Mineral Resources of the Funeral 

Mountains Wilderness Study Area, 

Inyo County, California

U.S. GEOLOGICAL SURVEY BULLETIN 1709-A

ERRATA FOR U.S. GEOLOGICAL SURVEY BULLETIN 1709-A

 In the Abstract, on page A1, line 20 should read "the potential for borate 

resources is moderate."

 In the Abstract, line 25 should read "There is high mineral resource

potential for limestone, quartzite, and sand and gravel in the study area; 

however, there is little likelihood that these deposits will ever be 

exploited due to their distance from current markets."

 In the "Mineral Resource Potential Section" of the Summary, on page A3, the 

second paragraph should read "Those parts of the study area (fig. 2) 

composed of Quaternary alluvium (Qa) and Tertiary conglomerate (Tc) have a 

high resource potential for sand and gravel. Those parts of the study 

area composed of Devonian to Cambrian age limestone (Pzl) have a high 

resource potential for limestone and quartzite."

 In the "Mineral Resource Potential" section of the Summary, on page A3, the 

last sentence should have the word "coal" deleted from it.

 In the "Mineral and Energy Resources" section, the last line on page A8 and 

the first line on page A9 should read "Although limestone, quartzite, and 

sand and gravel are abundant in the study area, there is little likelihood 

that these deposits will be exploited as they are too far from current 

markets."

 In the "Conclusions" section, the second to the last paragraph on page A10 

should read "Limestone, quartzite, and sand and gravel are abundant in the 

study area, and there is high potential for undiscovered resources of 

these commodities, certainty level D; however, there are economic factors 

that could affect their development, and these are treated elsewhere in 

this report."

Chapter A

Mineral Resources of the

Funeral Mountains Wilderness Study Area,

Inyo County, California

By AUGUSTUS K. ARMSTRONG, JAMES G. FRISKEN, 

and ROBERT C. JACHENS 

U.S. Geological Survey

TERRY R. NEUMANN 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1709

MINERAL RESOURCES OF WILDERNESS STUDY AREAS:

NORTHEASTERN CALIFORNIA DESERT CONSERVATION AREA, CALIFORNIA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1987

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 Funeral Mountains 

Wilderness Study Area, Inyo County, California.

U.S. Geological Survey Bulletin 1709-A

Bibliography

Supt. of Docs. No.: I 19.3:1709-A

1. Mines and mineral resources California Funeral

Mountains Wilderness. 2. Geology California Funeral

Mountains Wilderness. 3. Funeral Mountains Wilderness

(Calif.) I. Armstrong, Augustus K. II. Series.

QE75.B9 No. 1709-A 557.3 s 86-600290

[TN24.C21 [557.94'87]
STUDIES RELATED TO WILDERNESS

Bureau of Land Management Wilderness Study Area

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 

mineral surveys on certain areas to determine the mineral values, if any, that may be 

present. Results must be made available to the public and be submitted to the President 

and the Congress. This report presents the results of a mineral survey of the Funeral 

Mountains Wilderness Study Area (CDCA-143), California Desert Conservation Area, 

Inyo County, California.

CONTENTS

Summary Al

Abstract 1

Character and setting 1 

Identified resources 1 

Mineral resource potential 3 

Introduction 3

Area description 3 

Previous and present investigations 3 

Appraisal of identified resources 3 

Mining history 3

Mines, prospects, and mineralized zones 6 

Conclusions 6

Assessment of undiscovered resources 6 

Geologic setting 6 

Structural geology 7 

Stratigraphy 7 

Geophysics 7 

Geochemistry 8 

Mineral and energy resources 8 

Bentonite and zeolite 8 

Limestone, quartzite, and sand and gravel 8 

Base and precious metals 9

Model for strata-bound lead-zinc deposits 9 

Model for mesothermal-epithermal gold, copper, and lead-zinc 9 

Boron 9

Other commodities 9 

Conclusions 9 

References cited 10 

Appendix 1. Definition of levels of mineral resource potential and levels of certainty 15

FIGURES

1. Index map showing location of the Funeral Mountains Wilderness Study Area, Inyo 

County, California A2

2. Mineral resource potential map of the Funeral Mountains Wilderness Study Area, 

Inyo County, California 4

3. Major elements of mineral resource potential/certainty classification 15

Table

1. Mines, prospects, and mineralized zones in and adjacent to the Funeral Mountains 

Wilderness Study Area, Inyo County California A12

MINERAL RESOURCES OF WILDERNESS STUDY AREAS:

NORTHEASTERN CALIFORNIA DESERT CONSERVATION AREA, CALIFORNIA

Mineral Resources of the

Funeral Mountains Wilderness Study Area,

Inyo County, California

By Augustus K. Armstrong, James G. Frisken, and Robert C. Jachens 

U.S. Geological Survey

Terry R. Neumann 

U.S. Bureau of Mines

SUMMARY

Abstract

At the request of the Bureau of Land 

Management, 13,709 acres of the Funeral Mountains 

Wilderness Study Area (CDCA-143) were studied by 

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

Mines. The study area is located in the southeastern 

part of the Funeral Mountains in the Death Valley 

region of eastern California. Geologic, geophysical, 

and geochemical studies were conducted in the study 

area during 1983-1984.

Four lapsed mining claims are present within the 

study area. There are no active mines in the study 

area, and there is no evidence of past production from 

any claim. The study area contains no identified 

mineral resources. Three drainage basins in the 

central, eastern, and western parts of the study area 

contain anomalous concentrations of lead and zinc, and 

have a low potential for lead and zinc resources. 

Borate deposits may be present in the subsurface of 

the southwestern part of the study area; the potential 

for borate resources is low. Parts of the study area 

were determined to have low potential for resources of 

bentonite, zeolite minerals, and strontianite (a 

strontium mineral). Concentrations of these 

commodities are such that any production from them 

is likely to be small. Limestone, quartzite, and sand 

and gravel are found within the study area and have a 

low economic potential due to the distance from 

current markets. Oil, gas, and geothermal resources 

were not found in the study area and so the potential is 

considered low. There is no potential for uranium or 

thorium resources.

Character and Setting

The Funeral Mountains Wilderness Study Area is 

located in southeastern Inyo County, California 

between the eastern boundary of Death Valley 

National Monument and the California-Nevada border 

(fig. 1). Death Valley Junction, the nearest community 

to the study area, is located 7 mi to the southeast.

