Mineral Resources of the South Jackson 

Mountains Wilderness Study Area, 

Humboldt County/ Nevada

U.S. GEOLOGICAL SURVEY BULLETIN 1726-B

Chapter B

Mineral Resources of the South Jackson 

Mountains Wilderness Study Area, 

Humboldt County, Nevada

By MARTIN L. SORENSEN, DONALD PLOUFF, 

and ROBERT L. TURNER 

U.S. Geological Survey

MICHAEL M. HAMILTON 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1726

MINERAL RESOURCES OF WILDERNESS STUDY AREAS 

HUMBOLDT AND PERSHING COUNTIES, NEVADA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1987

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center, Box 25425

Denver, CO 80225

Library of Congress Cataloging-in-Publication Data

Mineral resources of the South Jackson Mountains 

Wilderness Study Area, Humboldt County, Nevada.

U.S. Geological Survey Bulletin 1726-B

Bibliography

Supt. of Docs. No.: I 19.3:1726-6

1. Mines and mineral resources Nevada South Jackson

Mountains Wilderness. 2. Geology Nevada South

Jackson Mountains Wilderness. 3. South Jackson

Mountains Wilderness (Nev.) I. Sorensen, Martin L. II.

Series

QE75.B9 No. 1726-B 557.3 s 87-600012

ITN24.N3] [553'09793'54)
STUDIES RELATED TO WILDERNESS

Bureau of Land Management Wilderness Study Area

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

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

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

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

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

South Jackson Mountains Wilderness Study Area (NV-020-603), Humboldt County, 

Nevada.

CONTENTS

Summary Bl

Abstract 1

Character and setting 1

Identified resources 1

Mineral resource potential 1 

Introduction 3

Description of area 3

Previous and present studies 3

Acknowledgments 3 

Appraisal of identified resources 3

Mineral exploration history and current activity 3

Identified resources 5 

Assessment of potential for undiscovered resources 6

G eology 6

Geochemical studies 6

Geophysical studies 7

Mineral and energy resource potential 8 

Iron resources 8

Gold, silver, lead, and zinc resources in massive sulfide deposits 8 

Oil and gas resources 8 

Geothermal resources 10 

References cited 10 

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

of assessment and geologic time scale 13

FIGURES

1. Index map showing location of the South Jackson Mountains Wilderness Study Area, 

Humboldt County, Nevada B2

2. Map showing mineral resource potential in the South Jackson Mountains Wilderness 

Study Area, Humboldt County, Nevada 4

3. Aeromagnetic map of South Jackson Mountains Wilderness Study Area, Humboldt 

County, Nevada 9

TABLE

1. Mines and prospects in and near the South Jackson Mountains Wilderness Study 

Area 11

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

HUMBOLDT AND PERSHING COUNTIES, NEVADA

Mineral Resources of the South Jackson Mountains 

Wilderness Study Area, Humboldt County, Nevada

By Martin L. Sorensen, Donald Plouff, and Robert L. Turner 

U. S. Geological Survey

Michael M. Hamilton 

U.S. Bureau of Mines

SUMMARY

Abstract

The South Jackson Mountains Wilderness Study 

Area (NV-020-603) is in south-central Humboldt 

County, Nev. At the request of the Bureau of Land 

Management, mineral surveys were conducted on 

10,300 acres of the wilderness study area by the U.S. 

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

this report, the area studied is referred to as "the 

study area". The results of geologic, geochemical, 

geophysical, and mineral surveys conducted in 1984 

and 1985 delineate one area in the northeastern part of 

the study area with a moderate potential for 

undiscovered iron resources in metavolcanic rocks and 

two areas, in the southeast and northeast corners of 

the study area, with moderate potential for 

undiscovered gold, silver, copper, lead, or zinc in 

metavolcanic rocks. The potential for undiscovered oil 

and gas and geothermal resources is low.

Mining in the Jackson Creek unorganized mining 

district, just north of the study area boundary, and in 

the Red Butte unorganized mining district, 

approximately 3 mi south of the study area boundary, 

began early in this century. The Claudia mine in the 

Red Butte mining district and the Prodigal mine (Bull 

Creek claims) about 4 mi south of the study area 

produced small amounts of gold, silver, copper, and 

lead between 1919 and 1947. The Red Boy mine, about 

1 mi east of the study area, produced small amounts of 

gold, silver, copper, lead, and zinc during 1940 and 

1948.

Identified Resources

There are no identified resources in the South 

Jackson Mountains Wilderness Study Area. Several 

commodities are present within the study area, 

including silver, copper, and iron, and lesser amounts 

of gold, lead, zinc, vanadium, barium, and cobalt. The 

deposits of these commodities, however, are too small 

or too poorly exposed to allow resource estimates.

Character and Setting

The South Jackson Mountains Wilderness Study 

Area (NV-020-603) includes approximately 10,300 

acres on the west flank of the Jackson Mountains in 

south-central Humboldt County, about 50 mi northwest 

of Winnemucca, Nev. (fig. 1). The north-trending 

Jackson Mountains are flanked by the Desert Valley to 

the east and the Black Rock Desert to the west. 

Elevations in the study area range from 4,400 ft along 

the west boundary to 8,923 ft at King Lear Peak. The 

study area is underlain mostly by marine sedimentary 

and volcanic rocks that have been complexly folded 

and faulted and intruded by dikes, sills, and small 

plugs.

Mineral Resource Potential

o An intense aero magnetic high covering 2 mi

within the study area between Hobo and Bliss Canyons 

(fig. 3) indicates the presence of rocks with a high 

magnetite content at relatively shallow depth. The 

area of this aeromagnetic high has a moderate 

potential (fig. 2) for undiscovered iron resources 

similar to those at the Iron King mine. Magnetic 

gradients that may represent mineralized contact 

zones between plutons and country rocks are present in 

the northeastern and southeastern parts of the study 

area. Two areas overlain by these magnetic gradients 

have a moderate potential for gold, silver, copper, 

lead, or zinc in vein deposits similar to those at the

Bl
APPROXIMATE BOUNDARY 

5J OF

SOUTH JACKSON MOUNTAINS

WILDERNESS STUDY 

AREA (NV-020-603)

Figure 1. Index map showing location of the South Jackson Mountains Wilderness Study Area, Humboldt 

County, Nevada.

B2
Avalanche and Red Boy properties.

