U.S. Geological Survey 

Heavy Metals Program 

Progress Report 

1966 and 1967 

U.S. Geological Survey 

Heavy Metals Program 

Progress Report 

1 966 and 1967 

G E 0 l 0 G I C A l S U R V E Y C I R C U l A R 560 

Washington 1968 
United States Department of the Interior 

STEWART l. UDALL, Secretary 

Geologica\ Survey 

William T. Pecora, Director 

First printing 1 968 

Second printing 1968 

Free on appiK:ation to !he U.S. Geologico! Survey, Washington, D.C. 20242 
Summary---------------------------------

Introduction-------------------------------

Organization ------------------------------

Projects started during 1966-67-------------

Analytical support for program--------------

Geologic drilling---------------------------

Airborne geophysical surveys---------------

New facilities and equipment----------------

Publications-------------------------------

Field studies on land-----------------------

Alaska----------------------------------

Arizona---------------------------------

California-------------------------------

Colorado--------------------------------

Georgia---------------------------------

~aine ---------------------------------- ~aryland-------------------------------

~assachusetts---------------------------

~issouri -------------------------------

~ontana -------------------------------- Nevada---------------------------------

New Hampshire--------------------------

New ~exico ----------------------------- New York-------------------------------

North Carolina--------------------------

South Carolina---------------------------

South Dakota ---------------------------- Utah------------------------------------

VVyoming--------------------------------

~arine investigations ----------------------

Alaska----------------------------------

California-------------------------------

California and Oregon--------------------

Oregon --------------------------------- Oregon and VVashington-------------------

CONTENTS 

Page 

1 Marine investigations--Continued 

1 VVashington------------------------------

2 Gulf of Mexico --------------------------

2 Topical studies----------------------------

3 Heavy metals in organic-rich rocks--------

3 Gold content of coal, peat, and 

3 associated rocks-----------------------

4 Gold content of black shales---------------

4 Metal- rich Cretaceous asphaltic sandS stone near Durango, Colo. --------------

5 Gold in marine sediments-----------------

6 Gold content of batholithic rocks-----------

6 Fossil placer deposits--------------------

7 Mercury as a possible indicator of 

8 uranium on the Colorado Plateau--------

8 Stream transport of lead particles---------

9 Concentration of gold in particle-size 

9 fraction--------------------------------

9 Fluvial geochemistry of gold and silver----

9 Behavior of gold in weathering 

9 environments--------... -----------------

12 Studies of sulfide and telluride 

13 mineral systems-----------------------

13 Solution chemistry of gold at high 

13 temperatures and pressures------------

13 Research on analysis of gold--------------

14 Research on analysis of gold in 

14 heavy mineral concentrates-------------

14 Research on determination of trace 

15 elements in placer gold-----------------

15 Research on analysis of the platinum 

16 group metals--------------------------

16 Research in spectrography and 

16 spectrophotometry---------------------

16 Miscellaneous research------------------

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U.S. Geological Survey Heavy Metals Program 

Progress Report, 1966 and 1967 

SUMMARY 

The Heavy Metals program was started in April1966 

as a joint effort by the Geological Survey and the Bureau of Mines to stimulate domestic production of a 

group of metals that are in short supply. These metals 

are. gold, si~ver, platinum-group metals, mercury, tin, 

anumony, bismuth, nickel, and tantalum. About 90percent of program effort during the first year and a half 

?as been on gold because of its international monetary 

Importance. The Geological Survey part of the program 

has been mainly to identify exploration targets to be 

further explored and developed by private industry; 

that of th~ Bureau. of Mines to conduct mining and 

~etal!urg1cal studies of subeconomic mineral deposIts, either targets established by the Geological Survey or previously known marginal deposits, in order 

to make them economic through technological improvements .. To attain its objectives in this program, the 

Geological Survey is conducting a wide variety of field 

and laboratory studies to increase the knowledge of 

the geology, geochemistry, and occurrence of the heavy 

metals on the land and in the marine environment to 

improve capabilities for discovering concealed ~re de~osits, and to develop more accurate and rapid analyucal methods for detecting small amounts of gold and 

other metals. 

By December 1967, about 235 employees of the Geological Survey were participating in the program, and 

more than 100 projects were und~r way. To provide 

adequate analytical support for the program, fixed 

laboratory facilities were greatly expanded and 20 

mobil.e laboratories were assembled. A total of 240,000 

chem1cal and spectrographic analyses had been made 

by the end of 1967. To supplement studies undertaken 

within the Geological Survey, research contracts or 

grants were awarded to 15 universities and one research laboratory. 

In the first 21 months of operation, the Heavy Metals program has produced several significant results: 

Cortez, Nev.-Identification of an area containing 

abnor.mal amounts of gold led to the discovery by private mdustry of over three million tons of open-pit 

ore averaging 0.3 ounce gold per ton. 

Cripple Creek, Colo.-Samples from an area 3,800 

feet .lo~g and 500 feet wide average $2.50 per ton gold 

and md1cate a potentially large low-grade deposit. 

Northwestern Wyoming. -Conglomerates in this area 

contain 6-35 cents in gold per cubic yard of r~'lck, and 

although these values are low, the volume of rock involved is enormous -50 cubic miles or· more-and the 

possibility of finding higher grade concentraticns within the area are good. 

Ely, Nev.-Anomalously large amounts of g'lld, silver, tellurium, and mercury are found in rocks around 

the copper deposits of the Ely district and point to 

areas warranting further investigation and exploration. 

Northumberland Canyon, Nev.-A large deposit of 

barite was discovered in east Northumberland Canyon, 

Nye County, Nev., by geologists assigned to a Heavy 

Metals project. Exploration by private industry is expected to prove that a major resource ispres~nt. 

Mercury-vapor detector.-This simple instrument, 

developed in Geological Survey laboratories, is· capable 

of analyzing 60-100 samples per day for mercury in 

concentrations as low as 5 parts per billion. 

INTRODUCTION 

The Heavy Metals program was undertaker in April 

1966 as a 5-year open-ended joint effort by the Geological Survey and the Bureau of Mines to increase 

the output of a group of metals that were being produced from domestic sources in much less than the 

amounts required by the national economy. Th~se metals include gold, silver, platinum-group metrls, antimony, bismuth, mercury, silver, tan t a 1 u m and tin; 

nickel was added subsequently. About 90 percent of the 

program effort during the first 21 months has been on 

gold because of its international monetary imr0rtance. 

As wide as p o s s i b 1 e a range of effort h~s be en 

brought to bear on the problem of exploration target 

identification, including geologic mapping, geochemical exploration, ground and airborne geophysical surveys, oceanographic studies, laboratory research on 

the mineralogy and chemistry of the heavy metals, research on chemical, spectrographic, and radioactivation analytical methods, and broad literature search 

for any relevant published material. 

Results of investigations are published aR soon as 

possible, mostly as circulars but also as maps in one 
of the regular map series of the Geological Survey and 

as chapters in the annual volumes summarizing Geological Survey Research. Nine circulars, three maps, 

and 18 Geological Survey Research chapters have been 

published so far. 

A vail able funds were allocated to six broad fields 

of effort in approximately the following percentages; 

costs of analytical, administrative, and other general 

support are distributed proportionately: 

Lode gold deposits 

Continental gold placers 

Marine gold placers 

Residual gold deposits 

Metals other than gold 

Ancillary research 

ORGANIZATION 

Percent 

41 

17 

18 

4 

10 

_lQ_ 

100 

In December 1967, some 235 employees of the Geological Survey were participating in the program. 

About 180 of these were professionals, including 135 

geologists, 30 chemists, and 8 geophysicists; more 

than 40 were hired since inception of the program. 

The program is directed by the Office of Economic 

Geology and is staffed by personnel from 14 units of 

the Geologic Division, two of which, the Branch of 

Heavy Metals and the Exploration Unit, were organized 

specifically for the program. The Water Resources Division also is taking part. Participating units include 

the following: 

Geologic Division 

Office of Economic Geology 

Branch of Heavy Metals 

Branch of Exploration Research 

Branch of Organic Fuels 

Branch of Resources Research 

Exploration Unit 

Office of Regional Geology 

Branch of Alaska Geology 

Branch of Regional Geophysics 

Office of Experimental Geology 

Branch of Experimental Geochemistry and Mineralogy. 

Branch of Field Geochemistry and Petrology 

Branch of Geochemical Census 

Branch of Theoretical Geophysics 

Branch of Analytical Laboratories 

Branch of Isotope Geology 

Office of Marine Geology and Hydrology 

Water Resources Division 

Rocky Mountain Region 

In order to supplement the in-house capabilities of 

the Geological Survey, certain special facilities and 

2 

talents of the scientific community have been enlisted 

through awards of research contracts and grants to 

15 universities and one independent research laboratory. Ten contracts totaling $600,000 were for research 

in the marine field; most of these programs invblve 

use of oceanographic vessels of the respective institutions for cooperative studies by Geological Survey 

and university scientists. Eight contracts tot a 1 in g 

$170,000 were for land- based research. Total expenditure for research contracts was $770,000. 

All state geologists have been informed on the program and many have offered valuable suggestions for 

consideration as field or laboratory projects. 

PROJECTS STARTED DURING 1966-67 

During the first 21 months of the program, about 

108 new projects were started. MoPt of these were 

staffed entirely by Geological Survey personnel; nine 

were staffed by both Geological Survey and contract 

personnel, and eight by contract personnel only. Included were 80 field projects, 18 combined field-laboratory projects, and 10 laboratory projects. Fie 1 d 

projects were carried out on land in 25 states and in 

the littoral regions of seven states. 

Most field projects were in or W'7.St of the Rocky 

Mountains, but several were in nort'1-central states, 

in the Appalachian region, and on the coasts of the 

Atlantic and Gulf of Mexico. Several general types of 

projects have been undertaken: 

1. Intensive studies of known heavy metal districts, 

aimed at obtaining basic information on the occurrence of these metals (15 proj'7.cts). 

2. Studies of larger areas known to contain small and 

(or) low-grade deposits, aimed at recognizing possible large low-grade resources ( 37 projects). 

3. Studies of broad regions not kno, .. n to contain deposits of heavy metals but having geologic characteristics favorable for their occurrence, aimed at 

locating resources heretofore u n r e cognized 

because of lack of exposures or inadequacy of 

methods of detection. Several of t'1eseprojects are 

wide-scope investigations of the occurrence and 

distribution of heavy metals in time and space (28 

projects). 

Combined laboratory-field projects include studies 

of abundances of heavy metals in VE'rious rock types 

(7 projects); behavior of heavy metrls during weathering, solution, transport, and deposition (5 projects); 

associations of heavy metals with organic material 

(3 projects); research on geophysical methods as applied to exploration for heavy metals (2 projects); and 

research on sulfur isotopes in ore deposits ( 1 project). 

Laboratory projects include research on analysis of 

rocks, soils, and waters by chemical, spectrographic, 

spectrophotometric, and radiometric methods; studies 

of mineral systems involving heavy metals; and research on the platinum metals, the geochemistry of 

gold, and the crustal abundances of heavy metals. 
Research contracts have been awarded to the following institutions for cooperative studies in the marine geology of heavy metals; all the studies but one 

involve use of oceanographic research vessels: 

University of Alaska-Gulf of Alaska continental 

shelf. 

Duke University-North Carolina continental shelf. 

Louisiana State University-Gulf Coast studies. 

University of Oregon-Oregon continental shelf. 

Oregon State University-continental margin of 

southern Oregon and northern California. 

Scripps Institution of Oceanography-Northern California continental shelf. 

University of Southern California-Southern California continental shelf. 

Stanford University-subaerial and subaqueous flow 

of slurries. 

Texas A&M University-Gulf Coast studies. 

University of Washington-Bering Sea and Washington continental shelf. 

For land-based studies, research grants have been 

awarded to the following institutions: 

University of Alaska- geological and geochemical 

investigations of the Ester-Cleary mineralized 

belt, Fairbanks district, Alaska. 

University of Colorado-the use of very low frequency waves in geophysical exploration. 

Colorado School of Mines-adsorption of precious 

metals by organic deposits. 

Colorado School of Mines-symposium on geochemical exploration. 

Colorado State University-solubilization of trace 

mineral elements by soil micro-organisms. 

Oregon State University-sulfur isotope investigations, Bingham district, Utah. 

South Dakota School of Mines and Technologycompilation of information on ore deposits in the 

rocks of the northern Black Hills. 

Tracerlab, Inc.-research and development on a 

direct- reading field instrument for the detection 

of selected chemical elements. 

ANALYTICAL SUPPORT FOR PROGRAM 

At an early stage in planning the Heavy Metals program it became apparent that the analytical capability 

of the Geological Survey would have to be greatly expanded to handle expeditiously the very large number 

of rocl,<, soil, and water samples expected as many 

new projects got under way. In particular, muchmore 

rapid services were required to facilitate the day-byday planning of fieldwork by project geologists. Consequently, fixed laboratory facilities at the Denver, 

Colo., and Washington, D. C., centers were enlarged 

and the small fleet of mobile laboratories, first used 

by the Branch of E:x1Jloration Research in its own studies and in support of field parties engaged in Primitive 

Area evaluations, was increased to 26 vehicles, 15-20 

of which have been assigned at various times to Heavy 

Metals projects. Extensive new laboratory space was 

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leased at the Table Mountain Research Center of Colorado School of Mines near Golden, Colo.; two fire assay 

furnaces were installed in Washington, D.C., and a 

second put in operation at Denver; and about 40 new 

chemists and technicians were hired, most b~r the Field 

Services Section of the Branch of E xp 1 or at ion Research. 

During the first 21 months of the program, more 

than 66,000 analyses for gold, 125,000 analyses for 

other metals (arsenic, antimony, beryllium, bismuth, 

chromium, cobalt, copper, iron, lead, manganese, 

mercury, molybdenum, nickel, silver, tantalum, tellurium, tin, tungsten, uranium, and zinc), and 48,000 

semiquantitative spectrographic analyses for from 30 

to 60 elements each, as well as nearly 800 chemical 

analyses of the platinum-group metals, were completed, for a total of nearly 240,000 analyses. About 

3,500 of these analyses were madeunderco'1tractwith 

commercial laboratories, the rest were made in laboratories of the Geological Survey. 

