Mineral Resources of the

Owens Peak Wilderness Study Area,

Tulare and Kern Counties, California

U.S. GEOLOGICAL SURVEY BULLETIN 1705-A

Chapter A

Mineral Resources of the

Owens Peak Wilderness Study Area,

Tulare and Kern Counties, California

By MICHAEL F. DIGGLES, JAMES G. FRISKEN, 

ANDREW GRISCOM, and HERBERT A. PIERCE 

U.S. Geological Survey

J. DOUGLAS CAUSEY 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1705-A

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1986

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 Owens Peak Wilderness Study 

Area, Tulare and Kern Counties, California

U.S. Geological Survey Bulletin 1705-A

Bibliography

Supt. of Docs. No.: I 19.3:1705-A

1. Mines and mineral resources California Owens

Peak Wilderness. 2. Geology California Owens Peak

Wilderness. I. Diggles, M.F. II. Series.

QE75.B9 No. 1705-A 557.3 s 86-600270

[TN24.C2] [553'.09794'86]
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 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 part of the Owens Peak 

(CA-010-026) Wilderness Study Area, Tulare and Kern Counties, California.

CONTENTS

Summary Al

Abstract 1

Character and setting 1 

Identified mineral resources 1 

Mineral resource potential 3 

Introduction 3

Location and physiography 3 

Procedures and sources of data 3 

Acknowledgments 6 

Appraisal of Identified Resources 6

Mining and mineral exploration history 6 

Mines, prospects, and mineral occurrences 6 

Appraisal of identified resources 6 

Assessment of Mineral Resource Potential 6 

Geology 6

Paleozoic(?) metamorphic rocks 6 

Triassic and (or) Jurassic granitic rocks 7 

Cretaceous granite and granodiorite 7 

Quaternary surficial deposits 7 

Structure 7 

Geochemistry 7

Methods and background 7 

Results and interpretation 8 

Geophysics 9

Aeromagnetic data 9 

Electrical data 9 

Conclusions 10 

References cited 10

Appendix 1. Definition of levels of mineral resource potential and 

certainty 13

FIGURES

1. Index map showing location of Owens Peak Wilderness Study Area. Tulare and Kern Counties. 

California A2

2. Generalized geologic map and areas of mineral resource potential in the Owens Peak Wilderness 

Study Area, California 4

3. Major elements of mineral resource potential/certainty classification 13

TABLE

1. Prospect in the Owens Peak Wilderness Study Area (CA-010-026) A12

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA

Mineral Resources of the Owens Peak 

Wilderness Study Area, Tulare and 

Kern Counties, California

By Michael F. Diggles, James G. Frisken, Andrew Griscorn, and Herbert A. Pierce 

U.S. Geological Survey

j. Douglas Causey 

U.S. Bureau of Mines

SUMMARY 

Abstract

The part of the Owens Peak Wilderness Study 

Area (CA-010-026) designated as suitable for mineral 

surveys encompasses 14,430 acres in the southern 

Sierra Nevada. Field work was carried out in 1981 

through 1985 to assess the mineral resource potential 

of the area.

The wilderness study area is underlain by granitic 

rocks that intruded metasedimentary rocks. Tungsten, 

occurring in the mineral scheelite, sometimes is 

present in skarns along the contacts between these two 

rock types.

There are four areas of mineral resource 

potential in the Owens Peak Wilderness Study Area 

(CA-010-026). The area of Burnt House Canyon has 

moderate mineral resource potential for tungsten and 

low mineral resource potential for copper and zinc. 

The area around Spanish Needle Creek has moderate 

mineral resource potential for tungsten and low 

mineral resource potential for lead. The canyon east 

of Lament Meadow has low mineral resource potential 

for tungsten, copper, and barite. The area of lower 

Three Pines Canyon has low mineral resource potential 

for tungsten and copper.

In this report, any reference to the Owens Peak 

Wilderness Study Area, the "wilderness study area," 

and "study area" refers only to that part of the 

wilderness study area designated by the U.S. Bureau of 

Land Management as suitable for mineral surveys.

Character and Setting

There are two Owens Peak Wilderness Study 

Areas (CA-010-026 and CDCA-158) in the southern

Sierra Nevada west of the range crest and north of 

Walker Pass (fig. 1). The mineral resources of the 

eastern wilderness study area, CDCA-158, are 

described by Diggles and others (1985). This report 

covers the western wilderness study area (CA-010- 

026); it is approximately 14,430 acres in area and is 

located 15 mi east of Isabella. The terrane is 

generally steep and rugged, with elevations ranging 

from about 4,500 ft in the valleys to 8,453 ft at the 

summit of Owens Peak.

Most of the area is underlain by plutonic rocks of 

the Sierra Nevada batholith. The majority of these 

rocks are leucocratic, nonfoliated Cretaceous (63 to 

138 million years before present) granites and 

granodiorites. There is also an older set of more mafic 

granitic rocks of Jurassic age (240 to 570 million years 

before present) that are granodioritic to tonalitic in 

composition. The oldest intrusive rocks in the 

wilderness study area are probably Triassic (205 to 240 

million years before present) and (or) Jurassic gabbros 

and diorites. The granitic rocks intrude Paleozoic(?) 

(240 to 570 million years before present) 

metamorphosed sedimentary rocks composed of 

quartz-mica schist, quartzite, and marble. There are 

zones of garnet-epidote-wollastonite calc-silicate 

hornfels near marble-granite intrusive contacts.

Identified Mineral Resources

In 1983, U.S. Bureau of Mines personnel 

conducted an appraisal of the mineral resources of the 

Owens Peak Wilderness Study Area (CA-010-026). This 

study was done in conjunction with the mineral 

appraisal of the Owens Peak (CDCA-158) and Little 

Lake Canyon (CDCA-157) Wilderness Study Areas. 

