Mineral Resources of the Dry Valley Rim 

Wilderness Study Area, Washoe County, 

Nevada, and Lassen County, California

U.S. GEOLOGICAL SURVEY BULLETIN 1706-D

Chapter D

Mineral Resources of the

Dry Valley Rim Wilderness Study Area,

Washoe County, Nevada,

and Lassen County, California

By MICHAEL F. DIGGLES, JAMES G. FRISKEN, and 

DONALD PLOUFF 

U.S. Geological Survey

J. MITCHELLLINNE 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1 706

MINERAL RESOURCES OF WILDERNESS STUDY AREAS:

NORTHEASTERN CALIFORNIA AND PART OF ADJACENT WASHOE COUNTY, NEVADA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988

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 Dry Valley Rim Wilderness Study 

Area, Washoe County, Nevada, and Lassen County, California

U.S. Geological Survey Bulletin 1706-D

Bibliography

Supt. of Docs. No.: I 19.3:1706-D

1. Mines and mineral resources Dry Valley (Calif, and Nev.)

2. Dry Valley Rim Wilderness (Calif, and Nev.) I. Diggles, 

M.F. II. Series.

QE75.B9 No. 1706-D 557.3s 87-600036 

[TN25.D79] [553'.09793'55]
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 Dry Valley 

Rim (CA-020-615) Wilderness Study Area, Washoe County, Nevada, and Lassen County, California.

CONTENTS

Summary Dl

Abstract 1

Character and setting 1

Identified resources 1

Mineral resource potential 2 

Introduction 3

Location and physiography 3

Previous studies 3

Acknowledgments 3 

Appraisal of identified resources 3

Mining history 5

Identified resources 5 

Assessment of mineral resource potential 6

Geology 6

Geochemistry 7

Methods and background 7 

Results and interpretation 8

Geophysics 8

Aerial gamma-ray data 8 

Gravity data 9 

Aeromagnetic data 9

Mineral resource assessment 9 

References cited 10 

Appendixes

Definition of levels of mineral resource potential and certainty of assessment 14

Resource/reserve classification 15

Geologic time chart 16

FIGURES

1. Index map showing location of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada 

and Lassen County, California D2

2. Generalized geologic map and areas of mineral resources and resource potential in the Dry Valley Rim 

Wilderness Study Area, California and Nevada 4

TABLE

1. Mining claims and mineralized sites in the Dry Valley Rim Wilderness Study Area D17

Contents V

MINERAL RESOURCES OF WILDERNESS STUDY AREAS:

NORTHEASTERN CALIFORNIA AND PART OF ADJACENT WASHOE COUNTY, NEVADA

Mineral Resources of the 

Dry Valley Rim Wilderness Study Area, 

Washoe County, Nevada, and 

Lassen County, California

By Michael F. Diggles, James G. Frisken, and Donald Plouff 

U.S. Geological Survey

J. Mitchell Linne 

U.S. Bureau of Mines

SUMMARY 

Abstract

At the request of the U.S. Bureau of Land Management, 

approximately 54,480 acres of the Dry Valley Rim Wilderness 

Study Area (CA-020-615) were evaluated for mineral resources 

(known) and mineral resource potential (undiscovered). In this 

report, the area studied is referred to as the "wilderness study 

area" or simply "the study area;" any reference to the Dry Valley 

Rim Wilderness Study Area refers only to that part of the wilderness study area for which a mineral survey was requested by the 

U.S. Bureau of Land Management.

The study area is underlain by horizontal to gently 

dipping middle Miocene volcanic rocks including andesite, lava 

and lahar deposits, basalt lava, and minor rhyolite ash-flow tuff. 

These strata form a gently west-dipping homocline bounded on 

the east by a north-trending normal fault located along Dry Valley 

Rim. The Red RockCanyon and WillowSprings areas contain an 

estimated 85 million tons of inferred subeconomic zeolite resources. These two areas have moderate mineral resource 

potential for zeolites. The zeolites occur as amygdule fillings in 

basaltic lava. Mining of zeolites in basalts is highly unlikely due 

to their low grade and difficulties and costs of extracting zeolites 

from basalts. A small area a long the southeast margin of the study 

area has low mineral resource potential forperlite. All three areas 

that have resource potential are located in and around prospects 

along the east boundary of the study area. The wilderness study 

area has no resource potential for geothermal energy or oil and 

gas.

Character and Setting

The Dry Valley Rim Wilderness Study Area is located 

in Washoe County, northwestern Nevada, and Lassen County, 

northeastern California (fig. 1). The area encompasses 54,480 

acres managed by the U.S. Bureau of Land Management and 

is located about 40 mi east of Susanville. Access to the study 

area is provided by several dirt roads that join boundary roads. 

Elevations range from 3,800 to 6,200 ft; most relief occurs 

along Dry Valley Rim. The rim is 1,500 ft higher in elevation 

than the Smoke Creek Desert to the east. Areas west of the rim 

form gentle slopes and rolling hills. Steep rim rock walls and 

talus-covered canyons are common in the eastern part of the 

area, while most of the study area is gradually sloping, covered 

only by sparse sagebrush and native grasses.

Identified Resources

No metallic resources are identified. The Red Rock 

and Willow Springs areas contain 85 million tons of altered 

basalt containing amygdules that host an inferred subeconomic resource of zeolites. This basalt, more than 50 percent of 

which consists of amygdules filled with chabazite (a zeolite 

mineral), constitutes an identified subeconomic zeolite resource.

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D1
The Broken Shovel claims, located along the southeast 

boundary of the study area, contain a 100,000-ton occurrence 

of perlite. While usable for lightweight aggregate, the deposit 

is too small for economic production. However, if considered 

for perlite production with other nearby deposits, this occurrence could become a subeconomic resource.

Montmorillonitic clays are present in alluvial sediment 

in the Capricorn claims adjacent to the study area. Alluvial 

sediments contain more than 30 percent (volume) clays. The 

material is not usable as pozzolan and was not tested for other 

uses such as absorbency, oil clarification, or insecticide carrier.

Mineral Resource Potential

Amygdule-rich basalt that crops out in the Red Rock 

Canyon and Willow Springs areas has moderate resource

potential for zeolites. Zeolite (chabazite) is present within 

middle Miocene basalt as amygdule-fill material (see appendix for geologic time chart). The areas of alteration that contain 

the zeolites are proximal to a north-trending fault that probably 

controlled the movements of alteration fluids. In both areas, 

zeolite-filled amygdules form more than 50 percent of the 

rock. The zeolite occurrence at Red Rock Canyon is the larger 

of the two; it contains about two to three times the volume 

present in the Willow Springs area. The quality of the zeolites 

around Red Rock Canyon and west of Willow Springs may be 

adequate for use as an absorbent in animal husbandry. These 

two areas have moderate mineral resource potential for zeolites.