GEOLOGIC DRILLING 

Drilling to obtain geologic information is a valuable 

aid to the geologist in providing necessary data on the 

third dimension of a given area. Funding, therefore, 

was provided to obtain such information, and contracts for diamond core drilling in four areas have 

been let. These areas are: 

1. Iron Canyon, at the south end of Battle Mountain, 

10 miles southwest of Battle Mountain, Nev. Drilling began in April 1967 and was continuing at the 

year's end. 

2. Tenabo, on the east side of the Shoshone Range, 

30 miles southeast of Battle Mountain, Nev. Drilling started in July 1967 and was still in progress 

at the year's end. 

3. Swales Mountaia, in the lndepenctence Mo·.mtains, 15 

miles north of Carlin, Nev. Drilling began in May 

1967 and was finished in September. 

-:~:. Squaretown, 11 miles east-northeast of The Forks, 

Maine. Drilling started in June 1967 anc was completed in September. 

To facilitate geologic mapping and samrling in the 

deeply weathered rocks of the Southeastern United 

States, two truck-mounted auger drills were acquired. 

Augering has been done at Kershaw, S.C., rnd at several places on the coastal plain of the So·Jtheastern 

States. 

AIRBORNE GEOPHYSICAL SURVEYS 

Various kinds of information may be provided the 

geologist through use of airborne sensors. These surveys offer rapid and economic coverage oflarge areas 

and are particularly valuable to the reconnaissance 

projects of the Heavy Metals program. Airh')rne magnetic surveys have been carried out both by the Branch 
of Regional G eo p h y s i c s and under con t r a c t by 

commercial firms. A total of about41,500 square miles 

of aeromagnetic surveying has been done, including 

about 20,000 square miles in western and north-central Nevada; 15,000 square miles in Montana, Idaho, 

and Washington; 5,000 square miles in southwestern 

and north-central Colorado; and 1,500 square miles in 

California. In addition, about 1,200 square miles of 

combined low-level airborne magnetic, electromagnetic, and radioactivity surveys were flown in California, Maine, and South Carolina. Aeromagnetic maps 

covering all or parts of about 85 quadrangles in western 

and north-central Nevada were placed on open-file in 

1967. 

NEW FACILITIES AND EQUIPMENT 

To provide adequate field and laboratory support for 

the projects initiated under the Heavy Metals program, 

considerable new equipment was acquired and new 

laboratory facilities planned. 

A new mineralogy laboratory was designed for the 

Denver Field Center, and construction began in 1967. 

This laboratory will be completely equipped for mineral studies essential to the program and will include 

an X-ray diffractometer. New equipment also was acquired for the Washington, D.C., and Beltsville, Md., 

laboratories. 

In addition to equipment for general-use laboratories, considerable new equipment for individual investigators was also purchased. This equipment included petrographic and binocular microscopes and a 

laser-fired probe for research in spectrography. 

In order to increase the capacity for geophysical 

support of the program, equipment for automatic plotting of aeromagnetic data, for aeromagnetic surveying, 

and for studies of induced-polarization methods and 

borehole geophysics was acquired. 

Many field projects in the program are in areas 

distant from living facilities and supplies. To facilitate 

fieldwork in these remote areas, nine small house 

trailers were purchased. 

PUBLICATIONS 

Results of various investigations made under the 

Heavy Metals program are to be published as quickly 

as possible. Since inception of the program the following reports have been published: 

Map 1-471: Distribution of selected accessory min· 

erals in the Osgood Mountains stock, Hum bo 1 d t 

County, Nevada, by G. J. Neuerburg; publishedMay 

1966. 

Professional Paper 550-B-G eo 1 o g i c a 1 Survey Research 1966, Chapter B; published June 1966: 

Field determination of nanogram quantities of mercury in soils and rocks, by Margaret Hinkle, K. W. 

Leong, and F. N. Ward. 

Tellurium and mercury in jasperoid samples, by 

T. G. Lovering, H. W. Lakin, and J. H. McCarthy. 

Determination of silver in mineralized rocks by 

atomic absorption spectrophotometry, by C 1 au de 

Huf:~man, Jr., J. D. Mensik, and L. F. Rader. 

Professional Paper 550-C-G eo 1 o g i c a 1 Survey Research 1966, Chapter C; published August 1966: 

Metal sorption by northwest Florida humate, by 

V. E. Swanson, I. C. Frost, L. F. Rader, Jr., and 

Claude Huffman, Jr. 

Distribution of selected metals in the Stockton district, Utah, by W. J. Moore, G. C. Curtin, R. J. 

Roberts, and E. W. Tooker. 

Determination of microquantities of mercury in 

sulfide ores by Penfield tube-dithizone and semiquantitative spectrographic methods, by J. I. Dinnin 

and H. W. Worthing. 

Circular 534: Gold geochemical anomaly in the Cortez 

d i s t ric. t, Nevada, by R. L. Erickson, G. H. Van 

Sickle, H. M. Nakagawa, J. H. Mc.Sarthy, Jr., and 

K. W. Leong; published August 19t6. 

Circular 535: Distribution of gold, silver, tellurium, 

and mercury in the Ely mining district, Whjte Pine 

County, Nevada, by G. B. Gott and J. H. McCarthy, 

Jr.; published October 1966. 

Map GP-561: Aeromagnetic mapofpartsoftheMother 

Lode gold and Sierra Foothills corner mining districts, California, and its geologic interpretation, 

by J. R. Henderson, A. A. Stromquist, and A. J espersen; published October 1 966. 

Circular 540: A simple mercury vapor detector for 

geochemical prospecting, by W. W. Vaughn; published February 196 7. 

Circular 541: Gold-bearing sedimentary rocks in 

northwest Wyoming-A preliminary report, by J. C. 

Antweiler and J. D. Love; published February 1967. 

Circular 543: Distribution of gold, tellurium. silver, 

and mercury in part of the Cripple Creek district, 

Colorado, by G. B. Gott, J. H. McCarthy, Jr., G. H. 

Van Sickle, and J. B. McHugh; publishedAprill967. 

Professional Paper 575-B-Geologi cal Survey Research 1967, Chapter B; published May 1967: 

4 

Silver and mercury geochemical anomalies in the 

Comstock, Tonopah, and Silver Reef districts, Nevada-Utah, by H. R. Cornwall, H. W. Lakin, H. M. 

Nakagawa, and H. K. Stager. 

Mineralized veins at Black Mcuntain, western 

Seward Peninsula, Alaska, by C. L. Sainsbury and 

J. C. Hamilton. 

Results of some geophysical inve.~tigations in the 

Wood Hills area of northwestern Nevada, by C. J. 

Zablocki. 
Map 1-496: Distribution of selected accessory minerals in the Caribou stock, Boulder County, Colorado, by G. J. Neuer burg; published June 1967. 

Professional Paper 575-C-Geological SurveyResearch 1967, Chapter C; published July 1967: 

Determination of palladium in the parts-per-billion 

range in rocks, by F. S. Grimaldi and M. M. 

Schnepf e. 

Circular 555: Bedded barite in east Northumberland 

Canyon, Nye County, Nevada, by D. R. Shawe, F. G. 

Poole, and D. A. Brobst; published August 1967. 

Circular 544: Determination of gold in geologic materials by solvent extraction and atomic-absorption spectrometry, by Claude Huffman, Jr., J. D. 

Mensik, and L. B. Riley; published September 1967. 

Circular 545: Marine sediment sample preparation 

for analysis for low concentrations of fine detrital 

gold, by H. Edward Clifton, Arthur Hubert, and 

R. Lawrence Phillips; published October 1967. 

Professional Paper 575-D-Geological Survey Research 1967, Chapter D; published November 1967. 

Age of volcanic activity in the San Juan Mountains, 

Colorado, by T. A. Steven, H. H. Mehnert, and J. D. 

Obradovich. 

Callaghan window-A newly discovered part of the 

Roberts thrust, Toiyabe Range, Lander County, 

Nevada, by J. H. Stewart and A. R. Palmer. 

Preliminary report on sulfide and platinum-group 

minerals in the chromites of the Stillwater Complex, Montana, by N. J. Page and E. D. Jackson. 

Bismuth and tin minerals in gold- and silverbearing sulfide ores, Ohio mining district, Marysvale, Utah, by A. S. Radtke, C. M. Taylor, and 

J. E. Frost. 

A geochemical anomaly of base metals and silver 

in the southern Santa Rita Mountains, Santa Cruz 

County, Arizona, by Harald Drewes. 

Upper Pleistocene features in the Bering Strait 

area, by C. L. Sainsbury. 

A spectrophotometric method for the determination of traces of platinum and palladium in geologic 

materials, by C. E. Thompson. 

Atomic absorption determination of bismuth in altered rocks, by F. N. Ward and H. M. Nakagawa. 

Circular 549: Economic significance of revised age 

relations of rocks in the Cornucopia mining district, Elko County, Nevada, by R. R. Coats; published December 1967. 

FIELD STUDIES ON LAND 

Brief descriptions are given of results achieved 

during the first year and a half of the program. Abbreviations commonly used include: 

5 

ppm = parts permillion(1 ppm: 0.0001 percent, or 

about 0.03 oz per ton) 

ppb =parts per billion (1 ppb = 0.0000001 percent) 

For gold, 1 ppm equals about $1.00 per ton. 

Analytical data for gold, silver, and platinum are 

usually given in ppm or ppb. Results frequently are 

reported as "less than" a certain amount, this amount 

being the limit of detection of the analyti~al method 

employed. Such a result means that the element was 

not detected and, if present at all, occurc only in an 

amount below the limit of detection. 

Alaska 

Summary of Alaska field season, 196t.-Because 

Alaskan logistical problems require plan'1ing a year 

or so in advance of actual geologic fieldwork, only 

some preliminary studies were made during the first 

year of the program. 

Fairbanks district.-A map showing locations of 

all lode mines and prospects in the Fairbanks area 

was compiled, together with a table summarizingdata 

on each deposit. 

McGrath area. -Quartzite conglomerates west of 

Big River, southeast of McGrath, were examined as 

possible sources of reported placer gold. They proved 

to be barren, the gold being derived instea1 from moraine. 

Seventy Mile area.-P Iacer gold along sever a I 

creeks in the Seventy Mile area of the Yukon River in 

eastern Alaska appears to be derived frorr. veinlets in 

bedrock, from mineralized fault zones, or from highlevel gravels rather than from Tertiary gravels. 

Gold nuggets from the Seventy Mile area have traceelement contents that reflect their mineral associations. Gold from Woodchopper Creek, in which stream 

sediments contain abundant cassiterite, also contains 

tin, as well as bismuth, molybdenum, antimony, copper, 

lead, and zinc. 

Seward Peninsula.-A system of tin-bearing veins 

was discovered at Black Mountain on the Seward Peninsula. The veins are 1,000-5,000 feet long and consist 

of quartz and fluorite with cassiterite, sulfides of 

copper, lead, and zinc, and traces of silver and bismuth. 

Summary of Alaska field season, 1967.-Projects 

were carried out in 13 areas of Alaska during the 

summer of 1967, ranging in type from detailed mapping 

of mineralized districts to geochemical reconnaissance and in locations from Seward Peninsula to eastern and southeastern Alaska. About 7,500 samples 

were collected, and most were submitted for gold determination and spectrographic analysis. Analytical 

data are incomplete as yet, but at least nine projects 

yielded significant economic results, anc in at least 

six, gold was detected in amounts greater than 0.02 

ppm. This work indicates that samples of s~ream sediment, soil, and spring deposits are all us~ful in prospecting for gold lodes and placers. 
Geophysical studies near Fairbanks-Preliminary 

tests of magnetic and electrical methods as tools for 

exploration for gold placers and lode deposits were 

completed in the Fairbanks district. 

Resistivity soundings give a reasonably clear picture of bedrock configuration below gravels despite 

problems posed by permafrost. At Wiseman, about 200 

m i 1 e s north of Fairbanks, resistivity measurements 

suggest that bedrock is too deep to reach with present -day dredges. 

Efforts to detect narrow gold-quartz and s u 1 fide 

veins on Cleary Dome north of Fairbanks were made 

using electromagnetic( EM) and induced -polarization 

(IP) methods. The veins apparently are too small to 

detect using EM, but both distribution and attitude of 

sulfide concentrations were established using IP. 

Magnetic profiles failed to reveal any concentrations of magnetite such as might be associated with 

placer gold. 

Reconnaissance studies in southern Brooks 

Range. -Geochemical sampling in the Chandalar and 

Wiseman quadrangles in the southern Brooks Range 

of north-central Alaska revealed a silver anomaly that 

extends the potential silver-bearing area around a 

known silver prospect. A gold anomaly was found along 

the Mikado shear zone 0.5 mile west of the Mikado 

mine at Chandalar Lake. Samplingofapparentlyfavorable areas in the Table Mountain and Co 1 e en quadrangles along the northeast border of Alaska yielded 

negative results. 

geologic mapping in Wrangell Mountains. -Geologic 

mapping of six IS-minute quadrangles in the Wrangell 

Mountains in south-central Alaska has been completed. 

These maps will provide a sound base for further study 

of the heavy metal potential of the region. 

Gold in gravel of Kougarok River.-Small amounts 

of gold have been found in gravels of the Kougarok 

River in the western part of Seward Peninsula. Seismic profiles near the mouth of the river indicate a 

buried north-trending channel, possibly indicating a 

pre-gravel drainage direction. These gravels, formerly thought to be of Tertiary and Pleistocene age, are 

now believed to be entirely of Pleistocene age. 

Gold veins at Nuka Bay.-Several quartz-arsenopyrite veins at Nuka Bay, at the southwest end of Kenai 

Peninsula, southwestern Alaska, contain as much as 

10 ounces of ,gold per ton. The veins are short and 

discontinuous, and ore shoots are erratic, but smallscale mining may be feasible. 

Arizona 

Gold deposits of Gold Basin and Lost Basin. -Study 

of gold lode and placer deposits of the Gold Basin-Lost 

Basin are·a south of Lake Mead in northwestern Arizona 

has shown that alluvial placers of Pliocene(?) and Quaternary age on the flanks of the Lost Basin Range are 

the most promising. Small veins of quartz, sulfide minerals, and gold are abundant in Precambrian rocks of 

the region, and some contain coarse gold, but most are 

6 

too small to be of economic interest. Placer deposits 

derived from Pliocene(?) pediment gravels have 

formed along arroyos on the east side ofthe Lost Basin Range over an area of 8-10 square miles. On the 

west side of the range, some placer deposits in Quaternary alluvial fans are being mined on a small scale. 