The potential for oil and gas and geothermal 

resources in the study area is low.

INTRODUCTION 

Description of Area

The South Jackson Mountains Wilderness Study 

Area (NV-020-603) is on the west flank of the Jackson 

Mountains in south-central Humboldt County, Nev., 

approximately 50 mi northwest of Winnemucca (fig. 1).

The north-trending Jackson Mountains, flanked 

by the Desert Valley to the east and the Black Rock 

Desert to the west, are in the western part of the 

Basin and Range physiographic province. The range 

rises a short distance south of Quinn River Crossing, 

trends generally south for approximately 45 mi, and 

ends near the south boundary of Humboldt County. It 

has a maximum width of 12 mi. The range is bordered 

by Nevada Highway 140 on the north, Nevada Highway 

49 on the south, and unimproved desert roads on the 

east and west. The terrain is generally rugged, 

particularly along the west slopes of King Lear Peak, 

which rises to an elevation of 8,923 ft.

of Mines, and the Bureau of Land Management (BLM). 

Claimants, mine owners, and mining companies were 

contacted to obtain information on claim location, 

history, and economic geology.

The descriptions of geologic structure, 

stratigraphy, and history used in this report are based 

on studies of the Jackson Mountains by Willden (1963) 

and Russell (1981, 1984). The descriptions of mines 

and prospects in and near the study area are taken 

from unpublished data of the USBM.

Acknowledgments

The assistance and cooperation of V.C. Dunn and 

other personnel of the BLM, Winnemucca, Nev., is 

gratefully acknowledged. Billiton Exploration USA, 

Inc., Wescord Resources, Long Lac Mineral 

Exploration, Inc., and claim owners Terry Harris, Fred 

Sherill, and Bud Johnson provided valuable 

information. Vaughn Girol, Vince Vandenbasch, and 

Spencee Willett, USBM, and C.F. Erdman and V.E. 

Langenheim, U.S. Geological Survey, assisted in the 

field investigations. Samples collected by the U.S. 

Geological Survey were analyzed by M.J. Malcolm and 

D.L. Fey of the U.S. Geological Survey, Denver, Colo.

Previous and Present Studies

Reports on the Red Butte and Jackson Creek 

mining districts by Ransome (1909, p. 27-30), Hill 

(1912, p. 213-214), and Vanderburg (1938) contain brief 

descriptions of early mining activity. The U.S. Bureau 

of Mines (USBM) examined the Red Boy and Humboldt 

King mines during World War II as part of a War 

Minerals program and examined the Humboldt King 

property again for the Defense Minerals Exploration 

Administration in 1954 (USBM files). The first 

detailed geologic studies in the Jackson Mountains 

were by Willden (1958, 1960, 1961, 1963, 1964) and 

included geologic mapping, discussions of geologic 

history, and descriptions of mineral deposits. Iron 

deposits examined by Shawe and others (1962) included 

several about 1 mi east of the study area. Solak (1962) 

and Fisher (1962) described the geology and magnetic 

properties of iron deposits near the Iron King mine. 

Russell (1981, 1984) mapped and described the geology 

of the Jackson Mountains. Reports by Barringer 

Resources, Inc. (1982) and the U.S. Bureau of Land 

Management (1983a, 1983b, 1983c) include 

geochemical results, mining history, and other 

information pertaining to the study area.

Field investigations for the present study were 

conducted during 1984 and 1985. The U.S. Geological 

Survey (USGS) field checked published geologic maps 

and remapped selected areas, evaluated published 

geochemical data (Barringer Resources, Inc., 1982), 

sampled selected areas for geochemical analysis, 

collected and evaluated gravity data, and evaluated 

aeromagnetic data for the study area. The USBM 

evaluated known mineral deposits, mines, prospects, 

and mining claims, investigated the history of mining, 

and appraised identified mineral resources. The USBM 

researched the pertinent literature, Humboldt County 

mining records, and files of the USBM, Nevada Bureau

APPRAISAL OF IDENTIFIED RESOURCES

By Michael M. Hamilton, U.S. Bureau of Mines 

Mineral Exploration History and Current Activity

Although mining of precious metals in the region 

began in the 1860's, it was not until the early 1900's 

that mining activity began in the Jackson Mountains. 

The Red Butte unorganized mining district south of the 

study area was first prospected for gold and copper in 

1907. The total production from the district was three 

carloads of copper-lead ore, one carload of lead-zincsilver ore, and about 20 tons of antimony ore, most of 

which was shipped during World War I (Vanderburg, 

1938, p. 41). The Claudia mine, about 5 mi south of 

the study area, was developed in the 1910's and 

produced a total of 25.8 oz gold, 144 oz silver, 262 Ib 

copper, and 943 Ib lead in 1919 and 1947 (USBM 

records). In 1986 the mine was being developed for 

possible future production. The Iron Chief prospect, 

about 7 mi south of the study area, was probably 

active in the 195O's but there is no production record. 

The Prodigal mine (Bull Creek claims), about 4 mi 

south of the study area, produced 1.43 oz gold, 213 oz 

silver, and 648 Ib copper in 1923 (USBM records).

The Jackson Creek unorganized mining district, 

approximately 2 mi north of the study area, centered 

around the Harrison Grove mine (New Northern Light), 

which was patented in 1907. Hill (1912, p. 213) 

reported copper mining in the Jackson Creek area 

shortly thereafter. Production from this mining 

district probably totals less than 1,000 tons of copper 

ore (USBM unpub. data). The Jackson Queen and the 

Humboldt King properties, about 1 mi north of the 

study area (fig. 2), were active in the 1910's and 1920's 

with intermittent exploration to the present. The 

Humboldt King mine probably produced a small amount

B3
118°35' 118°30'

APPROXIMATE BOUNDARY OF r '- 

SOUTH JACKSON MOUNTAINS 

WILDERNESS STUDY AREA (NV-020-603)

r

f..

^

*7 . ; ,' " :

a. ' '< , , ?°

,TK*v^> ' '-^ " --^ _ JX- < -'r'^;,

ffZ^s^.. "KJJ )- 4 <^r^' 'V ' ^J » >

X y1J < ^^^1^^^/fS^^ '^

^ ^-^ //f ^f^^^'^^^/J^^^f^ ?' ^l^^^^^^M^^-^^^ ' y /'/' XvA'SrcC^i;^^ W-t-K^f A^^/'^f^^^-^-^ ? \c-J ^ f ° rv >

^^i^^F^^^^X^ 1 'H *v

^fe^^fC^iSl)^ 

Sp^|^^t^§|^^ ^fMfea^/S^-^^3^! Ak^i^:

Figure 2. Mineral resource potential of the South Jackson Mountains Wilderness Study 

Area, Humboldt County, Nevada. Contour interval 40 ft. Geology generalized from 

Sorensen (1986).

