 

is present in the recrystallized parts of some of the 

nodular limestone beds. The localized concentrations 

are generally lens shaped and parallel to the beds which 

enclose them. The size and shape of these lenses are 

mainly controlled by the amount and distribution of 

carbonaceous material in the sediments. The lenses 

range in thickness from several inches to as much as 

5 feet and the length of the outcrop ranges from several 

feet to more than 100 feet. A zone, as mapped, may 

be-a series of lenses within 2 or 3 feet of the same 

stratigraphic horizon.

The zones were traced mainly by prospect pits 

(fig. 2B); however, there are a few outcrops of mineralized rock. Zones shown in plate 1 were drawn 

conservatively and extended only where exposures indicated the presence of copper. Uranium-bearing 

copper minerals are not present in all the zones and 

places where uranium was found are indicated by 

sample localities. Two to seven zones were mapped 

with the largest number at the north and south ends of 

the area where exposures are best. Outcrops in 

arroyos indicate the presence of other zones that extend 

under the soil cover. These zones have not been prospected and could not be traced beyond -the arroyos in 

which they are exposed.

At all localities where uranium has been found it 

is intimately associated with copper minerals. The 

greatest amount of uranium is generally in the most 

highly carbonaceous sediments. No uranium was 

found in noncarbonaceous sediments although copper 

minerals do occur in them.

Individual prospects and sample localities are 

described on page 9 of this report.

Occurrence

The copper deposits of the Coyote district, including those that are uranium-bearing, may be grouped 

in four general categories that are defined by the 

lithology of the enclosing sediments. The categories 

are:

(1) Nodules of copper sulfides and small amounts 

of copper carbonates in shale. Uraninite occurs in 

some of the copper sulfide nodules.

(2) Small amounts of copper sulfides and larger 

amounts of copper carbonates in sandstone. Uraninite 

may be present in some of the copper sulfide, and 

metatyuyamunite is associated with some of the copper 

carbonates.

(3) Traces of copper sulfides and carbonates in 

recrystallized parts of nodular limestone. No uranium 

was found in deposits of this category.

(h) Finely disseminated copper carbonate (and 

sulfide?) and uranium occur throughout the interval of 

the Sangre de Cristo formation that contains the 

mineral deposits.

Deposits in shale

Most of the copper deposits, including those that 

are uranium-bearing, are found in shale beds of the 

Sangre de Cristo formation. Nodules composed mainly 

of chalcocite, but also containing bornite, covellite, 

pyrite, and carbonaceous material, occur as replacements of plant stems, twigs, and leaves, and as 

irregularly shaped masses in highly carbonaceous clay 

shale, siltstone, and fine-grained shaly sandstone. 

Nodules from unweathered parts of prospect pits show 

almost no alteration except for a. few nodules that are 

surroundedby a thin film of azurite or malachite. Average 

size of the nodules found is about 2 inches in largest dimension; however, much larger nodules have been found during 

mining and prospecting. According to local residents nodules "thesizeof a.man'shead" were removed from the prospects at localities 31 and 32 near the south end of the area.

Many of the nodules contain uranium intimately 

associated with the copper minerals. Uraninite was 

identified in polished sections of nodules collected at 

locality 26 by W. I. Finch and H. Stager of the U. S. 

Geological Survey. i Unusually high radioactivity 

of small nodules found at other localities, particularly 

12 and 13 may indicate the presence of uraninite.

Coaly clay shale at locality 3, and at several 

other localities, contains considerable amounts of 

disseminated copper and some uranium. The only 

minerals observed in these shales were azurite and 

malachite, as slight stains.

Deposits in sandstone

Copper carbonates and sulfides occur in the 

thick arkosic sandstone beds that are intercalated with 

shale beds in the mineralized part of the Sangre de 

Cristo formation. Malachite is the cementing agent 

around some sand grains and usually grades imperceptibly into interstitial calcite, which is the principal 

cementing agent of the sandstone. In places malachite 

apparently has replaced calcite, but it generally grades 

into greenish-colored calcite and in most places both 

probably were deposited at the same time. Twigs, 

logs, and wood fragments in the sandstone are commonly replaced by copper sulfides. On the weathered 

surface sulfide-replaced wood fragments are usually 

altered to azurite and malachite with only a small core 

of copper sulfide remaining. Some of the calcite 

cement is replaced by malachite around these weathered 

sulfide bodies.

