Mineral Resources of the NeW, Water 

Mountains Wlldernes.\ Study 

LaP~ c~~ 

ARIZONA 
/ 

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Chapter B 

Mineral Resources of the New Water 

Mountains Wilderness Study Area, 

La Paz County, Arizona 

By DAVID R. SHERROD, DAVID B. SMITH, 

RICHARD D. KOCH, WILLIAM F. HANNA, and 

JAMES A. PITKIN 

U.S. Geological Survey 

MICHAEL E. LANE 

U.S. Bureau of Mines 

U.S. GEOLOGICAL SURVEY BULLETIN 1702 

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

SOUTHWESTERN AND SOUTH-CENTRAL ARIZONA 
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use_ of trade, product, or firm names 

in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1989 

For sale by the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging-in-Publication Data 

Mineral resources of the New Water Mountains Wilderness Study Area, La Paz 

County, Arizona. 

(U.S. Geological Survey bulletin ; 1702-8) 

8 ibl iography: p. 

Supt. of Docs. no.: I 19.3:1702-8 

1. Mines and mineral resources-Arizona-New Water Mountains 

Wilderness (Ariz.) 2. New Water Mountains Wilderness (Ariz.) I. Sherrod, 

David R. II. Series. 

QE75.B9 no. 1702-B 557.3 s 88-600429 

[TN24.A6] [5531.09791 ?] 
STUDIES RELATED TO WILDERNESS 

Bureau of Land Management Wilderness Study Areas 

The Federal Land Policy and Management Act (Public. Law 94-579, October 21, 

1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct min- · 

eral surveys of certain areas to determine the mineral values, if any, that may be present. 

Results must be made available to the public and submitted to the President and the Congress. This report presents the results of a minera_l survey of part of the New Water 

Mountains Wilderness Study Area (AZ-020-125), La Paz County, Arizona. 
CONTENTS 

Summary 

Abstract 

B1 

B1 

Character and setting B1 

Identified resources B1 

Mineral resource potential of the New Water Mountains Wilderness Study 

Area B2 

Introduction B3 

Location and physiography B3 

Previous and present investigations 

Acknowledgments B3 

Appraisal of identified resources 

Methods of investigation 

History and production 

Mineral deposits B5 

B3 

B3 

B5 

Assessment of mineral resource potential 

Geology B5 

Geochemical studies B7 

Methods of investigation 

Summary of results 

Geophysical studies B8 

Gravity and aeromagnetics 

Gamma-ray spectrometry 

B7 

Electrical geophysics B9 

B7 

B8 

B8 

B3 

B5 

Mineral and energy resources of the New Water Mountains Wilderness Study 

Area B9 

Sedimentary-rock-hosted gold and silver B9 

Epithermal gold and silver B10 

Copper and manganese B11 

Lead and zinc B11 

Geothermal energy B 11 

Oil and gas B11 

Lime B12 

References cited B12 

Appendixes 

Definition of levels of mineral resource potential and certainty of 

assessment B16 

Resource/reserve classification B17 

Geologic time chart B 18 

FIGURES 

1. Index map showing location of New Water Mountains Wilderness Study Area, 

La Paz County, Arizona B2 

2. Map showing mineral resource potential and generalized geology of New Water 

Mountains Wilderness Study Area, La Paz County, Arizona B4 

3. Complete Bouguer gravity anomaly map of New Water Mountains Wilderness 

Study Area B9 

4. Aeromagnetic anomaly map of New Water Mountains Wilderness Study 

Area B10 

TABLE 

1. Sampled areas in and near the New Water Mountains Wilderness Study Area, La 

Paz County, Arizona 86 

Contents V 
Mineral Resources of the New Water 

Mountains Wilderness Study Area, 

La Paz County, Arizona 

By David R. Sherrod, David B. Smith, Richard D. Koch, 

William F. Hanna, and James A. Pitkin 

U.S. Geological Survey 

Michael E. Lane 

U.S. Bureau of Mines 

SUMMARY 

Abstract 

The New Water Mountains Wilderness Study Area 

(AZ-020-125) is located in La Paz County, west-central Arizona. On the basis of a preliminary request of the U.S. 

Bureau of Land Management, 24,120 acres of the New Water 

Mountains Wilderness Study Area were evaluated for mineral 

resources (known) and mineral resource potential (undiscovered). Throughout this report, reference to the New Water 

Mountains Wilderness Study Area or to the study area refers 

only to that part of the wilderness study area for which a 

mineral survey was requested by the U.S. Bureau of Land 

Management. Fieldwork for this report was conducted in 

1984 and 1985. Although 200 claims have been located 

adjacent to the study area and a few claims and two prospects are located within its boundaries, there are no identified 

resources in the study area. Inferred subeconomic resources 

of stone and sand and gravel in the study area have no 

unique qualities and are similar to material available closer to 

markets. 

The resource potential for gold and silver is moderate in 

the northwestern and northeastern parts of the study area and 

low in the north-central and south-central parts. The resource potential for copper and manganese is low in the 

northeastern part of the study area. Minor amounts of lead 

and zinc accompany gold, silver, copper, and manganese 

occurrences in the New Water Mountains Wilderness Study 

Area. Therefore, a low resource potential for lead and zinc 

is assigned to the northwestern, north-central, northeastern, 

and south-central parts of the study area. There is low resource potential for geothermal energy along range-bounding 

faults in the eastern part of the New Water Mountains Wilderness Study Area. The entire study area has low resource 

potential for oil and gas. 

Manuscript approved for publication October 17, 1988. 

There is unknown resource potential for lime, which 

could be developed from inferred subeconomic resources of 

marble in Paleozoic rocks in the northwest part of the study 

area. Although inferred subeconom ic resources of sand and 

gravel occur in the study area, these materials are abundant 

closer to existing markets in the region. 

Character and Setting 

The New Water Mountains Wilderness Study Area is 

in the New Water Mountains of La Paz County, Ariz., 

about 10 mi southeast of Quartzsite, Ariz. (fig. I). The 

mountains slope gently from the surrounding alluvial plain 

and steepen to the 3,639-ft-high bluff of Black Mesa. The 

study area is underlain by steeply dipping sedimentary, 

volcanic, and plutonic rocks of Proterozoic, Paleozoic, and 

Mesozoic age (see geologic time chart in appendixes). A 

sequence of Tertiary volcanic and sedimentary rocks unconformably overlies pre-Tertiary rocks, and this younger 

sequence has been slightly to moderately tilted during 

basin-and-range normal faulting. 

Identified Resources 

No mineral resources were identified in the New Water 

Mountains Wilderness Study Area. Inferred subeconomic 

resources of stone and sand and gravel in the study area 

have no unique qualities. Prospecting, claim staking, and 

mining near the study area have been intermittent during 

the 20th century; U.S. Bureau of Land Management records 

show that about 200 claims were located adjacent to the 

New Water Mountains Wilderness Study Area. Ore containing 175 short tons of copper and 514 troy oz of silver 

was produced from mines in the New Water Mountains, but 

there was no recorded production from the study area. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 81 
Mineral Resource Potential of the 

New Water Mountains Wilderness Study Area 

Areas having moderate and low resource potential for 

gold and silver are identified for the New Water Mountains 

Wilderness Study Area, and areas having low resource 

potential for copper, manganese, lead, zinc, geothermal 

energy, and oil and gas are also present (fig. 2). 