Potential resources may exceed SCO million cubic 

yards of gravel containing 0.01-0.02 oz gold ($0.35 -

$0. 70) per cubic yard. A sampling program is being 

planned with the U.S. Bureau of Miner:. 

California 

Aeromagnetic map of part of the Mother Lode. -An 

aeromagnetic map of pans of the Mother Lode gold and 

Sierra Foothills copper mining districts in Calaveras, 

Stanislaus, and San Joaquin Counties, together with a 

geologic interpretation (U.S. Geol. Survey Map GP -561), 

shows that many of the ore deposits in this region are 

related to the Bear Mountains and Melones fault zones, 

which locally are intruded by ultranafic rocks that 

give rise to magnetic highs. Magnet:c evidence suggests a similar buried fault zone 8-9 miles southwest 

of the Bear Mountains zone. Possitle near-surface 

magnetite- and ilmenite-bearing sands, which elsewhere in the region are known to contain placer gold, 

also are indicated by the magnetic data. 

Aeromagnetic surveys of the Mother Lode-Grass 

Valley area to the north in the Sierra Nevada have been 

completed. Some electromagnetic anomalies detected 

by aerial surveys have been checkei on the ground; 

the conductive units appear to be black slates or phyllites and flat-lying volcanic rocks and gravels. 

Tertiary gravels, Nevada County.-A.s an initi~l 

stage in the study of Tertiary gold-bearmg gravels m 

the Sierra Nevada, the San Juan F idge channel in 

Nevada County was traced for abou'" 15 miles. The 

sinuovs channel is \:i-ln miles wide and along its axis 

is filled with 200-300 feet of gravel. P a 1 eo current 

data show that the ancient river flowed from east to 

west. Twenty samples were collected for study and 

analysis. Much gravel was removed from this channel 

during hydraulic mining prier to 1885, but a 1 a r g e 

amount remains. 

Field tests of 8ix geophysical metrods for studying 

possible gold-bearing Tertiary stream gravels in the 

Sierra Nevada were made north of Nevada City and are 

being evaluated. Seismic-refraction rrethods sup p 1 emented by gravity measurements arpear to be best 

for determining bedrock configuration. ResistivitY 

methods provide knowledge of condu-::tive layers and 

may be able to locate the productive "blue lead" when 

other methods fail. Magnetic methois are useful if 

concentrations of magnetite-rich black sands are associated with gold, and induced polarization may detect 

disseminated sulfides that in placee- are associated 

with gold concentrates. Electromagnetic techniques do 

not appear promising at this preliminary stage. -

Low-level (400ft above terrain) magnetic, electromagnetic, and radiation profiles were flown across the 
San Juan Ridge channel northeast of Nevada City and 

will be compared with results from earlier ground 

tests. 

Studies and sampling in Klamath Mountains gold 

region. -Areas around most of the principal gold mines 

and districts in the Klamath Mountains of northern 

California and southern Oregon were studied, and 

zones of shearing and alteration near mines and along 

roadcuts were sampled. Most samples contained < 0,1 

ppm gold, but several had as much as 2.1 ppm gold. 

In particular, samples from the Liberty district near 

Sawyers Bar contained as much as 2.1 ppm gold in 

fault zones at known deposits and as much as 0.3 ppm 

in shear zones half a mile or more from known deposits. 

In addition, about 7 5 samples were collected from 

basal Cretaceous beds overlying rocks of the Klamath 

terrane around Redding and Yreka, Calif., and Medford, Oreg. All plutons in the Klamath Mountains of 

southwest Oregon were sampled for age determination 

by the potassium -argon method, 

Geochemical studies in the Masonic district_.-Preliminary results of a geochemical study of the Masonic 

district in northern Mono County indicate that altered, 

generally silicified, and locally pyritized v o 1 can i c 

rocks in the center of the district average about 0.1 

ppm gold. No significant correlation was found between 

gold and copper, lead, or silver. 

Colorado 

Alamosa Creek, Conejos and Rio Grande Counties.-

An extensive area of hydrothermally altered volcanic 

and plutonic rocks of intermediate composition along 

the upper Alamosa Creek 3 miles south of Summitville in the eastern San Juan Mountains locally contains anomalous amounts of lead, copper, molybdeum, 

and zinc. A presumably late zone of quartz-alunitepyrophy llite alter at ion some 2 miles 1 on g is superimposed on a more widespread area of quartz-muscovite or illite-kaolinite a 1 t era t ion. The 1 ate 

alteration may be related to intrusive rocks similar 

to those of the Summitville gold-copper-silver district; 

if so, ore deposits may be present in the area, perhaps 

at depth. 

Eastern San Juan Mountains.-Reconnaissance geologic study and geochemical sampling has been done 

in several hydrothermally altered volcanic centers in 

the eastern San Juan Mountains. Samples are being 

studied to determine the nature of occurrence of the 

small amounts of precious metals detected. 

The highest gold contents, as much as 50 ppm, are 

in relatively small bodies of silicified intrusive rocks 

containing barite, pyrite, and copper sulfides. More 

extensive altered pyritized zones peripheral to intrusives generally have < 0.2 ppm gold. Pyrite from some 

altered rocks is being analyzed for gold and trace 

elements to determine whether it is a principal carrier 

of gold or other elements. Barite from several goldrich samples also is being analyzed. 

Research on stream -sediment sampling, San Juan 

Mountains. -Stream-sediment samples from 57 localities in the northwestern San Juan Mountains were collected and concentrated by panning as a test of sampling 

procedures. Most analyzed samples of concentrate 

weighed about 15 g; large samples were split and analyses made of each split. Three types of areas were 

sampled: ( 1) areas not known to have gold deposits; (2) 

areas known to have some gold veins but few if any 

prospects or small mines; and (3) areas having numerous veins and productive mines. 

Results may be summarized as follows: 

I. Agreement :1mong analyses of two or more splits 

of the same sample was good enough that considerable confidence can be placed in a single analysis 

of a 15-g sample. 

2. One or two samples from a stream are adequate 

for a preliminary appraisal of the gold potential of 

a given drainage basin; all samples from apparently 

barren areas yielded calculated values o~ O.OOOXO.OOOOX ppm, nearly all samples from weakly mineralized areas gave calculated values of O.OOX0. OOOX ppm, and samples from s t r on g 1 y mineralized areas gave calculated values ranging from 

O.X-O.OOX ppm. 

3. Among samples containing a calculated amount of 

0. 01 ppm or more, gold was seen in 13 of 15 panned 

concentrates. 

Hahns Peak, Routt County. -At Hahns Peak, geologic 

mapping shows a steep -dipping b r e c c i a pipe in porphyry that intrudes Cretaceous sedimenta.ry rocks. 

Within the breccia pipe, a lens 150 feet long and 40 

feet thick contains about 90 ppm silver, about 0. 5 percent lead, and a trace of gold. Analyses of about half 

of the 400 sampl.;>s of porphyry and sedimentary rock 

show that some 8 percent contain > 0.1 ppm gold. 

Reopening of the Southern Cross adit has permitted 

additional sampling of the Ha:1ns Peak breccia, exposed in the outer 235 feet of the 1,000-foot adit. Samples to be analyzed for silver and base metals were 

collected at 25-foot intervals; disseminated pyrite was 

the only sulfide mineral recognized in the field. 

Several hundred samples of soil and stream sediments within a 4-5 mile radius of Hahns Peak also 

were collected; many panned mineral co:'lcentrates 

contain detectable gold, and other analyses are pending. 

Terti a r y gold placers in Iron Sprin~s Divide 

area.-Analysis of heavy mineral concentrates from 

modern alluvium has outlined an area ofhigl' gold content in sand lenses in claystone and siltstone of the 

Wasatch Formation. The area lies just no:--th of Iron 

Springs Divide in Moffat County, northwest Colorado, is 

about 1. 5 miles wide and 6 miles long, and trends 

N. 70° W. The fine grain size and shape of the gold particles suggest hydrologic equilibrium with the enclosing sand; furthermore, ~old is most abundant at the base 

of lensen in the coarsest sediment, and no consistent 

7 
correlation has been found between gold content and 

iron or manganese now being deposited from g r o u n d 

water. Bulk sand samples have as much as 2.5 ppm 

gold. All evidence indicates that the gold deposits are 

placers. The association of gold with garnet, monazite, 

and pebbles of quartz, feldspar, and granitic rocks indicates derivation from Precambrian rocks to the east 

or north. 

Recent placer deposits reworked from those in the 

Wasatch Formation are 10-50 feet below the surface 

and therefore only potential areas can be identified 

without drilling. Modern alluvium along Lay Creek west 

of Craig was tested by 25 holes drilled with a portable 

auger. At least three deep low-grade gold-bearing 

sandy zones were identified. Dredges on the Yampa 

River below Round Bottom and on Lay Creek above 

Jackrabbit Spring reportedly will test these placers. 

Samples of zeolitic sandstone and shale of Eocene 

age from 8 localities in Moffat County reported to contain platinum and gold were analyzed by 8 methods in 

Washington and Denver. On the basis of the most 

sensitive method for each element, all samples contained<10 ppb gold, <10 ppb platinum, and <2 ppb palladium. 

Silver Cliff-Rosita, Custer County.-M anganese 

oxide veinlets at Silver Cliff, near Westcliffe, contain 

an average of about 70 oz silver per ton. Inasmuch as 

these veinlets, 0. 5 to 2 inches wide, are fairly abundant over an area of 1,000 by 500 feet, a substantial 

silver resource may be present. 

Altered rocks from vents in the Silver Cliff-Rosita 

volcanic field are being studied to decipher the relation of manganese-silver-lead-copper mineralization 

to rock alteration. 

Magnetic and gravity surveys at Cripple Creek.-

Gravity and ground-magnetic data were obtained at 

250 stations in the Cripple Creek district, T e 11 e r 

County. The stations were spaced 14 mile apart along 

traverses. Preliminary study of data indicates that 

magnetic lows generally correlate with known areas 

of intense alteration. A preliminary Bouguer gravity 

contour map of the district shows a 10-milligal gravity 

minimum that conforms to the outline of the C r i p p 1 e 

Creek basin. Local gravity minima correspond closely 

with geochemical anomalies and with altered and mineralized areas. Ground-magnetic and gravity-contour 

maps have similar configurations. 

Aeromagnetic surveys.-About 3,000 traverse miles 

of aeromagnetic. survey was flown in the region between North Park and Central City. 

Georgia 

Heavy Metals projects in the Southeastern United 

States are concerned with three major lines of investigation: (1) geological, geochemical, and geophysical 

studies, principally in areas of known gold deposits, in 

search of clues to unknown or buried gold deposits; (2) 

investigation of the behavior of gold during weathering 

and sedimentation to establish basic p r inc i p 1 e s concerning the mobility of gold and the mechanisms by 

which it is transported and deposited, which in turn 

will enable us to identify favorable geological evironments in which to search for new deposits; and (3) 

study of sedimentary rocks in Trj as sic basins and 

along the coastal plain to search for gold that has been 

eroded from lode deposits in older rocks. Work to date 

has been done mainly in Georgia ani North and South 

Carolina, which have been the main gold-producing 

states of the region. 

Reconnaissance of Dahlonega gold belt completed.-

A reconnaissance study of the Dahbnega gold belt of 

Georgia and North Carolina was completed. S m a 11 

amounts of gold can be detected at ole mines, and trace 

amounts, less than 0.25 ppm, are widespread. Most 

of the ore mined along the belt probably contained less 

than $1.00 per ton in gold; however, only a few exposures of ore were found. 

Of 478 samples of mica schist, mica gneiss, amphibolite, quartzite, vein quartz, and granite in the southwestern part of the gold belt, 198, or41 percent, contained detectable gold (limit of detection, 0.02 ppm). 

Of these, 89 samples contained 0.02-0.04 ppm, 50 

contained 0.05-0.1 ppm, 28 contaired 0.1-0.49 ppm, 

and 32 contained 0.5 ppm or more. About 65 p~rcent 

of the samples were from roadcuts, the rest from the 

vicinity of an old gold mine. No particular rock type 

was consistently highest in gold, but mica schist and 

vein quartz had the highest assays. 

Of 37 samples collected at the C a 1 h o u n mine, 

Lumpkin County, only five contained detectable gold. A 

channel sample across a pillar of the main vein assayed 

0.38 ppm gold; quartz stringers contained 0.02 and 0.06 

ppm gold; and two samples of soft wet iron hydroxide 

deposited recently on the walls of a s':ope and adit contained 0.14 and 2.19 ppm gold, respectively. No gold 

was found in fresh mica schist anc vein quartz near 

the iron hydroxide. 

Maine 

Mineral zoning at West Pembroke:_.-Geologic study 

and sampling of mineral deposits around West Pembroke, eastermost Maine, have disclosed a well - defined pattern of mineral zoning. The deposits are along 

small north- or east-trending faults in weakly metamorphosed silicified shale and volcanic rocks of Silurian age. A central zone characterized by intensely 

altered rocks with copper and some gold is succeeded 

outward by a zone rich in zinc and the, by a peripheral 

zone of lead, zinc, and silver. Sulfide minerals include 

chalcopyrite, pyrite, sphalerite, gal-:ma, arsenopyrite, 

and possibly silver sulfarsenides; gangue is quartz, 

carbonates, and barite. Analyses ofl~rge samples from 

stockpiles at opencuts gave the following results: 

Au Ag Cu Pb Zn 

Zone (ppm) (ppm) (percent) (percent) (percent) 

Copper -gold 0.05-0.5 3.3-3.7 0.63-0,85 0.003-0.007 0.25-0.43 

Zinc .02 2.5 .1 .005 1.4 

Zinc-lead -silver <,02 55 .007 .18 .66 

8 
The gold content of some samples from the coppergold central zone is several ounces per ton. 

About 67,000 feet of drill core from the Barrett and 

Big Hill deposits have been made available by Dolsan 

Mines, Ltd., for logging and sampling to determine 

lithologies and metal distribution. 

Panned concentrates of beach and stream sediments 

were collected from 138 localities over an area of 400 

square miles in the Pembroke-Calais region. Gold 

was detected in 21 samples, mostly in amounts ranging 

from 0.6 to 2.5 ppm; ofthese, 12were from an area of 

only 15 square miles in which the Devon i an Perry 

Sandstone is exposed. This sandstone merits further 

investigation as a potential source of gold. 