The Funeral Mountains are a repetitious series of 

fault blocks underlain predominantly by carbonate rock 

of Cambrian through Mississippian age (570-330 million 

years before present (Ma); see Geologic time chart, 

last page of report).

The northeast-trending range of fault-controlled 

mountains encloses small, narrow interior valleys and 

is bounded by broad, coalescing alluvial fans. The 

study area is characterized by rugged peaks, steep, 

sloping ridges, and narrow drainages.

Relief within the study area is over 4,300 ft. 

Pyramid Peak, a dominant feature near the center of 

the study area, is the highest point at 6,703 ft. The 

surface elevation drops sharply to 2,400 ft at the 

southwest corner of the study area.

In this report, the area studied is referred to as 

"the wilderness study area", or simply "the study area".

Identified Resources

None of the prospects within the study area have 

identified resources of industrial commodities. 

However, the American Borate Company operates the 

Billie mine 4 mi southwest of the study area (fig. 2). 

Small-scale mining at the Sidehill mine, 2 mi east of 

the eastern boundary of the study area, produces clay 

for cosmetic and pharmaceutical products. The I.M. 

Vanderbilt mine (fig. 2, No. 14), operated by Industroa; 

Mineral Ventures, produces hectorite and sepiolite 3.5 

mi northeast of the study area near Franklin Wells.

Al
FUNERAL MOUNTAINS

WILDERNESS STUDY AREA

(CDCA-143)

Figure l.-~Index map showing location of the Funeral Mountains Wilderness Study Area, 

Inyo County} California.

A2
Carbonate rocks underlie much of the Funeral 

Mountains, and major deposits of limestone and 

dolomite could be developed. A number of possible 

quarry sites, all located near Highway 190, would each 

have more than 20 million tons of resources. However, 

these deposits are too far from large markets and are 

not likely to be developed in the near future. Existing 

quarries in the Spring Mountains, Nevada, about 45 mi 

southeast of the study area, will continue to meet 

limestone requirements for local markets.

Sand and gravel are plentiful in the study area, 

but alternate sources are readily available closer to 

local markets.

Mineral Resource Potential

Geochemical studies indicate that a low resource 

potential for lead and zinc exists in three areas. In the 

eastern, central, and western parts of the study area. 

Three additional areas are recognized in the study 

area. A moderate resource potential for large borate 

deposits in lake-bed sediments in the southwestern 

part of the study area. Bentonite and zeolite deposits 

are found in altered volcanic rocks in the southeast 

corner of the study area. Their resource potential is 

low. Strontium concentrations are found in small 

deposits in the western part of the study area. The 

resource potential for strontium is low.

Limestone, quartzite, and sand and gravel are 

abundant in the study area, and their resource 

potential is high, but the economic potential is low 

beause of the distance to potential markets.

No indication of the presence of coal, oil, gas, 

and geothermal resources were found and their 

potential is low.

INTRODUCTION 

Area Description

The Funeral Mountains Wilderness Study Area 

(CDCA-143) is located in the southeastern part of the 

Funeral Mountains in the Death Valley region of 

eastern California (fig. 1). The study area contains 

13,709 acres and is located between the eastern 

boundary of Death Valley National Monument and the 

California-Nevada border. Death Valley Junction, 

approximately 7 mi to the southeast, is the nearest 

community. Access to the eastern boundary of the 

study area is by California State Highway 127 and a 

graded gravel road through Franklin Wells; access to 

the western boundary is by State Highway 190 and a 

jeep trail to Red Amphitheater. Interior access is 

poor, with only one known trail leading to a small 

valley between Pyramid Peak and Mine Mountain.

The terrain of the Funeral Mountains is typical 

of the Basin and Range physiographic province. The 

northwest-trending, fault-controlled mountains enclose 

small, narrow interior valleys and are bounded by 

broad, coalescing alluvial fans. The mountains are 

characterized by rugged peaks, steep, sloping ridges, 

and narrow drainages. Maximum relief within the 

study area is more than 4,300 ft. The highest point is

Pyramid Peak (6,703 ft), near the center of the study 

area. The surface elevation is 2,400 ft at the 

southwest corner of the study area. The region is 

sparsely vegetated, reflecting low annual 

precipitation, intense summer heat, and mild winters.

Previous and Present Investigations

Little information related to mineral resource 

potential is available for the area of the southern 

Funeral Mountains. The most detailed sources of 

geological information are reports by Hunt and Mobey 

(1966), McAllister (1970, 1971a, 1971b, 1973, 1976), 

Cemen and others (1982), Troxel (1968), and Denny and 

Drewes (1965). U.S. Bureau of Land Management 

unpublished mineral potential reports by Marcus (1980) 

and Schulte (1982) contain additional data. The U.S. 

Department of Energy conducted a uranium-potential 

survey of all land encompassed by the Death Valley 1° 

x 2° quadrangle, which includes the study area (Cook, 

1980).

The U.S. Bureau of Mines conducted a mineral 

survey of the study area during 1983 (Neumann, 1984). 

Prior to the field work for this report, a search of 

pertinent Federal and Inyo County mining-claim 

records was conducted to determine claim locations 

and mining activities. U.S. Bureau of Mines personnel 

collected 50 chip, grab, and select samples during a 

field investigation; the majority of the samples were 

sedimentary rocks. Grab and select samples were 

collected from mine and prospect dumps, stockpiles, 

and mineralized zones. Complete data for all samples 

are available for public inspection at the U.S. Bureau 

of Mines, Western Field Operations Center, E. 360 

Third Avenue, Spokane, Washington, 99202.

Armstrong conducted studies in the Funeral 

Mountains in 1980, 1983, and 1984. In 1984, Frisken 

conducted field and laboratory studies of the 

geochemistry of the wilderness study area. Mineral 

resources and mineral resource potential were 

classified according toGoudarzi (1984).

Frederic C. Johnson, a geologist with the 

American Borate Company, provided valuable 

information about the access, local geology, and 

mineral resource potential of the region.

APPRAISAL OF IDENTIFIED RESOURCES

By_ Terry R. Neumann, U.S. Bureau of Mines

Mining History

At the present time, there is no active mining 

within the study area and there is no evidence of past 

production from any claim within the study area. 

However, areas adjacent to the study area have had a 

rich and colorful mining history.