Paleozoic carbonate rocks crop out in the western part 

of the study area; similar strata outside the study area 

contain replacement-type gold and silver mineralization. 

Minor lead and zinc mineralization is associated with the 

gold and silver. Moderate resource potential for gold and 

silver and low potential for lead and zinc are assigned to 

these carbonate rocks in the northwestern part of the study 

area on the basis of geochemical anomalies in stream-sediment samples. 

Northeast of the study area, some Tertiary normal 

faults have associated gold, silver, copper, manganese, 

lead, and zinc mineralization, and these faults continue into 

the study area. Geochemical anomalies and mineralization 

are associated with these faults in and near the northeastern 

part of the study area. The area of these anomalies has 

moderate resource potential for gold and silver, and it has 

low resource potential for copper, manganese, lead, and 

330 

37' 

30" 

r-·- -· 

-·--·' 

Proposed additions to J 

KOFA NATIONAL 

WILDLIFE REFUGE r _J 

~-.J 

zinc. Geochemical anomalies also occur along Tertiary 

normal faults in the south-central part of the study area but 

no rock alteration or mineralization was noted there. The 

geochemically anomalous area in the south-central part of 

the study area is assigned low resource potential for gold, 

silver, lead, and zinc. 

Discontinuous, small quartz veins containing minor 

lead, zinc, copper, and gold are present in sedimentary 

rocks in the north-central part of the study area. These 

rocks have low resource potential for gold, silver, lead, and 

zinc. 

The resource potential for geothermal energy is low in 

the study area and limited to a zone along the major rangebounding fault separating the New Water Mountains from 

the Ranegras Plain in the eastern part of the study area. 

Aquifers in the Ranegras Plain contain low-temperature 

geothermal waters. The resource potential for oil and gas 

in the study area is low on the basis of unfavorable evidence regarding the presence of hydrocarbon source rocks. 

There is unknown resource potential for lime, which 

could be developed from inferred subeconomic resources 

of marble in Paleozoic rocks in the northwestern part of the 

study area. Although inferred subeconomic resources of 

sand and gravel occur in the study area, these resources are 

abundant closer to markets in the region. 

Figure 1. Index map showing location of New Water Mountains Wilderness Study Area, La Paz County, Arizona. 

82 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
INTRODUCTION 

This mineral survey was requested by the U.S. Bureau 

of Land Management and represents a cooperative effort by 

the U.S. Geological Survey and the U.S. Bureau of Mines. 

An introduction to the wilderness review process, mineral 

survey methods, and agency responsibilities is provided by 

Beikman and others (1983). The U.S. Bureau of Mines 

evaluates identified resources at individual mines and 

known mineralized areas by collecting data on current and 

past mining activities and through field examination of 

mines, prospects, claims, and mineralized areas. Identified 

resources are classified according to a system that is a 

modification of that described by McKelvey (1972) and the 

U.S. Bureau of Mines and U.S. Geological Survey (1980). 

Studies by the U.S. Geological Survey are designed to 

provide a scientific basis for assessing the potential for 

undiscovered mineral resources by determining geologic 

units and structures, possible environments of mineral 

deposition, presence of geochemical and geophysical 

anomalies, and applicable ore-deposit models. Mineral 

assessment methodology and terminology as they apply to 

these surveys were discussed by Goudarzi (1984 ). See 

appendixes for the definition of levels of mineral resource 

potential, certainty of assessment, and resource/reserve 

classification. 

Location and Physiography 

The New Water Mountains Wilderness Study Area 

(AZ-020-125) is in La Paz County, Ariz., about 10 mi 

southeast of Quartzsite, Ariz. (fig. 1). The New Water 

Mountains are in the Basin and Range physiographic province of southwestern Arizona, a part of the Sonoran Desert 

region of the southwestern United States and northern 

Mexico. The mountains are a southeast-trending prong of 

the Plomosa Mountains and are bounded on the northeast, 

east, and south by undissected alluvial fans of the Ranegras 

Plain and Alamo Wash. The study area has gentle relief 

except near the slopes of Black Mesa and along the rangefront faults. Elevations range from about 1,400 ft at the 

edge of the Ranegras Plain to 3,639 ft at the summit of 

Black Mesa. 

Access to the area consists of dirt roads that leave U.S. 

Interstate 10, 3 mi north of the study area, and a road that 

follows the El Paso natural gas pipeline right-of-way (pipeline road) on the south. The dirt roads diverge into several 

jeep trails that allow access along many of the arroyo 

floors. 

Previous and Present Investigations 

A large part of the study area was first mapped in 

detail by Miller (1966, 1970). Robison (1979, 1980) and 

Davis (1985) remapped and reinterpreted some critical 

contacts in Mesozoic rocks of the area. Harding (1978, 

1980, 1982) and Harding and Coney (1985) studied the 

Mesozoic McCoy Mountains Formation in the New Water 

Mountains and elsewhere and established the regional 

depositional setting for these strata. Reynolds and others 

(1986) assigned many of the thrust faults in the region 

(including those in the study area) to a belt of Late Cretaceous thrusting. 

The U.S. Geological Survey mapped the geology of 

the study area in 1984 and 1985 (Bagby and others, 1987) 

and sampled stream sediment and bedrock in 1984 (Adrian 

and others, 1987). In 1985, the U.S. Bureau of Mines 

mapped and sampled mines, prospects, and mineralized 

areas and reviewed U.S. Bureau of Land Management 

mining-claim and mineral-lease records and geologic literature. Details of the sampling procedures and results are 

presented in Lane (1986). 

Acknowledgments 

We gratefully acknowledge all logistical support and 

advice supplied by the manager and employees of the Kofa 

National Wildlife Refuge (U.S. Fish and Wildlife Service) 

during the fieldwork for this study. The U.S. Bureau of 

Mines thanks claim owner Robert Muller (Mammoth, 

Ariz.) and geologist Don Hammer (Newmont Exploration, 

Ltd., Tucson, Ariz.) for assistance and information concerning the Eagle Eye mine within the Moore patented 

claims. 

APPRAISAL OF IDENTIFIED RESOURCES 

By Michael E. Lane 

U.S. Bureau of Mines 

Methods of Investigation 

Two geologists spent 20 days examining mines and 

prospects inside and within approximately 1 mi of the study 

area boundary. Surface workings and accessible mines 

were surveyed, mapped, and sampled (Lane, 1986). 

A total of 151 samples was taken; 2 samples were from 

within the study area. Chip samples were taken across 

geologic structures and grab samples were taken from 

dumps. All samples were fire assayed for gold and silver; 

selected samples were analyzed by semiquantitative optical 

emission spectrographic methods for 40 elements and by 

atomic-absorption spectrometry for copper (Lane, 1986). 