B4
EXPLANATION

Area with moderate mineral resource potential 

Area with low mineral resource potential

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

of assessment

Au 

Ag 

Cu 

Fe 

Pb 

Zn 

Geo

Commodities

Gold

Silver

Copper

Iron

Lead

Zinc

Geothermal

Oil, Gas

[ ] Deposit types

1 Veins or replacement deposits associated with dioritic intrusions

2 Epithermal base- and precious-metal deposits

Geologic map units

Ti Intrusive rocks (Tertiary)

KJi Intrusive rocks (Cretaceous and Jurassic)

K1 v Volcanic and volcaniclastic sedimentary rocks (Cretaceous to 

Triassic)~Includes Happy Creek Volcanic Complex, 

Boulder Creek beds of Russell (1981), and King Lear 

Formation

Pzs Sedimentary rocks (Paleozoic)

Contact

Normal fault

Thrust fault-Sawteeth on upper plate

Mine or prospect-See table 1 for description

Mines and prospects

1 Avalanche prospect

2 Bluebird prospect

3 Clover prospect

4 Cold Springs prospect

5 Crystal prospect

6 Cuprite prospect

7 Humboldt King mine

8 Iron Girl prospect

9 Jackson Queen prospect

10 Red Boy mine

11 Red Star prospect

12 Shamrock prospect

13 White Point prospect

14 unnamed prospect

Figure 2. Continued.

of copper ore. Exploration of copper deposits in 

Christiorsson Canyon and on the west side of the 

Humboldt King property by Louisiana Land and 

Exploration Company and McPhar Geophysics in 1973 

revealed no minable deposits.

Iron deposits in the Jackson Mountains were 

explored and developed during the 1950's and 1960!s. 

The Iron King and Red Bird mines, about 4 mi 

northeast of the study area, collectively produced 

about 1.3 million tons of high-grade magnetite ore 

between 1952 and 1966 (Moore, 1971, p. 174 and 178). 

During this period, most of the iron deposits in and 

near the study area were explored. The Bull Iron 

prospect, about 3 mi south of the study area, and the 

Red Star and Iron Girl prospects (fig. 2) were drilled in 

an unsuccessful attempt to locate minable deposits. 

At present, there is little interest in mining iron 

deposits in the Jackson Mountains.

The Red Boy mine, about 1 mi east of the study 

area (fig. 2), produced a total of 1 oz gold, 748 oz 

silver, 49 Ib copper, 5,073 Ib lead, and 12,446 Ib zinc in 

the two years of operation, 1940 and 1948 (USBM 

production records).

Recent mineral activity in the Jackson 

Mountains consists of exploration and staking of 

claims. In the late 1970's, the Lillian claim group was 

mapped and sampled for low-grade, bulk-tonnage, 

precious-metal deposits. In 1984, Wescord Resources, 

Reno, Nev. initiated an exploration program for 

volcanogenic massive-sulfide deposits at the 

Avalanche, Red Boy, Red Star, and Clover properties 

(fig. 2). In 1985, Wescord Resources leased its interest 

to Long Lac Minerals Exploration, Inc., Sparks, Nev., 

which plans to continue detailed mapping, sampling, 

geochemical surveys, and possible drilling.

County claim location records indicate that, 

from 1900 to the present, approximately 550 lode 

claims have been located in the southern part of the 

Jackson Mountains, many of which are relocations of 

previous claims. None were patented. In early 1986, 

there were eight active properties with a total of 126 

claims.

Identified Resources

There are no identified resources in the South 

Jackson Mountains Wilderness Study Area. Several 

commodities are present within the study area in 

amounts too small to allow resource estimates, 

including silver, copper, and iron, and lesser amounts 

of gold, lead, zinc, vanadium, barium, and cobalt.

Volcanogenic deposits associated with the Happy 

Creek Volcanic Complex include mineral occurrences 

at the Red Boy, Humboldt King, and Avalanche 

properties. The Red Boy mine, about 1 mi east of the 

study area, has two exposures of sulfi de-bear ing veins 

that contain anomalous concentrations of gold, silver, 

lead, and zinc. This occurrence may extend into the 

study area in the Clover Creek and Big Cedar Creek 

areas. Veins bearing silver, copper, and minor cobalt 

and nickel occur on the Humboldt King property and 

constitute the largest exposed mineral deposits 

adjacent to the north side of the study area.

Locally high-grade gold-silver-lead-antimony 

veins at the Claudia, Tip and Dip, and Lillian

B5
properties, 3 to 5 mi south of the study area, have 

been explored. The Claudia mine has the only exposed 

sulfi de-bear ing zone of significant size (table 1). 

Tentative plans to resume mining at the Claudia mine 

are based on an assumption of reserves at depth 

sufficient to support a small mining operation. 

Silicified Tertiary rocks on the west side of the Lillian 

claims may have been the source of anomalous 

concentrations of gold detected in stream sediments 

(Barringer Resources Inc., 1982).

ASSESSMENT OF POTENTIAL FOR UNDISCOVERED 

RESOURCES

by Martin L. Sorensen, Donald Plouff, and Robert L.

Turner

U.S. Geological Survey

Geology

The South Jackson Mountains Wilderness Study 

Area is in the western part of the Basin and Range 

Physiographic Province, an area characterized by 

narrow, north-trending block-faulted ranges that are 

separated by broad alluviated valleys. It is underlain 

mostly by marine sedimentary and volcanic rocks that 

are late Paleozoic and Mesozoic in age (380-150 

million years before present (Ma); see Appendix 1 for 

geological time chart). These rocks have been 

complexly folded, faulted and intruded by dikes, sills, 

and small plugs.