Greenwater Valley, located 12 mi south of the 

study area, was the site of the most spectacular boom 

in the history of mining in Death Valley. According to 

Latschar's (1981) meticulous account, copper was 

discovered in 1905 in the Greenwater district, 12 mi

A3
116»35'

FUNERAL MOUNTAIN S WILDERNESS 

STUDY AREA (CDCA-143)

Figure 2. Mineral resource potential map of the Funeral Mountains Wilderness Study 

Area, Inyo County, California.

A4
EXPLANATION

Area with moderate mineral or geothermal energy resource 

potential, certainty level C (M/C)

Area with low mineral or geothermal energy resource potential

See Appendix 1 for definition of levels of mineral resource potential and certainty of assessment 

v ,. Mine with identified mineral resource 

Commodities

B Boron

Bentonite Bentonite

Pb Lead

Sr Strontium

Zn Zinc

Zeolite Zeolite

Geologic map units

Qa Alluvium (Quaternary)

Tc Conglomerate (Tertiary)

Pzl Limestone (Devonian to Cambrian)

 Contact

 Fault-Dashed where inferred

X i Mine-Number refers to list of workings

X c Prospect, claim, or mineralized area Number refers to list of workings

Mines, prospects, claims, and mineralized areas

1 Red Amphitheater mine

2 Red Amphitheater mineralized zone

3 Bentonite Placer prospect

4 Yellow Heart prospect

5 Deborah prospect

6 Kaolin Extension prospect

7 Kaolin mine

8 Kingfish No. 1 prospect

9 Kingfish No. 2 prospect

10 Sidehill mine

11 Blanco prospect

12 Unnamed prospect

13 Southeast corner mineralized zone

14 I.M. Vanderbilt mine

15 Billie mine

Figure 2. Continued

A5
south of the study area. By 1907, the district included 

4 towns, with a total of 2,000 inhabitants and 73 

incorporated mining companies with $140 million in 

mining capital. The boom collapsed when shafts more 

than 1,400 ft deep failed to produce sufficient amounts 

of ore. Within 3 years, the district was virtually 

abandoned, with only small amounts of copper having 

been produced. In Gold Valley, 12-16 mi southwest of 

the study area, small-scale mining of gold, silver, 

copper, and lead accompanied the Greenwater boom; 

activity in the area ceased by 1910.

Between 1905 and 1907, a gold-prospecting boom 

reached its peak in an area 6 to 18 mi north of the 

study area. In the northern Funeral Mountains, the 

Keane Wonder and Chloride Cliff mines, and the EhoLee mining district straddle the lower Funeral Mountains 

from Schwab Camp on the west to the Lee mines on 

the east. The production potential of the mines and 

prospects was greatly exaggerated and overpublicized. The Funeral Mountains were then left 

much as they had been found, except that numerous 

shafts, tunnels, and prospect holes now dot the 

countryside (Latschar, 1981).

Underground borate mining began in 1907 at the 

Lila C mine 7 mi southeast of the study area. In 1914, 

development shafts were sunk into the large borate ore 

bodies at Ryan, 3 mi southwest of the study area. By 

1928, the Ryan mines were closed. In 1976, Tenneco 

started shafts for the Billie mine adjacent to the Ryan 

property.

Three mining operations have recently produced 

industrial minerals within 3.5 mi of the study area. 

The American Borate Company operates the Billie 

mine 4 mi southwest of the study area (fig. 2). As of 

February 1982, the Billie mine produced 210,552 tons 

of ore-grade colemanite and ulexite-probertite from a 

boron-bearing spring-lacustrine deposit (F.C. Johnson, 

American Borate Company geologist, oral commun., 

1983). The berates are used principally in glass 

products. After 10 years of production, the Billie mine 

was put on standby in early 1986.

Clay for cosmetic and pharmaceutical products 

(Lease, J.R.T. Vanderbilt Co., oral commun., 1983) is 

produced at the Sidehill mine (fig. 2, No. 10) 2 mi east 

of the study area. The J.R.T. Vanderbilt Company 

intermittently mines bentonitic clay from an early 

Miocene tuffaceous red sandstone unit. Hectorite, a 

lithium-rich clay, and sepiolite (meershaum) are mined 

from Quaternary lakebed sediments near Franklin Wells 

(fig. 2) by Industrial Mineral Ventures, Inc. The 

hectorite and sepiolite were formed by alteration of 

volcaniclastic sediments. Hectorite is used in drilling 

mud and as a component of construction materials; 

sepiolite is sold as a soil conditioner.

Until 1983, the Anaconda Copper Company 

operated the Ash Meadow open-pit zeolite mine 10 mi 

east of the study area. Since 1979, Anaconda has been 

mining clinoptilolite, a zeolite mineral used mainly for 

agricultural fertilizers and waste-water ammonia 

absorption. The company sold the property in 1983, 

and it is now idle.

Mines, Prospects, and Mineralized Zones

Eleven mines and prospects and two mineralized 

zones were examined by the Bureau of Mines during 

this study. Of these, four prospects and two

mineralized zones are located within the study area; 

the remaining prospects are adjacent to it. The four 

prospects within the study area, Bentonite Placer, 

Yellow Heart, Deborah, and an unnamed prospect in 

the southeast corner of the area (fig. 2, Nos. 3, 4, 5, 

and 12), are all inactive. No patented claims or 

existing leases are located within the study area; the 

nearest patented property is the Sidehill mine, 2 mi 

east of the study area (fig. 2, No. 10).

Outcrops of mineralized rock traced from 

existing claims are located in the southeast corner of 

one mineralized zone (fig. 2, No. 13) and in the Red 

Amphitheater mineralized zone (fig. 2, No. 2). Table 1 

includes descriptions of mines, prospects, and 

mineralized zones examined for this report.

Conclusions

The study area contains no identified mineral 

resources. However, three prospects, the Bentonite 

Placer, the Deborah, and an unnamed prospect (fig. 2, 

Nos. 3, 5, 12), contain occurrences of zeolite minerals 

and bentoitic clay. A mineralized zone in the 

southeast corner of the study area (fig. 2, No. 13) 

containing bentonite and zeolite minerals, and the Red 

Amphitheater mineralized zone (fig. 2, No. 2) 

containing strontium are also classified as mineral 

occurrences. Seven mines and prospects containing 

resources of bentonitic clay, pumice, and dimension 

stone are located adjacent to the wilderness study 

area.