Reconnaissance sampling, western Maine. -Samples 

from 180 localities in western Maine (Rangely, 

Phillips, and Kennebago quadrangles), comprising 

metasedimentary rocks, altered and silicified zones, 

and sulfide veins, were analyzed for gold. A vein of 

arsenopyrite in gabbro assayed 0. 2 ppm gold, and a 

bed of metasandstone in the Upper Ordovician Nile 

Brook Formation contained 0.03 ppm gold; in other 

samples, gold content was below the limit of detection 

(0.02 ppm). These preliminary results suggest that the 

stratified rocks of western Maine are not likely sources 

of gold. 

Evaluation of geochemical-geophysical anomaly, 

Squaretown. -A geochemical and geophysical (electromagnetic) anomaly northeast of The Forks in westcentral Maine was tested for evaluation by 10diamonddrill holes totaling 1, 950 feet in length. The anomaly is 

at least 5,000 feet long. Several zones of disseminated 

to massive sulfide minerals, mainly nickeliferous and 

cobaltiferous pyrrhotite with minor chalcopyrite, were 

cut near the southeast margin of the Moxie gabbronorite pluton. Preliminary assays show rather low 

metal content ( ~1 percent combined metals) but much 

core remains to be analyzed. Magnetic susceptibility 

measurements have been completed on the core, and 

studies of induced polarization are in progress. 

Gold prospects along coast.-Suites of samples collected from two old prospects at Deer Isle and Castine 

along the east side of Penobscot Bay contain from 0.14 

to 8 ppm gold. Although both prospects are so situated 

as to offer little possibility for further development or 

mining, they do indicate a general area that warrants 

additional search for gold. 

Maryland 

Great Fails district.-The gold district near Great 

Fails, Md., was sampled and more than 400 analyses 

of vein material, wall rock, and saprolite were made 

in mobile laboratories. One small u n m in e d vein at 

Great Falls yielded a sample containing 18 ppm gold, 

and all vein quartz sampled has more than 0. 1 ppm 

gold. 

9 

Massachusetts· 

Waste quartz-siderite rock from a prospect in northeast Massachusetts contains several ppm gc1d. 

Missouri 

Heavy metals in mafic rocks near Irontor..-A geochemical study of platinum-group metals and sulfide 

minerals in fresh mafic rocks of the ShepherctMountain 

intrusive near Ironton, southeast Missouri .• has been 

started. 

Moman a 

Geophysical studies in Wickes district.-Detailed 

ground-magnetic, gravity-profile, ·and some AFMAG 

data have been collected around the Monta.Il a Tunnels 

area in the Wickes district, Jefferson County, north 

of Butte. The aeromagnetic low previously recognized 

was confirmed and correlates closely with a geochemical anomaly. Magnetic lows suggestive: of altered 

rock were found across the Minah vein and O"\ the west 

side of Alta Mountain. Continuity between th~Montana 

Tunnels geochemical anomaly source and th~ Alta vein 

to the east was tested by gravity and AFMAG, but nearby powerlines apparently affect AFMAG results. 

Soil sampling at Virginia City.-About90C soil samples, mainly of residual soil on hillsides, have been 

collected over an area of about 25 square miles around 

Virginia City, Madison County. Of 87 sampl~s thus far 

analyzed, 13 show between 0.8andl.5ppmgold. Semiquantitative spectrographic analyses and g'Jld determinations will be made on all samples. 

Mapping of Tertiary basalt overlying gold-bearing 

Precambrian rocks shows that the prebasal<: drainage 

was similar to the present drainage and that extensive 

placers are not likely to occur beneath the basalt. 

Gold content of Oligocene conglomerate, Jefferson 

County.-A sample of the basal6 inches of an Oligocene 

conglomerate in Jefferson County, west-cer-:ral Montana, contains about 0. 25 ppm gold. A chanr~l sample · 

of the total thickness of conglomerate, ab"'ut 6 feet, 

contains only 0.02 ppm. The conglomerate consists of. 

rounded clasts of Cretaceous volcanic rock:1 in a magnetite-rich sandy matrix. 

Ruby River valley, Madison County.-Matrix material concentrated from Tertiary conglomerate in the 

upper Ruby River valley showed gold in 8 of 15 samples. However, analyses ranged from only 0.02 to 0.1 

ppm gold, and the conglomerate layers a1·e thin and 

lenticular, therefore they appear to have little economic potential. 

Nevada 

G eo 1 o gi c and geo chemical studies started at 

Aurora.-Geologic mapping and geochemical sampling 

have been started in the Aurora dis t r i -;; t, Mineral 

County. Gold is in quartz veins in northeast-trending 
silicified reefs that cut altered andesites. Preliminary 

results indicate gold to be in seams of gray chalcedonic 

quartz. Geologic features of the district and the nearby 

Bodie district in Mono County, Calif.,include collapse 

breccia, peripheral intrusive rocks, and a central 

structural dome. 

Carlin, Eureka County.-The Car I in gold mine, 

discovered in 1962 and brought into production in 1965, 

is the largest new gold mine to be found in the United 

States since discovery of Goldfield, Nev., in 1902. Reserves were estimated in l 965 to be about 11 million 

tons of ore averaging 0. 32 oz per ton ($11. 00 per ton). 

Exploration leading to discovery of the mine by Newmont Mining Corp. was guided by earlier work of the 

Geological Survey. 

The Carlin deposit is being studied in cooperation 

with the company staff. The stratigraphic and structural setting of the deposit, and the mineralogy and 

chemistry of the gold ore as well as of altered and 

unaltered country rock are being investigated with the 

aim of determining the processes by which the deposit 

formed; such knowledge will be of great value in the 

search for other similar deposits of very fine grained 

gold in Nevada and perhaps elsewhere. Study of the 

minor-element content of the ore has been completed. 

The deposit is in the Lynn window of the Roberts 

Mountains thrust fault, in which rocks of the 1 ower 

plate are exposed over an area of about 25 square 

miles. Fieldwork to date suggests that host rocks 

(Roberts Mountains Formation of Silurian age) are intensely altered; that rock alteration and metallization 

are closely related; that anomalous amounts of mercury and arsenic are associated with the gold ore; and 

that ore distribution shows little, if any, detailed relation to the Roberts Mountains thrust fault. 

Fallon-Manhattan mineral belt, Church i 11 andNye 

Counties.-The mineral potential of the northwesttrending Fallon-Manhattan belt in Nye and Churchi 11 

Counties has been evaluated. Many important ore deposits are along northwesterly-striking faults of preTertiary age. The abundance of mineral deposits in 

exposed pre-Tertiary rocks suggests that numerous 

deposits remain to be discovered along other similar 

faults concealed beneath Tertiary rocks. 

A major northwest-trending lineament extending 

from the Toiyabe Range through the Manhattan district 

in the Toquima Range southeast as far as the Hot Creek 

and Reveille Ranges in northern Nye County, is marked 

by faults and alteration in volcanic rocks. Ore deposits at Manhattan are in Paleozoic rocks closely resembling those at Carlin, and similar rocks and ore 

deposits may be present beneath altered volcanic rocks 

elsewhere along the lineament. Further geologic mapping and geochemical sampling is planned to test these 

ideas. 

Western Church i 11 County. -Reconnaissance geochemical sampling in western Churchill County revealed detectable amounts of gold in 27 of 81 samples. 

Rocks sampled inc 1 u de d quartz veins, silicified or 

otherwise altered volcanic rocks, and altered meta10 

morphic rocks. The area has been prospected, but little or no production is recorded. Tw~nty-five samples 

contained 0.1-8. 7 4 ppm gold, and two others contained 

78 and 93 ppm gold. The mercury content ranges from 

0.03 ppm to 300 ppm, and all but two samples contain 

0. 1 ppm or more. The most promising area is the south 

part of Fireball Ridge, in the northwest corner of the 

county; six of the nine highest grade samples were 

collected here. The highest gold content was in a dike 

or plug of altered rhyolite cutting metamorphic rocks. 

This area is to be resampled in detail. 

Comstock (Virginia City) district, Storey County.-

The bonanza silver-gold district of Comstock is being 

restudied, in particular the alterat1on pattern associated with ore deposits along the Comstock fault as 

a possible clue to concealed deposits. The work is a 

continuation and amplification of earlier geochemical 

studies published in Geological Sur·rey Professional 

Paper 575-B, p. Bl O-B20, 1967. Gee logic, geochemical, and geophysical investigations, aided by X-ray 

study of many samples show that alunitized rocks resembling those at Virginia City occur along the Comstock fault for several miles to the rorth. 

An induced-polarization anomaly recognized during 

a preliminary survey along the Comstock fault about 

5 miles north of Virginia City, Store~' County, was resurveyed using both induced-polarization and electromagnetic methods, as the original anomaly was difficult to interpret. In addition, an aeromagnetic survey 

of the entire Virginia City quadrangle was completed. 

Integration of geologic and geophysical studies is in 

process. 

A magnetometer survey of pote'l.tial gold-placer 

ground at the mouth of ?ixmile Canyon in the Comstock district was made in cooperation with the U.S. 

Bureau of Mines. 

Cortez, Lander County. -A gold geochemical anomaly discovered near Cortez was anrounced in August 

1966 in Circular 534. As a result, a consortium of 

mining companies, Cortez Joint Venture, started a 

drilling and sampling program almost immediately. In 

June 1967, the Joint Venture announ~ed that approximately three million tons of ore averaging 0.3 oz per 

ton ($1 0.50 per ton) had been disc c v ere d, and that 

merallurgical studies preparatory tc design of a concentration plant were under way. The geologic setting 

of the deposit closely resembles that of the Carlin 

mine, 60 miles north; the deposit is in the lower plate 

of the Roberts Mountains thrust fault, which is exposed 

in the Cortez window over an area of about 20 square 

miles, the host rock is the Roberts Mountains Formation, and the ore is similar in nature and grade. 

Reconnaissance geochemical sampling northeastward for 5 miles from Cortez to tl'~ Buckhorn mine 

revealed several areas of anomalous gold and silver 

content. Several samples collected along a fault zone 

in the Buckhorn district contain anomalous amounts of 

gold, silver, and mercury; some hav~ lOppm or more 

of gold. The samples are of high I y altered volcanic 
rocks. These findings appreciably extend the area of 

potential precious metal deposits around the Buckhorn 

mine. The thickness of basalt flows in the district has 

been estimated by resistivity soundings, as has the 

extent of an underlying Tertiary conglomerate. 

The age of Caetano Tuff and quartz porphyry dikes 

associated with the Cortez gold deposit is Oligocene 

(about 32 million years). Rhyolite east of Cortez and 

generally believed to cut Pliocene(?) basaltic andesite 

that is altered and gold- bearing in the Buckhorn district is now known to be of the same age. These new 

data suggest either that (1) the Buckhorn basalt is 

older than Pliocene and its mineralization may be related to the same kind of rocks as that at Cortez, or 

(2) the Buckhorn mineralization is younger than that 

at Cortez and related to different rocks. Further field 

study will be done to determine, if possible, the true 

relative ages of the various rocks. 

Chert from the Fourmile Canyon Formation (Silurian) in the upper plate of the Roberts Mountains thrust 

fault near Cortez contains anomalous amounts of tellurium. Of 31 samples analyzed, three contain ::.1Qp"['m 

tellurium (highest value 20 ppm), 10 contain 1.0-9. 9 

ppm, 14 contain 0.1-0. 9 ppm, and four contain < 0.1 

ppm. Samples high in tellurium in general also are 

relatively high in gold, silver, and mercury. 

Ely, White Pine County. -A geochemical anomaly 

discovered in the Ely mining district was announced in 

Circular 535. Analyses of 1,400 samples show that an 

area 5 m i 1 e s long and 3 m i 1 e s wide, inc 1 u ding 

part of the great copper deposits of Ely, contains anomalous amounts of gold, silver, tellurium, andmercury. 

Gold content of scattered samples is in the commercial range, and tellurium analyses suggest that a major 

resource may be present. Although no new company 

activity has been reported to date, hopefully the gold 

and tellurium potential will encourage further investigation. 

Goldfield, Esmerelda County.-The famous old bonanza gold camp of Goldfield is being restudied in order 

to learn more about the structural control of the ore 

deposits and the nature of the alteration associated 

with them, and thus if possible to establish criteria 

for exploration in areas of similar geologic setting not 

known to be mineralized. 

More than 2,500 samples were collected, 27 adits 

totaling 7,500 feet in length were mapped, and geochemical sampling of 100 localities along silicified veins 

and 90 localities in the Combination-January cuts also 

was done. Surface mapping of 9 square miles of the 

district was done utilizing colored aerial photographs. 

More than 200 sam p 1 e s of altered rock are being 

studied by microscope and X- ray methods in an attempt to identify alteration types indicative of gold 

mineralization. 

Geochemical maps of the Combination-January mine 

area showing distribution of eight minor elements have 

been prepared, and analysis of geochemical data from 

the oxidized zone in this area has been completed. In 

order of decreasing correlation coefficient, antimony, 

11 

tellurium, silver, zinc, lead, bismuth, arsenic, and 

mercury show high to moderately high positive correlation with gold, whereas copper, molybderum, barium, strontium, iron, and manganese show only insignificantly low correlation. Atomic-absorption analyses 

of 133 samples of unmined near-surface silicified vein 

mate rial along the Combination vein show 2. 4-3.8 ppm 

gold. These results are high enough to warra'1t checking of larger sam p 1 e s by fire assay. Qusrtz-poor 

altered rocks high in limonite and alunite also are 

reI at i v e 1 y high in gold, whereas quartz-limonitealunite rocks contain little gold. 

Work at Goldfield indicates that rock alteration is 

similar in both gold-bearing and barren arers, therefore structural interpretations are most imrortant in 

assessing the potential of the district. Geolo?:ic mapping of an additional 10 square miles seems n~cessary 

to resolve structural problems. 

Iron Canyon, Lander County.-In Iron Canyon just 

east of Copper Canyon at the south end of Battle Mountain, which is 10 miles southwest of the town of Battle 

Mountain, geologic mapping and surface indications of 

mineralization suggested that an environment favorable for ore deposits might exist at shallow depth. To 

more sharply define a possible exploration target, geo- -

logic drilling was begun in Aprill967. At the end of 

December 1967, drill hole 1 had reached r depth of 

more than 3,900 feet, entirely in Scott Canyon Formation (Lower or Middle Cambrian(?)) in the ur'Jerplate 

of the Roberts Mountains thrust fault. Traces of gold 

(0.02-0.1 ppm, with one thin interval assay:ng 0.08-

0.5 ppm and another interval of 180 feet having several 

assays of 0. 7-1 0 ppm) and mercury (as much as 5. 4 

ppm) were found in the upper 2,600 feet; analyses are 

not yet available for deeper rocks. Locally, pyrite, 

marcasite, arsenopyrite, pyrrhotite, chalcop:rrite, and 

sphalerite have been identified. 