The area of silicic volcanic rocks around the Broken 

Shovel claims has low resource potential for perlite. The 

perlite is hosted in displaced blocks of what possibly originated 

as a rhyolite flow-dome complex.

120°30' 120° 15' 120°00'

40°20'

Smoke 

Creek

Desert

APPROXIMATE BOUNDARY OF

DRY VALLEY RIM

WILDERNESS STUDY

AREA (CA-020-615)

Figure 1. Index map showing location of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and 

Lassen County, California.

D2 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
Montmoriilonitic clay is present in alluvial sediment 

east of Red Rock Canyon at the Capricorn claims area east of 

the study area. Here the clays are mixed with silt-sized 

particles in the alluvium. This material is not suitable as a 

pozzolan but may qualify as fuller's earth, which is used as 

absorbents and for bleaching oils. The clay occurrence does 

not extend into the study area; therefore, there is no mineral 

resource potential for clay in the Dry Valley Rim Wilderness 

Study Area.

The wilderness study area has no resource potential for 

geothermal energy (Higgins, 1981) or oil and gas.

INTRODUCTION

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

of Land Management and is the result of a cooperative effort 

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

An introduction to the wilderness review process, mineral 

survey methods, and agency responsibilities was provided by 

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

evaluates identified resources at individual mines and known 

mineralized areas by collecting data on currentand past mining 

activities and through field examination of mines, prospects, 

claims, and mineralized areas. Identified resources are classified according to the system described by U.S. Bureau of 

Mines and U.S. Geological Survey (1980). Studies by the U.S. 

Geological Survey are designed to provide a reasonable scientific basis for assessing the potential for undiscovered mineral 

resources by determining geologic units and structures, possible environments of mineral deposition, presence of geochemical and geophysical anomalies, and applicable ore-deposit models. Goudarzi (1984) discussed mineral assessment 

methodology and terminology as they apply to these surveys. 

See appendixes for the definition of levels of mineral resource 

potential, certainty of assessment, and classification of identified resources.

Location and Physiography

The Dry Valley Rim Wilderness Study Area is located 

in the eastern part of the Modoc Plateau in Lassen County, 

northeastern California, and Washoe County, northwestern 

Nevada (fig. 1). The area encompasses 54,480 acres of public 

land administered by the U.S. Bureau of Land Management 

and located about 40 mi east of Susanville. The study area is 

bounded on the east by the lower Smoke Creek Ranch Road, 

the Dry Valley Road, and the Pipe Springs Road. The north 

boundary is located 1-2 mi southeast of Smoke Creek Ranch 

Road; the south boundary is a jeep trail located 5-6 mi north of 

the Wendel Road; and the west boundary is the Skedaddle 

Road. Access to the study area is provided by several dirt roads 

and jeep trails that join the boundary roads. Elevations range 

from 3,800 to 6,200 ft. Most of the study area is gently sloping 

and sparsely covered with sage and grasses. Steep rim rock

walls and talus-covered canyons are common in the eastern 

one-third of the area along Dry Valley Rim.

Previous Studies

The geology of the study area has been previously 

mapped in reconnaissance at 1:250,000 scale. Bonham (1969) 

describes the Nevada side of the study area and Lydon and 

others (1960) give the geology of the California side. Diggles 

and others (1988a) mapped the geology at 1:48,000 scale, 

Munts and Peters discussed the mineral resources, and Diggles 

and others (1988b) described the mineral resource potential of 

the Skedaddle Mountain Wilderness Study Area to the west of 

this study area. Adrian and others (1987) presented geochemical data for both study areas. Aeromagnetic data are published 

for this area (U.S. Geological Survey, 1972) and radiometric 

data are given by Geodata International, Inc. (1978), and 

Western Geophysical Company of America (1981). In addition to those collected for this study, gravity data are given by 

Snyder and others (1982).

Acknowledgments

The authors thank Harry Banfield and Robert Swinney 

of Lassenite Industries for sharing information on pozzolan 

occurrences in the area. We greatly appreciate help from L.L. 

Teeter of the U.S. Bureau of Land Management's Susanville 

office for logistic and helicopter support. D. A. Dellinger, L.D. 

Batatian, and John Mariano, U.S. Geological Survey, M.S. 

Miller, U.S. Bureau of Mines, and R.P. Maddox, Helo-Wood 

Co., helped to complete the field work.

APPRAISAL OF IDENTIFIED RESOURCES

By}. Mitchell Linne 

U.S. Bureau of Mines

U.S. Bureau of Mines personnel examined library 

materials and production records for information on mines, 

claims, and prospects. Ground and aerial field studies evaluated the known mines, prospects, and mineralized zones in or 

near the study area. Field work was conducted during May and 

June 1985. Seven alluvial (placer) and 52 rock samples were 

collected and analyzed at the Western Field Operations Center 

in Spokane, Wash. Rock samples of perlite, zeolitic basalt, and 

alluvial sediment were analyzed by various methods for specific end uses. All rock samples were checked for radioactivity 

and fluorescence, and 27 were assayed for gold and silver by 

fire assay or by a combined fire assay-atomic absorption 

method. Several samples from each locality were analyzed for 

40 elements by semiquantitative emission spectrography. 

Perlite samples were checked under a petrographic microscope to determine index of refraction, perlitic texture, and

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D3
120°05' 120°00' 119°55' 119°50'

APPROXIMATE BOUNDARY OF

DRY VALLEY RIM

WILDERNESS STUDY AREA ^~ 

s

40°25' -

40°20' >

Figure 2. Generalized geology and areas of mineral resources and resource potential in the Dry Valley 

Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California.

D4 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
z 

p

x

Qal

Tb

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EXPLANATION

^Area with moderate mineral resource potential 

"Area with low mineral resource potential

See appendix for definition of levels of mineral resource 

potential (M,L) and certainty of assessment (C,D)

Commodities

Zeolites 

Perlite

Prospect Red symbol indicates identified 

resources

Red Rock zeolite 

Capricorn claims 

Rocky Springs zeolite 

Willow Springs zeolite 

Broken Shovel claims

Correlation of map units

| Qal | | QUATERNARY 

Unconformity

percent glass. A representative sample was sent to the New 

Mexico Bureau of Mines and Mineral Resources, Socorro, 

New Mexico, for expansion testing. Samples of altered zeolitic basalt were analyzed for quantity and type of zeolites and 

cation exchange capacity. Samples of alluvial sediment were 

screened for pozzolan suitability by using whole rock analysis. 

Two samples were sent to the U.S. Army Corps of Engineers' 

Waterways Experiment Station, Vicksburg, Miss., for determination of the pozzolan activity index. Complete anal ytical 

methods and assay results were presented by Linne (1987) and 

are available at Western Field Operations Center, U.S. Bureau 

of Mines, E. 360 3rd Avenue, Spokane WA 99202.

Mining claims and mineralized sites are shown on fig. 