Bentonitic clay and zeolite in the study area are 

present in altered zones in Tertiary waterlain 

tuffaceous sediments. Local concentrations are 

relatively low grade, thin, and discontinuous; only 

bentonite at the Deborah prospect (fig. 2, No. 5) and 

Kaolin mine (fig. 2, No. 7) meet industry standards as 

pelletizing agents (such as taconite) and as bonding 

media. Because the beds are steeply dipping, 

substantial amounts of overburden would need to be 

removed for surface mining.

High concentrations of strontium (fig. 2, No. 2) 

in Tertiary mudstones in the Red Amphitheater 

mineralized zone approach commercial grades (more 

than 1 percent strontium), but small tonnage and low 

average grade preclude classifying the zone as a 

resource.

Limestone, quartzite, and sand and gravel in the 

study area are suitable for many types of construction 

uses. However, similar materials are available closer 

to existing markets, making exploitation of the 

deposits in the study area economically unfeasible.

No energy resources have been identified within 

the study area.

ASSESSMENT OF UNDISCOVERED RESOURCES

By Augustus K. Armstrong, James G. Frisken, and 

Robert C. Jachens U.S. Geological Survey

Geologic Setting

The Funeral Mountains trend northwest, are 

fault controlled, and have rugged relief. They rise

A6
4,300 ft above the adjoining pediments that are largely 

coalesced alluvial fans. The mountains possess typical 

basin-and^-ange topography and are comprised of 

Paleozoic stratified rocks. These rocks are 

unconformably overlain by 3,000-5,000 ft of fluvial and 

lacustrine deposits of Tertiary age. The rocks in the 

foothills are overlapped by Quaternary alluvium; at 

some distance from the highlands, the fan deposits 

intertongue with playa deposits.

Structural Geology

Structural features within the study area consist 

of strike-slip faults, high-angle faults, folds, 

and tilted and warped strata. High-angle faulting was 

accompanied by tilting, as illustrated by Cenozoic 

sedimentary rocks that now dip as steeply as 60°. 

Many of the high-angle faults are northeast-trending 

normal faults that have arcuate traces and whose 

planes may flatten at depth. These planes are present 

throughout the area. Some of the earlier normal faults 

were rotated to subhorizontal positions during 

progressive high-angle faulting and tilting. Other lowangle faults underlie gravity-slide blocks. The basinand^*ange structures present in the area are the result 

of block faulting due to east-west or southeastnorthwest extension that developed over a 

considerable span of time during the Cenozoic era 

(Burchfiel and others, 1983).

The Funeral Mountains are bounded on the 

southwest by the Furnace Creek strike-slip fault 

zone. Denny and Drewes (1965) believed that the 

oldest movements along this fault zone took place 

during the Oligocene. It was probably during this time 

that movement took place along subsidiary faults in 

the older rocks. By Miocene or Pliocene time, the 

Funeral Mountains were elevated in relation to the 

area southwest of the Furnace Creek faults.

Stratigraphy

A complexly faulted stratigraphic sequence of 

Cambrian to Mississippian age marine sedimentary 

rocks is exposed in the southeastern part of the 

Funeral Mountains. This exposure is 18 miles long and 

about 9,000 ft thick. McAllister (1971b) correlated the 

sequence in the Funeral Mountains with the formations 

that have been described in the Nopah Range 

(Hazzard, 1937; Burchfiel and others, 1982). Mesozoic 

strata are absent.

The older Cenozoic deposits are confined to the 

eastern side of the wilderness study area, where they 

form a 1,000-8,000-ft thick sequence of stream and 

lake sediments and basalt. Younger Cenozoic deposits 

are composed of lake, stream, and fan sediments 

interbedded with volcanic rocks. These are found 

along the flanks of the Funeral Mountains.

The Cambrian through Mississippian strata in the 

study area are predominantly carbonate rocks that 

were deposited in shallow marine environments.

The Bonanza King and Nopah Formations are 

composed of Cambrian-age gray to light-brown, 

subtidal limestone and dolomite. They are about 3,600 

ft thick. The Lower and Middle Ordovician Pogonip

Group dolomites are 2,200 ft thick. The Middle 

Ordovician Eureka Quartzite is 160 ft thick and 

contains white quartzite. The Middle and Upper 

Ordovician Ely Springs Dolomite is more than 400 ft 

thick and is composed of fossiHferous dark-gray 

dolomite and limestone. The Silurian and Lower 

Devonian Hidden Valley Dolomite, 1,400 ft thick, is a 

massive gray dolomite. The dolomite of the Middle 

and Upper Devonian Lost Burro Formation is 2,500 ft 

thick. Mississippian rocks crop out a few hundred 

yards east of the study area. The Mississippian Tin 

Mountain Limestone and Perdido Formation together 

are composed of 820 ft of limestone, chert, and 

shale. Younger Paleozoic rocks were eroded prior to 

the deposition of Tertiary fanglomerates.

Between the Spring Mountains, Nevada, and 

Death Valley, California, the Mesozoic sedimentary 

and volcanic units have been eroded away. These units 

are absent in the study area.

The oldest Tertiary unit in the study area is an 

unnamed conglomerate that is 60 ft thick and consists 

of pebble-to-boulder size clasts bound by a sandy 

matrix. The clasts are derived from Proterozoic and 

Paleozoic rocks. The overlying Oligocene and Miocene 

Horse Spring Formation of Cemen and others (1982) is 

500 ft thick and consists of a succession of interbedded 

limestone, siltstone, and tuff. Above the Horse Spring 

Formation is the Red Sandstone; it is 1,000 ft thick 

and is composed of a variety of rocks ranging from 

mudstone to conglomerate. The clasts were derived 

from Paleozoic bedrock similar to the rocks within the 

study area that were described above and Tertiary 

volcanic rocks not found within the study area. Above 

the Red Sandstone unit are 300 ft of pinkish-gray to 

white fresh-water micritic algal limestones.

Overlying the algal limestone is the Miocene Bat 

Mountain Formation of Cemen and others (1982) that 

is correlative with the upper fanglomerate of Denny 

and Drewes (1965). The Bat Mountain Formation is 

1,500 ft thick and consists of clasts of Proterozoic and 

Paleozoic sedimentary rocks in a sand and clay matrix.

The Miocene and Pliocene (?) Furnace Creek 

Formation is 7,000 ft thick and crops out in the 

southwestern part of the study area. The boratebearing rocks of the Furnace Creek Formation are 

light-colored, fine-grained rocks originally deposited 

as lakebed sediments. The formation also contains 

basalt, thin limestone layers, and gypsum beds.