Uranium is present in small irregular masses 

of copper sulfide, particularly those which contain 

particles of carbonized vegetable matter. "Blooms" 

of a yellow mineral identified as metatyuyamunite 

(King, 1952) were found at localities 8, 15, and 18 

associated with malachite in weathered outcrops and 

in material on the dumps of the prospects. This 

metatyuyamunite is a recent alteration product of an 

other uranium mineral that is associated with the 

copper sulfides. Compressed carbonized logs found 

in the sandstone beds at some localities and thin, highly 

carbonaceous sandstone beds contain uranium but no 

uranium minerals were observed.

1Personal communication from W. I. Finch; minerals determined by 

A. Rosenzweig of the U. 5. Atomic Energy Commission and L. B. Riley of 

the U. S. Geological Survey.
The greatest amount of copper in the thick sandstone beds is near both upper and lower contacts of the 

sandstone with the enclosing copper-bearing shale. 

The amount of copper generally decreases rapidly 

toward the center of individual beds of sandstone so 

that 3 to 8 inches from the contact there are only traces 

of copper.

Deposits in limestone

Traces of copper carbonates and sulfides are 

present in the recrystallized parts of some of the limestone beds of the Sangre de Cristo formation. Small 

grains and irregular nodules of copper sulfide having 

a maximum diameter of a quarter of an inch were 

found at a few places in bands of acicular calcite crystals 

that surround irregular masses of dense gray limestone. 

Malachite occurs as green disseminations in the acicular 

calcite and fills small fractures in the dense limestone. 

No uranium was found in the limestone beds.

Finely disseminated copper minerals

Finely disseminated copper carbonate, and Drobably copper sulfide, are present in most beds of the 

Sangre de Cristo formation that contains the more concentrated deposits. Slight stains of malachite were 

observed on weathered outcrops of most of the sandstone 

beds. Samples of greenish-gray and gray shale collected at random from several stratigraphic horizons 

across the mapped area contain as much as 0.03 percent 

copper and 0.003 percent uranium, with an average of 

0. Oil percent copper and 0. 001 percent uranium.

Mineralogy

Fifteen polished sections of copper sulfide nodules 

from the Coyote mining district were prepared and 

studied. Chalcocite is the most common copper mineral 

in most of the nodules; however, bornite and covellite 

are alsqjpresent in smaller quantities. Pyrite is found 

in all but two of the nodules studied. Malachite stringers 

occur as fracture fillings. Other associated minerals 

include .quartz grains, calcite, and possibly siderite. 

Irregularly shaped fragments of vitrain surrounded by 

chalcocite are common in many nodules (fig. 3B).

Woody cell structure is well preserved in many 

of the nodules. In others the cells have been crushed 

to form compact vitrain, or have been partly replaced 

by copper and iron sulfides. Most of the nodules exhibit 

textures inherited from replaced cell structure and one 

specimen contains all gradations from the inherited 

texture through partly replaced cell walls to complete 

cells filled by copper sulfide. The cell walls are 

generally composed of vitrain with chalcocite filling 

the cell interiors. Cell walls replaced by pyrite were 

observed in only one specimen. Covellite and chalcocite are found in spaces between the rows of cells 

(fig. 3A). All gradations of mineralization were observed from slight to complete replacement of woody 

material by copper sulfides.

No order of replacement among the copper minerals could be determined, except that malachite was 

formed last in small fractures in the nodules. Although 

some pyrite is present in most of the nodules, only

a few specimens suggest that chalcocite replaced the 

pyrite. In most cases, pyrite and chalcocite seem to 

have been deposited contemporaneously. Bornite and 

chalcocite (fig. 3C) are found in a more or less graphic 

intergrowth which indicates that they are contemporaneous. Covellite is found associated with plant cell 

structure and appears to be contemporaneous with the 

chalcocite inasmuch as one grades into the other 

(fig. 3A).

Origin of deposits

The copper deposits of the Coyote district, including those that are uranium bearing, appear to be 

of sedimentary origin. Probably small amounts of 

copper and uranium were originally deposited with the 

sediments of the Sangre de Cristo formation and later 

concentrated into zones during compaction of the 

sediments. No evidence of the introduction of mineralbearing solutions after deposition could be recognized, 

and only slight alteration of the deposits by ground 

water and surface water has occurred since lithification 

of the sediments.