Ten mines, prospects, and mineralized areas were 

examined and sampled, one of which, the Golden Age

Al
1 18 

36°00'

15' 1 18°00' 1 17°45'

35°45'

Kennedy Meadows

to Bishop

s395

Little Lake

Little Lake

I \ LITTLE LAKE CANYON 

^WILDERNESS STUDY AREA 

/ \ (CDCA-157)

Meado

OWENS PEAK WILDERNESS 

STUDY AREA (CA 010-026)

6Pearsonville 1NYO CO 

TULARE CO KERN CO

KERN CO

OWENS PEAK WILDERNESS - 

STUDY AREA (CDCA 158)

AREA OF AAAP

Figure 1. Index map showing location of Owens Peak (CA-010-G26) Wilderness Study 

Area, Tulare and Kern Counties, California.

A2
prospect, is in the Owens Peak Wilderness Study Area 

(CA-010-026) (fig. 2, no. 1; table 1).

Metallic and nonmetallic mineral resources were 

not identified in the wilderness study area. The 

Golden Age prospect, located in Burnt House Canyon, 

encompasses two different mineral occurrences. Small 

skarns containing minor quantities of tungsten have 

been exposed in exploratory trenches. Sand and gravel 

deposits are sparse and small, and energy minerals 

were not identified in the wilderness study area.

Mineral Resource Potential

There are four areas of mineral resource 

potential in the Owens Peak Wilderness Study Area 

(CA-010-026) (fig. 2). The area of Burnt House 

Canyon, where the Golden Age prospect is located, is 

underlain by gneissic diorite and biotite granodiorite 

with minor pods of metamorphic rocks, including calcsilicate hornfels. Geochemical analyses of heavymineral concentrates from stream sediment indicate 

that tungsten, zinc, and copper are present. Inspection 

of the concentrates showed the presence of pyrite, and 

illumination under short-wave ultraviolet light showed 

the presence of scheelite and willemite. There is a 

pegmatite dike in the area that contains abundant 

muscovite. Samples from this prospect contain 

anomalous amounts of tungsten. The area has 

moderate mineral resource potential for tungsten and 

low mineral resource potential for copper and zinc.

Spanish Needle Creek is underlain by quartzmica schist containing local pods of calcareous 

metamorphic rocks. Heavy-mineral concentrate 

samples from the area contained anomalous 

concentrations of tungsten, as well as a minor lead 

anomaly. Visual inspection of samples with a shortwave ultraviolet lamp showed that scheelite is 

present. The area has moderate mineral resource 

potential for tungsten and a low mineral resource 

potential for lead.

The canyon east of Lament Meadow and west of 

Sand Canyon is underlain by granodiorite containing 

minor pegmatite dikes and local pods of metamorphic 

rocks. Geochemical samples contained anomalous 

concentrations of barium and slightly anomalous 

concentrations of tungsten and copper. The area has 

low mineral resource potential for tungsten, copper, 

and barite.

The area of lower Three Pines Canyon is 

underlain by granodiorite that contains local bodies of 

calc-silicate hornfels in metamorphic rocks. 

Geochemical studies show slightly anomalous 

concentrations of tungsten and copper accompanied by 

low concentrations of the associated skarn-related 

elements bismuth and molybdenum. The area has low 

mineral resource potential for tungsten and copper.

INTRODUCTION 

Location and Physiography

The Owens Peak Wilderness Study Area (CA-010- 

026) is located 15 mi east of Isabella, Calif, and 1 mi 

north of Walker Pass in the southern Sierra Nevada

(fig. 1). The study area consists of about 14,430 acres 

and extends from Walker Pass northward to Chimney 

Meadow, and from the Sierra Nevada crest on the east 

to Canebrake Road on the west. Access to the area is 

by California Highway 178 from the south, county road 

J41 from the north, and spurs off of Highway 178 and 

Canebrake Road from the west. There is no road 

access from the east. The terrane is generally steep 

and rugged with elevations ranging from about 4,500 ft 

in the Canebrake Creek valley in the southwest to 

8,453 ft at the summit of Owens Peak in the east. The 

vegetation is typically sagebrush and mountain 

mahogany on the lower slopes. Higher ground is 

covered by vegetation of the Transition Zone (Storer 

and Usinger, 1963): Jeffrey pine, incense cedar, black 

oak, ceanothus, and rare sugar pine on the north side 

of Lament Peak. The middle elevations are in the 

Upper Sonoran Zone, where pinon and digger pine, live 

oak, ceanothus, manzanita, and chinquapin dominate.

Procedures and Sources of Data

The U.S. Geological Survey conducted field 

investigations of the Owens Peak Wilderness Study 

Area (CA-010-026) from 1982 to 1985. This work 

included detailed geologic mapping where necessary, 

field checking of existing maps, geochemical sampling, 

and inspecting outcrops for scheelite using ultraviolet 

lamps. Aeromagnetic data were collected in 1981. 

The general geology of the area west of the Sierra 

Nevada crest was described by Miller (1931, 1946) and 

Miller and Webb (1940). The Inyokern quadrangle, 

adjacent to the wilderness study area to the southeast, 

was mapped by Dibblee (1954). A detailed geologic 

map of the Owens Peak Wilderness Study Area (CA010-026) was made by Biggies and Clemens (1986). 

The mineral resource potential of the Owens Peak 

(CDCA-158) and Little Lake Canyon (CDCA-157) 

Wilderness Study Areas, east and northeast of this 

study area, were described by Biggies and others 

(1985). The mineral resource potential of the 

Rockhouse Basin Wilderness Study Area, 15 mi west of 

the study area, was described by Taylor and others 

(1984) and summarized by Taylor (1984).

The U.S. Bureau of Mines gathered information 

about current and past mining activities in and near 

the wilderness study area and conducted field studies 

between March and July 1983. Data were taken from 

U.S. Bureau of Land Management mining-claim 

recordation indices, and land-status and use records, 

the U.S. Bureau of Mines Mineral Industry Location 

System, and Tulare and Kern County claim records. 

When possible, they contacted claim owners to obtain 

permission to examine their claims.