Drill hole 2 was started in December 1967 and has 

reached a depth of more than 500 feet. 

Shoshone Range, Lander County. -Geological and 

geochemical studies are being made in the Shoshone 

Range, particularly in the area between the G0ld Acres 

mine and Tenabo, 30 miles southeast of Batrle Mountain. The Gold Acres mine, which has produced about 

150,000 ounces of gold, is at the intersection of northeast- and northwest-trending structures, ani. several 

other structurally similar areas are being studied in 

detail. Geochemical surveys have revealed several 

areas of anomalously high gold and bismuth content. 

Geochemical maps based on 1,000 samples vrere prepared to show the distribution of 15 elements. and they 

reveal several gold-silver anomalies in areas that will 

be studied further to determine whether their structural settings are favorable. Some geochenical differences between Gold Acres and Tenabo are apparent 

and may be significant in interpreting geochemical anomalies; at Gold Acres, there is positive correlation between the metal pairs gold-lead, gold-iron, 
silver-lead, and silver-tin, whereas atTenabopositive 

correlations are shown by gold-silver, gold-bismuth, 

gold-iron, and silver-copper. 

The Gold Acres mine is in the breccia zone of the 

Roberts Mountains thrust fault, and to determine the 

position of this favorable s t r u c t u r e at depth in the 

Tenabo area, geologic core drilling began in July 1967. 

Drill hole 1 was started in chert and argillite of the 

Devonian Slaven Chert in the upper plate of the Roberts 

thrust, containing scattered pyrite and pyrrhotite and 

local veins of galena and sphalerite. The thrust fault 

was cut at about 3,030 feet and the hole bottomed at about 4,000 feet in the lower plate of the fault. The rocks 

of the lower plate penetrated by the drill hole consist 

of about 900 feet of tremolitic limestone (Silurian 

Roberts Mountains Formation?) overlying 100 feet of 

argillite of uncertain stratigraphic identity. Core samples are being analyzed. Drill hole 2 was started in 

December 1967, about 3 miles southeast of hole 1, 

on an alluvial fan where geophysical data indicate the 

alluvium to be 200-300 feet thick. 

Bleached chert over an area of about 1 square mile 

near the Gold Acres mine contains anomalous amounts 

of mercury, zinc, copper, bismuth, arsenic, antimony, 

and silver. No mines and only a few prospect pits are 

in the area, which is on the flank of a magnetic anomaly. No gold has been detected, but theelements mercury, arsenic, and antimony are known to be associated 

with gold elsewhere in north-central Nevada. This assoCiation, plus the occurrence at Gold Acres of gold 

along the Roberts Mountains thrust fault, which underlies the anomaly at an unknown depth, indicates a possible area. for further exploration. 

Swales Mountain, Elko County.-At Swales Mountain 

in the Independence Mountains 15 miles north of Carlin, 

gold, silver, and base metals occur along the axial region of an anticline intruded by quartz porphyry. Both 

the anticline and intrusive are younger than the Roberts 

Mountains thrust fault. Geologic mapping of Paleozoic 

rocks in the Independence Mountains from U.S. Highway 

40 north to Pie Creek has been completed, and an evaluation of the mineral potential of the Swales Mountain 

quadrangle is in preparation. 

In order to check complex stratigraphic and structural relations at depth and to test the occurrence of a 

possibly favorable environment for ore deposits, three 

geologic core drill holes (totaling ·3,956 ft) were completed between May and September 1967. The drill holes 

revealed that ( 1) most of the limestone underlying 

Swales Mountain is Roberts Mountains Formation(Silurian) in the lower plate of the Roberts Mountains 

thrust fault; (2) mineralization in both upper and lower 

plate rocks is related to intrusive contacts rather than 

to stratigraphic or structural horizons; and ( 3) little 

leached and bleached limestone similar to that at tlhe 

Carlin mine is present. 

Mapping started in Tuscaroradistrict.-Reconnaissance geologic mapping started recently in the Mt. 

Blitzen quadrangle northwest of Tuscarora, Elko 

County, has revealed extensive areas of hydrothermally altered rocks. Geochemical studies are under 

way. 

Resistivity soundings in north-cen<:ral Nevada. -Resistivity soundings were made in the Buckhorn area in 

Eureka County northeast of Cortez, to more clearly 

define geologic structure; on alluvium at Tenabo, in 

Lander County, to obtain estimates- of depth to bedrock; and at the north end ofBattleMountain, in Humboldt County, to clarify geologic stru~ture. In the latter 

area, a two-dimensional model of th~ bedrock surface 

is being constructed from magnetic and gravity data. 

Isotopic composition of lead in go~d from Nevada.-

The isotopic composition of lead in gold in a placer 

concentrate from the Battle Mountain area, Lander 

County, is very similar to that of le<ld from galena in 

various lead-silver prospects elsewhere in north-central Nevada. The isotopic data sugg~st a relationship 

between lead-silver mineralization and Tertiary igneous activity. 

Isotopic an a 1 y sis of lead in bulk gold ore from 

Cortez, in Lander County, shows the ratioPb206/Pb204 

to be higher than for lead from an:r galena in northcentral Nevada thus far analyzed. Lead from unaltered 

host rock (Roberts Mountains Formation) will be analyzed to determine whether the lead ir Cortez ore might 

have been concentrated from the hof\1: rock rather than 

introduced with the gold. 

New Hampshire 

12 

Iron Mountain deposit.-The Iro"' Mountain ironberyllium deposit, at Bartlett in east-central New 

Hampshire, consists of magnetite cut by veins of 

galena, sphalerite, quartz, fluorite, and the complex 

beryllium silicate danalite. These ve:1ns contain 90 ppm 

silver and 0.06 ppm gold. Because t"le magnetite contains 0. 03 percent tin, other magnet~.te deposits in New 

England will be checked for their tin content. 

Preliminary sampling at the Milar mine.-The Milan 

mine in northeastern New Hampshire is a massive 

pyrite-chalcopyrite deposit in schist; the ore commonly has yielded a few dollars per ton in gold. However, 

one sample collected at the mine cont"'ined 70ppm gold. 

Additional analyses are being made. 

Geologic map~ng and sediment sampling in New 

Hampshire and aine.-Detailed stream-sediment 

sampling and geologic mapping of selected areas in 

eastern New Hampshire and southw«!stern Maine, including the central part of the Ossipe«! Lake quadrangle 

in New Hampshire, have been completed. 

Heavy metals in White Mountains. -Galena from lead 

ores in small deposits along the north-trending White 

Mountains ring-dike belt, New Hamoshire and Maine, 

contains 0.03-5 percent silver, more than 1 percent 

bismuth, and as much as 0.01 percent tin. Further 

analytical data will be forthcoming. 
New Mexico 

M o go II on-Mont i c e 11 o area, Sierra and Catron 

Count:fes:-=:.-A.Itered areas alongfau-lts Tnvolcan1c-rocks 

between Mogollon and Monticello in west- central New 

Mexico contain anomalous amounts of cadmium, manganese, beryllium, tellurium, niobium, and zinc. The 

anomalous areas are as much as 2 miles wide. These 

areas may represent halos over buried ore deposits 

in Paleozoic limestone which is a host rock for ore 

deposits in the Magdalena district to the northeast. 

Most of the post- volcanic ores in the area contain appreciable amounts of gold and silver. The region has 

been little prospected. Further work is necessary to 

locate possible exploration targets. 

New York 

Gold content of Shaw an gunk Conglomerate.-Two 

samples of basal pyritic Shawangunk Conglomerate 

(Silurian) in southern New York contain 0.1 and 0.3 

ppm gold. This conglomerate extends over many square 

miles, and has beensampledextensivelyinNewJersey 

and Pennsylvania also. 

North Carolina 

Geochemical studies near Taylorsville.-Vis i b 1 e 

gold was found in heavy mineral concentrates from 27 

of 114 localities sampled near Taylorsville in western 

North Carolina. A small unworked placer deposit may 

offer a clue to the location of a concealed lode deposit, 

but further study and perhaps geologic drilling will be 

needed to evaluate the potential of the area. 

Gopper and gold anomalies in central North Carolina. -Preliminary analytical res u Its show several 

areas of anomalously high copper and gold content in 

Rowan, Davidson, and Randolph Counties in central 

North Carolina. Areas containing 80-600 ppm copper 

are in the Silver Hill-Gold Hill shear zone and in the 

shear zone of the Laughlin, Ward, and Cid prospects; 

in the latter area, several samples contain as much as 

2-8 ppm gold. The most favorable host rock is rhyolite, 

rhyodacite, and mudstone oftheOrdcvician Cid Formation. 

A lens of gabbro about 2 m i 1 e s long and 700 feet 

wide lies within the Silver Hill-Gold Hill shear zone. 

The east contact zone of the gabbro with tuffaceous 

mudstone has anomalous amounts of copper (80-400 

ppm) across a width of 400 feet. Further sampling has 

been done to locate possible extensions of this mineralized zone or other zones of similar trend. 

Gold in younger sedimentary rocks. -More than 300 

samples were collected from Coastal Plain and Triassic sedimentary rocks in North and South Carolina and 

Georgia. As much as 2 ppm of gold was found in Triassic rocks, and up to 1 ppm of gold was found in Coastal 

Plain rocks. Several copper anomalies, having as much 

as 500 ppm of copper, alsowerediscoveredin Triassic 

rocks. 

Gold-niobium-tin placer, western North Carolina.-

Heavy-mineral concentrates panned alon?: a small 

stream-placer deposit northwest ofMorgarton in westcentral North Carolina contain 2-5 percent niobium, 

0.5-0. 7 percent tin, and visible gold. The area is in 

the Brevard fault zone, and other samples from the 

zone also show anomalously high content c~Nb and Sn. 

The niobium and tin minerals are believed to have been 

derived from pegmatites; however, furth~r study is 

needed to evaluate the area as a possible source of 

these elements. 

South Carolina 

Haile-Brewer-Lamar belt.-This areair north-central South Carolina contams several gold prospects 

and mines, one of which, the Haile, was the largest gold 

mine in the Southeastern United States. All of these 

mines appear to be in the same stratigraphic unit, and 

work at the Lamar mine showed that a 1 though only 

quartz veins have been mined, wall rocks may also be 

gold bearing. 

A new discovery along this belt, the De Kalb prospect, near Kershaw, S. C., was broughttot'"le attention 

of the Geological Survey by Henry S. Johnson, State 

Geologist of South Carolina. A cooperative program 

with the Bureau of Mines was undertaken to study and 

sample this prospect. More than 500 trench and au&er 

samples were collected from the B soil hcrizon; most 

contain between 0.1 and 1.0 ppm gold. Samples taken 

in roadcuts across the strike of the rocks showed that 

most of the gold is concemtratedin a 1,200 .. foot stratigraphic interval. Results were as follows~ 

Feet 

0-1,900 

1,900-3,100 

3, 1 00-3,600 

Averag~ ppm 

0.06 

.27 

.06 

Samples collected at depths of M inch, 8 inches-3 

feet, and 3-6 feet below the surface at t'"le prospect 

suggest that gold is concentrated at or near the surface, probably by removal of soil and saprolite by sheet 

wash. A small amount of gold is being pro'iuced using 

a "Gold Saver" machine. 

The Haile-Brewer belt is believed to be offset from 

its continuation, the De Kalb-Lamar-McCormick belt, 

along a fault with an estimated left lateral displacement of 4 miles. Both wide 1 y spaced r'1d detailed 

sampling across the Haile-Brewer trend f"iled to find 

any extension of a molybdenum anomaly at the Haile 

mine. 

McCormick County.-Ground magnetometer studies 

by the Geological Survey of South Carolinr at the J ennings mine near McCormick, in conjunction with geologic mapping and geochemical sampling by the U.S. 

Geological Survey, show that silicic to intermediate 

13 
gold- and copper-bearing pyroclastic rocks extend at 

least 1.6 miles along the strike and are 25-75 feet 

thick. The rocks average about 0.03 ppm gold, and no 

high assays have been reported to date. Geochemical 

sampling traverses along roads and streams have completed the preliminary geologic study of the county. 

Analytical work and airborne geophysical studies remain to be done. 

South Dakota 

Black Hills, Lawrence and Pennington Counties.-

Detailed geologic mapping of about 50 square miles of 

Precambrian rocks in the Black Hills has yielded a 

tentative stratigraphy of the rocks containing the great 

Homestake gold deposits. Knowledge of this stratigraphy will permit recognition and exploration of the 

Homestake Form a ti on, the ore-bearing unit at the 

Homes take mine, in areas of favorable structure. Tertiary intrusions in the Precambrian rocks are mineralized locally, and metallization in the contiguous 

Precambrian rocks seems to increase toward the intrusives; however, the problem of whether the mineralization is entirely Tertiary or is both Precambrian and Tertiary is unsolved. 

Under a research contract the South Dakota School 

of Mines and Technology compiled geologic data on all 

mineral deposits in the northern Black Hills. Study of 

joint patterns and orientation of ore bodies in Paleozoic 

rocks in the Galena, Squaw Creek, Ruby Basin, and Bald 

Mountain mining districts suggests that ore deposition 

is controlled by northeasterly trending structures that 

do not reflect the northerly trend of the underlying 

Precambrian rocks. 

Systematic geochemical s amp 1 in g was done in an 

area of 6 square miles in the Galena district; sampling was on a )!(-mile grid, at 20-foot intervals along 

several lines, and at 6-foot intervals across two Paleozoic sections. Copper, lead, and zinc were determined in all samples; any sample showing a high concentration of one or more of these metals also was 

an a 1 y zed for silver, and some for gold. High zinc 

analyses (to 1,500 ppm) are reported from several 

Cambrian and Ordovician beds and high lead(to 15,000 

ppm or I. 5 percent) from the lower two of these beds, 

together with minor amounts of copper (to 600 ppm). 