Evidence of syngenetic origin

Sediments of the lower part of the Sangre de 

Cristo formation are relatively impermeable to ground 

water. Examination of many samples of sandstone and 

conglomerate indicates that they are tightly cemented 

by calcite and other fine material. Large quantities 

of unaltered magnetite sand and copper-sulfide nodules 

are present in sandstone and shale beds near the 

weathered surface. Oxidation of the minerals and 

weathering of the enclosing sediments below the surface 

has progressed downward for only a short distance at 

most localities.

The impermeability of the lower part of the 

Sangre de Cristo formation suggests that the copper 

and uranium mineralization, which is widespread 

throughout this sequence, occurred before lithification 

of the sediments.

Delicate plant cell structure preserved in many 

of the copper sulfide nodules collected from shale beds 

suggests mineralization at or shortly a.fter burial of 

the plant remains and before compaction of the surrounding shale caused collapse of the cell structure. Most 

of the unmineralized plant material that was observed 

has been compressed and flattened. Large pieces of 

compact slightly permineralized vitrain were observed 

at several localities, and many of the sulfide nodules 

contain slightly mineralized particles of vitrain indicating that mineralization continued during compaction 

of the sediments.

Small amounts of copper and uranium probably 

were carried in solution by the water in which sediments of the lower part of the Sangre de Cristo formation were transported and deposited. The favorable 

environment presented by fairly large accumulations 

of plant material in areas where mud and silt were 

being deposited caused precipitation of part of the 

copper and uranium carried by the water. Hydrogen 

sulfide gas generated by decaying vegetable matter 

may have been an agent in precipitation of copper and 

iron sulfides. A small amount of copper sulfide may
have been formed by the replacement of iron sulfide 

which was accumulating in decaying vegetable matter; 

however, polished sections examined by the writers 

contain only a small amount of pyrite, and that appears 

to have been deposited contemporaneously with the 

copper sulfides.

Evidence of diagenetic concentration

Many of the nodular limestone beds show evidence 

of partial solution and recrystallization. Copper carbonates and sulfides are disseminated in the recrystallized parts of the limestone, but occur only as fracture fillings in the dense limestone cores of the nodules. 

Solution and recrystallization must have occurred during the early stages of compaction at a time when 

the enclosing shaly sediments contained much water 

and were still in a highly plastic condition. Solution

Figure 3. A, Photomicrograph of part of a copper, sulfide nodule showing plant cell structure. Chalcocite 

(cc), covellite (cv). Cell walls are composed of 

vitrain. x!32. iB, Chalcocite (cc) and vitrain along 

margin of a copper sulfide nodule. x340. C, Graphic 

association of bornite (b) and Chalcocite (ccT in a 

copper sulfide nodule. Pyrite (p) is shown in upper 

part of photomicrograph. x380.

cavities around the limestone nodules and on the surface of limestone beds are completely filled by shale. 

There is no slaty cleavage or other evidence of shearing which would have developed in the shale around 

voids left by the.dissolved parts of the limestone if 

solution had occurred after induration of the shale.

Sulfide bodies are concentrated at the contacts 

of sandstone with mineralized shale and the grade of 

these bodies generally decreases rapidly inward from 

the contact. Any individual sandstone bed may be mineralized at either the upper or lower contact, or both. 

The writers believe that before lithification of the sediments, the sandstone beds served, as aquifers for 

circulation of connate water driven from the surrounding shale beds during compaction. The carbon of 

partly decomposed stems, twigs, and leaves and other 

woody fragments present in the sandstone- provided an 

environment which caused precipitation of copper and 

uranium minerals from the connate water which was 

forced through the sandstones. Much of the calcite 

cement of the sandstone was probably deposited from 

the connate-water at this time as was most of the interstitial malachite.

Migration of connate water through the shale 

during compaction also caused greater localization of 

uranium and copper deposits in the more highly carbonaceous parts of the shale beds.

The process of diagenetic concentration was 

halted when all, or nearly all of the connate water 

was forced out of the shale, or when the sandstone 

beds became cemented by calcite.

The writers observed no features indicating that 

mineral-bearing solutions were introduced after
lithification of the sediments. Mineralized zones apparently are controlled by sedimentary structures and no 

relationship of amount or distribution of mineralized 

rock to joints and faults was observed. At several localities faults cut and off set the zones but the principal 

joints and faults are not mineralized except for slight 

stains of malachite found near weathered sulf ide bodies. 

At many places across the area, thin stringers of calcite 

and gypsum occur as fillings in small fractures in the 

shale beds. These stringers transect mineralized 

zones and have no apparent genetic relation to them.