The U.S. Bureau of Mines conducted a search for 

all mines, prospects, claims, and mineralized zones 

within the study area. Mapping and sampling were 

done where warranted. In addition to the 15 rock 

samples and 53 panned-concentrate samples collected 

by the U.S. Geological Survey, the U.S. Bureau of 

Mines collected a total of 8 rock and 4 placer 

samples. U.S. Bureau of Mines' rock samples were 

assayed for gold and silver using a combined fire 

assay-ICP (Inductively Coupled Plasma) method, for 

tungsten by both colorimetric and x-ray fluorescence

A3
118°05' 118°00'

35°50 -

35°40' -

APPROXIMATE BOUNDA 

OF

OWENS PEAK WILDERNESS 

STUDY AREA (CA 010-026)

Figure 2. Generalized geologic map and areas of mineral resource potential in the Owens 

Peak (CA-010-026) Wilderness Study Area, California.

A4
EXPLANATION

GEOLOGIC TERRANE HAVING MODERATE MINERAL RESOURCE POTENTIALCommodities as shown. See appendix 1 and figure 3 for definition of levels of 

mineral resource potential.

GEOLOGIC TERRANE HAVING LOW MINERAL RESOURCE POTENTIAL

COMMODITIES

Ba Barite

Cu Copper

Pb Lead

W Tungsten

Zn Zinc

CORRELATION OF MAP UNITS 

QUATERNARY

CRETACEOUS

JURASSIC AND (OR) TRIASSIC

PALEOZOIC (?)

DESCRIPTION OF MAP UNITS

Qs Surficial deposits (Quaternary)

Kg Granitic rocks (Cretaceous)

J"Kg Granitic rocks (Jurassic and (or) Triassic)

Pzm Metamorphic rocks (Paleozoic ?)

MAP SYMBOLS

 - - CONTACT-Dashed where approximately located

 ... FAULT-Dashed where inferred, dotted where concealed 

X1 PROSPECT-Number refers to Table 1

Figure 2. Continued.

A5
methods, and for molybdenum and tellurium by 

atomic-absorption spectroscopy. All samples were 

analyzed by semiquantitative spectroscopy for 40 

elements, including antimony, barium, cadmium, 

cobalt, chromium, copper, gold, iron, lead, lithium, 

magnesium, manganese, molybdenum, nickel, platinum, 

silver, tin, titanium, vanadium, and zinc.

The 4 placer samples collected from stream 

channels near mineral properties and concentrated in 

the field were examined by microscope, ultraviolet 

lamp, and magnetic separator for gold, scheelite, 

ilmenite, garnet, zircon, and magnetite. Complete 

results of the U.S. Bureau of Mines' work in the 

wilderness study area are given by Causey and Gaps 

(1985).

Acknowledg ments

The authors greatly appreciate the cooperation 

of the local property owners. Gary D. Walker and 

Robert Waiwood of the U.S. Bureau of Land 

Management's Bakers field office lent assistance. 

Diane E. Clemens. David A. Dellinger, James E. 

Conrad, L. Darlene Batatian, Karen E. Carter. 

Kimberley R. Greene. M. Alisa Mast, Julian C. Grey, 

A. Dean McCollaum, Soren E. Jensen, Jr., J. Donald 

Landells. Jackson Ruby, Wiley Cranney, J. Mitch 

Linne, Terry Close, Terry Neumann, Richard S. Gaps, 

and Edward Me Hugh helped to complete the field 

work.

APPRAISAL OF IDENTIFIED RESOURCES

JBy_ J. Douglas Causey. U.S. Bureau of Mines

Mining and Mineral Exploration History

Gold was discovered prior to 1880 in Indian Wells 

Canyon, 10 mi east of the wilderness study area. 

(Troxel and Morton, 1962), but no gold has been found 

in the wilderness study area.

Tungsten was found in the wilderness study area, 

but the only production has come from outside the 

study area in Indian Wells Canyon. Mining took place 

near the end of World War II and between 1951 and 

1956. The interest in tungsten between 1951 and 1956 

was high because the U.S. General Services 

Administration was purchasing tungsten concentrates 

for $63 per short ton unit of contained WO3 . The 

market price was about $56 in 1986 (Engineering and 

Mining Journal, 1986).

Since World War II, activity in the region has 

been limited to exploration and small-scale mining, 

mainly for tungsten in scheelite-bearing skarn 

deposits.

There were no producing mines in or adjacent to 

the wilderness study area in 1983.

Mines, Prospects, and Mineral Occurrences

Scheelite-bearing skarn is present at the Golden 

Age prospect (no. 1, fig. 2). No extensive areas

containing scheelite are exposed on the prospect; 

mainly small isolated skarn bodies, no more than 40 ft 

in diameter, are present in the metamorphic rocks and 

along contacts with granodiorite. These bodies are 

related to calcareous zones in roof pendants in the 

Sierra Nevada batholith. Epidote-garnet-quartz skarns 

containing small amounts of scheelite. malachite, 

azurite, and chrysocolla occur at the Golden Age 

prospect.

Appraisal of Identified Resources

Metallic mineral resources were not identified in 

the Owens Peak Wilderness Study Area (CA-010-026). 

The Golden Age prospect encompasses two mineral 

occurrences with minor quantities of tungsten.

Sand and gravel resources were not found in the 

study area during this investigation. There is a 

possibility that rock types found in the wilderness 

study area could meet local demand for dimension 

stone, road metal, riprap, and other stone resources. 

However, similar material of equal or better quality is 

abundant closer to local markets.

ASSESSMENT OF MINERAL RESOURCE POTENTIAL

By Michael F. Diggles. James G. Frisken, Andrew 

Griscom. Herbert A. Pierce U.S. Geological Survey

Geology

The geology of the wilderness study area 

consists dominantly of granitic rocks of the Sierra 

Nevada batholith that represent at least three major 

periods of intrusive activity (Evernden and Kistler, 

1970). Most of the wilderness study area is underlain 

by leucocratic, nonfoliated Cretaceous rocks of 

granitic to granodioritic composition. There is also an 

older set of granitic rocks of Jurassic age that are 

often more mafic in composition and stromatic to 

schlieric in texture. The oldest intrusive rocks in the 

area are presumably Triassic and (or) Jurassic in age. 