2. Summary descriptions of these areas are presented in table 

1. Detailed descriptions of deposits and economic analysis are 

given in Linne (1987).

Mining History

No mining activity has been recorded within the study 

area. The earliest recorded mining activity near the study area 

was extraction of salt from brines at Buffalo Springs in the 

Smoke Creek Desert before 1885 (Russell, 1885) to 1907 

(Lincoln, 1923). Buffalo Springs is approximately 20 mi 

northeast of the study area.

The Sand Pass mining district, located 22 mi north of 

Sand Pass (6 mi east of the southeastern corner of the study 

area) is approximately adjacent to the study area on the 

northeast comer and may include the area of the Capricorn 

claims (fig. 2 and table 1, No. 2). The Sand Pass bentonite 

property described by Rollin and others (1971) may be identical to the Capricorn claims property. This area was originally 

claimed in 1935 as the Whitetail group and in 1969 as association placer claims Capricorn 11-13. The claims are currently 

being prospected by Starr Hill and Richard Bailey. Standard 

Oil Company prospected fuller's earth within the Sand Pass 

mining district, probably during the early 1920's (Lincoln, 

1923). Fuller's earth is a term for a variety of mineral 

materials, chiefly montmorillonite and palygorskite clays, 

used for bleaching oils and as absorbents.

The Sheepshead gold-mining district, in which the 

Washoe Lassen Mining Company reported work in 1907 

(Yale, 1907), apparently lies adjacent to the southeast end of 

the study area (Hill, 1912). No workings from this district were 

seen in the study area. The Art Wilson Company clay mine is 

situated approximately 10 mi southeast of the study area 

(Schilling and Hall, 1981). The Willow Springs perlite deposit 

(Bonham, 1969), located about 1 mi east of the study area 

boundary in Black Diamond Canyon, was also known as the 

Silver Gray claims.

Identified Resources

No metallic resources were identified within the study 

Figure 2. Continued. area. The Red Rock Canyon and Willow Springs areas are

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California DS

Tb 

TV 

Tl

 TERTIARY

Geologic map units

Alluvium (Quaternary) Unconsolidated silt, sand, and gravel 

deposited by fluvial processes; also includes colluvial, 

aeolian, lacustrine, and landslide deposits

Basalt (Tertiary) Olivine basalt flows consisting of finegrained to aphanitic or glassy rocks with phenocrysts of 

olivine (less than 1 mm), often altered to iddingsite or with 

iddingsite rims

Volcanic rocks (Tertiary) Volcanic rocks consisting of intercalated basalt, andesite, rhyolite ash-flow tuff, and lahar deposits. Basalt is locally zeolitic and rhyolite is locally perlitic

Lahar deposits (Tertiary) Volcanic debris flow and breccia. 

Occurs as thick sequences of flows in northern part of study 

area, elsewhere as lobate flows filling channels and as 

crusts on sides of channels. Contain poorly sorted, angular 

to sub-rounded clasts of basaltic, andesitic, and (or) dacitic 

material, in a clast-supported matrix of fine lithic fragments 

and ash

Contact

Fault Dotted where concealed; bar and ball on downthrown 

side
underlain by 85 million tons of altered basalt that contain 

inferred resources of zeolites in amygdules. This material, 

averaging more than 50 percent chabazite, constitutes a subeconomic zeolite resource. This zeolite-bearing material is 

relatively low in grade and would require beneficiation to 

upgrade it for high-value uses such as catalysts and molecular 

sieves. Natural zeolites have a small market in the United 

States; that market is presently met by other higher grade 

deposits. Detailed analyses of the zeolite-bearing material are 

given by Linne (1987).

Perlite is present at the Broken Shovel claims, located 

along the southeast boundary of the study area. The claims 

encompass a 100,000-ton occurrence of the material. While 

usable for lightweight aggregate, the deposit is too small for 

economic production. However, if considered for perlite 

production with other nearby deposits in the Skedaddle Mountains (estimated 184,000 tons within 15 mi) (Diggles and 

others, 1988b) and at Black Diamond Canyon (estimated 1 

million tons within 3 mi), this occurrence could become a 

resource.

Montmorillonitic clays are present at the Capricorn 

claims, adjacent to the study area. The claims are located on 

alluvial sediment that contains more than 30 percent montmorillonitic clays. The montmorillonitic material is of poor 

quality and is not suitable as pozzolan, a cement additive. It 

was not tested for other uses such as an absorbent in oil 

clarification or as an insecticide carrier.

Of the seven placer samples, only one panned-concentrate sample from Skedaddle Creek near the California-Nevada State line near Skedaddle Ranch Road contained gold 

(0.8 X 10'7 troy oz in a 1.75-lb pan-concentrate sample, 3.1 

parts per billion). Therefore, placer gold resources are not 

indicated.

Sand and gravel resources are not present in the study 

area. Rocks in the study area could be used for road metal, 

riprap, and other stone resources, but similar material of equal 

or better quality is abundant closer to local markets.

ASSESSMENT OF MINERAL RESOURCE POTENTIAL

By Michael R Diggles, James G. Frisken, and

Donald Plouff

U.S. Geological Survey

The U.S. Geological Survey conducted field investigations of the Dry Valley Rim Wilderness Study Area in 1985. 

This work included geologic mapping (Diggles and others, 

1986), field checking of existing maps, geochemical sampling, 

gravity surveys, and inspecting outcrops for mineralization.

Geology

The Dry Valley Rim Wilderness Study Area is underlain by a 17-mi-long, north-trending fault block that strikes

north to N. 10° E. and dips slightly (5°) to the west. The rim is 

1,500 ft higher in elevation than the Smoke Creek Desert to the 

east. Rocks in the study area are mostly middle Miocene 

andesite, andesitic lahar deposits and basalt and include minor 

amounts of rhyolitic ash-flow tuff. These rocks are middle 

Miocene in age on the basis of potassium-argon age determinations made on correlative rocks 6 mi to the west (Diggles and 

others, 1988a).

The oldest rocks in the study area are andesite flows 

and lahar deposits, commonly intercalated with olivine basalt. 

These rocks underlie the northeastern part of the study area in 

continuous sections at least 800-1,000 ft thick. They are 

exposed to the south along the fault scarp at the base of Dry 

Valley Rim for most of its length. The andesite contains 

phenocrysts of calcic plagioclase, clinopyroxene (augite), and 

minor orthopyroxene (hypersthene) in fine-grained to 

aphanitic plagioclase-rich matrix. The silica (SiO2) content of 

these rocks ranges from 53 to 62 weight percent. Dacite that 

crops out in the Skedaddle Mountains to the west (Diggles and 

others, 1988a) is not present in this study area except as clasts 

in lahar deposits. A potassium-argon age of 12.810.2 Ma 

(million years) was determined for andesite flows in the 

Skedaddle Mountains (Diggles and others, 1988a). Flows that 

are petrographically similar and stratigraphically equivalent to 

these extend eastward into the Dry Valley Rim study area.