The informally designated McGill Canyon unit of 

Russell (1981, 1984) is the oldest rock unit exposed in 

the southern Jackson Mountains. It is considered to be 

late Paleozoic on the basis of fossils that range from 

Devonian through Permian in age. Within the study 

area, the McGill Canyon unit consists mostly of shale, 

locally sandy mudstone, and fine- to medium-grained 

sandstone. The uppermost part of the McGill Canyon 

unit is a fault-bounded section of massive gray 

limestone of Mississippian to Permian age. The McGill 

Canyon unit is everywhere underlain by west-dipping 

thrust faults and so is allochthonous with respect to all 

other nonintrusive rock formations in the southern 

Jackson Mountains.

The informally designated Boulder Creek beds of 

Russell (1981, 1984) are stratigraphically younger than 

the McGill Canyon unit but mostly are structurally 

beneath those rocks. The Boulder Creek beds are 

considered to be Triassic and Jurassic(?) in age on the 

basis of Triassic fossils (Russell, 1981, p. 45-46; 1984, 

p. 317). Within the study area, the Boulder Creek beds 

form a sequence of generally deformed shale, 

sandstone, limestone, chert, and volcanogenic 

sedimentary rocks. Locally, pelitic and calcareous 

sedimentary rocks grade upward to volcaniclastic 

sedimentary rocks that are conformably overlain by 

the Happy Creek Volcanic Complex.

The Happy Creek Volcanic Complex (Sorensen 

1986) forms the scenic prominence of King Lear Peak 

and underlies much of the higher parts of the study 

area. The complex consists of andesite and basal ticandesite flows and flow breccias, volcaniclastic 

sedimentary rocks, and quartz-diorite and diorite

intrusions (Russell, 1984, p. 318). These rocks are 

considered to be Jurassic and Triassic(?) in age on the 

basis of a whole-rock rubidium/strontium isochron age 

of 160 Ma (Russell, 1984, p. 318) and because the unit 

locally is conformable above the Triassic and 

Jurassic(?) Boulder Creek beds (Russell, 1984, p. 318).

The King Lear Formation, named by Willden 

(1958; 1963, p. D18) for exposures on the southeast 

side of King Lear Peak, is the youngest sedimentary 

rock unit within the study area. The King Lear 

Formation consists of alluvial fan deposits of 

mudstone, volcanic sandstone and conglomerate, and 

sparse lacustrine limestone. Fossils within the 

limestone suggest an Early Cretaceous age for the unit 

(Willden 1963, p. D2x).

Unconsolidated Quaternary alluvium is present 

near the head of Alaska Canyon, just south of Hobo 

Canyon, near the ridgecrest northeast of Bliss Canyon, 

and in many of the larger stream canyons in the study 

area (Sorensen, 1986).

Rock units older than the King Lear Formation 

have been intruded by dikes, sills, and small plugs or 

stocks. Some of the intrusions are very fine grained 

white felsite, but most are greenish-brown- to tanweathering rocks consisting of phenocrysts of 

plagioclase, pyroxene, hornblende, and sparse quartz in 

a fine-grained groundmass that commonly contains 

epidote and sericite. Russell (1981, p. 170-179) 

indicates that these rocks were emplaced during 

Jurassic to Cretaceous time, after the eruption of the 

Happy Creek Volcanic Complex and before deposition 

of the King Lear Formation.

A small dacite porphyry plug is present east of 

Bliss Canyon along the east boundary of the study 

area. It consists of abundant plagioclase phenocrysts 

and very scarce quartz phenocrysts in a dark-greenishgray groundmass that contains fine-grained epidote 

and mafic material. These rocks are probably Tertiary 

in age (Willden, 1963, p. D30).

Geologic structure within the study area is 

typified by west-dipping thrust faults. The McGill 

Canyon unit is underlain by thrusts that have emplaced 

it structurally above Boulder Creek and Happy Creek 

units in the northwestern and southwestern parts of 

the study area. The Boulder Creek beds are cut by 

thrust faults that have telescoped the section in the 

northwestern part of the study area. The west-dipping 

Deer Creek thrust (Willden, 1963), which is exposed 1 

mi southeast of King Lear Peak, may underlie the 

study area.

Geochemical Studies

Geochemical studies were conducted as an aid in 

the mineral resource assessment of the South Jackson 

Mountains Wilderness Study Area. These studies were 

conducted at two levels, a review of the results of a 

regional reconnaissance survey, and a detailed study of 

a small area on the west side near Bliss Canyon, where 

the reconnaissance data suggested possible 

mineralization. For the detailed survey, the sampling 

density averaged one sample per square mile.

During the reconnaissance study, conducted by 

Barringer Resources, Inc. (1982), 89 stream-sediment 

samples were collected from localities in and near the

B6
original wilderness study area, which is larger than the 

area on which this mineral assessment was focused. 

We present here only the results for the current 

10,300-acre study area. The drainage basins of the 

sampled streams range from approximately one-half to 

several square miles. The report by Barringer 

Resources, Inc. (1982, v. 4), provides a complete 

description of sample preparation and analytical 

techniques. The resulting chemical analyses were 

examined for indications of geochemical anomalies by 

constructing histograms for arsenic, copper, lead, and 

zinc (elements that are commonly indicative of several 

types of mineral deposits) and by defining the 

threshold value for anomalous concentrations for each 

of these elements as its mean value plus two standard 

deviations.

Arsenic, copper, and zinc are present at low 

levels in all samples. Copper (greater than 130 ppm) 

and zinc (greater than 165 ppm) concentrations are 

slightly anomalous in samples from localities east and 

southeast of the study area; arsenic (greater than 37 

ppm) and zinc (greater than 165 ppm) are slightly 

anomalous in samples from localities along a 

northeast-trending zone near the west boundary of the 

study area, where the background levels of lead (10-20 

ppm) are high. Gold (0.17 ppm) is present in one 

sample collected 3.5 mi south of the study area near 

Navajo Peak. Silver (0.010 ppm, 0.005 ppm) was 

detected in two samples collected 1.5 mi north of the 

study area near Jackson Creek. Cadmium, chromium, 

and nickel are present at low concentrations in 

samples from scattered localities on the west side of 

the study area. These reconnaissance geochemical 

data do not indicate any significant mineral deposits 

within the study area, but they do suggest the 

necessity for more detailed sampling in the zone of 

elevated arsenic and zinc values along the west 

boundary of the study area.

Additional stream-sediment concentrate and 

rock samples for a more detailed study were collected 

near the mouth of Bliss Canyon in the northwestern 

part of the study area to determine the source of the 

arsenic and zinc detected in the reconnaissance 

study. All rock types were sampled and include 

unmineralized outcrop, mineralized outcrop, and 

mineralized or altered stream boulders. Nine streamsediment concentrate samples and eight rock samples 

were collected from the 1.5-mi-long zone. Methods of 

collection, preparation, and analysis, and the results of 

those chemical analyses are described in Day and 

others (1986).