These rocks are mesocratic to melanocratic. gabbroic 

to dioritic. and schistose to gneissic. The granitic 

rocks intrude Paleozoic(?) quartz-biotite-muscovite 

schist, quartzite. and marble. There are zones of 

garnet-epidote-wollastonite calc-silicate hornfels near 

marble-granite contacts.

Paleozoic(?) Metamorphic Rocks

Metamorphic rocks in the area consist of quartzmica schist, phyllite. quartzite. marble, calc-silicate 

hornfels, and metadacite. The most common rock 

type among the metamorphic units is quartz-mica 

schist. Skarns formed where plutonic rocks intruded 

calcareous rocks. These contact-metamorphic zones 

are important for their mineral resource potential. 

Garnet, epidote. wollastonite. and scheelite (CaWO4) 

are present in these zones. The biotite-actinolite 

hornfels show relict compositional layering. 

Metavolcanic rocks consist of granoblastic.

A6
equigranular augite-tremolite-hornblende amphibolite 

and chlorite-actinolite greenschist. The metamorphic 

rocks define a large roof pendant that crops out from 

Indian Wells Canyon to Canebrake Creek. The pendant 

may correlate in part with the Jurassic or older 

Kernville Series of Miller, (1931) which is located 4 mi 

west of the wilderness study area.

Triassic and (or) Jurassic Granitic Rocks

The older of two general sets of plutonic rocks in 

the wilderness study area consists of Triassic and (or) 

Jurassic gabbro, diorite, tonalite, quartz diorite, and 

granodiorite. The gabbro is melanocratic. coarse 

grained, and seriate to porphyritic. It is present in 

small bodies that seldom exceed 0.7 mi in area. The 

diorite is mesocratic to melanocratic, medium grained, 

seriate, and stromatic to schlieric. It is exposed from 

west of Owens Peak southeast into Indian Wells 

Canyon. The tonalite, quartz diorite. and granodiorite 

are mesocratic. medium grained, seriate to 

porphyritic, and stromatic to schlieric. These rocks 

are present in limited exposures in the northern part of 

the wilderness study area but dominantly crop out 

north and west of it. They are locally rich in mafic 

inclusions that have been assimilated to varying 

degrees.

Cretaceous Grar^ite and Granod iorite

The younger of the two sets of plutonic rocks 

consists of Cretaceous granite, alaskite, and 

granodiorite. In general, the younger plutonic rocks 

are more leucocratic than the older ones and are 

nonfoliated. The granite is leucocratic. fine- to 

coarse-grained, and equigranular. It is exposed in a 

limited area near the eastern edge of the wilderness 

study area and extends eastward into the Owens Peak 

(CDCA-158) Wilderness Study Area at Indian Wells and 

Sand Canyons. Numerous small pods of medium- to 

coarse-grained alaskite, alkali-feldspar granite, and 

associated aplite and pegmatite bodies are present 

along the crest of the Sierra Nevada in and near the 

wilderness study area (Diggles, 1984). The 

granodiorite is leucocratic. medium to coarse grained, 

and seriate to porphyritic.

Quaternary Surficial Deposits

Quaternary surficial deposits include Holocene 

stream-channel deposits consisting of poorly sorted 

gravel, sand, and silt found in channels and flood 

plains, and older Quaternary stream-channel deposits 

on dissected terraces.

Structure

The metamorphic rocks in and near Burnt House 

Canyon have a strong foliation that trends generally 

northwest. These rocks underwent at least two periods 

of uplift following major intrusive events (Nokleberg 

and Kistler, 1980).

The dominant geomorphic and structural features 

in the wilderness study area are a series of en echelon 

faults that run west-northwest across the range and 

controlled the formation of the major canyons in the 

eastern and northern parts of the wilderness study 

area. This series of faults is best exposed in Ninemile 

Canyon, where shearing and offset, as well as potassic 

alteration (shown by potassium-feldspar alteration of 

plagioclase) can be seen along shear zones in 

roadcuts. Overprinting this fault system is the Sierra 

Nevada front fault zone along which the range was 

uplifted. Parts of the range-front faults can be seen in 

saddles from the base of the range to its crest.

Geochemistry

Methods and Background

In the spring of 1984, the U.S. Geological Survey 

conducted reconnaissance stream-sediment sampling 

of the western Owens Peak Wilderness Study Area 

(CA-010-026). The eastern Owens Peak Wilderness 

Study Area (CDCA-158) was sampled and mapped in 

1982 (Diggles and others, 1985; Detra and others, 

1985). Sampling from the two studies overlap. The 

1984 reconnaissance of the Owens Peak Wilderness 

Study Area (CA-010-026) was designed to detect types 

of mineral occurrences found in the eastern wilderness 

study area. Nonmagnetic heavy-mineral concentrates 

were collected from 53 sampling sites. In addition, 15 

mineralized or altered rock samples were collected. 

The data from this sampling program are presented by 

Adrian and others (1986). Areas thought to be 

mineralized were sampled in greater detail than other 

areas. The nonmagnetic fraction of the heavy-mineral 

concentrates was chosen as the primary geochemical 

sampling medium because this concentrate, prepared 

from panned, active stream sediment, tends to retain 

minerals related to hydrothermal mineralization and 

alteration. It also excludes clays, organic matter, and 

the common rock-forming minerals, some of which 

account for metal anomalies unrelated to 

mineralization. An example of the use of concentrates 

to locate tungsten mineralization is described by 

Theobald and Thompson (1959).