Sample data are summarized in table 1, and complete analytical data for all samples are available for public inspection at the U.S. Bureau of Mines, Intermountain Field 

Operations Center, Building 20, Denver Federal Center, 

Denver, CO 80225. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 83 
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Area having moderate mineral resource potential (M) 

Area having low mineral resource potential (l) 

Area having unknown mineral resource potential (U) 

Levels of certainty of assessment 

Data not adequate for determination of potential 

Data give good indication of level of potential 

Data clearly define level of potential 

Commodities 

Ag Silver Geo Geothermal Pb Lead 

Au Gold L Lime O,G Oil, Gas 

Cu Copper Mn Manganese Zn Zinc 

Qa 

Ot 

Ta 

1tm 

Tb 

Trd 

Tts 

K..ms 

K.k'na 

EXPLANATION 

Geologic map units 

Alluvium (Quaternary) 

Talus deposits (Quaternary) 

Fanglomerate (Pliocene and Miocene) 

Basalt of Black Mesa (Miocene) 

Basalt (Miocene) 

Rhyolite and rhyodacite (Miocene) 

Tuff and tuffaceous sedimentary rocks (Miocene and Oligocene?)---lncludes sedimentary breccia at its base 

McCoy Mountains Formation (Cretaceous and 

Jurassic)-Divided into: 

Sandstone 

Quartz arenite 

Jqp, 

Pzs 

E?m 

0 

11 

2 3 MILES 

APPROXIMATE BOUNDARY 

OF 

NEW WATER MOUNTAINS 

ILDERNESS STUDY AREA 

(AZ-020-125) 

Geologic map units-ContinU£d 

Quartz porphyry and volcanic rocks (Jurassic) 

Sedimentary rocks (Paleozoic)-lncludes dolomite and 

marble 

Quartz monzonite (Proterozoic) 

Contact-Approximately located 

---L.- · · Fault-Dotted where concealed. Ball and bar on 

downthrown side 

• • • Thrust fault---Sawteeth on upper plate 

Wiill Sampled area-Numbers refer to table 1 

Figure 2. Mineral resource potential and generalized geology of New Water Mountains Wilderness Study Area, La Paz County, Arizona. Geology mapped by F.K. 

Miller, 1963-66, and by M.j. Grubensky, R.D. Koch, and D.R. Sherrod, 1984. 
History and Production 

Few mining claims are in the study area, according to 

U.S. Bureau of Land Management records. There are about 

200 unpatented claims nearby but outside the study area. 

The 23 Moore patented claims are adjacent to the northern 

boundary and include the Eagle Eye mine. Keith (1978) 

stated that ore totaling about 518 short tons (st) and containing 175 short tons of copper and 514 troy oz of silver 

was produced from mines in the New Water Mountains. 

Production and mining activity are summarized in table 1. 

Oil and gas leases are held on land about 1 mi northeast but do not extend into the study area. No geothermal 

leases are recorded near .or in the study area. The nearest 

geothermal well is 8 mi north in the Ranegras Plain 

(Witcher and others, 1982). 

Mineral Deposits 

There are no identified metallic mineral resources in 

the New Water Mountains Wilderness Study Area. Two 

small pits were found in the southeast comer of the study 

area but analyses of samples from them showed no significant metal content. 

With the possible exception of the Black Mesa mine 

and the Moore patented claims, there is no extension into 

the area of significantly mineralized occurrences or structures from outside the study area. Samples taken from the 

limestone-replacement deposits at the Black Mesa mine 

contain gold and silver-15 samples have silver contents 

ranging from 0.2 to 16.1 troy oz/st and 8 samples have gold 

contents ranging from 0.01 to 0.58 troy oz/st. The average 

gold content was 0.22 troy oz/st; however, if the highest 

content is ignored, the average gold content is only 0.09 

troy oz/st. Therefore, this deposit is considered subeconomic unless large tonnages are identified by additional 

work. Similar mineral occurrences could exist in the 

marble within the boundary, but no evidence of past mining 

activity exists within the study area. 

Near the Eagle Eye mine at the west end of the Moore 

patented claims, secondary copper minerals (mostly 

chrysocolla) are abundant in fractures and faults in rhyolite. 

The rhyolite extends into the study area and could be 

mineralized, but there is no evidence of past mining activity. Mapping, sampling, and drilling are necessary to determine the extent of any possible mineral occurrences. 

Of the 18 samples taken at the west end of the Moore 

claims, only 1 contains a trace of gold and 11 contain silver 

concentrations ranging from 0.1 to 1.6 troy oz/st. All 

samples contain copper, and the average concentration is 

1.1 weight percent; the highest value was 2.85 percent. 

Inferred subeconomic resources of marble in Paleozoic 

rocks could be developed for lime. The study area contains 

numerous inferred subeconomic resources of sand and 

gravel in dry washes. These resources have no unique 

characterisrics and can be· found in abundance closer to 

existing markets in the region. 

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL 

By David R. Sherrod, David B. Smith, Richard D. Koch, 

William F. Hanna, and james A. Pitkin 

U.S. Geological Survey 

Geology 

The New Water Mountains, in the southwestern part of 

the Basin and Range physiographic province, are a late 

Tertiary horst of Proterozoic to Tertiary igneous and sedimentary rocks (fig. 2). A Late Cretaceous thrust fault 

separates the pre-Tertiary rocks into two structural plates. 

Tertiary volcanism commenced in the Oligocene or early 

Miocene. Normal faulting, characteristic of basin-andrange tectonism, began about 20 million years ago (Ma) 

and created the New Water and southern Plomosa Mountains. 

Proterozoic quartz monzonite is the oldest rock unit 

exposed in the New Water Mountains Wilderness Study 

Area (Miller, 1970). The quartz monzonite is nonconformably overlain by Cambrian sedimentary rocks, which 

form the base of a northeast-striking, southeast-dipping 

homocline of sedimentary and volcanic strata that are Paleozoic and Mesozoic in age. The Paleozoic rocks include 

Devonian and Mississippian dolomite and marble that 

contain carbonate-replacement deposits of gold and silver 

at the Black Mesa and Six Price mines, outside the western 

and northern boundaries of the study area, respectively (fig. 

1). 

The pre-Tertiary rocks, which form the upper plate of 

the Poorman thrust (Reynolds and others, 1986), were 

folded, faulted, and metamorphosed to lower greenschist 

facies during Late Cretaceous thrusting (Harding and 

Coney, 1985; Reynolds and others, 1986; Sherrod and 

Koch, 1987). Penetrative deformation was slight, however, 

producing only a local, incipiently developed flat-lying 

cleavage. The structurally lower plate contains only Mesozoic sedimentary rocks in the study area. The Proterozoic, 

Paleozoic, and Mesozoic rocks were beveled during latest 

Late Cretaceous and early Tertiary erosion. 

The oldest Tertiary rocks in the study area comprise 

coarse sedimentary breccia, which overlies the pre-Tertiary 

rocks. The unit probably marks an Oligocene(?) or early 

Miocene episode of faulting and deposition, as interpreted 

from the poorly developed bedding of the breccia, the large 

clast size in the beds, and the abrupt termination of the 

breccia against older crystalline rocks. The upper part of 

the sedimentary breccia is interbedded with overlying silicic volcaniclastic rocks. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 85 
Table 1. Sampled areas in and near the New Water Mountains Wilderness Study Area, La Paz County, Arizona 

[Au, gold; Ag, silver; Cu, copper; Mn, manganese; Pb, lead; ppm, parts per million. Sample numbers refer to data tabulated by Lane (1986)] 

Map no. 