Chemical analyses of the rocks indicate low 

levels of arsenic, antimony, bismuth, and zinc in 

carbonate rocks from the McGill Canyon unit. 

Spectrographic analysis of the slightly magnetic and 

nonmagnetic fractions of heavy-mineral separates 

from the rock samples disclosed the presence of low 

levels of antimony, arsenic, barium, chromium, copper, 

lead, nickel, and silver. Spectrographic analyses of the 

nonmagnetic fraction of the stream-sediment 

concentrates indicate the presence of gold at one site, 

silver, lead, and zinc at two sites, and barium and 

strontium at most sites. The stream-sediment 

concentrates are derived from the Happy Creek 

Volcanic Complex and the McGill Canyon unit.

Thus, both rock units seem to be slightly

mineralized but none of the geochemical analyses 

indicate significant mineralization within the study 

area.

Geophysical Studies

J.S. Duval (written commun., 1985) estimated 

concentrations of potassium, equivalent uranium, and 

equivalent thorium by examining unpublished 

composite-color maps of gamma-ray spectrometric 

data. The maps were prepared at a scale of 

1:1,000,000 from radiometric data acquired in regional 

surveys contracted by the U.S. Department of Energy 

as part of the National Uranium Resource Evaluation 

(NURE) program. Flightlines were flown at an altitude 

of about 400 ft above mean terrain (Geodata 

International, Inc., 1979). One north and three eastwest-bearing flightlines spaced at intervals of about 3 

mi covered the study area. Radioelement detection 

was diminished in the west half of the study area 

where flight levels exceeded 700 ft above the ground. 

Based on criteria discussed by Duval (1983), the study 

area has moderate radioactivity with values of 1.0-2.5 

percent potassium, 2 to 5 ppm equivalent uranium, and 

4 to 11 ppm equivalent thorium. There is no indication 

of anomalous concentrations of radioelements.

The U.S. Geological Survey established 40 

gravity stations in the surrounding area in 1984 to 

prepare a regional Bouguer gravity anomaly map 

(Donald Plouff, unpub. data, 1984). The map also 

includes anomalies determined from principal facts for 

six gravity stations from the Defense Mapping Agency 

gravity file (available from Terrestrial Geophysics 

Data Service, National Oceanic and Atmospheric 

Administration, Boulder, Colo.). The gravity map 

shows that the study area lies along the crest of an 

elongated gravity high that is about 6 mi wide and 

varies from about 10 to 20 milligals (mGal) in 

amplitude. Gravity gradients that exceed 10 mGal/mi 

along a relatively closely spaced profile located about 

4 mi south of the study area suggest that contacts of 

the Jackson Mountain block with the less dense rocks 

in the flanking basins are steep and fault controlled.

A regional aeromagnetic map (U.S. Geological 

Survey, 1972) that includes the study area shows a 

broad magnetic high over an 8 by 24 mi area of the 

Jackson Mountains. The survey was flown at a 

constant barometric elevation of 9,000 ft above sea 

level and at flightline spacings of 2 mi. A later 

aeromagnetic survey (U.S. Geological Survey, 1985) 

provides more detailed magnetic data for evaluating 

the resource potential of the study area. The 

flightlines were spaced 0.5 mi apart and were flown 

about 1,000 ft above the mean terrain.

The detailed aeromagnetic map shows that the 

Boulder Creek beds and McGill Canyon unit generally 

have a low magnetization, which is attributed to an 

inherent lack of magnetic minerals rather than an 

effect of rock alteration. The magnetic pattern shows 

little correlation with mapped faults, because the 

near-surface rocks on adjacent sides of the faults have 

nearly the same magnetization.

A prominent magnetic high with an amplitude of 

nearly 500 nanoteslas (nT) and a diameter of 1.8 mi is 

located south of Hobo Canyon in the northeastern part

B7
of the study area (fig. 3, location A). A magnetic 

saddle over Hobo Canyon separates that high from 

another magnetic high farther to the northeast with an 

amplitude of 100 nT and a diameter of 1.3 mi. Both 

magnetic highs are underlain by the Happy Creek 

Volcanic Complex, which is locally covered by a 

veneer of the King Lear Formation. The intensity of 

the magnetic high south of Hobo Canyon indicates that 

the near-surface rocks underlying the anomaly have a 

relatively high magnetite content. The Iron King 

deposit (fig. 3), which is localized along a contact 

between diorite intrusive rocks and the Happy Creek 

Volcanic Complex (Willden, 1963, p. 53), underlies a 

complexly shaped magnetic high that has a smaller 

areal extent, somewhat higher magnetic gradients, and 

a somewhat greater contour curvature than the 

prominent anomaly south of Hobo Canyon. A 4.5- by 

5.5-mi magnetic high, centered about 4 mi north of the 

study area (fig. 3, location B), is caused by an 

underlying pluton.

The Avalanche prospect near the head of Bliss 

Canyon coincides with a magnetic gradient at the 

southwest edge of the prominent magnetic high (fig. 3, 

location A) south of Hobo Canyon. The Red Boy mine, 

about 1 mi east of the study area, coincides with a 

steep magnetic gradient that extends into the 

southeast corner of the study area (fig. 3, location 

C). Both gradients may reflect a mineralized contact 

zone between intrusive rocks and less magnetic 

country rock.

Mineral and Energy Resources Potential

Iron Resources

Iron occurrences associated with dioritic 

intrusions are present as veins and contact 

replacement deposits in the Happy Creek Volcanic 

Complex at several localities in the Jackson Mountains 

(Willden, 1963, p. D53). The close association of 

deposits and intrusions suggests that the iron may have 

been removed from andesite during emplacement of 

the diorite stocks or, alternatively, that the dioritic 

magma may have been the source of the iron (Willden, 

1963, p. D54). The most significant deposit near the 

study area is at the Iron King mine, which underlies a 

prominent, complexly shaped aeromagnetic high. A 

large aeromagnetic high overlying the Happy Creek 

Volcanic Complex south of Hobo Canyon (fig. 3) 

suggests the presence of an intrusive body and 

indicates rocks with a high magnetite content at 

relatively shallow depths. Therefore, the area just 

south of Hobo Canyon has a moderate resource 

potential, certainty level C, for iron resources in 

deposits similar to those at the Iron King mine (fig. 