Silver (as much as ISO ppm) is found only in samples 

of high lead content. Lead, zinc, and silver are virtually absent from Precambrian rocks, but copper is 

present in amounts as high as 1,200 ppm in Precambrian graphitic schist. 

Utah 

Hea mineral content of Cretaceous and Tertiary 

conglomerates, northeast of Salt Lake icy.- anne 

heavy-mineral concentrates from 75 samples of Cretaceous and Tertiary conglomerates, and of stream 

sediment derived from them, along Echo Canyon and 

Lost Creek northeast of Salt Lake City, are sparse and 

contain very little gold. Concentrates from 35-pound 

samples average only about 2 g, as compared with 

50-100 g obtained from the same size samples of 

gold- bearing Paleocene Pin yon Conglomerate in northwest Wyoming. 

Wyoming 

New Rambler mine, Albany County.-Preliminary 

analyses by wet chemical methods of 3f samples from 

the vicinity of the New Rambler mine in the Medicine 

Bow Mountains showed 0. 2-20 ppm of the platinum 

metals. Twenty samples of dump material averaged 1 

ppm. Most of the metal appears to be palladium. Analyses of five of these samples were checked by three 

methods. Results of these check analyees are as follows: 

Method 

Tellurium extraction colorimetric 

Electrolysis (spectrographic) 

Fire assay (spectrographic) 

Average o~ 5 samples (ppm) 

2.3 

2.1 

4.0 

The average ratio of palladium to platinum in these 

analyses is about 5: 1. The dump contains about half 

a million tons of broken rock, and the mine therefore 

may represent an appreciable palladium resource. 

Atlantic City district. -Residua 1 eoil over goldbearing quartz veins in the Atlantic Cit:·, district contains as much as 80 ppm arsenic, but the average is 

only IS ppm and there is no detectable arsenic ( 10 

ppm) in soils above many veins. Thur, geochemical 

sampling in the area involving only arsenic would not 

be entirely successful in locating hidden veins. Soil 

over some a p p a r en t 1 y unmineralized Precambrian 

graywacke also contains more than t'le background 

amounts of arsenic. Of 50 samples of graywacke at 

these localities, 8 contain 0.1 ppm or more of gold. 

Jackson Hole and vicinity, Teton County. -A description of gold- bearing conglomerates in Jackson Hole 

was published in Circular 541 in February I967. In 

summary, analyses of 1,200 samples and 750 panned 

concentrates of quartzite conglomerates from seven 

formations of Late Cretaceous to Mio-:-ene age at 53 

localities show the average gold con ten<: to range from 

35 to 222 ppb. A 11 u vi u m derived from these rocks 

averages 103 ppb. The most thoroughly sampled formations, Upper Cretaceous Harebell Formation and 

Paleocene Pinyon Conglomerate, contain 65 ppb and 86 

ppb respectively, or about 11 cents and 14 cents per 

cubic yard. New discoveries of quartzite conglomerate 

in the upper Green River basin, along upper Pilgrim 

Creek northeast of Jackson Lake, and in some headwaters of the Hoback River indicate thrt the previous 

estimate of 50 cubic miles of potential gold-bearing 

conglomerate is considerably too low. 

Pinyon Conglomerate in the southern part of its outcrop area appears to have appreciably more gold than 

in the northern part. About 30 samples from a section 

nearly 1,000 feet thick near Burnt Mountain in the 

southern area average 120 ppb gold, wh~reas similar 

sections in the northern area may average only 5 ppb. 

14 
Gold and magnetite are closely associated in placer 

deposits along streams in the region. To test the idea 

that magnetite might be a guide to gold, magnetometer 

traverses were made along P a c if i c Creek, Buffalo 

Fork, and the Gros Ventre River and its tributaries. 

Encouraging results were obtained along the Pacific 

Creek and Buffalo Fork drainages, and this work was 

followed by resistivity soundings to determine the 

thickness of the placers. Magnetic contour maps of 

placer areas show some correspondence between gold 

content and magnetic intensity on the basis of 134 gold 

analyses; however, the correspondence is not considered reliable because of the small number ofsamples. Magnetic field data are effective in delineating 

concentrations of heavy minerals. No correlation was 

found between gold values and magnetic susceptibility 

on one hand, or between magnetic susceptibility and inplace magnetic intensity on the other. 

Correlation of Upper Cretaceous and P a 1 eocene 

rocks. in Jackson Hole and the Bighorn Basin, using 

heavy mineral suites, is being studied. Preliminary 

examination of suites from paired samples from 25 

localities suggests that the association tourmalinezircon is characteristic of the Upper Cretaceous Harebell Formation in the Gros Ventre River basin; greenbrown hornblende-garnet is typical of conglomerates of 

both the Harebell and the Pinyon Conglomerate; and 

garnet- zircon-tourmaline is distinctive of rocks of the 

Bighorn Basin. 

Platinum in placer deposits of Teton and Park 

Counties.-Platinum was found in sluice concentrates 

of heavy minerals from two localities in northwestern 

Wyoming. Analytical results are as follows: 

Locality Platinum (ppb) Palladium (ppb) 

Crandall Creek 

Pacific Creek: magnetic fraction 

nonmagnetic fraction 

120 

45 

29 

37 

6 

<4 

Crandall Creek drains an area of Tertiary volcanic 

rocks east of Yellowstone Park; Pacific Creek drains 

a large area of Pinyon Conglomerate and Hare be 11 

Formation south of the Park. A similar sluice concentrate of gravel along the Gros Ventre River and 

also derived from Pinyon Conglomerate contained 

<lO ppb platinum and <4 ppb palladium. 

MARINE INVESTIGATIONS 

Marine investigations under the Heavy Metals program were initiated on the west coast of the U n i ted 

States and in Alaska. Because marine studies require 

contracting for use of oceanographic research vessels 

well in advance of actual wurk, only a modest start was 

achieved during 1966. Contracts with 10 universities 

were awarded in 1966-67, and thus enabled a comprehensive marine program to get under way in 1967. 

Alaska 

Nome area, Seward Peninsula.-A 2-month cruise of 

the U.S. Bureau of Mines drilling ship "Virginia City" 

was finished in early September 1967. Some 50 holes 

were drilled during a cooperative Bureau-Survey program within a distance of 10 miles from Nome to investigate the stratigraphic and geomorphic distribution of gold; the deepest hole was 240 feet, and many 

were more than 100 feet deep. In addition, 500 miles 

of continuous seismic profiling was done uf'ing the tug 

"Yamhill" of the U.S. Army CorpsofEngineers. About 

120 bottom grab samples were collected, snd surface 

and bottom currents measured at each drilling site. 

Low but perhaps economic concentraticns of gold 

were found over a large area. Surface sediments have 

a higher gold content than the ave rage for a total 

sedimentary section; the highest offshore concentration was found in bottom sediments off a mo1ern beach 

having a relatively high gold content. Gold concentrations were not found on bedrock but do occur in 

offshore g 1 a cia 1 drift that had been reworked by 

streams during times of low sea level. 

Onshore work included study of raised terraces and 

beaches. Similar onshore work also was done on St. 

Lawrence Island in the Bering Sea. Syste'Us of submerged beach ridges at depths of 25-30 feet in southern Kotzebue Sound are indicated by new bathymetric 

data. 

Seward Peninsula and St. Lawrence Island.-Unjer 

a research contract, RjV "Thompson" of the University of Washington has completed sampling for heavy 

metals, acoustical profiling, and m::-·asurements of 

magnetic field between Seward Peninsula and St. Lawrence Island, western Alaska. 

Gulf of Alaska. -A 14-day cruise in the northeastern 

Gulf of Alaska between Yakataga and Cape foencer was 

made by the University of Alaska's RfV "Acona" as 

part of a U.S. Geological Survey-University of Alaska 

research contract. During the voyage, 1,085 miles of 

continuous seismic reflection profiles was made and 

131 sediment samples were collected. 

Seismic records from the continental shelf of the 

northeast e r n part of the Gulf of A 1 ask a between 

Yakataga and Cross Sound at the north end cf Chichagof 

Island are being interpreted. Upper strata of the shelf 

are deformed, mainly along trends parallel to the coast 

but, in the area west of Yakutat Bay, also along northeast trends. The courses of Yakutat andAlsek Sea Valleys are controlled partly by tectonic featur~s and partly by a bank of sediments deposited on the shelf during 

glaciation. 

Southeastern Alaska.-More than 100 core and grab 

samples have been collected offshore frcm potential 

gold-bearing areas near Ketchikan, Helm Bay, 

Wrangell, and Sitka in southeastern Alaska. All samples have been processed and will be analyzed for heavy 

metals. 

15 

Bering Sea.-More than 300 bottom samples from the 

Bering Sea collected by scj.entists of the University of 

Washington have been analyzed and preliminary results 

are encouraging. About half the samples contain 0.1 

ppm ($0.1 0 per ton) or m.:~re of gold and rrany contain 
nearly 1 ppm ($0.05 per ton) of silver. Further extensive sampling was done during the summer of 1967. 

California 

Sediment sampling of streams, southern California. -Sediments at the mouths of streams at 57 localities in southern California between Point Concepcion, west of Santa Barbara, and the Mexican border 

have been sampled. Although the heavy metal content 

appears to be very small, the identification of tracer 

minerals or mineral suites may aid in locating offshore concentrations. Sampling continues along the 

coast from Point Concepcion north to the Santa Ynez 

River and also on Santa Catalina, Santa Rosa, and Santa 

Cruz Islands. This work is being done under a research contract with the University of Southern California. 

Acoustic seismic profiling, San Francisco Bay.-

Stratigraphic control of bottom sediments in deeper 

water parts of San Francisco and San Pablo Bays has 

b;!en obtained by running about 400 miles of continuous 

acoustic sampling profiles. This reconnaissance survey will indicate areas requiring more detailed coverage and will aid in selection of sample sites. 

Northern California continental shelf. -During a 40-

day cruise of the R/ V "Oconostota" under a research 

contract with Scripps Ins tit uti on of Oceanography, 

3, 700 kilometers (2,300 miles) of intersecting acoustic 

reflection profiles was run across the continental 

shelf between the coast of northern California and the 

Mendocino fracture zone. In addition, 125 bottom samples were collected. 

California and Oregon 

Offshore studies.-R/V "Polaris" made a 38-day 

cruise along the coast of southwestern Oregon. This 

vessel, formerly operated under charter from the University of California, was acquired by the Geological 

Survey in May 1967. Subbottom acoustical profiles were 

obtained across potential heavy metals- bearing sands 

between Coos Bay and the Rogue River and samples 

were collected in the same area. 

Acoustic profiling along 1 70 miles of lines between 

Crescent City, Calif., and the delta of the K 1 am a th 

River showed that Recent sediment in the area is 0-

200 feet thick. Filled Pleistocene river channels, the 

modern delta of the Klamath River, and Pleistocene 

faults account for the range in thickness. Samples of 

Recent sediment were co 11 e c ted for heavy metals 

analysis. 

Gold contents significantly higher than background 

were detected in black sands off the coast of Oregon 

and in sediments off California that may be on Mesozoic basement or that may have been reworked from 

o•Jtcrops of a folded P 1 i o c en e unconformity during 

lower stands of sea level. The Oregon black sands were 

located by acoustical p r of il in g and reconnaissance 

sampling and are offshore from beach sands containing 

significant amounts of gold. 

Gold in beach sands. -More than 1,000 samples of 

terrace, beach, and nearshore sands from southern 

Oregon and northern California have been analyzed for 

gold. Reproducible results can be obtaired by analyzing 

the fraction finer than 100 mesh and hEving a specific 

gravity greater than 3. 2; analyses of splits of raw samples were not reproducible. 

A mobile sedimentology laboratory, sup p o r ted by 

a mobile analytical laboratory, w::ts used in the field 

at Bandon, Oreg., to concentrate heavy minerals in 

sediment samples prior to chemic a 1 analysis. The 

sensitivity of these analyses thus was great 1 y increased. A marine heavy metals sedimentology laboratory recently established at Menlo Park, Calif., is 

being utilized in preparing additional samples from 

these areas. 

Oregon 

Gold on continental shelf, southernOregon.-Anomalously high concentrations of fine gold w·~re found in 

surface sediments on the continental sh~lf off southern 

Oregon by the Department of Oceanography of Oregon 

State University operating under a reeearch contract 

with the Geological Survey. The gold is associated with 

heavy m1nerals tentatively believed tor~ on submerged 

beaches of late Pleistocene age. Prom ising areas were 

resampled using box and piston corers. About 235 samples were collected by the research vessels ''Cripple 

Creek" and "Yaquina". In addition, about 565 nautical 

miles of acoustical subbottom profiling and 145 miles 

of magnetometer traverse was run. Sea-bottom t=>hotographs were taken at 22 localities. 

Each area of relatively high gold content is associated with a concentration of heavy miner a 1 s and 

marked by a positive magnetic anomaly that suggests 

a considerable concentration of magnet:ic black sands 

beneath the surface sediments. The gold content is low, 

generally <0.03 ppm, but may reflect a larger concentration at depth; this possibility can be tested only 

by drilling. 

Oregon and Washington. 

Heavy metals studies along coast.-· Terrace and 

beach sands, Tertiary sediments, and a granodiorite 

intrusion on the coast of northwest Washington w~re 

sampled, and coastal terrace and beach deposits near 

Newport, west-central Oregon, previously shown to 

contain anomalous amounts of gold, were resampled. 

Washington 

16 

Studies on continent a 1 shelf. -Reconnaissance 

acoustical subbottom profiling and sampling in nearshore areas of the continental shelf off the coast of 

Washington were done during an 8-day cruise by RjV 

"Oceaneer" of the University of Washington under a 

research contract. Local thick deposits of Recent sediments that may be sources of heavy m·=tals w·=re recognized. Systematic sampling will be done after interpretation of records has been completed. 
As part of the study of the mineral potential of the 

continental shelf, 200 samples were collected by the 

RjV 11 0ceaneer" between the mouth of the Columbia 

River and Cape Flattery. These samples were collected along subbottom acoustical profile tracks run 

earlier. 

Test of vibratory corer.-A vibratory coringdevice 

developed by Ocean Science and Engineering Corp. was 

tested by the RjV 11 0ceaneer11 on the continental shelf 

near the mouth of the Columbia River. Testing was 

done in collaboration with personnel from the University of Washington and the U.S. Bureau of Mines. Cores 

of well-compacted fine sand as much as 2 meters long 

were obtained with little disturbance of sedimentary 

structures. Samples will be analyzed for heavy metals. 