Rhyolite ash-flow tuff and lithic tuff are exposed in the 

fault scarp of the central part of Dry Valley Rim stratigraphically above the andesite. The ash-flow tuff forms beds 20-50 

ft thick and consists of pinkish-white ashy matrix with nonwelded pumice fragments 0.04 to 0.4 in. long. Lithic rhyolite 

tuff is matrix-supported and includes angular to sub-rounded 

clasts that are mostly rhyolite ash flow and include subordinate 

clasts of aphyric basalt and porphyritic andesite. The rhyolite 

tuff is locally zeolitic. Zeolites probably formed during and 

after burial by sediments or by reaction of pore waters with 

aluminosilicate minerals (Hay, 1978). No rhyolite domes were 

seen, but perlite is present in discontinuous blocks of altered 

rhyolitic material that may have been derived from domes east 

of Dry Valley Rim in the area now faulted down and buried by 

alluvium.

Thick lahar deposits are exposed stratigraphically 

above the andesite in the northern part of the study area and 

crop out locally above rhyolite ash-flow and lithic tuff in the 

central part of Dry Valley Rim. Lahar deposits are volcanic 

debris flows containing at least 80 weight percent solids 

(Fisher and Schmincke, 1984). These lahar deposits have a 

composite thickness of as much as 400 ft and are the dominant 

rock type in the mountains south of Smoke Creek as well as in 

the upper levels of the northern part of Dry Valley Rim. They 

consist of volcanic mud flow breccia mapped as lobate flows 

filling channels and as crusts on sides of channels. The flows 

contain poorly sorted, angular to sub-rounded clasts averaging 

about 4 in. in diameter of basaltic, andesitic, and (or) dacitic 

material within a lithic and ashy matrix. These lahar deposits 

are commonly interstratified with fluvial sedimentary rocks 

and andesite flows. They typically crop out as resistant ridges.

D6 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
Olivine basalt flows cap the western dip slope of the 

study area. The basal flows in the basalt sequence are exposed 

at the top of the central and southern parts of Dry Valley Rim. 

The sequence comprises thin (10-30 ft) flows that have a 

composite thickness exceeding 800 ft. Rows are fine grained 

to aphanitic lava that commonly contains olivine phenocrysts 

(less than 0.04 in.) that are characteristically altered to iddingsite to various degrees. These rocks have silica contents 

of 50-53 weight percent. Diggles and others (1988a) determined a potassium-argon age of 12.3±0.4 Ma on basalt in the 

Skedaddle Mountains that is stratigraphically correlative with 

the flows in the study area.

Pleistocene Lake Lahontan, a large pluvial extension 

of Pyramid and Honey Lakes, occupied the Smoke Creek 

Desert and Dry Valley basins during glacial periods. The Dry 

Valley basin includes a small part of the eastern margin of the 

study area and is underlain in part by lake sediments deposited 

during the lacustrine inundation.

North of the study area boundary, a flat-lying basalt 

flow is present that may be as young as Pliocene. Quaternary 

surficial deposits are comprised of colluvium, alluvium, and 

talus, as well as aeolian, lacustrine, and fluvial deposits.

The major structure in the study area is the normal fault 

scarp that forms Dry Valley Rim. Faulting along the Dry 

Valley Rim began in the Miocene and continued through the 

Quaternary. The amount of displacement along this fault is at 

least 2,000 ft. North-trending normal faults such as this are 

characteristic of Basin and Range tectonics and commonly 

have vertical displacements on the order of several thousand 

feet. The study area lies along a major northwest-trending 

lineament called Walker Lane. Right-lateral shear along this 

feature is interpreted as having formed a regional stress pattern 

that controlled Basin and Range structures (Albers, 1967). 

Moody and Hill (1956) proposed that right-lateral shear systems along Walker Lane control the north-south orientation of 

many of the ranges in the western Basin and Range Province.

Geochemistry

Methods and Background

A reconnaissance geochemical study of the Dry Valley 

Rim Wilderness Study Area was undertaken in June 1985 by 

the U.S. Geological Survey. A sample-location map, tables of 

analytical data, and a description of sampling, preparation, and 

analytical methods are presented in Adrian and others (1987). 

Three sample media were selected on the basis of their ability 

to reveal anomalies where present in the volcanic terrane of 

northeast California. Forty-six stream-sediment samples and 

45 nonmagnetic, heavy-mineral panned concentrates were 

prepared from stream-sediment material collected mostly 

from dry stream beds. The stream sediment reflects bedrock 

geochemistry and can indicate major areas of mineralization. 

The nonmagnetic fraction of panned concentrates contains

minerals with high specific gravity that are associated with 

mineralization and alteration. Fifteen rock samples, thought 

possibly to be mineralized or altered, were collected as stream 

cobbles or from outcrops within the study area. Sixty nonmineralized rocks of basaltic to andesitic composition were collected during the geological mapping studies of this study area 

and the contiguous Skedaddle Mountain Wilderness Study 

Area (Diggles and others, 1988b). These were analyzed to 

provide background geochemical data for both study areas.

All of the samples were analyzed for 31 elements 

including antimony, barium, cadmium, cobalt, chromium, 

copper, gold, iron, lanthanum, lead, magnesium, manganese, 

molybdenum, nickel, silver, thorium, tin, titanium, tungsten, 

vanadium, yttrium, and zinc using a six-step semiquantitative 

emission spectrographic method routinely used by the U.S. 

Geological Survey (Grimes and Marranzino, 1968). In addition, the minus-80-mesh sediments were analyzed for uranium 

and thorium by the delayed neutron technique (Millard, 1976). 

The rocks were analyzed for uranium, thorium, arsenic, cadmium, bismuth, antimony, zinc, and mercury; five of these 

samples were analysed for gold. These additional analyses of 

rock samples were run by atomic-absorption methods described by Koirtyohann and Khalil (1976) and O'Leary and 

Viets (1986).

Nonmetallic commodities with recorded production in 

Washoe County and (or) eastern Lassen County include clays, 

diatomite, tufa, limestone, sodium chloride, berates, gypsum, 

perlite, silica, feldspar, lightweight aggregate, and sand and 

gravel (Bonham, 1969). With the possible exception of borate, 

these commodities would not be detected by our geochemical 

methods. Samples collected from an iron-stained, vesicular, 

volcanic outcrop cut by a small tributary on the north side of 

Red Rock Canyon contain over 50 percent chabazite. Similar 

zeolite-bearing cobbles were noted in the stream bed of Rocky 

Spring Canyon, about 2.5 mi to the south-southeast.

Dacitic to rhyolitic flows and domes as well as surface 

evidence of alteration and mineralization present in the Skedaddle Mountain Wilderness Study Area (Diggles and others, 

1988a) were not found in the Dry Valley Rim Wilderness 

Study Area (Diggles and others, 1986). The data from rocks 

collected from silicic outcrops and altered areas were omitted 

in compiling background geochemical data for the Dry Valley 

Rim Wilderness Study Area.