(fig. 2) 

2 

3 

4 

5 

6a, b 

7 

8a, b 

Locality 

Six Price 

mine area 

Poorman mine 

area 

Apache Chief 

mine area 

Black Mesa 

mine area 

Cave Creek 

area 

Summacy 

Sampled area consists of limestone, 

siltstone, quartzite, and granite country rock. NE- to NW -striking faults 

and quartz veins were sampled. All 

contain visible hematite, limonite, 

and calcite. 

Area consists mostly of quartzite, 

phyllite, and small exposures of 

shale and sandstone. Country rocks 

contain faults and/or associated 

quartz veins or stringers. Hematite, 

limonite, calcite, and minor 

chl}'socolla and malachite are present 

in structures. 

Area consists of limestone, sandstone, 

quartzite, and siltstone containing 

faults and quartz veins. Some faults 

occur along bedding planes. Visible 

minerals include malachite, chcysocolla, hematite, gypsum, and 

limonite. 

Samples 76-82 were collected from 

fault gouge and massive specularite/ 

quartz vein, both in diabase. 

Samples 83-101 were in limestone. 

Breccia and faults contain hematite, 

limonite, calcite, and vugs. Keith 

(1978) reports presence of cerussite, 

anglesite, · galena, chcysocolla, 

malachite, brochantite, native Cu, 

and cerargyrite. 

Alluvium in wash along Cave Creek. 

Shafts are about 50 ft deep. 

Near southeast Samples were collected at 2 isolated 

corner of pits in massive to fragmented valstudy area canic rocks. 

Eagle Eye 

mine area 

(Moore 

claims) 

Area composed mostly of Tertiacy andesite and rhyolite. Cu mineralization is associated with NW -trending 

faults. Mesozoic quartzite, shale, 

and siltstone crop out in small exposures near Eagle Eye mine. Cu 

minerals are predominantly chcysocolla, azurite, and malachite present 

in fractures, faults, and breccia 

zones. 

Workings 

Inclined shaft; 3 pits; 

2 shafts, 1 caved 

and 1 about 25 ft 

deep. 

2 inclined shafts, 2 

vertical shafts, 10 

pits, 1 adit, and 1 

trench. 

4 inclined shafts, 6 

vertical shafts, 6 

pits, 3 adits, 2 

trenches. 

1 vertical shaft, 5 pits, 

3 adits. 

6 shafts, 1 pit 

2 pits 

3 vertical shafts, 2 

adits, 13 pits, 1 

trench. 

East, west, 

and south 

of Ramsey 

mine 

4 samples (145-149) collected across 3 shafts, 3 pits 

faults containing minor chrysocolla 

in andesite and 1 of dump material. 

Samples 150-151 were of sandstone 

dump material. 

Sample and production data 

8 samples were collected on faults and/or quartz 

veins. Highest Au content is 0.04 oz/st in a chip 

sample collected over 1.9 ft; 4 samples contain trace 

Au. All samples were collected about 1/4 mi outside the study area. 

18 samples. 9 contain trace Au, 5 contain 0.1 oz/st 

Ag, 1 contains 60 ppm Cu. All samples were 

collected about 3/4 mi outside the study area. 

Worked between 1909 and 1911; produced about 

100 st of ore averaging 3.8 oz/st Au and 0.8 oz/st 

Ag (Keith, 1978). 

49 samples. 3 contain Ag above 1 oz/st: 9.2 oz/st in 

a grab sample, 2.3 oz/st in a chip sample collected 

over 1.3 ft, and 7.2 oz/st in a chip sample collected 

over 0.4 ft. Remaining samples contain less than 

0.4 oz/st Ag. The highest Au content is 0.01 oz/st 

in a chip sample collected over 1.3 ft. Remaining 

samples contain trace or undetectable Au. 3 

samples contain Cu: 3.2 percent, 0.35 percent, and 

0.39 percent. Samples were collected 1/4 to 1 mi 

outside the study area. 

26 samples. Of 6 samples collected in diabase 

country rock, all but 2 contain trace Au; Ag (0.20 

oz/st) is contained in only 1 sample. Of 19 samples 

collected in limestone, the highest Au content is 

0.58 oz/st in a chip sample collected over 5.5 ft, 

and the highest Ag content is 16.1 oz/st in a chip 

sample collected over 2.4 fL 14 samples contain a 

trace or more Au, and 15 samples contain 0.3 oz/st 

or more Ag. Samples were collected just outside 

the study area. From 1940's to 1964, production 

was 51 tons of ore averaging 25 percent Pb, 13 oz/ 

st Ag, 2 percent Cu, 0.02 oz/st Au (Keith, 1978). 

7 samples collected. None contains detectable Au, 

Ag, or other metals. 

2 samples collected; neither contains detectable Au, 

Ag, or other metals. 

34 samples collected. 3 contain Au (trace, trace, 0.01 

oz/st). 25 samples contain Ag: the highest value is 

1.6 oz/st in a chip sample collected over 2.5 ft and 

the lowest is 0.1 oz/st. Cu was detected in all 

samples; the highest value is 3.3 percent in a chip 

sample collected over 2.6 ft, and the lowest value is 

23 ppm. Keith (1978) reported that 480 tons of 

3.7-percent Cu ore were shipped from 1941-1944. 

6 samples collected. 5 contain detectable Au (0.01 

oz/st, 4 contain trace) and Ag (6.4 oz/st in a chip 

sample collected over 1 ft is the highest and 0.4 oz/ 

st is the lowest). 4 samples contain Cu: from 5.8 

percent in a chip sample collected over 1 ft to 1.48 

perce?t. 

86 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
Volcanism commenced in the New Water Mountains 

with the eruption of basaltic lava flows and rhyolitic domes 

and flows about 23-20 Ma. Pyroclastic flows were a minor 

part of this volcanism. 

Fanglomerate overlies the volcanic sequence and all 

older units on the the south, east, and north sides of the 

study area, and it is locally overlain by Miocene basalt that 

caps Black Mesa. Where not overlain by the basalt of 

Black Mesa, the fanglomerate forms moderately dissected 

hills. 

The basalt of Black Mesa is a sequence of lava flows 

that erupted about 17 Ma (Shafiqullah and others, 1980). 

This is the youngest volcanic sequence in the study area. 

Sedimentation may have continued for a while after the 

eruption of the basalt of Black Mesa, but the region is now 

being eroded and dissected by intermittent streams that 

connect with the Colorado River. 

Northwest-trending, steep to vertical normal faults 

bound the northeast margin of the New Water Mountains, 

and most have down-to-the-northeast displacements. As a 

result of the faulting, the Tertiary units dip 6°-30° southwest. The range-bounding faults probably formed as part 

of basin-and-range extensional tectonism that affected 

much of southwestern Arizona (for example, Eberly and 

Stanley, 1978; Spencer and Reynolds, 1986). Several 

mines and mineralized areas are located along these faults 

1-3 mi northeast of the study area. 