The Pliocene and Pleistocene age Funeral 

Formation is 700 ft thick and consists of poorly sorted 

conglomerate composed of Paleozoic limestone, 

Cenozoic volcanic clasts, and thick basaltic sequences.

The Quaternary deposits of the study area are 

composed of Pleistocene and Holocene alluvium. The 

surface of the older alluvium has been smoothed by the 

breakdown of coarse material and the development of 

desert pavement. The younger alluvium consists of 

gravel deposited along recent stream channels. The 

gravel is fresh gray in the youngest channels and is 

coated brown (desert varnish) along abandoned stream 

courses.

Geophysics

An aeromagnetic survey of the study area was

A7
flown by High Light Helicopters (Puyallup, Wash.) and 

compiled by Geodata International (Dallas, Tex.) under 

contract to the U.S. Department of Energy as part of 

the National Uranium Resource Evaluation Program 

(NURE). In 1977 and 1978, total-field magnetic data 

were obtained along north-south flight lines spaced 

approximately 1 mi apart and flown at an average 

elevation of 400 ft. Because of the ruggedness of the 

Funeral Mountains, actual terrain clearance varied 

from about 300 to 1,400 ft. Corrections were applied 

to the data to compensate for diurnal variations of the 

Earth's magnetic field and the International 

Geomagnetic Reference Field (updated to the months 

that the data were collected) and were subtracted to 

yield a residual magnetic field.

The residual magnetic field over the study area 

is characterized by long-wavelength (4 mi), lowamplitude anomalies generally measured at less than 

50 nanoteslas. The long wavelengths of these 

anomalies and their broad, gently sloping flanks 

indicate that the magnetic sources may lie at depths 

of a mile or more below the survey altitude. These 

anomalies are probably caused by magnetic variations 

within the Proterozoic crystalline basement, or by 

relief of the basement surface that is concealed 

beneath the thick section of carbonate rock exposed at 

the surface. The lack of correlation between the 

topography and the residual magnetic field indicates 

that the exposed carbonate rocks are not magnetic. 

The data show no anomalies within the study area that 

would indicate large, shallow magnetic bodies, such as 

the magnetic plutons exposed in the Kingston Range to 

the southeast and the Black Mountains to the 

southwest.

Geochemistry

The reconnaissance geochemical survey was 

based on analyses and evaluations of heavy-mineral 

concentrates of 34 samples collected from dry washes 

in the study area. The survey was conducted in order 

to identify patterns of stream-sediment chemistry that 

might reflect mineralizing processes in the major rock 

units of drainage basins within the study area.

All samples were analyzed for 29 elements by a 

6-step, semiquantitative emission-spectrographic 

method (Grimes and Marranzino, 1968). These 

analyses helped identify drainages containing 

anomalous concentrations of metallic elements. 

Anomalous values were determined by enrichment of 

the rocks relative to crustal abundance.

Three of the drainage basins in the study area 

contain highly anomalous concentrations of barium, 

lead, and zinc. The drainage basin occupying the 

eastern part of the study area contains anomalous 

concentrations of barium (10,000 parts per million 

(ppm)), lead (300 ppm), and zinc (1,000 ppm). Samples 

collected from the drainage basin occupying the 

central part of the study area contain anomalous 

concentrations of barium (10,000 ppm), lead (2,000 

ppm), and zinc (20,000 ppm). A watering station is 

located at the head of the central drainage, and so 

galvanized pipe used in the construction of the station 

may account for some anomalous concentrations of 

lead and zinc. There is no way to distinguish

contamination from naturally occurring lead and 

zinc. The westernmost drainage basin in the study 

area with pronounced geochemical anomalies contains 

concentrations of barium (10,000 ppm), zinc (2,000 

ppm), and lower concentrations of lead (100 ppm). 

Low concentrations of copper (300 ppm) were found in 

the southern part of the westernmost anomalous 

drainage area. Silver was not detected. However, a 

flake of gold was found in a dry-pan sample collected 

from a drainage basin in the eastern part of the study 

area.

The combination of highly anomalous 

concentrations of barium, lead, and zinc indicates that 

these metals may be derived from hydrothermal vein 

deposits, or that they may occur as low-temperature, 

strata-bound lead and zinc deposits in the Paleozoic 

carbonate rocks exposed in the study area.

The Bureau of Mines collected six chip samples 

from the Red Amphitheater mineralized zone that 

contained strontium (0.062-1.7 percent), lithium 

(0.024-0.08 percent), and boron (0.0041-0.042 

percent). This occurrence is believed to be the result 

of hot water from thermal springs altering 

sedimentary clastic rocks (Neumann, 1984).

Mineral and Energy Resources

Bentonite and Zeolite

Bentonite and zeolite deposits in the study area 

generally occur in altered silicic volcanic rocks of the 

Miocene Horse Springs Formation. These are fresh 

water lakebed sediments and ash-fall deposits. Just 

outside the study area, the only active mine is the 

Sidehill mine, which produces bentonite for the 

cosmetic and pharmaceutical industries. Although a 

large number of tuff beds are present in the Horse 

Spring Formation, only one bed is mineralogically 

suitable or thick enough for mining.

Bentonitic clay and zeolite minerals found in the 

study area occur in alteration zones in Tertiary 

tuffaceous lakebed deposits. The bentonite deposits in 

the study area are erosional remnants of the Miocene 

lake beds and are thin and discontinuous.

Sheppard (1985) described the Pliocene-Miocene 

Ash Meadows zeolite deposit (10 mi east of the study 

area) as clinoptilolite^ich tuffs that were formed by 

reaction with alkaline ground water. Similar deposits 

are unknown within the study area.

The resource potential for bentonitic clay and 

zeolite minerals in the study area is low with a D level 

of certainty. See fig. 3 and appendix 1 for definitions 

of mineral resource potential and levels of certainty.

Limestone, Quartzite and Sand and Gravel

There are numerous limestone, quartzite, and sand and 

gravel deposits in the study area that are suitable for 

use as construction materials. However, much of the 

carbonate rock in the study area is dolomite or 

dolomitic limestone and is unsuitable for making 

cement. The potential for limestone, quartzite, and 

sand and gravel is high with a D level of certainty. 

Although limestone, quartzite, and sand and gravel is

A8
abundant in the study area, the economic potential is 

low.

Base and Precious Metals

Geochemical investigations in the study area 

indicate a low potential for lead and zinc resources. 