In U.S. Geological Survey reconnaissance geochemical resource assessment studies, a semiquantitative spectrographic method (Grimes and Marranzino, 1968) is used for the 

initial studies. This method allows for both the rapid and 

economical analysis of large numbers of samples; a limitation 

is that some commodity elements will not be detected because 

this method is not sufficiently sensitive. The presence of such 

commodity elements may be inferred by analysis of other 

elements, pathfinders, that are characteristically associated 

with the commodity element of interest and easily detected by 

this method. When anomalous concentrations of such pathfinder elements are determined, selected samples areresubmitted for analysis by more sensitive techniques.

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D7
Results and Interpretation

The stream-sediment and panned-concentrate sample 

data were evaluated by comparing them to background concentrations. Background concentrations are considered to 

represent samples from an unmineralized provenance. The 

geochemical threshold values for rock and stream-sediment 

samples were calculated at three times the arithmetic means of 

element concentrations of local basalts and andesites. The 

threshold is the concentration of a given element above which 

a sample is considered anomalous in that element. For elements with extrapolated mean values below the lower level of 

determination, the lower level of determination is assigned as 

threshold value. The threshold values for the nonmagnetic 

concentrates are chosen on the basis of prior experience. 

Threshold values in parts per million (ppm) for elements 

present in anomalous concentrations in concentrate samples 

are: lead, 100; molybdenum, 10; copper, 100; barium, 5,000; 

manganese, 2,000; arsenic, 500; chromium, 300; vanadium, 

500; lanthanum, 500; and yttrium, 500. For rock and minus80-mesh sediments the thresholds are lead, 30; molybdenum, 

5; copper, 100; barium, 3,000; manganese, 1,500; arsenic, 5; 

chromium, 200; vanadium, 500; lanthanum, 100; yttrium, 50; 

and uranium, 3.

Analyses of stream-sediment and panned-concentrate 

samples from the Dry Valley Rim Wilderness Study Area have 

concentrations that are at or near threshold values, do not occur 

in combinations indicative of metallic ore deposits, and are 

scattered throughout the study area. No gold, sulfides, or other 

ore-related minerals were noted during microscopic examination of the nonmagnetic and slightly magnetic concentrate 

fractions.

No evidence of extensive alteration was noted in the 

field. Some low-level anomalies of yttrium, lanthanum, and 

arsenic in U.S. Geological Survey stream-sediment and 

panned concentrate samples, as well as gold in a U.S. Bureau 

of Mines placer sample, were detected. The five rock samples 

analysed by the U.S. Geological Survey contained no anomalies. The mineralized material may be derived from detrital 

sediment or lahar flows from the Skedaddle Mountains, a site 

underlain by an area of known gold mineralization (fig. 1). The 

anomalies would therefore not be related to mineralization 

within the Dry Valley Rim Wilderness Study Area.

Three concentrates with particularly high lead values 

(1,500, 5,000, and 7,000 ppm) all contain metallic lead, presumably from lead gunshot. Numerous shotgun shells were 

noted at these and other sites. Three other sites produced 

heavy-mineral concentrates with anomalous lead values ranging from 150 to 500 ppm, which may or may not be due to lead 

shot. The 500 ppm lead value is associated with 15 ppm 

molybdenum and is located at the mouth of Parker Canyon. No 

gold or silver was detected in samples collected from the study 

area.

A single small pebble of polycrystalline apatite collected from upper Skedaddle Creek at the 5,400 ft elevation 

contained 34 ppm uranium, 150 ppm lanthanum, 70 ppm

yttrium, and 2,000 ppm manganese. Apatite commonly contains abundant lanthanum and other rare-earth elements, yttrium, and uranium (De Voto, 1978). The minus-80-mesh 

sediment collected at the same site is not anomalous in either 

uranium (1.9 ppm) or thorium (3.9 ppm). Two other rock 

samples, collected as clasts from lahar deposits southwest of 

Smoke Creek contained 3.8 and 5.2 ppm uranium. The latter 

sample also contained 7 ppm arsenic, 1,500 ppm manganese, 

and 3,000 ppm barium. The clasts in the lahar deposit probably 

originated from outside the study area. Two minus-80-mesh 

stream-sediment samples also have slightly anomalous uranium values of 3.3 ppm. They were collected from a stream 

bed in small tributaries of Skedaddle Creek. These scattered 

low-level uranium and thorium values do not suggest mineral 

resource potential.

Numerous small, rounded, light-colored pebbles of 

silicified rhyolite collected from a site west of Larkspur Reservoir contain lanthanum at a level greater than the 150 ppm 

threshold used to interpret anomalies in basalt and andesite. 

Lanthanum concentrations above 150 ppm in rhyolite, however, are not unusual and do not constitute an anomaly. The 

panned-concentrate sample collected at this site is not anomalous in lanthanum but contains 150 ppm lead and the streamsediment sample contains 300 ppm chromium and 500 ppm 

vanadium. These slightly anomalous values of chromium are 

attributed to chromite, which is present as minute inclusions in 

the olivine phenocrysts in basalt Vanadium anomalies are 

probably due to abundant magnetite in the stream sediment 

derived from the andesitic lavas and lahar deposits. No 

obvious area of alteration was seen upstream of this site and the 

data do not suggest mineral resource potential.

The geologic and geochemical data do not suggest that 

any areas are likely to contain mineral resources of rare earth 

or radioactive minerals. Seven nonmagnetic concentrates 

from scattered localities contained 500 ppm lanthanum and 

(or) 500 ppm yttrium. These values probably indicate the 

presence of rare earth accessory minerals such as allanite and 

do not suggest the presence of mineralized rocks. Thorium 

values in rocks and minus-80-mesh sediments are all less than 

20 ppm; only six are above 10 ppm and the highest thorium 

values in concentrates is 200 ppm (three samples).

Geophysics

Geophysical evaluation of the mineral resource potential of the study area was based on interpretations of three kinds 

of geophysical surveys. These were aerial gamma-ray, gravity, and aeromagnetic surveys.

Aerial Gamma-ray Data

Radiometric data were compiled by Geodata International, Inc. (1978), in Nevada and by Western Geophysical 

Company of America (1981) in California for the National

D8 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
Uranium Resource Evaluation (NURE) program of the Department of Energy. The coverage in Nevada consists of five 

east-west flightlines and one north-south flightline; the total 

length of the flightlines is about 35 mi. No flightlines crossed 

the part of the study area in California. Right altitudes ranged 

from 300 to 500 ft above the ground with fluctuations in 

altitude ranging from 200 ft over hillcrests to 1100 ft over 

canyons. Recordings were made of gamma-ray flux from 

radioactive isotopes of uranium, thorium, and potassium. No 

anomalous count rates were recorded in the study area. Count 

rates greater than three standard deviations above mean background level were recorded for thorium along an east-west 

flightline in California that terminates at the Nevada border 

about 0.5 mi south of the south edge of Smoke Creek Reservoir 

(fig. 2). The closest flightline to that location in Nevada, 

located about 1 mi south, did not indicate an anomaly.