Geochemical Studies 

Methods of Investigation 

A reconnaissance geochemical survey was conducted 

in the New Water Mountains Wilderness Study Area in 

1984 as part of a U.S. Geological Survey mineral resource 

assessment study of the Kofa National Wildlife Refuge and 

its proposed additions. Minus-80-mesh stream sediments 

and heavy-mineral concentrates derived ·from stream sediments were selected as the primary sample media because 

they represent a composite of rock and soil exposed in the 

drainage basin upstream from the sample site. Chemical 

analysis of the sediment samples helps to identify basins 

containing unusually high concentrations of elements that 

may be related . to mineral occurrences. Heavy-mineral 

concentrates are a useful sample medium in arid environments or in areas of rugged topography, where mechanical 

erosion predominates over chemical erosion (Bugrov and 

Shalaby, 1975; Overstreet and Marsh, 1981; Zeegers and 

others, 1985). 

Samples were analyzed for 31 elements including 

antimony, barium, cadmium, cobalt, chromium, copper, 

gold, iron, lead, magnesium, manganese, molybdenum, 

nickel, silver, thorium, tin, titanium, tungsten, vanadium, 

and zinc by semiquantitative emission spectroscopy. This 

method allows the rapid and economical analysis of numerous samples, but the lower limits of determination for many 

elements are somewhat high. Therefore, the following 

elements were analyzed by atomic absorption, which lowers the determination limit to less than 1 part per million 

(ppm) for most of them: antimony, arsenic, bismuth, 

cadmium, gold, mercury, silver, tellurium, thallium, and 

zinc. 

In this study the nonmagnetic fraction of the heavymineral concentrates was analyzed. This fraction concentrates ore and ore-related minerals such as pyrite, galena, 

cassiterite, sphalerite, chalcopyrite, stibnite, free gold, barite, and scheelite to permit determination of some elements 

that are not easily detected in bulk stream-sediment 

samples. 

Stream-sediment samples and heavy-mineral concentrates were collected from active alluvium in first-order 

(unbranched) and second-order (below the junction of two 

first-order) streams, as shown on U.S. Geological Survey 

topographic maps (scale 1:62,500). Rock samples for 

chemical analysis were collected both in and near the study 

area. Unaltered samples were collected to provide information on geochemical background concentrations, whereas 

samples from mines, prospects, and altered areas were 

collected to determine suites of elements associated with 

mineralization and alteration. Analytical data, sampling 

methods, sample preparation procedures, ~nalytical techniques, and sampling sites are presented in Adrian and 

others (1987). 

Summary of Results 

Three anomalous areas were defined as a result of the 

geochemical survey. An area in the northwestern part of 

the study area was defined by geochemically anomalous 

samples from streams that drain the west half of Black 

Mesa. This first area was delineated on the basis of streamsediment samples containing anomalous amounts of gold 

(0.068 ppm, in only one sample), silver (as much as 0.35 

ppm), zinc (270 ppm in one sample), and arsenic (20-30 

ppm). Nonmagnetic heavy-mineral concentrates contain 

anomalous amountS of silver (as much as 10 ppm), lead (as 

much as 10,000 ppm), and zinc (as much as 10,000 ppm). 

A sample of altered, limonite-bearing brecciated dolomite 

collected on the west flank of Black Mesa contains high 

concentrations of gold (0.7 ppm), silver (100 ppm), arsenic 

(510 ppm), antimony (650 ppm), mercury (greater than 10 

ppm), bismuth (100 ppm), copper (1,500 ppm), lead (5,000 

ppm), and zinc (7,000 ppm). A quartz vein sample with 

iron and copper stains, collected on the northern flank of 

Black Mesa approximately 0.5 mi north of the study area 

boundary, contains high concentrations of gold (0.6 ppm), 

silver (5 ppm), arsenic (680 ppm), antimony (greater than 

1,000 ppm), tungsten (25 ppm), zinc (7,000 ppm), bismuth 

(200 ppm), copper (2,000 ppm), and lead (greater than 

20,000 ppm). These anomalies probably indicate sedimenMineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 87 
tary rock-hosted gold and silver mineralization and (or) 

epithermal copper, lead, zinc, gold, and silver (base- and 

precious-metal) mineralization. The Black Mesa and Six 

Price mines lie in this same anomalous area just outside the 

western and northern study area boundaries. 

A second geochemically anomalous area lies along the 

south-central part of the study area and extends southeast 

beyond the study area boundary. This area was delineated 

on the basis of stream-sediment samples containing anomalous amounts of arsenic (20-30 ppm) and antimony (as 

much as 26 ppm), and nonmagnetic heavy-mineral concentrates containing anomalous values of arsenic (500-7 ,000 

ppm). These anomalies suggest the presence of epithermal 

base- and precious-metal mineralization along middle to 

late Tertiary normal faults. 

A third geochemically anomalous area lies in the 

northeast corner of the study area near the Eagle Eye mine. 

This area was delineated on the basis of stream-sediment 

samples containing low-level anomalies of arsenic (20 

ppm), zinc (as much as 220 ppm), and silver (as much as 

0.15 ppm) and nonmagnetic heavy-mineral concentrates 

containing anomalous concentrations of arsenic (500 ppm 

in one sample) and lead (as much as 2,000 ppm). A sample 

of copper-stained quartzite breccia at the Eagle Eye mine 

contains high amounts of silver (30 ppm), arsenic (970 

ppm), antimony (180 ppm), zinc (160 ppm), copper (2,000 

ppm), lead (700 ppm), and gold (0.05 ppm). As in the 

second area, these anomalies suggest epithermal gold, silver, copper, lead, and zinc mineralization. 

Geophysical Studies 

Gravity and Aeromagnetics 

The New Water Mountains Wilderness Study Area is 

covered by regional gravity (Lysonski and others, 1980; 

Aiken and others, 1981; U.S. Defense Mapping Agency 

Aerospace Center, 1974, 1975) and magnetic (LKB Resources, Inc., 1980) surveys having sufficient resolution to 

define anomalies as large as or larger than several square 

miles. Contours of complete (temain-corrected) Bouguer 

gravity anomalies are defined by about 30 stations surrounding the study area, most of which are on the Ranegras 

Plain to the northeast. Contours of total-field magnetic 

anomalies are defined by measurements made along four 

east-west lines and three north-south lines, all at a nominal 

altitude of about 400 ft above ground. Flightlines were 

flown about 3 mi apart and intersecting tielines were flown 

about 12 mi apart. Contractor-reduced data east of longitude 114° W. were reprocessed during this study to incorporate a more accurate geomagnetic reference field and to 

smooth the effects of flightline location errors. Contours 

derived from this reprocessing were later visually merged 

with contours west of longitude 114° W. 