2). See Appendix 1 for definition of levels of mineral 

resource potential and certainty of assessment.

Gold, Silver, Lead, and Zinc Resources in Massive 

Sulfide Deposits

Massive sulfide deposits consisting of 

volcanogenic exhalative sulfide minerals are commonly

associated with mafic to felsic volcanic rocks 

accumulated in a deep submarine volcanic-arc 

environment. The deposits are originally tabular to 

lens shaped, but may be remobilized by later magmatic 

or hydrothermal activity and redeposited along 

fractures, joints, or as epithermal hot-springs 

deposits.

The lithology and chemistry of the Happy Creek 

Volcanic Complex indicate its origin as a Mesozoic 

submarine volcanic arc (Russell, 1981, p. 160-169). 

Unpublished company reports (Wescord Resources, 

Reno, Nev. 1984, 1985) describe the Red Butte mining 

district and the area at the north boundary of the 

study area as possible volcanogenic exhalative vent 

zones, and classify an area between Hobo and Bliss 

Canyons as having resource potential for gold in 

epithermal deposits. Geochemical data indicate weak 

precious- and base-metal mineralization in rocks 

within the Hobo and Bliss Canyon drainage basins. 

Geophysical data indicate the Avalanche prospect is 

located on a magnetic gradient that is associated with 

the prominent magnetic high south of Hobo Canyon. 

The area of this magnetic gradient has a moderate 

potential, certainty level B, for silver and copper 

resources in massive sulfide deposits similar to that of 

the Avalanche prospect (fig. 2). Similarly, the Red 

Boy mine is located on a magnetic gradient that may 

represent a mineralized contact zone. The area of this 

magnetic gradient that lies within the study area has a 

moderate potential, certainty level B, for gold, silver, 

lead, and zinc resources in massive sulfide deposits 

similar to that of the Red Boy mine (fig. 2).

Oil and Gas Resources

The potential for oil and gas resources in the 

study area is low, certainty level C. Pre-Cretaceous 

rocks mostly consist of volcanic and volcaniclastic 

sedimentary rocks that lack hydrocarbons. Marine 

sedimentary and carbonate rocks constitute a small 

part of the pre-Cretaceous section, but probably have 

lost any hydrocarbons originally contained within them 

due to the low-grade regional metamorphism and 

igneous intrusion that occurred during Late Jurassic 

(WiUden, 1963, p. D59) or Early Cretaceous (Russell, 

1981, p. 185) time. The King Lear Formation of Early 

Cretaceous age postdates the regional metamorphism, 

but is not typified by organically rich rocks.

EXPLANATION

Magnetic contours-Showing residual magnetic intensity of 

Earth's magnetic field in nanoteslas (nT) (1 nT=l gamma); 

International Geomagnetic Reference Field has been removed 

and an arbitrary datum has been added; contour interval 100 nT. 

Hachures indicate area of closed low

Boundary of magnetic anomaly (A-C) discussed in text 

Selected mine or prospect

Figure 3. Aeromagnetic map of the South Jackson 

Mountains Wilderness Area, Humboldt County, Nevada.

B8
118°35' 118°30' 118°25'

41°20'

APPROXIMATE BOUNDARY

OF

SOUTH JACKSON MOUNTAINS

WILDERNESS STUDY

AREA (NV-020-603)

Figure 3. Continued.

B9
Geothermal Resources

Hot springs are not present in the study area. 

The nearest known hot springs are at Macfarlane's 

Bath House spring, 14 mi south of the study area, and 

an unnamed spring near Quinn River Crossing, 22 mi 

north of the study area. The potential for geothermal 

resources within the study area is low, certainty 

level C.

REFERENCES CITED

Barringer Resources, Inc., 198Z, Geochemical and 

geostatistical evaluation wilderness study area, 

Winnemucca district, northwest Nevada: Golden, 

Colo., Barringer Resources, Inc., 5 volumes.

Day, G.W., Turner, R.L., Malcolm, M.J. ; Briggs P.H., 

and Fey, D.L., 1986, Analytical results and sample 

locality map of heavy-mineral-concentrate and 

rock samples from the South Jackson Mountains 

Wilderness Study Area (NV-020-603), Humboldt 

County, Nevada: U.S. Geological Survey Open-File 

Report 86-272., 19 p. 1 plate, scale 1:50,000.

Duval, J.S., 1983, Composite color images of aerial 

gamma-ray spectrometric data: Geophysics, v. 48, 

no. 6, p 722-735.

Fisher, D.G., 196Z, Geology of the Iron King magnetite 

deposit, Jackson Mountains, Nevada: Salt Lake 

City, University of Utah, M.S. thesis, 51 p.

Geodata International, Inc., 1979, Aerial radiometric 

and magnetic survey Vya national topographic map, 

Nevada: U.S. Department of Energy Open-File 

Report GJBX-136 (79), v. 2, 72 p.

Hill, J.M., 1912, The mining districts of the western 

United States: U.S. Geological Survey Bulletin 507, 

309 p.

Moore, Lyman, 1971, Economic evaluation of 

California-Nevada iron resources and iron ore 

markets: U.S. Bureau of Mines Circular 8511, 

207 p.

Ransome, F.L., 1909, Notes on some mining districts in 

Humboldt County, Nevada: U.S. Geological Survey 

Bulletin 414, 75 p.

Russell, B.J., 1981, Pre-Tertiary paleogeography and 

tectonic history of the Jackson Mountains, 

northwestern Nevada: Evanston, HI., 

Northwestern University, Ph.D. dissertation, 206 p.

___1984, Mesozoic geology of the Jackson Mountains, 

northwestern Nevada: Geological Society of 

America Bulletin, v. 95, p. 313-323.

Shawe, F.R., Reeves, R.G., and Krai, V.E., 1962, Part

C, Iron ore deposits of Northern Nevada, in Iron ore 

deposits of Nevada: Nevada Bureau of Mines 

Bulletin 53, p. 79-125.

Solak, Remzi, 1962, Magnetic survey in the Iron King 

Mine area, Jackson Mountains, Nevada: Salt Lake 

City, University of Utah, M.S. thesis, 67 p.