Gravity Data

In 1985, gravity was measured at 7 stations in the study 

area, 3 stations along the border, and 21 stations within 3 mi of 

the study area. Five stations were previously established 

within 3 mi of the study-area in California (Snyder and others, 

1982) and ten stations in Nevada (A.H. Cogbill, written commun., 1985). A preliminary Bouguer gravity anomaly map 

(Donald Plouff, unpub. data, 1986) shows three anomalies in 

the study area. A narrow gravity low, about 2 mi in width and 

3 milligals (mGal) in amplitude, extends southeastward from 

Robbers Roost at the north margin of the study area along a 

ridgecrest for about 4 mi into the study area. The gravity low 

interrupts a north-dipping sloping gradient in gravity values 

that decreases 16 mGal from Willow Reservoir near the center 

of the study area to the north edge of the study area. This 

gravity gradient continues north for about 8 mi northwest of the 

study area. A broad gravity high extends from Willow Reservoir to about 5 mi south of the study area. This gravity high, 

and the broad decline in gravity to the north may reflect a 

change in the relative proportions of Cenozoic volcanic rock 

cover and denser pre-Cenozoic basement rocks. The higher 

gravity values are attributed to relatively shallow depths to the 

basement rocks.

Aeromagnetic Data

A regional aeromagnetic survey was flown over the 

Nevada part of the study area (U.S. Geological Survey, 1972). 

The survey was flown at an approximately constant barometric 

elevation of 9,000 ft above sea level and a flightline spacing of 

about 2 mi. The magnetic intensity level is generally higher in 

the study area than in surrounding areas, reflecting the normal 

magnetization of most of the volcanic rocks at the surface in 

this upland area. Inasmuch as the flight level exceeds 3,000 ft 

above the ground for most of the study area and the flight 

spacing is rather wide, only a few broad magnetic anomalies 

are observed in the study area.

A decrease in magnetic intensity of 100-300 nanoteslas 

(nT) characterizes the zone along the east edge of the study 

area. This decrease reflects the higher magnetic susceptibility 

of the volcanic rocks that underlie most of the study area 

compared to the sedimentary rocks that underlie the area to the 

east. This decrease is probably also due, in part, to a 1,000-ft 

increase in the flight altitude over the valley to the east. A 

magnetic high covers the part of the study area south of 

Larkspur Reservoir and extends for about 6 mi to the south. If 

the magnetic high is not entirely a topographic effect of nearsurface Cenozoic volcanic rocks but is partly an effect of the 

basement source of the gravity high, the pre-Cenozoic rocks 

concealed at shallow depth may be plutonic. The source of a 

small magnetic low, which nearly coincides with the gravity 

low in the northern 4 mi of the study area, is not known. The 

magnetic low is accentuated by a magnetic high of topographic 

origin, which covers the study area farther to the west.

Mineral Resource Assessment

Two areas in the Dry Valley Rim Wilderness Study 

Area have moderate mineral resource potential for zeolites. 

This mineral forms amygdule fillings in basaltic lava. Eightyfive million tons of inferred subeconomic resources of basalt 

containing over 50 percent amygdules filled with chabazite (a 

zeolite consisting of CaAl2Si4O12- 611^0) are identified in Red 

Rock Canyon and west of Willow Springs. The quality of the 

zeolites around Red Rock Canyon and west of Willow Springs 

may be adequate for use as an absorbent in animal husbandry. 

The areas surrounding Red Rock Canyon and Willow Springs 

have moderate mineral resource potential for zeolites with a 

certainty of D. Mining of zeolites in basalts is highly 

unlikely due to their low grade and difficulties and costs of 

extracting zeolites from basalts.

An area north of Parker Canyon has low mineral 

resource potential for perlite. Perlite is hydrated rhyolitic 

volcanic glass characterized by numerous small, crudely 

spheroidal fractures and contains 2 to 5 percent water. After 

mining, heating will soften the glass while the water causes it 

to expand from 4 to 20 times its original volume with a 

corresponding drop in density to as low as 5.0 lb/ft3 (8 percent 

that of water). Perlite has greater thermal and acoustic insulation properties than pumice, is more durable than plastics, does 

not moisten, and is fireproof (Kuzvart, 1984). It is used in lightweight aggregate, filters, potting soil, insulation, absorption 

material for oil-spill cleanup on ocean surfaces, and as filler for 

paints and plastics. A 100,000-ton occurrence of this mineral 

is present on the Broken Shovel claims; this perlite is of usable 

grade but is too small to be mined. The area of rhyolitic ash 

flows surrounding the Broken Shovel claims north of Parker 

Canyon has low resource potential for perlite with a certainty 

of C. If undiscovered resources are as small as the known 

occurrence in the study area, they would be too small to be 

mined. If, however, the known occurrence and (or) any 

undiscovered resources were considered with other nearby

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D9
deposits in the Skedaddle Mountains (estimated 184,000 tons 

within 15 mi) (Diggles and others, 1988b) and at Black 

Diamond Canyon (estimated 1 million tons within 3 mi) 

(Linne, 1987), they could be mined economically.

Gold was observed in one placer sample collected by 

the U.S. Bureau of Mines and some low-level anomalies of 

yttrium, lanthanum, and arsenic were detected in the U.S. 

Geological Survey stream-sediment sample-collection program. The rock samples collected by the U.S. Geological 

Survey contained no anomalies. The mineralized material may 

be derived from detrital sediment or lahar flows from the 

Skedaddle Mountains, 6 mi west of the study area. The 

Skedaddle Mountains are underlain by an area that underwent 

hot-spring alteration and known gold mineralization (Diggles 

and others, 1988b). As no evidence of similar hot-springs or 

other extensive alteration was noted in the field, the anomalies 

are not interpreted to be related to mineralization within the 

Dry Valley Rim Wilderness Study Area.

There is an occurrence of alluvial sediment east of Red 

Rock Canyon at the Capricorn claims area outside of the study 

area. This alluvial sediment contains beds of montmorillonitic 

clay with silt impurities. It may qualify as fuller's earth, which 

is used as absorbents and for bleaching oils. The occurrence of 

this material does not extend into the study area; therefore, 

there is no mineral resource potential for clay in the Dry Valley 

Rim Wilderness Study Area.

Aeromagnetic data indicate that the wilderness study 

area may be underlain by plutonic rocks at shallow depth. 

These rocks, if they exist, are pre-Tertiary rocks and therefore 

cooled tens of millions of years ago. The study area therefore 

has no geothermal energy potential with a certainty of D. This 

assessment is also given by Higgins (1981). There is no oil or 

gas resource potential in the study area (Scott and Miller, 1982; 

Scott, 1983) with a certainty of D. This conclusion is made on 

the basis of a thin sedimentary section for sources and (or) 

reservoirs.