The nonmagnetic heavy-mineral concentrates 

were examined microscopically to determine if orerelated minerals or man-made contaminants were 

present and then were examined under short-wave 

ultraviolet lamp for scheelite and willemite. They 

were then pulverized and 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 using a six-step 

semiquantitative e mission-spec trographic method 

(Grimes and Marranzino, 1968). The concentrates 

were also analyzed for tungsten by atomic absorption 

(Welsch, 1983), and the remaining nonmagnetic 

concentrate of each sample was analyzed for gold by 

atomic-absorption spectroscopy. Mineralized samples 

were also collected and examined under ultra-violet 

light for the presence of scheelite. Eight rock samples 

were analyzed for gold by atomic-absorption 

spectroscopic analysis using methods of Thompson and

A7
others (1968) and Ward and others (1969). All 15 rocks 

were analyzed for 31 elements by spectrographic 

analysis.

Threshold values for rocks were chosen at 2 to 3 

times crustal abundance values for similar 

nonmineralized rocks according to geochemistry-text 

tables (Rose and others, 1979), and for concentrates on 

the basis of past experience with this sample media 

and by comparison with thresholds used for the eastern 

Owens Peak (CDCA-158) Wilderness Study Area.

The geologic setting of the Owens Peak 

Wilderness Study Area (CA-010-026) is similar to that 

of the contiguous areas of the Owens Peak (CDCA158) Wilderness Study Area (Biggies and others, 1985), 

which have a low mineral resource potential for 

tungsten, lead, and copper along the border between 

the two study areas from upper Sand Canyon to upper 

Ninemile Canyon, and low to moderate resource 

potential for gold and tungsten along the southwest 

side of upper Indian Wells Canyon. The mineral 

occurrences described by the U.S. Bureau of Mines for 

the two wilderness study areas indicate that the gold 

and tungsten zones are present in skarns and 

metamorphic roof pendants, and that the most 

important minerals are scheelite in skarns and gold 

associated with pyrite, galena, and sphalerite in 

contact-metamorphic zones. Geochemically, these 

occurrences are best characterized by anomalous 

concentrations of tungsten, lead, and bismuth in the 

panned-concentrate samples. Slightly anomalous 

levels of copper and molybdenum also commonly are 

present in both wilderness study areas and are 

associated with skarns.

Results and Interpretation

The geochemical interpretations are based 

primarily on data from the heavy-mineral 

concentrates. The elements occurring in anomalous 

values in the concentrate samples are shown below 

with their established threshold values (in parentheses) 

in parts per million (ppm): barium (2,000), bismuth 

(20), copper (50), lanthanum (500), lead (70), 

molybdenum (10), thorium (500), tin (30), tungsten (15), 

and yttrium (700). The distribution of these elements, 

when present in anomalous concentrations, is used to 

help determine the areas of mineral resource potential 

shown on figure 2. The highest tin concentration (150 

ppm) is associated with a pegmatite that is possibly 

mineralized. Ten samples with tin values ranging from 

30 to 100 ppm fall either in the region northeast of 

Lament Meadows or east of the drainage divide in 

upper Indian Wells Canyon. Lower tin concentrations 

correlate well with yttrium and lanthanum 

concentrations and are therefore interpreted as being 

contained within accessory minerals of the 

granitoids. Most of the concentrate samples collected 

in or near the wilderness study area have tungsten 

concentrations in excess of 50 ppm, and samples from 

nine sites have concentrations greater than 500 ppm. 

Scheelite was identified in many of these samples. 

Anomalous lead concentrations as high as 1,000 ppm 

and bismuth concentrations as high as 300 ppm are, for 

the most part, associated with high tungsten 

concentration. The association of lead, bismuth,

copper, and molybdenum with tungsten is indicative of 

tungsten-skarn mineralization, but the intensity of the 

anomalies may simply reflect the close proximity of 

the sampling sites to outcrops of mineralized rock. 

Copper-stained rocks are common in the Lament 

Meadows area and willemite (Zn2SiO4) is present as 

fracture fillings at the Golden Age prospect. 

Wulfenite (PbMoO4) and powellite (CaMoO4) were 

identified in some heavy-mineral concentrates and 

their presence suggests molybdenum-bearing rocks 

may be present, but correlation among the presence of 

lead, molybdenum, and tungsten is not strong. The 

uncommon occurrence of zinc anomalies and 

widespread but low-level molybdenum, copper, and 

lead anomalies suggest that these metals, although 

present in the mineralized skarns, are probably not 

present in ore-grade concentrations. They may, 

however, have value as by-product metals.

Between Lament Meadow and upper Sand 

Canyon, the concentrate samples have uniquely high 

barium concentrations, but are not strongly anomalous 

in the tungsten-skarn suite of elements. Surrounding 

sample sites to the north, south, and east are 

characterized by anomalous tungsten, lead, copper, 

tin, and molybdenum. In addition, most of these sites 

have disseminated pyrite in intrusive igneous and in 

metamorphic rocks. High barium values and pyrite 

occurrences are uncommon elsewhere in the wilderness 

study area. The barium is probably derived from 

barite present in small pods of metamorphic rocks 

exposed near the Sierra Nevada crest above the 

sampling site. One stream-cobble sample has 2,000 

ppm barium and may indicate barite associated with 

mineralization upstream.

The most highly mineralized areas appear to be 

(1) the north end of the wilderness study area east and 

northeast of Lament Meadow, (2) upper Spanish Needle 

Creek, (3) central Burnt House Canyon, and (4) the 

ridge area at the south end of the wilderness study 

area. Metamorphic roof-pendant rocks extending over 

the Sierra Nevada crest from the Owens Peak 

Wilderness Study Area (CDCA-158) have high 

concentrations of bismuth, lead, tin, and tungsten on 

the east side of the crest where gold and tungsten have 

previously been mined (Diggles and others, 1985).

The most anomalous sample from the wilderness 

study area, a locally derived concentrate, was 

collected near a pegmatite near the Golden Age 

prospect. No obvious mineralization was noted in the 

pegmatite, although iron staining was present. Skarn 

mineralization took place nearby. The concentrate 

contained 300 ppm tungsten, 200 ppm lead, 500 ppm 

copper, greater than 1 percent barium, and 2 percent 

pyrite. Willemite was also reported from this 

pegmatite and was noted in nearby skarn rocks, as was 

copper staining. A sheared gneissic diorite outcrop 0.6 

mi east of the Golden Age prospect on a hillside north 

of the creek contained 150 ppm copper, 200 ppm 

bismuth, and 1,000 ppm manganese. Pyrite crystals in 

pegmatite were also seen nearby.