Original source of copper and uranium

The Sangre de Cristo formation is composed mainly 

of first-cycle sediments derived from pre-Cambrian 

crystalline rocks which are predominantly granitic. 

These basement rocks were exposed in the rising 

highlands on the east and west flanks of the Rowe-Mora 

basin in late Pennsylvanian and Permian time.

Small copper deposits in pre-Cambrian rocks occur 

at many localities in the mountains of northern New Mexico. 

Minor amounts of uranium are found at some of these 

localities, notably in the Petaca district of RioArriba 

County. Some of the deposits are located in areas 

which were part of the ancient highlands, and erosion 

of these mineral bodies in Pennsylvanian and Permian 

time undoubtedly furnished small quantities of copper 

and uranium to the sedimentary basins. However, most 

of the copper and uranium in the Coyote deposits were 

probably derived from the decomposition of large quantities of granitic rocks. Katz and Rabinowitch (1951) 

report the abundance of copper in igneous rocks of all 

types to be 100 grams per metric ton(0. 01 percent) 

and Rankama and Bahama (1950) give the average copper 

content of acidic igneous rocks as 16 grams per metric 

ton (0. 0016 percent). The abundance of uranium in all 

types of igneous rocks, according to Katz and Rabinowitch 

(1951), is 4 grams per metric ton (0. 0004 percent) and 

Rankama and Sahama (1950) give the abundance of uranium in granitic rocks as 3. 963 grams per metric ton 

(about 0. 0004 percent). If the granitic rocks that were 

eroded to supply the sediments of the lower part of the 

Sangre de Cristo formation in the Coyote district were 

average in their copper and uranium content they could 

have supplied sufficient quantities of copper and uranium to mineralize the rocks. The lower part of the 

Sangre de Cristo formation was deposited in a transitional marine-continental environment in which lagoons 

and coastal swamps were formed. These features provided areas in which connate water flowing from the 

granitic highlands accumulated and was buried with the 

sediments.

No mineral deposits were observed in the upper 

part of the Sangre de Cristo formation in the Coyote

district. Physical evidence indicates that this part of 

the formation was deposited under subaerial conditions 

which did not permit the accumulation of carbonaceous 

material that could have provided the environment 

necessary for precipitation of copper and uranium 

minerals.

LITERATURE CITED

Bachman, G. O., 1953, Geology of a part of northwestern Mora County, New Mexico: U. S. Geol. 

Survey Oil and Gas Inv. Map OM 137.

Harley, G. T., 1940, The geology and ore deposits 

of northeastern New Mexico: N. Mex. Bur. Mines. 

Bull. 15. 104 p.

Katz, J. J., and Rabinowitch, E., 1951, The chemistry of uranium: 609 p., New York, McGraw-Hill 

Book Company, Inc.

Lasky, S. G. , and Wooton, T. P. , 1933, The metal 

resources of New Mexico and their economic 

features: N. Mex. Bur. Mines Bull. 7. 178 p.

Lindgren, Waldemar, Graton, L. C. , and Gordon, C. H. , 

1910, Ore deposits of New Mexico: U. S. Geol. Survey Prof. Paper 68.

Northrop, S. A. , Sullwold, H. H. , Jr., MacAlpin, A. J. , 

and Rogers, C. P. , Jr., 1946, Geologic maps of 

a part of the Las Vegas basin and of the foothills of 

the Sangre de Cristo Mountains, San Miguel and 

Mora Counties, New Mexico: U. S. Geol. Survey 

Oil and Gas Inv. Prelim. Map 54.

Rankama, Kalervo, and Sahama, T. G., 1950, Geochemistry: Univ. of Chicago Press. 912 p.

Read, C. B. , and Andrews, D. A. , 1944, The upper 

Pecos River and Rio Galisteo region, New Mexico: 

U. S. Geol. Survey Oil and Gas Inv. Prelim. Map 8.

Read, C. B. , and Wood, G. H. , 1947, Distribution 

and correlation of Pennsylvanian rocks in late 

Paleozoic sedimentary basins of northern New 

Mexico: Jour. Geol., v. 55, no. 3, p. 220-236.'

UNPUBLISHED REPORTS

Bachman, G. O. , and Read, C. B. , 1952, Uraniumbearing copper deposits near Guadalupita, Mora 

County, New Mexico: U. S. Geol. Survey Trace 

Elements Memo. Rept. 435.

King, A. G., 1952, TDM-119 Supp. Rept., U. S. Geol. 