Only a few scattered drainage basins in the study area 

contain metallic anomalies. Lead and zinc 

concentrations are low; typical concentrations of lead 

and zinc in the pan concentrates of stream-sediment 

samples are 100-1,000 ppm and 500-20,000 ppm, 

respectively. The only copper values (100-200) may be 

the result of contamination. Barium concentration is 

as high as 10,000 ppm. Although a single flake of gold 

was found in the southeast part of the study area, gold 

was not detected elsewhere. Arsenic, mercury, 

molybdenum, and silver were not detected.

Model for Strata-bound Lead-Zinc Deposits

Two possible mineralization models may explain 

the occurrence of lead and zinc in the study area. The 

lead-zinc geochemical signature in the samples 

collected within the study area may be derived from 

strata-bound deposits of sphalerite and minor galena 

from primary and secondary voids of favorable beds in 

the lower Paleozoic carbonate rocks. The lower 

Paleozoic carbonate rocks of the Funeral Mountains 

are very smiliar in lithology, texture, and facies to the 

lower Paleozoic rocks of Missouri, Kentucky, and 

Tennessee that contain ore bodies of low-temperature, 

strata-bound lead and zinc (Pratt, 1982). Strata-bound 

ore deposits similar to those of the central United 

States have not been found in the western states. This 

is probably due to distinctly different late Paleozoic 

tectonic histories of the two regions.

Model for Mesothermal-epithermal Gold, Copper, and 

Lead- Zinc Vein Mineralization

Lead and zinc are found in veins, stockworks, and 

bedded replacement bodies in carbonate rock 

associated with a quartz-calcite gangue in the Death 

Valley region; the ore minerals are galena and 

sphalerite (Goodwin, 1957). On the basis of trace 

elements present in the mineral suites in heavymineral concentrate samples, the conceptual model for 

mineralization appears to be related to low- to 

moderate-temperature hydrothermal events. The 

geologic environment in a Paleozoic carbonate-rock 

terrane is conducive to this type of mineralizing 

phenomenon. The plutonic rocks may have provided 

the mineralizing fluids that formed veins in the 

surrounding reactive carbonate rocks. The Cerro 

Gordo mine in the Inyo Mountains is an example of this 

type of mineralization (Merriam, 1963).

The study area contains little evidence of local 

igneous activity in the form of exposed plutons or 

intrusive bodies, and only indirect evidence (in the 

form of recrystallized carbonates) that would indicate 

the presence of buried plutons that could form Cerro 

Gordo-type ore bodies.

Geologic and geochemical investigations in the 

study area indicate that three drainage basins (the 

eastern, central, and western) contain anomalous 

concentrations of lead and zinc; however, based on the 

proceeding analysis, the resource potential of the 

study area for lead and zinc is low with a C level of 

certainty.

Boron

Evans and others (1976) calculated that 6,675,400 

short tons of boron reserves were contained in the 

Ryan-Death Valley Junction area adjacent to the south 

side of the Funeral Mountains Wilderness Study Area. 

The Furnace Creek Formation is the host rock for the 

major boron deposits that are known to exist west and 

south of the study area. Undiscovered deposits of 

considerable size may be present in the southwestern 

part of the study area in the Furnace Creek 

Formation. Exploration drilling would be needed to 

locate these deposits. The resource potential for 

boron is moderate with a C certainty level.

Other Commodities

Strontium concentrations in Tertiary mudstones 

in the Red Amphitheater mineralized zone are locally 

higher than 1 percent. The strontium concentrations 

are found in small deposits. The resource potential for 

strontium is low with a D level of certainty.

In a study of the uranium resources of the Death 

Valley region, Cook (1980) showed that there was no 

indication of the presence of uranium or thorium 

within the study area. There is no resource potential 

for uranium or thorium within the study area.

Stratified sedimentary rocks in southeastern 

California, including those in the study area, have low 

potential for oil and gas because of the Mesozoic and 

Tertiary igneous activity and Cenozoic extensional 

tectonism of the region. Because of the area's igneous 

activity, complex tectonics, and high-temperature 

history, the resource potential for oil and gas is low 

with a C certainty level (Scott, 1983).

The Amargosa Desert, adjacent to the northeast 

side of the Funeral Mountains, is a large area 

favorable to the development of local sources of lowtemperature (less than 90°C) geothermal water 

(Sammel, 1979). The Shoshone area has similar 

geology and tectonic style to the Funeral Mountains. 

The presence of warm water from the Shoshone 

Springs, 20 mi southeast of the study area, indicates 

possible geothermal activity in the wilderness study 

area. The geothermal resource potential is low with a 

D level of certainty.

Conclusions

Geochemical evidence indicates that lead-zincbarium mineralization occurred within three drainage 

basins in the study area. These basins contain 

anomalous concentrations of barium, lead, and zinc. 

The combination of pronounced anomalies of barium, 

lead, and zinc indicates that these base metals may be

A9
derived from hydrothermal vein deposits, or that they 

may occur as low-temprature, strata-bound lead-zinc 

deposits in the Paleozoic carbonate rocks of the study 

area. The resource potential for lead and zinc is low 

with a C level of certainty.

Strontium deposits may be present in the 

southwestern part of the study area in the Furnace 

Creek Formation. The resource potential for 

strontium in this area is low with a D level of certainty.

Bentonite and zeolite-mineral deposits present in 

altered silicic volcanic rocks were formed by the 

hydrothermal alteration of feldspar. An altered zone 

in the southeast corner of the study area contains 

disconnected erosional remnants of bentonite beds. 

The resource potential for bentonitic clay and zeolite 

minerals is low with a D level of certainty.

Exploration in the wilderness study area may 

reveal small deposits of bentonite clay and zeolite 

minerals, and the Cenozoic lakebed deposits in the 

southwestern part of the study area may contain large 

deposits of borate minerals. An exploratory program 

that would drill through the Funeral Formation and 

penetrate to the Furnace Creek Formation may reveal 

an extension of the borate deposits that are present in 

the American Borate Company's Billie mine adjacent 

to the study area. These borate deposits are believed 

to have formed as the result of hot brines moving up 

along extensional fractures and faults during the 

deposition of the Furnace Creek Formation. The 

major fault system in the southwestern part of the 

study area is the Furnace Creek fault zone. The areas 

where north- and northeast-trending faults join the 

Furnace Creek fault zone prime locations for 

exploratory drilling to reach the lower part of the 

Furnace Creek Formation. Elsewhere in the region, 

along the Furnace Creek fault system, the junctures of 

these two sets of faults were determined to be the loci 

of ancient hot springs and major borate deposits. The 

resource potential for boron in the western part of the 

study area is moderate, with a C level of certainty.