Sorensen, M.L., 1986, Geologic map of the South 

Jackson Mountains Wilderness Study Area, 

Humboldt County, Nevada: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1829, scale 

1:48,000.

U.S. Bureau of Land Management, 1983a, Mineral and 

mining reconnaissance report of the west side of 

the southern Jackson Mountains: U.S. Bureau of 

Land Management, Winnemucca district, Nev., 

44 p.

___1983b, Wilderness technical report for 19 

wilderness study areas in northwest Nevada: U.S. 

Bureau of Land Management, unpub. report, 

Winnemucca district, Nev., 408 p.

___1983c, Winnemucca district, Draft Wilderness

Environmental Impact Statement: U.S. Bureau of 

Land Management, Winnemucca district, Nev., 

variously paged.

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

the Vya and part of the McDermitt 1° by 2° 

quadrangle, Nevada: U.S. Geological Survey OpenFile Report, scale 1:250,000.

___1985, Aeromagnetic map of the Jackson Mountains, northwestern Nevada: U.S. Geological 

Survey Open-File Report 85-670, scale 1:62,500.

Vanderberg, W.O., 1938, Reconnaissance of mining 

districts in Humboldt County, Nevada: U.S. Bureau 

of Mines Circular 6995, 54 p.

Willden, Ronald, 1958, Cretaceous and Tertiary 

orogeny in Jackson Mountains, Humboldt County, 

Nevada: American Association of Petroleum 

Geologists Bulletin, v. 42, no. 10, p. 2387-2398.

____I960, Geology of the Jackson Mountains, 

Humboldt County, Nevada: Stanford, Calif., 

Stanford University, Ph.D. dissertation, 120 p.

____1961, Preliminary geologic map of Humboldt 

County, Nevada: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-236, scale 

1:200,000.

___1963, General geology of the Jackson Mountains, 

Humboldt County, Nevada: U.S. Geological Survey 

Bulletin 1141-D, 65 p.

___1964, Geology and mineral deposits of Humboldt 

County, Nevada: Nevada Bureau of Mines Bulletin 

59, 154 p.

BIO
Table 1. Mines and prospects in and near the South Jackson Mountains Wilderness Study Area 

[Bureau of Mines, unpublished data, 1986; *, outside study area]

Nurabe r 

(fig. 2)

Name 

(commodity) Summary Workings and production Sample da ta

Avalanche prospect 

(silver, copper)

Bluebird prospect 

(copper, silver, 

barium)

Clover prospect 

(silver, copper, 

lead)

Cold Springs 

prospect 

(commodity 

unknown)

Crystal prospect

(commodity

unknown)

Cuprite prospect 

(silver, copper)

Humboldt King mine 

(silver, copper, 

cobalt)

Iron Girl prospect 

(iron)

Silver- and copper-bearing veins 

trend northeast and dip northwest in 

andesite in the Happy Creek Volcanic 

Complex near contact with a felsite 

intrusion. Main vein is 340 ft long 

and averages 4.2 ft wide. Currently 

being explored as a volcanogenic 

massive-sulfide deposit.

Several small, discontinuous, 

copper- and barium-bearing veins 

follow faults in andesite, 

greenstone, and basalt in the Happy 

Creek Volcanic Complex.

Sulfide veins in andesite in the 

Happy Creek Volcanic Complex and 

Boulder Creek sedimentary rocks are 

close to an alkalic granite plug. 

Granite is altered and contains 

pyrite. On east side of prospect, 

minor alteration present at the 

contact between an intrusive 

hornblendite and sedimentary 

rocks. Being explored for 

volcanogenic mass ive-sul fide 

deposits.

Altered shear zone in felsite 

strikes N. 40° E and dips 80° SE.

Highly altered shale and limestone 

with layered calcite deposits, 

hematite, and barite veins is 

adjacent to felsite intrusion.

Limestone inclusion in andesite of 

the Happy Creek Volcanic Complex 

contains garnet skarn with copper. 

Copper also found in andesite.

A 1,500-ft-long sulfide-bearing zone 

found in sheared andesite and in an 

adjacent, overlying thrust sheet. 

Geophysical anomalies on west and 

south sides of property may indicate 

massive-sulfide deposits at depth, 

possibly under a thrust sheet. 

Currently being explored for 

volcanogenic massive-sulfide 

deposits.

Three short lenses of magnetite 

found in andesite of the Happy Creek 

Volcanic Complex. Three other small 

occurrences of altered country rock 

have minor copper. Currently being 

explored for volcanogenic massivesulfide deposits.

One 50-ft adit with a small 

stope, one shallow shaft, 15 

prospect pits, and a number of 

bulldozer scrapes. No known 

production.

Three adits totaling 120 ft 

and four pits and trenches. 

No known production.

Two adits totaling 170 ft in 

length and seven prospect 

pits. No known production.

One adit 40 ft long, one caved 

adit, and one prospect pit. 

No known production.

One 35-ft-deep shaft and two 

cuts. No known production.

One pit. No known production.

Ten adits, three shafts, and 

numerous cuts, trenches, and 

pits are along mineral 

zones. There are several old 

drill sites. Most underground 

workings are inaccessible. No 

known production.

Four bulldozer contour cuts 

with drill sites, and two pits 

are on the main occurrence. 

Three bulldozer trenches are 

on smaller occurrences. No 

known production.

Eleven chip samples from veins and 

mineralized shear zones contain from 0.0 

to 0.04 parts per million (ppm) gold, 0.0 

to 35 ppm silver, and 0.02 to 12 percent 

copper. Two chip and four grab samples 

from structures on southwest side of 

property contain from 0.0 to 0.48 ppm 

silver and 0.0018 to 0.0037 percent 

copper.

Seven chip samples from oxidized veins and 

altered wallrock contain from 0.0 to 0.028 

ppm gold, 0.0 to 5.7 ppm silver, and 

0,0069 to 6.2 percent copper. Two select 

samples from dumps contain 0.0 and 0.007 

ppm gold, 6.5 and 12 ppm silver, and 8.4 

and 10 percent copper. One grab sample of 

basalt contains no significant mineral 

concentrations.

Three chip samples from sulfide veins and 

mineralized fractures contain from 0.0 to 

0.1 ppm gold and 0.0 to 11 ppm silver; 

three select samples contain from 0.01 to 

0.02 ppm gold, 3 to 99 ppm silver, 0.018 

to 0.40 percent copper, and 0.0027 to 3 

percent lead. Three grab samples of 

altered granite are devoid of signficant 

mineral values as are two from altered 

hornblendite.