Gold was not seen in the concentrates or 

detected in the analyses, including the atomicabsorption analyses (detection limit 0.05 ppm) of the 

combined magnetic and nonmagnetic concentrates. 

The U.S. Bureau of Mines' analyses of rocks from the 

Golden Age claims detected anomalous concentrations

A8
of gold but did not lead to the identification of gold 

resources there. Eight rock samples analyzed for gold 

by the U.S. Geological Survey showed no gold values at 

a detection limit of 0.1 ppm.

One skarn sample from an outcrop along the road 

up lower Spanish Needle Creek contained 1,000 ppm 

chromium and 500 ppm nickel. No nickel-chromium 

anomalies were identified within the area studied.

Scattered occurrences of skarn and mineralized 

calc-silicate rocks near contacts with the batholith 

probably account for all of the anomalies in the 

portion of the area studied, but follow-up work would 

be required to describe each occurrence.

Geophysics

Aeromagnetic Data

An aeromagnetic survey of the Owens Peak 

Wilderness Study Area (CA-010-026) (U.S. Geological 

Survey, 1982) was flown in 1981 by a private 

contractor. The aeromagnetic data were collected 

along parallel east-west flight lines spaced 0.5 mi 

apart at a constant elevation of 9,000 ft. The 

contractor subtracted the earth's main field from the 

data, gridded the data set using a grid spacing of 200 

meters, and machine-contoured the gridded data at a 

scale of 1:62,500 to produce the residual aeromagnetic 

map.

Variations in the earth's magnetic field on a 

residual map are generally caused by variations in the 

amounts of magnetic minerals present in different 

rock units, magnetite being the most common 

magnetic mineral in this area. Magnetic minerals may 

cause a high magnetic anomaly if they are 

concentrated or a low magnetic anomaly if they are 

absent. The resulting magnetic anomalies may act as 

a guide to mineral occurrences or deposits. Boundaries 

between more or less magnetic rock units are located 

approximately at the steepest gradient on the flanks of 

the magnetic anomaly because, at the latitudes of the 

study area, the inclination of the Earth's main 

magnetic field is relatively steep (61° below the 

horizontal). Comparison of the contoured 

aeromagnetic map with the geologic and topographic 

maps indicates that most of the magnetic anomalies 

are caused by topographic relief in magnetic terrane 

composed of Mesozoic plutonic rocks, in particular the 

mesocratic to melanocratic units. Relatively 

magnetic intrusive rocks are represented by diorite in 

Indian Wells Canyon, gabbro and quartz diorite in the 

eastern part of the wilderness study area, granodiorite 

at Lament Peak, and granodiorite at Morris Peak. 

These rocks, described by Diggles and Clemens (1986), 

tend to have similar magnetic properties, as shown by 

their mutual geologic contacts not being expressed as 

magnetic gradients. Major hills or mountains 

composed of these rocks usually are associated with 

magnetic highs. The weakly magnetic rock units are 

the metamorphic and granitic rocks exposed in Sand 

Canyon and near Owens Peak. These rocks are 

associated with magnetic lows, and the contacts with 

more mafic rocks tend to be associated with magnetic 

gradients. The faults in the northern part of the

wilderness study area appear as linear magnetic lows, 

but this is probably an effect of the low topographic 

expression of the faults. Limonitic alteration was 

mapped only in the southern part of the wilderness 

study area.

An unusual circular magnetic anomaly with an 

amplitude of about 200 gammas and a source width of 

about 0.7 mi is located at Owens Peak and has an 

associated magnetic low directly to the north. This 

feature is a topographic effect caused by the 

proximity of the rocks of Owens Peak itself, which was 

only 500 ft below the aircraft and is composed of a 

magnetic diorite also found in Indian Wells Canyon.

In general, the aeromagnetic data do not appear 

to provide any evidence for mineral resource potential 

in this area.

Electrical Data

Fourteen audiomagnetotelluric (AMT) soundings 

and two telluric traverses were carried out in and near 

the wilderness study area. The data collected show a 

north-northwest-trending, relatively low-resistivity 

trough on the west side of the wilderness study area, 

principally occurring within intrusive granitic rocks of 

the southern Sierra Nevada batholith. This trough 

encompasses the Golden Age prospect on the north 

side of Burnt House Canyon and correlates with a 

north-northwest-trending area of limonite alteration. 

Limonite minerals are secondary iron-bearing minerals 

that often form by weathering of minerals formed 

during hydrothermal alteration (Blanchard, 1968). This 

area of alteration corresponds with limonite minerals 

mapped from Landsat multispectral-scanner (MSS) 

data using a color-ratio compositing technique 

described by Rowan and others (1974) (D.H. Knepper, 

Jr, written commun, 1986). Two additional areas 

where MSS data show limonite anomalies are located 

in Three Pines Canyon and Spanish Needles Creek 

(D.H. Knepper, Jr., written commun, 1986).

It may be inferred from the electrical data that 

the low represents an area of general alteration in the 

granitic rocks. The two telluric traverses help to 

define the eastern boundary of the low-resistivity 

trough and correlate directly with the AMT data. The 

principal telluric line along Burnt House Canyon (line 

2, H.A. Pierce, unpub. data, 1985) shows that the 

electrical boundary extends over a lateral distance of 

more than 0.6 mi. This suggests a rather diffuse 

boundary for the inferred alteration within the 

intrusive rocks. A map of apparent resistivities (at 27 

Hertz) was produced for the 14 AMT sounding sites 

(H.A. Pierce, unpub. data, 1985). This map shows the 

extent and strike of the low-resistivity trough. The 

north and south ends of the trough are not well defined 

by these data. The trough presumably extends for 

some unknown distance beyond the survey area. A 

cross-section of the inverted soundings (8, 9, and 10, 

H.A. Pierce, unpub. data, 1985) show that this low 

extends 0.6 to 1.3 mi downward.