Limestone, quartzite, and sand and gravel are 

abundant in the area and there is a high potential for 

undiscovered resources of these commodities; 

however, there are economic factors which could 

affect development, and these are treated elsewhere 

in this report.

No indication of oil or gas was found in the 

study area; the resource potential for oil and gas is low 

with a certainty level of C. The potential for 

geothermal resources is considered to be low with a D 

level of certainty.

REFERENCES CITED

Burchfiel, B. C., Hamill, G. S., IV, and Wilhelms, D. E., 

1982, Stratigraphy of the Montgomery Mountains 

and the northern half of the Nopah and Resting 

Spring Ranges, Nevada and California: 

Geological Society of America, Map and Chart 

Series MC-44, 9 p.

____1983, Structural geology of the Montgomery 

Mountains and the northern half of the Nopah 

and Resting Spring Ranges, Nevada and 

California: Geological Society of America 

Bulletin, v. 94, no. 11, p. 1359-1376.

Cemen, Ibrahim, Drake, Robert, and Wright, L. A., 

1982, Stratigraphy and chronology of the 

Tertiary sedimentary and volcanic units at the 

southeastern end of the Funeral Mountains, 

Death Valley Region, California, in Cooper, J. 

D., Troxel, B. W., and Wrights, L. A., eds., 

Geology of selected areas in the San Bernardino 

Mountains, Western Mojave Desert, and Southern 

Great Basin, California: Geological Society of 

America Guidebook, Field Trip No. 9, p. 77-87.

Cook, J. R., 1980, Death Valley 1° x 2° NTMS area, 

California and Nevada, data report, 

Hydrogeochemical and stream-sediment 

reconnaissance, (DPST-7 9-146-16): Savannah 

River Laboratory, Published by Savannah River 

Laboratory, Department of Energy, 95 p.

Denny, C. S., and Drewes, Harold, 1965, Geology of 

the Ash Meadows Quadrangle, NevadaCalifornia: U.S. Geological Survey Bulletin 

1181-L, 56 p.

Evans, J. R., Taylor, G. C., and Rapp, J. S., 1976, 

Mines and Mineral Resources in Death Valley 

National Monument, California Division of Mines 

and Geology, Special Report 125, p. 18-32.

Goodwin, J. G., 1957, Lead and zinc in California: 

California Jounral of Mines and Geology, v. 53, 

nos. 3 and 4, p. 353-724.

Goudarzi, G. H., 1985, Guide to the preparation of 

mineral survey reports on public lands: U.S. 

Geological Survey Open-File Report 84-787, 28

PGrimes, D. J., and Marranzino, A. P., 1968, Directcurrent arc and alternating-current spark 

emission spectrographic field methods for the 

semiquantitative analysis of geologic materials: 

U.S. Geological Survey Circular 591, 6 p.

Hazzard, J. C., 1937 (1938), Paleozoic section in the 

Nopah and Resting Springs Mountains, Inyo 

County, California: California Journal of Mines 

and Geology, v. 33, no. 4, p. 273-339.

Hunt, C. B., and Mabey, D. R., 1966, Stratigraphy and 

Structure of Death Valley, California: U.S. 

Geological Survey Professional Paper 494-A, 162

PLatschar, J. A., 1981, A history of mining in Death 

Valley National Monument, v. 11, Historic 

Preservation Branch, Pacific Northwest/Western 

Team, National Park Service, 763 p.

Marcus, S. M., 1980, An evaluation of the mineral 

potential of the Pyramid Peak G-E-M Resource 

Area: Bureau of Land Management unpublished 

report, 13 p. (Available from Bureau of Land 

Management, Barstow Resource Area, Barstow, 

California.)

McAllister, J. F., 1970, Geology of the Furnace Creek 

Borate Area, Death Valley, Inyo County, 

California: California Division of Mines and 

Geology Map Sheet 14, text 9 p.

___197la, Preliminary geologic map of the Funeral 

Mountains in the Ryan Quadrangle, Death Valley 

Region, Inyo County, California, U.S. Geological 

Survey Open-File Map 71-187.

___1971b, Silurian, Devonian, and Mississippian 

formations of the Funeral Mountains in the Ryan 

quadrangle, Death Valley Region, California: 

U.S. Geological Survey Bulletin 1386, 35p.

AID
____1973, Geologic map and sections of the Amargosa 

Valley borate area, southeast continuation of the 

Furnace Creek area, Inyo County, California: 

U.S. Geological Survey Miscellaneous Geologic 

Investigations Map 1-782.

___1976, Geologic map and sections of a strip from 

Pyramid Peak to the southeast end of the 

Funeral Mountains, Ryan quadrangle, 

California, in Troxel, B. W., and Wright, L. A., 

eds., Geologic features of Death Valley, 

California: California Division of Mines and 

Geology Special Report 106, p. 63-65.

Merriam, C. W., 1963, Geology of the Cerro Gordo 

mining district, Inyo County, California: U.S. 

Geological Survey Professional Paper 408, 83 p.

Neumann, Terry R., 1984, Mineral Resources of the 

Funeral Mountains Wilderness Study Area (BLM 

No. CDCA-143), Inyo County, California, U.S. 

Bureau of Mines Open File Report MLA 36-84, 19

P'

Pratt, W. P., 1982, A prospecting model for 

stratabound lead-zinc (barite-fluorite) deposits 

and occurrences: in R. L. Erickson ed., 

Characteristics of mineral deposits occurrences, 

U.S. Geological Survey Open-file report 82-795,

p. 155-157.

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.

Schulte, K. C., 1982, Mineral potential, Funeral 

Mountains Wilderness Study Area, a management 

summary Class C Recommended Area, 

Wilderness Study Area 143: Unpublished report 

available from Bureau of Land Management, 

Barstow Resource Area, California, 15 p.

Scott, E. W., 1983, Petroleum potential of wilderness 

lands, California: U.S. Geological Survey 

Miscellaneous Investigation Series Map 1-15, 38

PSheppard, R. A., 1985, Death Valley-Ash Meadow 

zeolite deposits, California and Nevada, in 

Tourtelot, H.A., ed., International Clay 

Conference; Los Angeles, California, 1985, Field 

Trip Guidebook, p. 51-55.