Three chip samples contain small amounts 

of copper, barium, and iron.

One grab sample of altered dump rock with 

calcite veins has no significant values.

One grab sample of altered limestone 

contained 3.5 ppm silver and 0.39 percent 

copper. One grab sample of andesite 

contains 0.022 percent copper.

Ten samples of altered metasedimentary 

rock contain no signficant mineral 

values. Twenty-three chip samples from 

the main mineralized zone contain from 0.0 

to 0.36 ppm gold, 0.0 to 26 ppm silver, 

and 0.017 to 7.8 percent copper; four grab 

samples average 0.035 ppm gold, 6.0 ppm 

silver, and 2.6 percent copper; one select 

sample contains 0.011 ppm gold, and 14 

percent copper. From other smaller veins 

seven chip samples contain from 0.0 to 

0.013 ppm gold, 0.0 to 36 ppm silver, and 

0.018 to 5.ft percent copper; two grab 

samples average 0.041 ppm gold, 5.9 ppm 

silver, and 0.12 percent copper; two 

select samples contain as much as 0.7 ppm 

silver and O.I percent copper. Two grab 

samples of altered volcanic rock contain 

no significant minerals. Twenty-two 

samples (company data) from the Humboldt 

King mine average 0.32 oz/ton silver, 1.8 

percent copper, 0.078 percent nickel, and 

0.076 percent cobalt.

Five gi'ab samples: two of magnetite and 

hematite average 60 percent iron, and 

three from altered country rock contain no 

significant values.

Bll
Table 1. Mines and prospects in and near the South Jackson Mountains Wilderness Study Area Continued

Number 

(fig. 2)

Name 

(commodity) Summary Workings and production Sample data

Jackson Queen 

prospect 

(gold, silver, 

copper)

Red Boy mine 

(gold, silver, 

copper, lead, 

zinc)

Red Star prospect 

(iron, copper)

Shamrock prospect

(commodity

unknown)

White Point

prospect

(uranium)

Un named pr os pe ct

(commodity

unknown)

Copper-bearing quartz veins in 

andesite and greenstone trend 

northeast and may be extensions of 

deposits exposed at adjacent 

Harrison Grove and Humboldt King 

mines. Currently being explored for 

volcanogenic massive-sulfide 

deposits.

Massive-sulfide deposits containing 

chalcopyrite, argentiferous galena, 

and sphalerite in andesite of the 

Happy Creek Volcanic Complex are 

poorly exposed at two locations 300 

ft apart. Currently being explored.

Fifty claims cover an area currently 

being explored for volcanogenic 

massive-sulfide -deposits. Several 

small iron deposits in the middle of 

the claim group are veins of 

magnetite and hematite in andesite 

of the Happy Creek Volcanic Complex.

Brecciated, bleached andesite is 

recemented with limonite and barite.

Exploration for uranium was in 

moderately altered Tertiary dacite.

Altered shear zone with pyiite and 

barite in a felsic intrusion trends 

N. 75° E. and dips 40° NW.

Four adits total about 300 ft 

in length. Also three 

prospect pits and one caved 

adit. No known production.

One shaft and two adits are 

caved or flooded. One 20-ftlong adit is open. There are 

also 11 prospect pits and one 

cut. Production in 1940 and 

1948 totaled 1 oz gold, 748 oz 

silver, 49 Ib copper, 5,073 Ib 

lead, and 12,446 Ib zinc. In 

1943 two carloads of ore, 

containing an unknown amount 

of metal, were shipped to a 

smelter.

Iron deposits are developed by 

several thousands of feet of 

bulldozer cuts and scrapes on 

both sides of Big Cedar 

Creek. These deposits were 

drilled in 1958 by Pacific 

Steel Co. No known 

production.

One prospect pit. 

production.

No known

About 1,300 ft of bulldozer 

trenches and scrapes. No 

known production.

One prospect pit. 

production.

Eleven chip samples from main mineral zone 

contain from 0.0 to 4 ppm gold, 0.0 to 22 

ppm silver, and 0.0027 to 12 percent 

copper; one grab sample from same zone 

contains 0.027 ppm gold, 1.7 ppm silver, 

and 0.017 percent copper. Two select 

samples from small veins contain 0.009 and 

0.021 ppm gold, 20 and 2.4 ppm silver, and 

6.7 and 0.82 percent copper.

Six chip samples of main sulfide-bearing 

vein contain 0.042 to 5.0 ppm gold, 3.8 to 

500 ppm silver, 0.014 to 0.13 percent 

copper, 0.058 to 10 percent lead, and 0.35 

to 7.0 percent zinc; one select sample 

from same vein contains 5 ppm gold, 190 

ppm silver, 0.10 percent copper, 1.9 

percent lead, and 24 percent zinc; one 

grab sample from a carbonate vein contains 

0.076 ppm gold, 120 ppm silver, 0,52 

percent lead, and 0.78 percent zinc. Two 

chip and two grab samples of altered 

andesite contain no signficant minerals.

Six chip samples from iron deposits 

average 53 percent iron; one chip sample 

of altered wallrock contains 0.20 ppm 

gold, 1.0 ppm silver, 0.41 percent copper, 

and 14 percent iron. Three grab samples 

of andesite contain no significant 

minerals.

Of two grab samples, one contains 0.17 

percent barium. There are no other 

significant values.

Nine samples average 9.1 ppm uranium. A 

geophysical survey showed low 

radioactivity of 150 to 200 counts per 

second.

One chip sample contains 0.015 percent 

copper.

B12
APPENDIX 1. Definition of levels of mineral resource potential and 

certainty of assessment

Definitions of Mineral Resource Potential

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 unlikely. 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 a 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 occurrence, where interpretations of 

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

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

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

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

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

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

t

LU 

CC

B C 

LEVEL OF CERTAINTY

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

Available information suggests the level of mineral resource potential. 

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

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.

B13
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 Proterozoic

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

Pateocene

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

O A

«JO

ww 

 ftft

- 96

_ 1OQ

one

f\M/\

 9on

ot/%

- IfiOGUU

- 410

- 47R HOU

_ cnn

o/u 

_ Qrtfl

icnn

 oKfin ZOUU

ouuu

OHUU

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

Informal time term without specific rank.

B14

GPO 785-048/48032