Survey Trace Elements Denver laboratory.

Read, C. B. , Sample, R. D. , and Shelton, J. S., 

1944, The Guadalupita copper prospects, Mora 

County, New Mexico. [Manuscript in files of 

U. S. Geol. Survey. ]

Zeller, H. D. , and Baltz, E. H. , Jr. , 1952, 

Uranium-bearing copper deposits in the Coyote 

mining district, Mora County, New Mexico: 

U. S. Geol. Survey Trace Elements Memo. 

Rept. 556.
Radioactivity- determinations and chemical analyses of samples from Coyote district, Mora 

Sample 2 

and 

locality 

no.

1

2

5

4

5

6

7

8

9

.0

.1

.2

Laboratory 

serial 

no.

D-76591

D-76592

D-76595

D-7659^

D-76595

D-77052

D-76596

D-76597

D-76589

D-77055

D-77054

D-76598

Radioactivity 

determinations

Equivalent 

uranium 

(percent)

0.009

.007

.020

.007

.018

.002

.014

.065

 059

.005

.001

.011

Chemical analyses

Uranium 

(percent)

0.006

.007

.004

.005

.014

.001

.010

.048

.018

.001

.001

.008

Copper 

(percent)

2.21

1-75

2.51

2.72

6.15

.005

4.16

6.59

14.58

.010

.050

5.72

Description

The prospect is on the slope of a steep hill over

sample was obtained from dark-gray lenticular c

lain and underlain by greenish-gray, silty, ver

stone. The shale contains many carbonized stem

malachite occurs as small flat flakes in the sa

At the same locality (l) a grab sample of arkosic 

shale contains much malachite and some chalcoci

interstitial material between highly angular to 

grains. The arkose contains carbonaceous mater

clay and silt. Copper minerals are concentrate

sandstone.

A small trench is located between two arkose ledg

in a dark carbonaceous clay shale that shows tr

A 2-foot channel sample was taken.

A .grab sample was taken from the dump of a nearly 

exposures. Dark-gray to black shale contains m

plant remains. Fossil twigs replaced by chalco

A grab sample of black carbonaceous shale was tak

filled prospect pit. The shale contains much c

and much disseminated malachite.

A 2-foot channel sample was collected from greeni

those occurring throughout the lower part of th

This locality was not prospected and no copper 

A small caved prospect has much medium-grained ar

This grab sample of sandstone contains much dis

carbonaceous material.

A small filled pit is located on same zone as sam

sandstone contains much carbonaceous material i

A large amount of malachite and chalcocite were 

Most of the rocks on the dump are at least mode

A grab sample of arkosic sandstone contains malac

of a yellow mineral that is highly radioactive. 

sample locality 18, the yellow mineral was iden

A 2-foot channel sample was collected from light 

crops out along the side of an arroyo. No copp

A 2-foot channel sample was collected from a bed 

is exposed along the margin of a shallow prospe

observed in the shale; however, malachite stain

nodular limestone.

The prospect is a large, partly filled trench. A 

and arkosic sandstone from the dump contains mu

malachite.

See footnotes at end of table.
Radioactivity determinations and chemical analyses of samples from Coyote district, Mora County

Sample a

locality 

no.

13

14

15 

16

17

18

19

20

21 

pp o nrj p-*

24

25

Laboratory

serial 

no.

D-76599

D-76600

D-76587

D-76601

D-76590

D-76602

D-77035

D-77036

D-76603

Radioactivity 

determinations

Equivalent 

uranium 

(percent)

0.018

.068

.004

.054

.039

.009

.005

.003

.008

Chemical

Uranium 

(percent)

0.015

.067

.0002

.032

.026

.004

.003

 c.OOl

.004

analyses

Copper 

(percent)

4.65

13.65

57-33

.66

.41

1.8l

.005

.005

7-49

Description

A vertical shaft 15 feet deep with a filled crossc

quantity of black carbonaceous shale on the dump

shale contains malachite and small renlform piec

of black carbonaceous clay material on the dump 

depth. The radioactivity of some of the chalcoc

is unusually high.

Coaly fragment (l by 1 by £ Inch) was found In the 

for sample 13. Radioactivity was 10 times backg

which may indicate that the sample contains uran

A small filled longitudinal trench is cut in the c

ledge. The sandstone Is fine- to medium-grained 

Copper and uranium are concentrated in fossil tw

was taken.