A prominent gravity high (fig. 3) in the Plomosa and 

New Water Mountains is associated with fairly dense 

Proterozoic, Paleozoic, and Mesozoic metamorphosed intrusive and .. sedimentary rocks. · Gravity anomaly values 

decrease gently to the southeast where Tertiary volcanic 

rocks of the New Water Mountains crop out and decrease 

more rapidly to the northeast where Tertiary and Quaternary alluvium form the Ranegras Plain. Our model of the 

gravity data suggests that the alluvium reaches a thickness 

of 600 ft adjacent to the study area, and it is likely thicker 

than 1,300 ft in the center of the Ranegras Plain. This 

model assumes a density contrast of 0.35-0.40 grams/cubic 

centimeter between · the basin fill and bounding rocks, 

which is consistent with the analysis by Oppenheimer and 

Sumner (1980). 

The aeromagnetic anomaly map (fig. 4) shows broadly 

northwest-trending contours that slope down to the southwest The prominent magnetic high in the northeast corner 

of figure 4 corresponds to the Bear Hills (fig. 1), a northwest-trending fault block of Tertiary volcanic (chiefly 

basalt) and sedimentary rocks (R.D. Koch, unpublished 

data, 1985). Our modeling suggests that the source there 

could have an average total magnetization (scalar sum of 

induced and normally polarized remanent magnetization) of 

about 4.5 Amperes/meter and a ratio of remanent to induced magnetization of about 0.12-that is, about twice as 

magnetic as some altered basalts or unaltered basaltic 

andesite of southwestern Arizona (Klein and Johnson, 

1983) but only half as magnetic as some unaltered basalt 

from other parts of Arizona and New Mexico. The aeromagnetic data suggest that the volcanic rocks of the Bear 

Hills extend along strike to the southeast beneath a shallow 

cover of alluvium in the Ranegras Plain. 

The gravity and magnetic anomaly data are much too 

sparsely distributed to permit correlation of anomalies with 

mineral occurrences associated with mines and prospects 

adjacent to the study area. In the regional geophysical data, 

known mineral occurrences tend to underlie flanks of 

anomalies instead of the anomaly maxima or minima. Because nothing more definitive than this gross correlation 

can be ascertained, the regional geophysical data do not 

point to mineral occurrences within the study area. 

Gamma-Ray Spectrometry 

Knowledge of natural radioelement distribution in the 

New Water Mountains Wilderness Study Area is based on 

aerial gamma-ray spectrometry surveys of the Phoenix and 

Salton Sea 1 o x 2° quadrangles (LKB Resources, Inc., 

1980). These surveys acquired gamma-ray data along 3-

mi-spaced east-west (Phoenix) and north-south (Salton Sea) 

flightlines at 400 ft above ground level. These flightlines 

provided only about 6 percent coverage of each quadrangle 

because a detector flown at 400 ft measures gamma radiation from an 800-ft-wide swath along a flightline. The 

coverage represents a reconnaissance sampling of the nearsurface (0- to 1- in. depth) distribution of the natural radioelements potassium (K), uranium (eU), and thorium (eTh). 

88 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
The prefix "e" (for equivalent) denotes the potential for 

disequilibrium in the uranium and thorium decay series. 

The New Water Mountains are characterized by radioelement concentrations of 1.0-2.5 percent K, 3-5 ppm eU, 

and 6-12 ppm eTh. These concentrations are expected 

levels for the Proterozoic and Phanerozoic sedimentary and 

igneous rocks that crop out in the study area. Generally, 

the higher concentrations relate to more silicic, more radioactive igneous rocks and detritus derived from them; lower 

concentrations relate to less silicic, less radioactive igneous 

rocks and their detritus. The sparse flightline coverage of 

the study area precludes making a more specific assessment 

of the mineral resource potential from the aerial gamma-ray 

data. 

Electrical Geophysics 

Electrical (telluric) geophysical survey lines that 

crossed the northern boundary of the study area indicate 

that some faults in Tertiary rocks extend slightly beyond 

their inferred limits shown on figure 2 (D.B. Hoover, written commun., 1988). The data also indicate greater structural complexity than can be shown in the McCoy Mountains Formation. It is perhaps surprising that there is virtually no electrical signature of the main northwest-trending fault that separates Tertiary volcanic rocks from the 

McCoy Mountains Formation at the two points where the 

telluric lines cross the fault (D.B. Hoover, written commun., 1988). No lines traversed this fault where it is 

mineralized (for example, at the Ramsey mine). 

Mineral and Energy Resources of the 

New Water Mountains Wilderness Study Area 

Sedimentary-Rock.Hosted Gold and Silver 

The Black Mesa and Six Price mines, which are near 

the western and northern boundaries of the study area, 

respectively, were excavated along polymetallic carbonatereplacement deposits developed in Paleozoic marble and 

dolomite (Bagby and others, 1987, domain Ill). These 

mines yielded a low tonnage of gold and silver ore with byproduct lead and copper (Keith, 1978). The dolomite and 

114°05' 114°00' 113°55' 113°50' ~0~-r~T-r--------r~r-r--r~.-----------~--~----~~~~-.-,--~~~--~~~~ 

40' 

33° 

35' 

~0 

0 

APPROXIMATE 

BOUNDARY OF 

NEW WATER MOUNTAINS 

WILDERNESS STUDY AREA 

(AZ-020-125) 

• 

2 

3a ~------------~----------~----------~------------L-----------------~----~ 

Figure 3. Complete Bouguer gravity anomaly map of New Water Mountains Wilderness Study Area. Contour 

interval 1 milligal. Hachures indicate area of lower anomaly values; dots indicate gravity stations. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 89 
marble extend into the western part of the study area and 

probably continue under Black Mesa, but they are cut off 

at shallow depths by the Poorman thrust, which projects to 

the surface on the south slope of Black Mesa (Miller, 1970; 

Reynolds and others, 1986; Sherrod and Koch, 1987). 

The western part of the study area is defined as having 

anomalous gold, silver, zinc, arsenic, and lead concentrations on the basis of stream-sediment samples and heavymineral concentrates. Field evidence indicates that the 

mineralization is spotty and discontinuous at the surface 

(Keith, 1978; this report). A moderate resource potential, 

certainty level C, for sedimentary-rock-hosted gold and silver is assigned to the northwestern part of the New Water 

Mountains Wilderness Study Area, corresponding to the 

area underlain by Paleozoic carbonate rocks (fig. 2). Any 

deposits that are present will most likely be small and 

a 

33° 

difficult to prospect, even using sophisticated geophysical 

methods. 

Epithermal Gold and Silver 

Gold and silver mineralization is found at several 

places along or near range-bounding normal faults outside 

the northeastern boundary of the study area. These deposits 

are epithermal and probably formed by water-dominated 

geothermal systems; the faults provided avenues for the 

upwelling hot water (Bagby and others, 1987, domain II 

and unspecified domain for polymetallic veins). Geochemical anomalies and field evidence indicate that alteration and mineralization extend along faults into two parts of 

the study area. 

113° 55' 113° 50' 

30'~--------------------~~~~~--~------------------~~------~--~------------~ 

0 2 3 MILES 

Figure 4. Aeromagnetic anomaly map of New Water Mountains Wilderness Study Area. Contour interval 20 nanoteslas. 