Troxel, B. W., 1968, Precambrian stratigraphy of the 

Funeral Mountains, Death Valley, California: 

Geological Society of America Special Papers 

121, p. 374-375.

All
TABLE 1. - Mines, prospects, and mineralised zones In and adjacent to the Funeral Mountains Wilderness Study Area (

[asterisk (*) Indicates outside study area]

Map Name Geology Workings and production Sampl

No .

*Red Amphitheater A flat-lying sequence of Tertiary lacustrine Several small pits where no Appears suitable 

mine(flagstone) mudstone Is exposed at the entrance to Red more than 10,000 tons of dimension stone 

partings and breaks Into slabs which average local construction. 

4 to 6 In. thick. The rock Is limey In 

places, grading Into marlstone.

small segment of Furnace Creek Formation None Six chip samples 

idstone and shale lap up on Paleozoic 1.7 percent), li

irlne sedimentary rocks at the west and boron (0.004

western boundary. The mudstone is 

tuffaceous, limey, and contains fibrous 

gypsum. The sediments are lacustrine In 

origin.

Bentonlte Placer A bentonitlc shale-muds tone bed as thick as One prospect pit Is 5 x 5 x Six chip samples 

prospect 4.2 ft strikes N. 10° E. and dips 45° SE. 2 ft. composed predomi

exposure. contained 10 to 

Yellow Heart Thin, gray-green zeolltic shale lies above One small cut Three chip sampl

prospect tuff and below alluvial fan gravels. Beds clinoptllollte a

strike N. 15° E., dip 27° NW., average

1.5 ft thick, and are Intermittently exposed

for 100 ft.

Gray-green bentonitlc bed averages 2.0 ft Five trenches (two 30 x 12 x Three chip and t

thick and Is exposed In workings In a 3 ft; the others less than 20 montmor1llonlte 

3.6 acre area. Best exposures are ft long) and three small gypsum. Four sa

along a 280-ft-long bentonitlc mudstone- prospect pits. clinop11lolite . 

limestone contact. standards for us

medium.

Four lenses of montraor11Ion 11e clay are Two trenches, each 18 x 6 x Four chip sample

dlscontlnously exposed for 260 ft between 3 ft deep. anomalous amount

limestone beds. The clay lenses are as much

as 8.2 ft thick (average 2.0 ft) and

parallel north to northwest striking

limestone units. Dips range from 45° to

70° E.
?n only on dump, displays Three sele< 

high-grade 

contains me 

pelletizing

hentonite bed chip sampl

One collapsed adit

A white-gray pumice bed is friable, gritty,

ucords are unavailable, 

ne small prospect pit

up 1 e s t ak 

Optical petrog

verified pumic

Three pits, the largest 

20 x 10 x 10 ft deep.

Six chip sampl

nontmorillonit

iUlnopr.iloH.te

Six chip sampl

Spring Formati

70

red sandstone 

quantities of 

CO
APPENDIX 1. Definition of levels of mineral resource 

potential and certainty of assessment

Mineral resource potential is defined as the 

likelihood of the presence of mineral resources in a 

defined area; it is not a measure of the amount of 

resources or their profitability.

Mineral resources are concentrations of naturally 

occurring solid, liquid, or gaseous materials in such 

form and amount that economic extraction of a commodity from the concentration is currently or potentially feasible.

Low mineral resource potential is assigned to 

areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment where 

the existence of resources is unlikely. This level of 

potential embraces areas of dispersed mineralized rock 

as well as areas having few or no indications of 

mineralization. Assignment of low potential requires 

specific positive knowledge; it is not used as a catchall 

for areas where adequate data are lacking.

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 a reasonable chance for resource 

accumulation, and where an application of genetic and 

(or) occurrence models indicates favorable ground.

High mineral resource potential is assigned to 

areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment 

favorable for resources, where interpretations of data 

indicate a high likelihood for resource accumulation, 

where data support occurrence and (or) genetic models 

indicating presence of resources, and where evidence 

indicates that mineral concentration has taken place. 

Assignment of high resource potential requires positive 

knowledge that resource-forming processes have been 

active in at least part of the area; it does not require 

that occurrences or deposits be identified.

Unknown mineral resource potential is assigned 

to areas where the level of knowledge is so inadequate 

that classification of the area as high, moderate, or

low would be misleading. The phrase "no mineral 

resource potential" applies only to a specific resource 

type in a well-defined area. This phrase is not used if 

there is the slightest possibility of resource 

occurrence; it is not appropriate as the summary 

rating for any area.

Expression of the certainty of the mineral 

resource assessment incorporates a consideration of (1) 

the adequacy of the geologic, geochemical, geophysical, and resource data base available at the time of 

the assessment, (2) the adequacy of the occurrence or 

the genetic model used as the basis for a specific 

evaluation, and (3) an evaluation of the likelihood that 

the expected mineral endowment of the area is, or 

could be, economically extractable.

Levels of certainty of assessment are denoted oy 

letters, A-D (fig. 3).

A. The available data are not adequate to 

determine the level of mineral resource potential. 

Level A is used with an assignment of unknown mineral 

resource potential.

B. The available data are adequate to suggest 

the geologic environment and the level of mineral 

resource potential, but either evidence is insufficient 

to establish precisely the likelihood of resource occurrence, or occurrence and (or) genetic models are not 

known well enough for predictive resource assessment.

C. The available data give a good indication of 

the geologic environment and the level of mineral 

resource potential, but additional evidence is needed 

to establish precisely the likelihood of resource occurrence, the activity of resource-forming processes, or 

available occurrence and (or) genetic models are 

minimal for predictive applications.

D. The available data clearly define the geologic 

environment and the level of mineral resource 

potential, and indicate the activity of resourceforming processes. Key evidence to interpret the 

presence or absence of specified types of resources is 

available, and occurrence and (or) genetic models are 

adequate for predictive resource assessment.

U/A

UNKNOWN 

POTENTIAL

H/B

HIGH POTENTIAL

M/B

MODERATE POTENTIAL

L/B

LOW POTENTIAL

H/C

HIGH POTENTIAL

M/C

MODERATE POTENTIAL

L/C

LOW POTENTIAL

H/D

HIGH POTENTIAL

M/D

MODERATE POTENTIAL

L/D

LOW POTENTIAL

N/D

NO POTENTIAL

LEVEL OF CERTAINTY

Figure 3. Major elements of mineral resource potential/certainty classification.

A14

GPO 785-048/48035