The presence of this low-resistivity trough adds 

certainty to the mineral resource assessment of the 

area around Burnt House Canyon by confirming the 

presence of alteration indicated by geochemical 

results.

A9
CONCLUSIONS

The Owens Peak Wilderness Study Area (CA-010- 

026) is situated in the Sierra Nevada physiographic 

province, which contains the largest concentration of 

tungsten deposits in the United States (Newberry, 

1982). The mineral-deposit model that is most 

appropriate to apply in this study area is the tungstenskarn felsic-plutonic-rock model (Einaudi and others, 

1981; Cox, 1983; Cox and Singer, 1986).

There are four areas that have mineral resource 

potential in the Owens Peak Wilderness Study Area 

(CA-010-026). The area of Burnt House Canyon is 

underlain by gneissic diorite and biotite granodiorite 

with minor pods of metamorphic rocks, including calcsilicate hornfels. The Golden Age prospect is located 

in this canyon and is described in table 1. Samples 

from this prospect have anomalous concentrations of 

tungsten. The results of the geochemical analyses 

indicate that tungsten is present in concentrations 

greater than 1,000 ppm. Minor zinc and copper were 

also detected. Alteration and skarn mineralization are 

indicated by anomalous concentrations of tungsten, 

lead, bismuth, copper, and molybdenum, and are 

confirmed by the results of AMT soundings and the 

presence of a limonite anomaly on MSS maps. Visual 

inspection of the concentrates showed scheelite (W), 

willemite (Zn), and pyrite. There is a pegmatite dike 

in the area that contains abundant muscovite. The 

area has moderate mineral resource potential for 

tungsten with a certainty level of C, and low mineral 

resource potential for copper and zinc with a certainty 

level of B.

The Spanish Needle Creek area is underlain by 

several hundred acres of quartz-mica schist containing 

local pods of calcareous metamorphic rocks. 

Geochemical sampling of the area showed anomalous 

concentrations of tungsten, as well as minor lead 

concentrations. Alteration of rocks in the drainage is 

indicated by a limonite anomaly on MSS maps. 

Inspection of concentrate samples under ultra-violet 

light showed that scheelite is present. The area has 

moderate mineral resource potential for tungsten with 

a certainty level of B, and low mineral resource 

potential for lead with a certainty level of C.

The canyon east of Lament Meadow and west of 

Sand Canyon is underlain by granodiorite containing 

minor pegmatite dikes and local pods of metamorphic 

rocks. Geochemical samples contained slightly 

anomalous concentrations of tungsten and copper. 

There are also anomalous concentrations of barium, 

and copper staining was seen in float. The area has 

low mineral resource potential for tungsten, copper, 

and barite with a certainty level of B.

The area of lower Three Pines Canyon is 

underlain by biotite-porphyritic granodiorite with local 

areas of calc-silicate hornfels in metamorphic rocks. 

Geochemical results show slightly anomalous 

concentrations of tungsten and copper accompanied by 

low concentrations of the associated skarn-related 

elements bismuth and molybdenum. Alteration of the 

rocks in this area is indicated by the presence of a 

limonite anomaly on MSS maps. The area has low 

mineral resource potential for tungsten and copper 

with a certainty level of B.

The lack of significant limonite anomalies and

the mineral assemblages observed in hand specimens 

indicate that mineralization in the wilderness study 

area is probably limited to small skarn bodies and 

pegmatites.

The wilderness study area has no geothermal 

energy potential (Higgins, 1981) and the geology is not 

conducive to petroleum or natural gas resource 

potential.

REFERENCES CITED

Adrian, B.M., Frisken, J.G., Biggies, M.F., and 

Malcolm, M.J., 1986, Analytical results and 

sample locality map of heavy-mineral 

concentrate and rock samples from the Owens 

Peak Wilderness Study Area (CA-010-026), Kern 

and Tulare Counties, California: U.S. Geological 

Survey Open-File Report 86-282, 21 p.

Blanchard, Roland, 1968, Interpretation of leached 

outcrops: Nevada Bureau of Mines Bulletin 66, 

196 p.

Causey, J.D., and Gaps, R.S., 1985, Mineral resources 

of the Little Lake Canyon (BLM NO. CDCA-157), 

Owens Peak (BLM NO. CDCA-158), and Owens 

Peak (BLM NO. CA-010-026) Wilderness Study 

Areas, Inyo, Kern, and Tulare Counties, 

California: U.S. Bureau of Mines Mineral Land 

Assessment MLA 2-85, 39 p.

Cox, D.P., ed., 1983, U.S. Geological SurveyIngeominas mineral resource assessment of 

Colombia: ore deposit models: U.S. Geological 

Survey Open-File Report 83-423, 65 p.

Cox, D.P., and Singer, D.A., eds., 1986, Mineral 

Deposit Models: U.S. Geological Survey Bulletin 

1693.

Detra, D.E., Erickson, M.S., Tucker, R.E., Biggies, 

M.F., and Parduhn, N.L., 1985, Analytical results 

and sample locality map of stream-sediment and 

heavy-mineral-concentrate samples from the 

Little Lake Canyon (CDCA-157) and Owens Peak 

(CDCA-158) Wilderness Study Areas, Inyo and 

Kern Counties, California: U.S. Geological 

Survey Open-File Report 85-34, 21 p.

Dibblee, T.W., Jr., 1954, Geologic map of the Inyokern 

quadrangle: U.S. Geological Survey open-file 

report 59-31 , scale 1:62,500.

Diggles, M.F., 1984, Peraluminous granite from the 

southern Sierra Nevada, California abs. : 

Geological Society of America Abstracts with 

Programs, v. 16, no. 5, p. 278.