810 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
The first area is in the northeastern part of the study 

area, near the Eagle Eye mine (fig. 1) (the mine is outside 

the study area). Sediment samples from drainages in this 

area have low-level anomalies for arsenic, silver, and zinc; 

the heavy-mineral concentrates contain anomalous concentrations of arsenic and lead. Some of the rhyolite in this 

area is visibly altered, and one rock sample contains 

anomalous concentrations of silver, arsenic, lead, manganese, and. copper. The alteration forms narrow zones along 

normal faults. This area is assigned a moderate resource 

potential, certainty level C, for gold and silver (fig. 2). 

The second area parallels a normal fault in the southcentral part of the study area. This area is not visibly 

altered, but sediment and concentrate samples from several 

drainages that cross the fault have geochemical anomalies 

for arsenic and silver, as discussed in the "Geochemistry" 

section. Because the area lacks visible signs of alteration 

or mineralization, it is assigned a low potential, certainty 

level C, for gold and silver (fig. 2). 

A third area is delineated on the basis of stream-sediment samples containing anomalous concentrations of gold, 

silver, zinc, and arsenic. This area lies in the northwestern 

part of the study area, and has moderate potential for gold 

and silver, certainty level C. 

A fourth area was delineated on the basis of copperstained quartz veins distributed sporadically in the Mesozoic McCoy Mountains Formation south of the Ramsey 

mine (fig. 1). Shallow prospecting holes have been dug 

along veins containing small amounts of pyrite, galena, 

sphalerite, and copper-bearing minerals; the pyrite may be 

auriferous. The veins could be either epithermal or metamorphic in origin (Bagby and others, 1987, domain II or 

VII) and are probably the source of the geochemical 

anomalies in sediment and concentrate samples collected 

from the area. Minus-80-mesh sediment from this area 

contains slightly anomalous amounts of arsenic and zinc; 

some of the heavy-mineral concentrates contain lead. Gold 

was detected in trace amounts in one sample of sediment. 

These veins are small, irregular, and discontinuous. A low 

resource potential for gold and silver, certainty level D, is 

assigned to the area underlain by the McCoy Mountains 

Formation northeast of Black Mesa (fig. 1), in the northcentral part of the study area (fig. 2). 

Copper and Manganese 

Copper mineralization in and near the study area is 

spotty and scattered but it locally forms small high-grade 

chimneys of ore-grade copper deposits in fracture veins and 

pipes in the Tertiary volcanic rocks just beyond the north 

and east margins of the study area and in the northeastern 

corner of the study area (Keith, 1978; this report). Sooty 

manganese oxides coat many fracture surfaces in this area 

but form small deposits. The northeastern part of the study 

area is assigned a low resource potential, certainty level C, 

for copper and manganese (fig. 2). 

Lead and Zinc 

Lead and zinc, chiefly in galena and sphalerite, respectively, are present in very small amounts with the gold, 

silver, copper, and manganese mineralization of the study 

area. Anomalous concentrations of lead and zinc are 

contained in sediment samples and heavy-mineral concentrates from many gulleys that drain mineralized areas. The 

mineralized areas are small and discontinuous. For these 

reasons, a low resource potential for lead and zinc, certainty level C, is assigned to those parts of the study area 

that have resource potential for gold, silver, copper, and 

manganese (fig. 2). 

Geothermal Energy 

The New Water Mountains are in the Basin and Range 

physiographic province, which is characterized by high 

regional heat flow. Heat-flow values of 101 milliwatts per 

square meter (mW/m2

) were measured 20 mi west of the 

study area and values of 100-150 mW/m2 were measured 

80 mi east (Muffler, 1979). The Ranegras Plain, which 

borders the New Water Mountains on the northeast, is 

considered "favorable for the discovery and development 

of local sources of low-temperature (less than 90 °C) geothermal water, (Sammet, 1979). The Ranegras Plain contains no thermal springs, but shallow wells (80- to 1,000-ft 

deep) have tapped water with temperatures of 27-35 °C. 

The water, heated during deep circulation, probably rises 

along range-bounding faults. Water of such low temperature could be used in space heating, agriculture, and perhaps industry. No igneous-related geothermal systems 

occur within 100 mi of the study area (Muffler, 1979). 

Thermal aquifers of the Ranegras Plain lie chiefly in 

Tertiary and Quaternary alluvial fill and are outside the 

study area. The major range-bounding fault along the 

northeast margin of the study area conceivably may have 

thermal fluids convecting near it on the basis of its proximity to the Ranegras Plain. Therefore, a low potential, certainty level C, for geothermal energy is assigned to the area 

northeast of that fault along the eastern boundary of the 

study area (fig. 2). 

Oil and Gas 

The New Water Mountains Wilderness Study Area is 

in a part of the Basin and Range physiographic province 

that is considered to have low or zero potential for oil and 

gas (Ryder, 1983). There are no tar or oil seeps, black 

shales, or other evidence of hydrocarbon source beds in the 

exposed sedimentary strata of the study area. The Paleozoic marine rocks exposed there are thin and structurally 

disrupted by the thrust faults of the Maria fold belt (Reynolds and others, 1986). The Mesozoic rocks, though 

chiefly deposited subaerially, include lacustrine rocks as 

well. The lacustrine strata contain some fossil sponges, 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 811 
fish scales, and gastropod remains (Miller, 1966; Sherrod 

and Koch, 1986), but they are not notably fossiliferous and 

are also structurally disrupted. The Tertiary alluvial fill of 

Ranegras Plain may have limited potential for oil or gas, 

but these rocks abut the New Water Mountains and do not 

extend beneath them. 

Oil plays would be based on the possibility of preTertiary source rocks underlying the thrust faults in the 

study area, for which there is no geologic or geophysical 

evidence. Therefore, the New Water Mountains Wilderness Study Area has low potential, certainty level C, for oil 

and gas resources (fig. 2). 

Lime 

Lime (from limestone or marble) is used for agricultural purposes and for the production of cement, but its 

bulk and low unit value limit the distance over which it can 

be transported economically. Also, the purity of lime is an · 

important consideration to its resource potential. 

Dolomite and marble form part of the Paleozoic sedimentary sequence exposed in the northwest part of the 

study area. They were not analyzed for this study. Therefore, there is unknown resource potential, certainty level A, 

for lime assigned to the northwestern part of the study area 

(fig. 2). Regardless of purity, the dolomite and marble are 

subeconomic at this time. 

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and ore deposits of Arizona and the southwest: Arizona 

Geological Society Digest, v. 16, p. 35-51. 

Robison, B.A., 1979, Stratigraphy and petrology of some Mesozoic rocks in western Arizona: Tucson, Ariz., University of 

Arizona, M.S. thesis, 154 p. 

---1980, Description and analysis of Mesozoic "Red Beds," 

western Arizona and southeastern California, in Jenney, J.P., 

and Stone, Claudia, eds., Studies in western Arizona: Arizona 

Geological Society Digest, v. 12, p. 147-154. 

Ryder, R.T., 1983, Petroleum potential of wilderness lands in 

Arizona, in Petroleum potential of wilderness lands in the 

western United States: U.S. Geological Survey Circular 902, 

p. C1-C22. 