Gulf of Mexico 

During a cruise of nearly 3,000 miles in the Gulf of 

Mexico, Texas A&M University recorded continuous 

acoustical profiles and collected samples from 60 localities. The work was done under a research contract. 

TOPICAL STUDIES 

Heavy Metals in Organic-Rich Rocks 

The frequently reported occurrence of heavy metals, 

including gold, in organic-rich rocks such as black 

shale and coal was the basis for starting a systematic 

program of sampling and analysis of these rocks from 

all parts of the United States. More than 700 samples 

have been analyzed to date, and considerable research 

carried out on the nature of the association of organic 

material and metals and on the analytical problems 

involved in detecting small amounts of gold and other 

metals in the presence of abundant organic material. 

The gold content of these rocks, on the basis of work 

done to date, appears to be very low, and in only a few 

was any detected with certainty. They do not at this 

time seem to be likely sources for gold, but many more 

rocks, part i c u 1 a r 1 y those of Alaska, remain to be 

studied. 

Gold Content of Coal, Peat, and Associated Rocks 

Four hundred samples of coal and associated rocks 

from Colorado, Wyoming, Utah, and Idaho contain 

<0,020 ppm gold. Some uncertainty still exists regarding the detection of small amounts of gold in carbonaceous rocks by routine analytical methods, but it seems 

likely that coals of the Rocky Mountain region are consistently low in gold. Even coals previously reported 

to contain substantial amounts of gold have proved to 

be barren. For instance, coal, coke, and carbonaceous 

shale from the Cambria coal field near Newcastle, 

Wyo., were analyzed for goldon both a 11 dry sample" 

and "ashed sample" basis; all samples contained less 

than 0.1 ppm. This is the field from which ash from 

coal and coke was reported by Stone (U.S. Geological 

Survey Bull. 499, 1912) to contain as much as $10 in 

gold per ton. 

17 

However, some western coals do contain s m a 11 

amounts of gold. Gold was detected in samr les of coal 

from the Kemmerer, Wyo., and Wales, Utah, coal 

fields, and these samples were analyzed repeatedly 

for gold, but analyses are nonreproducible. To test the 

idea that gold in these coals may be particulate rather 

than adsorbed in organic material, severa 1 fractions 

were prepared and stud i e d microscopically; no gold 

was found. The fractions will be analyzed for gold. 

Twelve samples of peat, muck, and driftwood from 

streams and wet areas near the Front Ran~e mineral 

belt in Colorado were analyzed for gold on a dry sample basis. Muck from Elk Park and peat fror1. Rudolphs 

Bog contained 0. 3 ppm gold; driftwood from Clear 

Creek and soft peat from Caribou Peat Bog contained 

0. 2 ppm. All other samples had less than L 1 ppm. 

Samples of ash, fly ash, and waste pro1ucts from 

coal-washing plants have been requested from 38 coalproducing companies in the Western States. These 

samples will be analyzed for gold and other elements. 

More than 900 samples of coals co 11 e c ted over a 

period of several years from the Appalachian and central interior areas will be analyzed for gold. 

Gold Content of Black Shales 

Chattanooga Shale (Devonian and Missirsippian).-

The gold content of 21 4 samples of Chattar0oga Shale 

and stratigraphic equivalents as determined by the 

cyanide-atomic absorption method, is <0.020 ppm. 

Checks on 15 samples by fire assay and atomic absorption confirmed these results. Silver content ranges 

from <0.2 to 4.5 ppm, and mercury from <0.02 to 1.5 

ppm. 

Neither silver nor mercury content shews any regional variation. Mercury appears to be closely associated with organic material, whereas sil'rer content 

apparently is independent of organic content. 

Analyses of 44 other samples of Chattanooga Shale 

from a drill hole in western Kentucky show <0.020 ppm 

gold, 0.2-1.0 ppm silver, and <0.020-0.2 ppm mercury, results very similar to earlier analyses. 

Carbondale Formation (Pennsylvani~.-Seven 

sam p 1 e s of black shale above No. 6 coal bed in the 

Carbondale Formation of Daviess County, Ky., were 

analyzed. All contain <0.02 ppm gold. 

Hermosa Formation (Pennsylvanian).-One sample 

of black shale from the Paradox M ember of the 

Hermosa Formation contained 0.2 ppm gold. 

Pierre Shale (UpPer Cretaceous).-Analysis of 26 

samples of the Sharon Springs Member of the Pierre 

Shale by the cyanide leach-atomic absorption method 

showed all samples to contain 0.020 ppn gold. One 

sample from the lowerpartoftheSharonSprings Member from northwest Kansas contained 0. 2 ppm gold. 
tvletal-rich Cretaceous Asphaltic Sandstone near 

Durango, Colo. 

Lenses of mdioacti ve black "asphaltic" material in 

the Cretaceous Dakota Sandstone near Durango, Colo., 

are enriched in gold (as much as 0.16 ppm) as well as 

in thorium, titanium, and other elements. The metalrich asphaltic material may be a form of thucholite. 

Gold in Marine Sediments 

The gold content of three marine samples has been 

determined by neutron act~vation. Results are: 

Manganese nodules, Blake Plateau (Composite sample), 0.2 ppb 

Phosphorite, Blake Plateau (composite sample), 7.:2 ppb 

Metal-rich sediment, Red Sea, L30 ppb 

The last figure is of particular interest inasmuch as 

these Red ~~a sediments have already been reported 

to contain 0. 9 percent copper, 2.6 percent zinc, 0.1 percent lead, 0.008 percent silver, and 0.002 percent tin. 

Gold ConteTlt of Batholithic Rocks 

Gold content of 8 samples from each of 3 batholiths 

was determined by neutron activation analysis. Results 

are as follows: 

Southern California batholith, 0. 2-4 ppb 

Sierra Nevada batholith, 0. 3-10 ppb 

Boulder batholith, 0.4- 3. 3 ppb 

Fossil Placer Deposits 

Studies of ancient deposits of sand and gravel formed 

in environments similar to those of modern placers 

were started early in the program with the hope that 

some might contain gold deposits similar to those of 

the Witwatersrand in the Republic of South Africa. 

Work on sandstones and conglomerates in several 

western and midwestern states has been unsuccessft!!l 

to date, but will continue as only a small part of the 

potential gold-bearing strata has been examined. 

Precambrian and Paleozoic rocks 

Great Lakes region.-Preliminary sampling and 

paleocurrent measurements were done in upper Precambrian and Cambrian clastic rocks in Minnesota, 

Wisconsin, Michigan, and New York, and in Devonian, 

Mississippian, and Penns y 1 van ian clastic rocks in 

Michigan, Ohio, Pennsylvania, and New York. 

Selected samples from 22 1 o c a I it i e s were fire 

assayed for gold. Five of the 22 samples contained 

0.027-0.0.50 ppm, the rest less than 0.025 ppm, the 

limit of detection of the analytical method. Samples 

with detectable gold were separated into 1 i g h t and 

heavy fractions and submitted for analysis, in order to 

test whether samples of these rocks can be effectively 

preconcentrated. Heavy minerals concentrated from 

pyritic conglomerates of the Precambrian Fond duLac 

Sandstone contain 2.1 ppm gold. Inasmuch as the whole 

rock contained only 0.0.50 ppm gold, and the concentration ratio is only about G, the heavy concentrate 

18 

contains about five times as much as gold as would be 

ex"!)ected; presumably the whole rock sample was not 

representative because of its relative!~' small size and 

the possible coarse nature of the gold. 

Northwestern United States.-Samples of selected 

conglomerates of the Precambrian Belt Series from 

11 localities in southwest Montana asrayed less than 

0.02 ppm gold. It seems likely therefor:- that conglomerates in this area of Belt rocks canno~ be considered 

as potential sources of gold. 

Of about 300 samples of quartzite from central Elko 

County, Nev., that were analyzed for gold, only one 

contained as much as 0.1 ppm. 

Southwestern United States.-Of 70 samples ofPrecambrian and lower Paleozoic conglomErates collected 

during a reconnaissance study of p o s s i b 1 e fossil 

placers in central Arizona, only one contained more 

than 0. 02 ppm gold, the limit of detection. A boulder 

conglomerate from the upper Precanbrian Scanlan 

Conglomerate in the northern Sierra Ancha of Gila 

County had 0.1 ppm gold. However, the matrix of this 

conglomerate has small quartz-lined vugs possibly indicative of hydrothermal activity, therefore the gold 

may not be of detrital origin. 

Quartzitic conglomerate from the rasal conglomerate of the Precambrian Pahrump Gro·.1p was sampled 

at eight localities between the Panamint and Kingston 

Ranges in southeastern California. These samples are 

to be analyzed for gold. 

Conglomerates of the younger Precambrian Uncompahgre Formation in the San Juan Mcuntains, Colo., 

contain less than 0.1 ppm gold. Samrles were taken 

from a basal conglomerate 3-8 feet trick and from 8 

conglomerate lenses in a section of qurrtzite and slate 

8,000 feet thick. 

No gold was detected in four splitsofheavy minerals concentrated from a 170-pound sam p 1 e ofPrecambrian Vallecito Conglomerate from Vallecito 

Can yon on the south flank of the San J urn Mountains in 

southwest Colorado. Detection limits ranged from 0. 3 

to 0.02 ppm. The heavy mineral content of the conglomerate is very low. 

Four samples of Precambrian con~:lomerate from 

the Las Tablas quadrangle westofTam\, N.Mex., contained less than 0.1 ppm gold. A heavy mineral concentrate from one sample also had less than 0.1 ppm. 

Con g 1om era t e beds in the P recrmbrian Ortega 

Quartzite in the Picuris Range near Pilar, Taos County, 

N. Mex., contain 0.05 ppm or less of gold. 

Mesozoic Rocks 

Analysis of 53 samples of black sanc1s of Late Cretaceous age from the Rocky Mountain region reveals 

that only nine contain detectable gold (limit of detection, 0.1 ppm); the highest gold content is 0. 3 ppm. Several samples earlier reported to contain as much as 
1 ppm gold were reanalyzed and no gold was detected. 

Fossil magnetite-bearing placers near Choteau, northwest of Great Falls, Mont., have been traced into areas 

with several hundred feet of overburden using a ground 

magnetometer. Beds with anomalies of as much as 

20,000 gammas yield anomalies of up to 10,000 gammas 

where co v e red by an est i m ate d 200 feet of overburden. 

Samples from two previously unstudied black sand 

deposits on the east flank of Teapot Dome, Natrona 

County, Wyo., are being analyzed for gold and rutile, 

and also spectrographically. The deposits are 1 and 

1.5 miles long, respectively. A third deposit in Elbert 

County, Colo., about 1 mile long and 200 feet wide, was 

mapped and partly sampled. 

Black sand deposits at Salt Creek, Wyo., and at the 

Long Shot deposit on the Kaiparowitz Plateau in Utah 

were sampled intensively. Of 83 samples from Salt 

Creek, only 8 contained 0.1 ppm or more gold, with 

a maximum of 0.45 ppm. At Long Shot, gold was detected in only 14 of 66 samples, the maximum being 

0.03 ppm. 

Black sandstone beds were studied and sampled in 

Montana, near Escalante, Utah, and near Page, Ariz. 

The Utah and Arizona rocks are twice as radioactive 

as others in the Rocky Mountains. 

Mercury as a Possible Indicator of Uranium on 

the Colorado Plateau 

Nearly 900 samples of sandstone and siltstone from 

the Colorado Plateau were analyzed for mercury. The 

number of sandstone samples from the Triassic Chinle 

Formation containing > 1 ppm m e r c u r y is 10 times 

higher near known uranium deposits than would be expected, assuming random distribution. Similarly, the 

number of siltstone samples is 7-8 times higher. Although caution must be used in areas of tectonism or 

hydrothermal mineralization, both of which tend to have 

rocks of high mercury content, these results suggest 

the use of mercury as an indicator of uranium. 

Stream Transport of Lead Particles 

An experiment designed to test the mode of transport and deposition of heavy particles by a stream was 

started in March, and the first results were obtained in 

September, at the end of the spring and summer runoff. One thousand pounds of lead particles more than 

0.18 mm in diameter and coated with fluorescent paint 

were dumped into the Trinity River, a tributary of the 

Klamath River in northwestern California. The particles had high roundness but low sphericity and thus 

a lower settling velocity than spheres of equivalent 

diameter. By mid-September, only a few particles had 

moved as much as 700 feet downstream, but many had 

moved as much as 200 feet. Further field checks will 

be made next year. 

If the lead particles (sp gr 11.4) aredeposi ted in 

about the same places as gold (sp gr 15-19), then gold 

concentrations might be located by searching for the 

more easily detected concentrations of fluorescent 

lead. This idea is also to be checked in the field. 

Concentration of Gold in Particle Size Fr"ction 

Studies of gold placer deposits along streams in 

northern California and on beaches of California and 

Oregon indicate that gold is concentrated in the size 

fraction 62-125 microns (0.062-0.125 mm). This finding suggests appropriate screening of sand and gravel 

samples as a useful prospecting technique that might 

yield gold concentrates in other areas where gold is 

too fine grained to be concentrated effectivel~'with the 

gold pan. 

Fluvial Geochemistry of Gold and Silver 

Work accomplished during the first year of this research project being carried out by personnel of the 

Water Resources Division included: construction of a 

mineral separation and concentration facility to determine distribution of gold in various size frrctions of 

stream sediments; development of methods fer detecl:-

ing minute quantities of gold and silver in wr.ters, involving for gold, collection by mercurous chloride or 

anion exchange, dissolution of collected gold, and analysis by atomic absorption, and for silver, collection by 

an ion exchange crystal (AMP) and an anion exchange 

resin; progress toward solving the problem of adsorption of traces of gold and silver onto contain~r walls; 

and a preliminary review of the literature on ~:eochemistry of gold and silver. 

Behavior of Gold in Weathering Environnents 

A principal finding tJ date has been that gold is 

mobilized in the zone of weathering and is coprecipitated with secondary iron oxides. The amount of gold 

thus mobilized may be appreciable, as much as 1 ,000 

times background. 

At Kershaw, S. C., in a warm, humid region of deep 

weathering, the gold content of iron-rich weathered 

granite and of iron-stained leached sericite schist is 

an order of magnitude greater than that of t'le parent 

rock. 