Diggles, M.F., and Clemens, D.E., 1986, Geologic map 

of the Owens Peak Wilderness Study Area (CA010-026), Tulere and Kern Counties, California: 

U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1833, scale 1:48,000.

Diggles, M.F., Tucker, R.E., Griscom, Andrew, Causey, 

J.D., and Gaps, R.S., 1985, Mineral Resources of 

the Owens Peak and Little Lake Canyon 

Wilderness Study Area, southern Sierra Nevada, 

California: U.S. Geological Survey Bulletin 

1708-B, 14 p.

Einaudi, M.T., Meinert, L.D., and Newberry, R.J., 

1981, Skarn deposits: in Skinner, B.J., ed., 

Economic Geology, 75th Anniversary Volume, p. 

317-391.

A10
Engineering and Mining Journal, 1986, E&MJ markets, 

ores, and concentrates: v. 178, no. 4, p. 17.

Evernden, J.F., and Kistler, R.W., 1970, Chronology of 

emplacement of Mesozoic batholithic complexes 

in California and western Nevada: U.S. 

Geological Survey Professional Paper 623, 42 p.

Grimes, 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.

Higgins, C.T., compiler, 1981, Geothermal resources of 

California: California Division of Mines and 

Geology, Geologic Data Map No. 4, scale 

1:750,000.

Miller, W.J., 1931, Geologic sections across the 

southern Sierra Nevada of California: University 

of California Publications, Bulletin of the 

Department of Geological Sciences, v. 20, p. 

331-360.

____1946, Crystalline rocks of southern California: 

Geological Society of America Bulletin, v. 57, p. 

457-464, 510-513, 518-542.

Miller, W.J., and Webb, R.W., 1940, Descriptive 

geology of the Kernville quadrangle, California: 

California Journal of Mines and Geology, v. 36, 

p. 343-368.

Newberry, R.T., 1982, Tungsten-bearing skarns of the 

Sierra Nevada. L The Pine Creek mine: 

Economic Geology, v. 77, p. 823-844.

Nokleberg, W.J., and Kistler, R.W., 1980, Paleozoic 

and Mesozoic deformations in the central Sierra 

Nevada, California: U.S. Geological Survey 

Professional Paper 1145, 24 p.

Rose, A.W., Hawkes, H.E., and Webb, J.S., 1979, 

Geochemistry in mineral exploration, 2d ed.: 

London, Academic Press, 657 p.

Rowan, L.C., Wetlaufer, P.H., Goetz, A.F.H., 

Billingsely, F.C., and Stewart, J.H., 1974, 

Discrimination of rock types and detection of 

hydrothermally altered areas in south-central

Nevada by the use Of computer-enhanced ERTS 

images: U.S. Geological Survey Professional 

Paper 883, 35 p.

Storer, T.I., and Usinger, R.L., 1963, Sierra Nevada 

natural history: Berkeley, University of 

California Press, 374 p.

Taylor, G.C., 1984, Rockhouse Basin Wilderness Study 

Area, Kern and Tulare Counties: California 

Geology, v. 37, p. 263-272.

Taylor, G.C., Loyd, R.C., Alfors, J.T., Burnett, J.L., 

Stinson, M.C., Chapman, R.C., Silva, M.A., 

Bacon, C.F., and Anderson, T.P., 1984, Mineral 

resource potential of the Rockhouse Basin 

Wilderness Study Area, Kern and Tulare 

Counties, California: California Division of 

Mines and Geology Special Report 157, 75 p.

Theobald, P.K., and Thompson, C.E., 1959, 

Geochemical prospecting with heavy-mineral 

concentrates used to locate a tungsten deposit: 

U.S. Geological Survey Circular 411, 13 p.

Thompson, C.E., Nakagawa, H.M., and Van Sickle, 

G.H., 1968, Rapid analysis for gold in geologic 

materials, in Geological Survey research 1968: 

U.S. Geological Survey Professional Paper 600-B, 

p. B130-132.

Troxel, B.W., and Morton, P.K., 1962, Mines and 

mineral resources of Kern County, California: 

California Division of Mines and Geology, County 

Report 1, 370 p.

U.S. Geological Survey, 1982, Aeromagnetic map of 

the Sierra Owens area, California: Open-File 

Report 82-1083, scale 1:62,500.

Welsch, E.P., 1983, As rapid geochemical spectrophotometric determination of tungsten with with 

dithiol: Talanta V. 30, p. 876-878.

Ward, F.N., Nakagawa, H.M., Harms, T.M., and 

VanSickle, G.H., 1969, Atomic-absorption 

methods of analysis useful in geochemical 

exploration: U.S. Geological Survey Bulletin 

1289, 45 p.

All
TABLE 1. - Prospect in Owens Peak Wilderness Study Area (CA-010-026)

Map 

no. Name Summary

Workings 

and production Samp

Golden Age Two types of deposits, skarn and pegmatite, 

Prospect crop out of Golden Age and Golden Age Nos. 1-5 

claims. Two outcrops of skarn are located 

about 300 ft apart; one is about 1 ft by 10 ft 

and the other about 40 ft by 80 ft. The skarn 

generally consists of garnet, epidote, and 

quartz. Small amounts of scheelite are 

present locally; one outcrop contains 

secondary copper minerals. Much of the 

surrounding rock is hornfels; a diorite-gabbro 

dike is also exposed. A muscovite-rich 

feldspar-quartz pegmatite pod, less than 100 

ft in diameter, is about 300 ft south of the 

skarn deposits. The muscovite is irregularly 

distributed with flakes as much as 1 in. in 

diameter. Some of the quartz and feldspar are 

intergrown.

Three trenches (50, 30, and 30 

ft long) and three small pits.

Eight samples we

from epidote, ga

skarn. One cont

contained 0.0137 

contained 0.076 

contained 0.06 a

trioxide. Two s

contained 0.0019 

sample of pegmat

gold. Muscovite 

10 percent of th
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 by 

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.

A13
o>

00 

-vl I o

-^

CD

^ 

00

o o

00