Sammel, E.A., 1979, Occurrence of low-temperature geothermal 

waters in the United States, in Muffler, L.J.P., ed., Assessment of geothermal resources of the United States-1978: 

U.S. Geological Survey Circular 790, p. 86-131. 

Shafiqullah, M., Damon, P.E., Lynch, D.J., Reynolds, S.J., 

Rehrig, W.A., and Raymond, R.H., 1980, K-Ar geochronology and geologic history of southwestern Arizona and adjacent areas: Arizona Geological Society Digest, v. 12, p. 

201-260. 

Sherrod, D.R., and Koch, R.M., 1987, Structure and stratigraphy 

of Mesozoic sedimentary and volcanic rocks in the New 

Water Mountains, southwestern Arizona, in Dickinson, W.R., 

and Klute, M.A., eds., Mesozoic rocks of southern Arizona 

and adjacent areas: Arizona Geological Society Digest, v. 18, 

p. 81-90. 

Spencer, J.E., and Reynolds, S.J., 1986, Some aspects of the 

middle Tertiary tectonics of Arizona and southeastern 

California, in Beatty, Barbara, and Wilkinson, P.A.K., eds., 

Frontiers in the geology and ore deposits of Arizona and the 

southwest: Arizona Geological Society Digest, v. 16, p. 

102-107. 

U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. 

Geological Survey Circular 831, 5 p. 

U.S. Defense Mapping Agency Aerospace Center, 1974, World 

relative gravity reference network, North America, pt. 2: U.S. 

Defense Mapping Agency Aersopace Center Reference Publication 25, with supplement updating gravity values to the 

International Gravity Standardization Net 1971, 1635 p. 

U.S. Defense Mapping Agency Aerospace Center, 1975, Holding, 

storage, and retrieval of gravity data: U.S. Defense Mapping 

Agency Aerospace Center Publication RP-75-003, 33 p. 

Witcher, J.C., Stone, Claudia, and Hahman, W.R., Sr., 1982, Geothermal resources of Arizona: Arizona Bureau of Geology 

and Mineral Technology, scale 1:500,000. 

Zeegers, H., AI Shanfari, S.M., AI Muflehi, Y.A., and Letalenet, 

J., 1985, Aspects of regional geochemical prospecting in 

desert conditions, in Prospecting in areas of desert terrain: 

London, The Institution of Mining and Metallurgy, p. 

131-140. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 813 
APPENDIXES 
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT 

LEVELS OF RESOURCE POTENTIAL 

H HIGH mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate a high degree of likelihood for resource accumulation, where data support mineral-deposit models 

indicating presence of resources, and where evidence indicates that mineral concentration has taken place. 

Assignment of high resource potential to an area requires some positive knowledge that mineral-forming processes 

have been active in at least part of the area. 

M MODERATE mineral resource potential is assigned to areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate reasonable likelihood for resource accumulation, and (or) where an application of mineral-deposit models 

indicates favorable ground for the specified type(s) of deposits. 

L LOW mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics 

define a geologic environment in which the existence of resources is permissive. This broad category embraces 

areas with dispersed but insignificantly mineralized rock, as well as areas with little or no indication of having 

been mineralized. 

N NO mineral resource potential is a category reserved for a specific type of resource in a well-defined area. 

U UNKNOWN mineral resource potential is assigned to areas where information is inadequate to assign a low, 

moderate, or high level of resource potential. 

LEVELS OF CERTAINTY 

A Available information is not adequate for determination of the level of mineral resource potential. 

B Available information only suggests the level of mineral resource potential. 

C Available information gives a good indication of the level of mineral resource potential. 

0 Available information clearly defines the level of mineral resource potential. 

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UNKNOWN POTENTIAL 

Abstracted with minor modifications from: 

B c 

H/B H/C 

HIGH POTENTIAL HIGH POTENTIAL 

M/B M/C 

MODERATE POTENTIAL MODERATE POTENTIAL 

L/B uc 

LOW POTENTIAL LOW POTENTIAL 

LEVEL OF CERTAINTY .... 

D 

H/D 

HIGH POTENTIAL 

M/D 

MODERATE POTENTIAL 

L/D 

LOW POTENTIAL 

N/D 

NO POTENTIAL 

Taylor, R.B., and Steven, T.A., 1983, Definition of mineral resource potential: Economic Geology, v. 78, no. 6, p. 1268-1270. 

Taylor, R.B., Stoneman, R.J., and Marsh, S.P., 1984, An assessment of the mineral resource potential of the San Isabel National Forest, south-central Colorado: U.S. 

Geological Survey Bulletin 1638, p. 40-42. 

Goudarzi, G.H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S. Geological Survey Open-File Report 84-0787, p. 7, 8. 

816 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
RESOURCE/RESERVE CLASSIFICATION 

IDENTIFIED RESOURCES UNDISCOVERED RESOURCES 

Demonstrated Probabi I ity Range 

Inferred 

Measured Indicated Hypothetical Speculative 

I Inferred 

I 

ECONOMIC Reserves 

Reserves 

I - I ~---~---- r---------- -~-

MARGINALLY Marginal Inferred 

Marginal ECONOMIC Reserves Reserves 

I - I 

----,----r---------- -~-

SUB- Demonstrated Inferred 

Subeconomic Subeconomic 

ECONOMIC Resources Resources I I I 

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from McKelvey, V.E., 1972, Mineral 

resource estimates and public policy: American Scientist, v. 60, p. 32-40; and U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles 

of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p. 5. 

Mineral Resources of the New Water Mountains Wilderness Study Area, La Paz County, Arizona 817 
GEOLOGIC TIME CHART 

Terms and boundary ages used by the U.S. Geological Survey in this report 

EON ERA PERIOD EPOCH 

Quaternary 

Holocene 

Pleistocene 

Neogene Pliocene 

Cenozoic Subperiod Miocene 

Tertiary Paleogene Oligocene 

Subperiod Eocene 

Paleocene 

Cretaceous Late 

Early 

Late 

Mesozoic jurassic Middle 

Early 

Late 

Triassic Middle 

Early 

Permian Late 

Phanerozoic Early 

Late 

Pennsylvanian Middle 

Carboniferous Early Periods 

Mississippian Late 

Early 

Late 

Devonian Middle 

Paleozoic Early 

Late 

Silurian Middle 

Early 

Late 

Ordovician Middle 

Early 

Late 

Cambrian Middle 

Early 

Late Proterozoic 

Proterozoic Middle Proterozoic 

Early Proterozoic 

Late Archean 

Archean Middle Archean 

Early Archean 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (3800?)- - - - - - - - - - - - - - - - - -

pre-Archean2 

1Rocks older than 570 Ma also called Precambrian, a time term without specific rank. 21nformal time term without specific rank. 

818 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma) 

0.010 

1.7 

5 

24 

38 

55 

66 

r---- 96 

138 

205 

-240 

290 

-330 

360 

410 

435 

500 

1

-570 

900 

1600 

2500 

3000 

3400 

4550 

GPO 685-041/9797 
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

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prices charged may differ from the prices in catalogs, announcements, 

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