REFERENCES CITED

Adrian, B.M., Frisken, J.G., Malcolm, M.J., Bradley, L.A., and 

Briggs, Paul, 1987, Location of stream sediments (S), 

heavy-mineral concentrates (C), rocks (R), and water 

samples (W) from the Skedaddle (CA-020-612) and Dry 

Valley Rim (CA-020-615) Wilderness Study Areas, Lassen County, California and Washoe County, Nevada: 

U.S. Geological Survey Open-File Report 87-494, 44 p.

Albers, J.P., 1967, Belt of sigmoidal bending and right-lateral 

faulting in the western Great Basin: Geological Society 

of America Bulletin, v. 78, p. 143-156.

Beikman, H.M., Hinkle, M.E., Frieders,Twila, Marcus, S.M., and 

Edward, J.R., 1983, Mineral surveys by the Geological 

Survey and the Bureau of Mines of Bureau of Land 

Management Wilderness Study Areas: U.S. Geological 

Survey Circular 901, 28 p.

Bonham, H.F., 1969, Geology and mineral deposits of Washoe 

and Story Counties, Nevada: Nevada Bureau of Mines 

Bulletin 70, 140 p.

De Voto, R.H., 1978, Uranium geology and exploration-lecture 

notes and references: Colorado School of Mines, p. 54.

Diggles, M.F., Batatian, L.D., and Dellinger, D.A., 1986, Geologic map of the Dry Valley Rim Wilderness Study Area, 

Lassen County, California and Washoe County, Nevada: 

U.S. Geological Survey Open-File Report 86-83, scale, 

1:48,000.

Diggles, M.F., Dellinger, D.A., and Batatian, L.D., 1988a, Geologic map of the Skedaddle Mountain Wilderness Study 

Area, Lassen County, California, and Washoe County, 

Nevada: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-2006, scale 1:48,000 [in press].

Diggles, M.F., Frisken, J.G., Plouff, Donald, Munz, S.R., and 

Peters, T.J., 1988b, Mineral resources of the Skedaddle 

Mountain Wilderness Study Area, Lassen County, California, and Washoe County, Nevada: U.S. Geological 

Survey Bulletin 1706-C [in press].

Fisher, R.V., and Schmincke, H.-U. 1984, Pyroclastic rocks: 

Berlin, Springer-Verlag, 472 p.

Geodata International, Inc., 1978, Aerial radiometric and magnetic survey Lovelock national topographic map, Nevada: U.S. Department of Energy Grand Junction Office 

Open-File Report GJBX-125 (78), v. 2, 69 p.

Goudarzi, G.H., 1984, Guide to preparation of mineral survey 

reports on public lands: U.S. Geological Survey OpenFile Report 84-787, 51 p.

Grimes, D.J., and Marranzino, A.P., 1968, Direct-current arc and 

alternating-current spark emission spectrographic field 

methods for the semiquantitative analysis of geologic 

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

Hay, 1978, Geologic occurrence of zeolites, in, Sand, L.B., and 

Mumpton, F.A., eds., Natural zeolites: New York, Pergamon.

Higgins, C.T., 1981, Geothermal resources of California: California Division of Mines and Geology, Geologic Data Map 

No. 4, scale 1:750,000.

Hill,J.M., 1912,The miningdistricts of the western United States: 

U.S. Geological Survey Bulletin 507, 309 p.

Koirtyohann, S.R., and Khalil, Moheb, 1976, Variables in the 

determination of mercury by cold vapor atomic absorption: Analytical Chemistry, v. 48, p. 136-139.

Kuzvart, Milos, 1984, Industrial minerals and rocks: Amsterdam, 

Elsevier, 454 p.

Lincoln, F.C., 1923, Mining districts and mineral resources of 

Nevada: Nevada Newsletter Publishing Company, 280

PLinne, J.M., 1987, Mineral resources of the Dry Valley Rim study 

area, Washoe County, Nevada and Lassen County, California: U.S. Bureau of Mines Open-File Report MLA18- 

87, 18 p.

Lydon, P.A., Gay, I.E., Jr., and Jennings, C.W., 1960, Geologic 

mapofCalifornia, Westwood(Susanville)sheet: California Division of Mines and Geology geologic map scale 

1:250,000.

Millard, T.H., Jr., 1976, Determination of uranium and thorium 

in the U.S. Geological Survey standard rocks by the 

delayed neutron technique: U.S. Geological Survey 

Professional Paper 840, p. 61-65.

Moody, J.D., and Hill, M.J., 1956, Wrench-fault tectonics: 

Geological Society of America Bulletin, v. 67, p. 1207- 

1246.

D10 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
Munts, S.R., and Peters, T.J., 1987, Mineral resources of the 

Skedaddle study area, Lassen County, California, and 

Washoe County, Nevada: U.S. Bureau of Mines OpenFile Report MLA 22-87, 53 p.

O'Leary, R.M., and Viets, J.G., 1986, Determination of antimony, 

arsenic, bismuth, cadmium, copper, lead, molybdenum, 

silver, and zinc in geological materials by atomic absorption spectrometry using a hydrochloric acid-hydrogen 

peroxide digestion: Atomic Spectroscopy, v. 7, p. 4-8.

Rollin, La Verne, Norton, R.C., and Schilling, J.H., 1971, 

Nevada's no. 1 basic industry: Reno, Nevada Bureau of 

Mines and Geology.

Russell, I.C., 1885, Geological history of Lake Lahontan: U.S. 

Geological Survey monograph 11, 288 p.

Schilling, John, and Hall, Joyce, 1981, The Nevada mineral 

industry, 1980: Nevada Bureau of Mines and Geology 

Special Publication MI-1980,41 p.

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

California, in Miller, B.M., ed., 1983, Petroleum potential or wilderness lands in the western United States: U.S. 

Geological Survey Circular 902-D, p D1-D12.

Scott, E.W., and Miller, B.M., 1982 (1984), Petroleum potential 

of wilderness lands, California: U.S. Geological Survey 

Miscellaneous Investigations Map 1-1538, scale

1:1,000,000.

Snyder, D.B., Roberts, C.W., Saltus, R.W., and Sikora, R.F., 1982, 

Magnetic tape containing the principal facts of 64,026 

gravity stations in the state of California: National 

Technical Information Service, U.S. Department of 

Commerce, Springfield, VA 22161, PB-82-168279, description, 30 p., PB-82-168287, magnetic tape.

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

U.S. Geological Survey Circular 831, 5 p.

U.S. Geological Survey, 1972, Aeromagnetic map of parts of the 

Lovelock, Reno, and Millet 1°x2° quadrangles, Nevada: 

U.S. Geological Survey Open-File Report 72-386, 1 

plate, scale 1:250,000.