A small circular pit contains much nodular limeston

apparently have been dissolved and recrystallize

Of malachite are found only in fractures of the 

tions of malachite are found throughout-the recr

was collected for examination by microscope.

A partly filled shaft 25 feet deep, with north and 

follows beds for an undetermined distance. Samp

nodules, selected from the dump.

A grab sample of fine- to medium-grained arkosic s

seminated malachite and carbonaceous material. A 

metatyuyamunlte, occurs as fine disseminations a

Metatyuyamunlte is associated with carbonaceous 

sandstone and also occurs in cracks within the s

the sample was taken is 20 feet by 10 feet and b

the arkosic sandstone on the dump counts over 5 

Geiger counter.

A grab sample of an arkosic sandstone from prospec

'metatyuyamunlte.

A grab sample of a carbonaceous shaly sandstone co

and chalcocite. Malachite also replaces twigs a

Small prospect pit contains greenish-gray clay sha

A 1-foot channel sample was taken.

Marine fossils in sandy limestone were found along 

pit. See page 3 in text.

A 2-foot channel sample of a greenish-gray clay sh

No copper minerals were observed.

A recently dug prospect pit 18 feet deep and approx

a gray shaly siltstone, some of which is red. Th

sample of a highly carbonaceous shaly siltstone. 

overlain by red shaly siltstone and underlain by 

stone. Many plant fossils are replaced with copp

flde nodules are ellipsoidal in shape and are or
26

27

28

29

50

51

52

55

D-76588

D-77057

D-76604

0-76585

D-76586

0-77058

D-77059

D-77040

.048

.005

.054

.011

.015

.005

.004

.041

.002

.061

.005

.008

.002

.005

( 3 )

52.85

.020

5.84

2.25

.80

5.245

6.759

l\Tf"*lT"l £>

J.NLJLJC/

The sample represents nodules of copper sulfides 

selected for highest radioactivity. Uraninite w

nodules collected from this locality by W. I. P

page 5 in text . )

A 2-foot channel sample was collected from greeni

minerals were observed.

A grab sample was collected from a 5i" inch carbon

exposed in a small prospect. The sandstone is 

stone, siltstone, and shale. Malachite and cha

sandstone and the highest radioactivity is in th

of the sandstone.

A weathered outcrop about 500 feet south of local

bonaceous sandstone, siltstone, and shale with mu

The thickness is about 2 feet; however, only 6 

material was sampled. The carbonaceous beds are 

fine- to coarse-grained sandstone.

A grab sample of carbonaceous black shale was col

prospect pit. Malachite wag observed in the sha

the carbonaceous material have malachite in the 

A caved trench, 100 feet long, is located between 

The dump contains sandstone with many carbonaceo

copper sulfides. Malachite-coated sericite grai

A grab sample was taken.

A grab sample was collected from dark-gray carbona

malachite, azurite, and some copper sulfides at 

A water sample was collected from a covered well n

of the road.

1 Analyses furnished by U. S. Geological Surrey, Denver laboratory, L. R. Rader, Jr., in charge. Radiation by Furman. Chemistry by McCarthy, Mountjoy, Niles, Schuch, and Skinner. Mineral analyses (referred 

to in text) by A. G. King.

2 Locality numbers refer to those shown on plate 

"Parts per million 0.01$.
UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY CIRCULAR 334 PLATE 1

STRUCTURE SECTIONS 

along lines A-A1 and B-B'

' NEW MEXICO

Contour interval 20 feet 

Datum is approximately sea level

EXPLANATION

Sedimentary 

Rocks

Guadalupfta 

1.6 miles

INDEX MAP

Prospect 

Vertical shaft 

Large open trench 

Sample locality

Earth dam 

Spring

Graded dirt road 

Dirt road

Mafdalena group

Approximate contact of geologic 

formation, dotted where concealed

Copper and uranium -bearing 

zone mapped where mineralized 

at surface. Solid line indicate* 

traceable mineralized rocks, 

dashed where inferred

Thrust fault. Dashed where 

approximately located, dotted 

where concealed. T indicate* 

over thrust block

Transverse fault. Arrows 

indicate direction of relative 

movement

Dip and strike of beds

Dip and strike of overturned beds

GEOLOGIC MAP SHOWING URANIUM-BEARING COPPER DEPOSITS IN THE COYOTE DISTRICT, MORA COUNTY, NEW MEXICO

Topography and geology by H. 0. Ztllvr and E. H. Baltz, Jr. 

1992