Western Geophysical Company of America, 1981, National 

gamma-ray spectrometer and magnetometer survey, 

Susanville quadrangle, California - Final report: U.S. 

Department of Energy Grand Junction Office Open-File 

Report GJBX-410 (81), v. 2, 95 p.

Yale, C.G., 1908, Gold, silver, copper, lead, and zinc in the 

United States Nevada, in U.S. Geological Survey, 

1908, Mineral resources of the United States, part 1, 

metallic products: U.S. Geological Survey, p. 337-398.

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D11

APPENDIXES
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT

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

characteristics define a geologic environment in which the existence of resources is permissive. This 

broad category embraces areas with dispersed but insignificantly mineralized rock as well as areas with 

few or no indications of having been mineralized.

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

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

of data indicate reasonable likelihood of resource accumulation, and (or) where an application of 

mineral-deposit models indicates favorable ground for the specified type(s) of deposits.

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

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

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

models indicating presence of resources, and where evidence indicates that mineral concentration has 

taken place. Assignment of high resource potential to an area requires some positive knowledge that 

mineral-forming processes have been active in at least part of the area.

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

moderate, or high levels of resource potential.

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

Levels of Certainty

o

Q.

LU

U 

oc 

D 

O CO

LU

<r

LU

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

B C 

LEVEL OF CERTAINTY

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

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

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

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

Abstracted with minor modifications from:

Taylor, R. B., and Steven, T. A., 1983, Definition of mineral resource potential: Economic Geology,

v. 78, no. 6, p. 1268-1270. 

Taylor, R. B., Stoneman, R. J., and Marsh, S. P., 1984, An assessment of the mineral resource potential

of the San Isabel National Forest, south-central Colorado: U.S. Geological Survey Bulletin 1638, p.

40-42. 

Goudarzi, G. H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S.

Geological Survey Open-File Report 84-0787, p. 7, 8.

D14 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
RESOURCE/RESERVE CLASSIFICATION

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

IDENTIFIED RESOURCES

Demonstrated

Measured

Res<

Mar 

Rest

Indicated

srves

ginal 

srves

Demonstrated 

Subeconomic 

Resources

Inferred

Inferred 

Reserves

Inferred 

Marginal 

Reserves

Inferred 

Subeconomic 

Resources

UNDISCOVERED RESOURCES

Probability Range

Hypothetical Speculative

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from U.S. Bureau of Mines 

and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p. 5.

Mineral Resources of the Dry Valley Rim Wilderness Study Area, Washoe County, Nevada, and Lassen County, California D15
GEOLOGIC TIME CHART 

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

EON

Phanerozoic

Proterozoic

Archean

pre Arc

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterczoic

Late Archean

Middle Archean

Early Archean 

hean 2

PERIOD

Quaternary

Tertiary

Neogene 

Subperiod

Paleogene 

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Carboniferous 

Periods

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

 -(3800?)- -

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

 -

, AGE ESTIMATES 

OF BOUNDARIES 

(in Ma)

- 0.010 

- 1.7

\J

- 24

oo

w/vj

cc

- 96 

 no

one

fTV/

- 290 ^<,j\J 

oorv

icn

- 410

~\Jtj

- 500

*j § \j 

Qnn

- 1600

- 2500

- 3000 

- 3400

AKKn

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

'Informal time term without specific rank

D16 Mineral Resources of Wilderness Study Areas Northeastern California, and part of Washoe County, Nevada
Table 1. Mining claims and mineralized sites in and adjacent to the Dry Valley Rim Wilderness Study Area 

[*, outside study area boundary]

Map No. (fig. 2) Name Summary Workings and Production Sample and resource data

Red Rock zeolite Chabazite fills voids in altered basalt over 

an area of about 150 acres with estimated 

thickness of 200 ft. Deposit centers on basalt dike and may be related to a northtrending fault. Road access is within 3 mi. Not previously reported in literature.

None Eleven samples were taken; samples contained between 36 

percent and 70 percent chabazite with a sample weighted 

average of 53 percent. Ammonia cad on exchange capacities for 

two samples were 1.5 (50 percent chabazite) and 1.84 (70 

percent chabazite) milliequivilant/gm. Deposit contains an 

esdmated 70 million tons of subeconomic zeolite-bearing 

resources.

Q.

3

2* Capricorn claims Remnant pediment or fan of pre-Lake

(Sand Pass Lahontan alluvial sediments over an area of 

bentonite) about 300 acres with an esdmated thickness 

of 50 ft. Material consists of more than 30 

percent montmorillinidc clay, less than 30 percent feldspar, and less than 10 percent 

each calcite, gypsum, and diatoms.

Three trenches between 20 and 

100 ft long and as much as 3 ft 

deep and one pit 2 ft deep and 5 ft 

in diameter. No production.

Twelve samples of alluvial sediment were taken; ten of these 

samples analyzed by X-ray diffraction contained over 30 

percent montmorillinidc clay. All twelve samples were 

analyzed for oxide content by whole-rock inductively coupledplazma (ICP) analysis and for loss-on-ignidon (wet chemical) as 

a screen for pozzolan suitability. Only one sample passed all chemical standards. Other samples had excess moisture and 

loss on ignition. Two samples submitted for pozzolan activity index; both failed American Society for Tesdng Material 

standards. None had visible bentonidc character.

Rocky Springs Chabazite fills voids in altered basalt over 

zeolite an area of about 20 acres with estimated

thickness of 25 ft. Deposit may be relatedto a north-trending fault.

Willow Springs Chabazite fills voids in altered basalt over 

zeolite an area of about 70 acres with estimated

thickness of 100 ft. Deposit may be related

to a north-trending fault.

Broken Shovel Perlite zone in a disrupted mass as much as claims 125 ft thick, 100 ft wide, and 700 ft long.

Perlidc material is surrounded by basalt.

Perlite crops out locally over a distance of

1.25 mi with a northerly trend along range

front.

NoneNoneNo apparent recent work. Claims 

were located in 1955.

Four samples taken contained between 10 percent and 45 

percent chabazite with a weighted average of 29 percent.

Three samples taken contained from 35 percent to 65 percent 

chabazite with a weighted average of 52 percent. One sample 

had an ammonia cation exchange capacity of 1.46 milliequivilant/gm (63 percent chabazite). Deposit contains an esdmated 

15 million tons of subeconomic zeolite-bearing resources.

Eleven samples of perlidc material were taken and checked 

optically. Eight had good perlidc texture and esdmated glass content ranged from 50 percent to 95 percent. One sample tested for expansion had a furnace yield of 95.5 percent, a 

negligible sinker fraction, compacted density of 12 lb/ft5 and 

high compacdon resistance of 97 and 270 Ib/in. 1 of 1 in. and 2 in. pressure, respecdvely. Largest exposed part of the deposit 

contains an esdmated 100,000 tons of perlite that would be 

suitable for lightweight aggregate.
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