Nine composite samples of secondary iron accumulations at mines in the Kershaw, S.C., and Dahlonega, 

Ga., areas contain from 0.020 to 1. 7 ppm gold. Four 

samples of concretions or hardpan contained between 

0. 5 and 1. 7 ppm, appreciably more than vein quartz 

in the same areas. These data indicate appreciable 

mobilization of gold during weathering as well as fixation of gold during accretion of iron hydroxide nodules. 

Iron concretions thus appear to be valuable prospecting 

guides, and particulate iron minerals may be principal 

sites of gold concentration in fine-grained detrital 

sediments. 

19 
At Hahns Peak, Colo., in a cool region of moderate 

rainfall, four samples of iron-stained weathered porphyry gruss contained 0.26-0.44 ppm gold in the hydrofluoric acid-soluble portions. A fifth sample of ironencrusted porphyry at a seep near a gold prospect contained 5.3 ppm gold in the acid-soluble part. 

Gold in all these samples probably was derived from 

nearby sources, as possibilities of dilution and pre-

' cipitation increase with distance from source. 

Study of heavy-mineral concentrates from samples 

in a vertical section extending from topsoil to quartz 

vein at the Van Cluse mine in Orange County west of 

Fredericksburg, Va., shows that: ( 1) gold is most a bundant in saprolitic vein quartz; (2) gold particles are 

most numerous, though smallest, in topsoil; and (3) 

gold is least abundant in the lowest lateritic horizon. 

In this weathering environment (semitropical with 

dense vegetation and moderate rainfall), gold appears 

to dissolve easily in the phreatic ground-water oxidation zone where associated with sulfide-bearing bedrock. Thus much gold enters colloidal or chemical 

solution and is either precipitated before reaching 

streams or is deposited with the clay or silt fractions 

of stream sediments. 

Fine-grained sodium-rich red and black Triassic 

shales from Connecticut, New Jersey, and Pennsylvania were sampled as examples of rocks that might 

be expected to have a higher than average gold content: they were derived from gold-bearing source rocks 

and deposited in closed basins; they are unusually alkaline; and they contain detritus of iron-enriched soil 

in which gold might have been concentrated. Preliminary analyses show no significant gold content, but 

more analyses remain to be made and further sampling 

will be done. 

Studies of Sulfide and Telluride Mineral Systems 

The solubility of gold in galena, pyrrhotite, and pyrite is being determined. Solubility is very low in both 

galena and pyrrhotite, < 0.1 mol percent at 450°C in 

galena (possibly more at 700°C), and< 0.01 mol percent 

at 700°C in pyrrhotite. Solubility in pyrite is uncertain 

yet because of slow reaction rates. 

The activity of tellurium in nickel telluride is being 

measured preliminary to studies of the stabilities of 

precious-metal tellurides and the mechanism of separation of tellurium, selenium, and sulfur in nature. 

Investigations of the systems Fe-As-S, Fe-Sb-S, and 

Fe-Bi-S continue as a necessary base from which to 

study possible enhancement of gold solubility in sulfides by group V elements. 

Solution Chemistry of Gold at High Temperatures 

and Pressures 

Study of the solubility of gold in various solutions at 

high temperatures and pressures was started in 1967. 

Results so far indicate that gold is only very slightly 

soluble in ammoniacal and sulfate-rich solutions at 

temperatures up to about 200°C, suggesting little or 

no complexing of Au+ under these conditions. 

Research on Analysis of Gold 

Research on analytical methods for detecting trace 

amounts of gold has been done in G~ological Survey 

laboratories for several years, but in anticipation of 

a greatly increased work load from tl ~ Heavy Metals 

program, this research has been expanded and several 

new approaches to developing accurate, rapid, simple, 

and economical methods have been utilized. Although 

problems remain to be solved, suitable methods wen~ 

devised to analyze large numbers of samples on a routine basis, both in fixed laboratories and in the newly 

constructed mobile laboratories. Pref'€nt research is 

on fluorescent, atomic absorption, fir~ assay, and neutron activation methods (or combinations of these) for 

determination of trace or background amounts of gold. 

An ultimate procedure for determining background 

amounts of gold, using fire assay concentration followed by the rhodamine-B-HAuCl4 fluorescence 

method, is being studied. The rhodamine-B fluorescence method has a sen sit i vi t y of about 3 ppb gold. 

Tests using radio-gold indicate that fire-assay concentration is very effective in recov~ring submicrogram amounts of gold; in four tests using 0.1 microgram of gold and three tests using 0.5 microgram, recovery ranged from 97.0 to 99.0 perc~nt. Recovery of 

gold varied only slightly with the amount of silver 

added, which ranged from 2 to 20 milligrams. The 

behavior of submicrogram amounts of gold in the rho:-

damine-B method has been checked using Au198 as a 

radiochemical tracer; no gold losses due to adsorption 

or reduction occur during cyanide decomposition and 

filtration. Gold dissolution is faster and simpler with 

sodium cyanide and sodium peroxide than with the 

cyanide-oxygen mixture formerly used. 

A radioactivation analysis method for determining 

background amounts of gold is being developed. The 

method involves irradiation of 0.5 g of sample for 4 

hours in a neutron flux of 5x1o12 njcm2jsec., solution 

and selective precipitation of gold, and gamma counting. The 3 sigma limit of detection for the method is 

about 0.05 ppb gold. Present capacity for this type of 

analysis is 30 samples per month. 

A combined fire assay-neutron activation method is 

being studied as a simpler and more rapid technique 

for determining background amounts of gold than pure 

activation. Results so far are similar to those achieved 

by activation analysis alone but are not sufficiently precise. Most of the variation in results iF due to variable 

blanks; reagent blanks tested for gold contain 15-36 

nanogram s ( 1o-9 g) of gold, so that the 3 sigma detection limit for the method is about 0.5 ppb gold for a 

15-g sample. By using apurifiedfluxandpure alumina 

crucibles, the accuracy of the method for determining 

gold in 15-g samples of rocks is imrroved to nearly 

that attainable by pure neutron activation on 0. 5-g samples. In four runs of Standard Rock W-1, values obtained by the combined method were 4.0, 3.2, 3.4, and 

3. 9 ppb, with an average of 3.6 +0.4 prh, as compared 

to values in six runs by neutron activetion of 2.9, 3.2, 

4.2, 3.8, 3.8, and 2.8 ppb, with an average of 3.4 :!:. 0.6 

ppb. 

20 
A comparison of the classical gravimetric fire assay with a fire assay-atomic absorption method has 

been made on 13 samples of gold ore from the Witwatersrand, South Africa. The two methods showed 

very close agreement on ore containing from 75to 440 

ppm gold. For 11 samples, the maximum difference in 

results was 5 ppm. :The two highest grade samples 

showed differences of 10 ppm and 25 ppm. 

Research on Analysis of Gold in Heavy Mineral 

Concentrates 

Fire assays of successive splits of heavy mineral 

concentrates show that all of a concentrate sample 

should be analyzed if meaningful results are tobe obtained. Analysis of 2-6 splits of 6 entire samples in 

the grain size range 60-80 mesh, consisting mainly of 

either zircon and garnet or of magnetite, showed that 

in general no single analysis gives a reliable value for 

gold content, particularly in samples containing 1 ppm 

or less of gold. 

Research on Determination of Trace Elements 

in Placer Gold 

A solution-spectrochemical method was developed 

to determine the trace-element content of detrital gold. 

Samples weighing 5-10 mg are needed. Limits of detection are similar to those of the standard 6-step 

semiquantitative spectrographic method, but accuracy 

is better. 

Research on Analysis of the Platinum Group Metals 

The platinum group of metals (platinum, palladium, 

rhodium, iridium, osmium, and ruthenium) presents 

particularly difficult problems of analysis for trace 

amounts. Research on these problems, started some 

time ago, has been greatly intensified as a result of 

the need to develop an accurate, rapid, and economical 

method of analysis before any field studies of the occurrence of these metals could profitably be undertaken. This research has been successful in that a reliable method is now available for determining platinum 

and palladium; however, it is lengthy and complicated, 

and further research will be directed toward simplification of techniques and increasing the an a I y tic a 1 

capacity of the laboratories. 

The method for the simultaneous determination of 

platinum and palladium with a detection limit of 10 ppb 

of either metal in a 10-g sample involves the following steps: 

1. Solution of sample. 

2. Concentration of platinum metals (platinum, palladium, rhodium, some iridium) and gold by coprecipitation with tellurium. 

3. Separation of gold and tellurium by extraction from 

4N HC1 into methyl isobutyl ketone. 

4. Separation of platinum and palladium by extraction 

as diethyldithiocarbamates into chloroform. 

5. Separation of palladium by extraction ofpalladiuma-furildioxime into chloroform. 

6. Determination of palladium and platinum spectrophotometrically. 

In this sequential method, gold and rhodium ~an also 

be determined in their respective fractions. 

The problem of low recovery of platinum and palladium in the presence of rhodium and iridium remains unsolved. In absence of rhodium and iridium, 

recovery of palladium averages 96 percent and of 

platinum, 90 percent, whereas when rhodium and 

iridium are present recovery is only about 73 percent. 

Apparently, aqua regia fails to dissolve completely the 

refractory palladium-platinum-rhodium-iridium alloys produced during the tellurium precipitation step 

for concentrating the platinum metals. Palladium loss 

is not attributable to adsorption on any insoluble material at any stage. Studi~s on solution of pl::ttinummetal concentrates continue. 

Research also has been done and continues onother 

methods for platinum group analysis: 

Experimental determinations of platinum and palladium by fire assay followed by spectrographc analysis on samples containing known amounts of these 

metals gives good recovery of both metals when silver 

and gold are used together as collectors. w:1en gold 

alone is used, better recovery is obtained on prlladium 

than on platinum at high concentrations and the reverse 

at low concentrations, but in general recovery is poorer 

than when both gold and silver are used. 

Radiotracers of platinum and palladium were used 

to measure recovery of these metals by fire assay at 

low concentrations using both gold and silver as collectors. Recoveries ranged from 90 percent in the silver bead using 2 micrograms of platinum to 97 percent in the gold bead using 50 micrograms of palladium. 

Losses were largely to the cupel and were almost 

negligible in slag. 

Determination of platinum and palladium in highsilver ore from the dump of the Copper Hill mine at 

La Plata, Colo., by the fire assay-spectrographic 

method gave excellent reproducibility, even vrhen solution of the fire assay bead in aqua regia r~oduced 

considerable white precipitate (silver chloride); the 

precipitate is relatively free of either platinum or 

palladium. Platinum content was 0.36-0.43 ppm and 

palladium content 0.37-0.45 ppm in three analyses. 

Results of other studies of fire assay methods to 

concentrate the platinum metals, using both gold and 

silver as collectors, show that: 

1. Very large amounts of osmium appear to be lost 

through volatilization. 

2. Appreciable amounts of osmium and ruthe'"lium are 

lost to the slag. 

3. Large amounts of osmium, ruthenium, and iridium 

are lost to the cupel. 

21 
Experiments with a silver oxide matrix for spectrographic determination of platinum showed that volatilization was complete in 130 seconds using a 70-30 

argon-oxygen atmosphere, whereas it was incomplete 

after 5 minutes in air. Detection limits were: 

ppm 

Platinum 1 

Palladium 1 

Rhodium 1 

Ruthenium 1 

Iridium 10 

Osmium 100 

Gold .1 

In an improved version of the fire assay-spectrographic method, gold is used as a collector for the 

platinum metals, and the bead is burned in an atmosphere of 70percent argon-30percent oxygen. Detection 

limits for a 20-g sample are: 

Platinum 

Palladium 

Rhodium 

ppb 

2-4 

.5-1 

4 

Detection limts are set by the purity of the fire assay 

flux and hopefully will be reduced by use of purified 

flux. The method is simple enough to permit limited 

reconnaissance studies. 

A combined fire assay concentration-radioactivation 

method for determining p a 11 ad i u m and platinum in 

rocks is being studied; pre 1 imina r y concentration 

would permit simpler and faster radiochemical processing. Silver is used as a collector in the fire assay 

in order to avoid the high radioactivity produced by 

irradiation of gold. The silver bead from fire assay and 

cupellation is irradiated for 7 hours in a reactor, after 

which platinum and palladium are isolated chemically 

for counting. 

Solution detection limits by atomic absorption using 

air-acetylene flame were determined for platinum (1 

ppm), palladium (0.3 ppm), and rhodium (0.1 ppm). Detectabilities were not improved by using a very hot 

nitrous oxide flame. 

The Wickers method for separating platinum from 

the other platinum metals on the macro scale does not 

seem to be effective on the microgram scale. The 

method depends on the high stability of the chloroplatinate ion as compared to the chloro-ions of other 

platinum metals, which can be precipitated as hydrated 

oxides by hydrolysis at pH = 6. 

A catalytic method for the determination of osmium 

and ruthenium, based on catalysis of the reduction of 

Ce(IV) by As(III), is being investigated. The reaction 

time between two definite concentrations of Ce(IV) is 

inversely proportional to the concentration of osmium 

or ruthenium during the early part of the reaction. 

Research in Spectrography and Spec':rophotometry 

Glass reference standards to aid in spectrographic 

determination of 45 elements, including all the heavy 

metals, are being prepared by the Corning Glass Works 

for use by the Analytical Laboratories and Exploration 

Research Branches. Five batches of 200 pounds each 

will be prepared, containing concentrations of <-<0.5, 

0.5, 5, 50, and 500 ppm, respectively, of all 45 elements. The glass matrix will simulate the composition 

of a silicate rock. Grinding to about 200 mesh will be 

done by Coors Porcelain Co. in high-purity aluminalined mills. 

Investigation of seven matrices for tl· ~ spectrochemical determination of some heavy metals in both air 

and argon -oxygen atmospheres has sh')wn that Ge02 in 

argon-oxygen appears to be the most useful; detection 

limits are <10 ppm for platinum, <SOrnm for iridium, 

and 1 ppm for gold, silver, and the other platinum 

metals. 

More than 25 elements have been tested for sensitivity of detection by atomic fluorescence. The method 

is highly sensitive for silver (1 ppb). Palladium and 

bismuth have detection limits of 1 ppm, but sensitivities are poor for platinum and the other platinum 

metals. 

Investigation of atomic absorption spectrophotometry for analysis of trace amounts ofbif!muth has shown 

that the method is accurate and rapid in the range 10 

to 400 ppm. The technique is useful in scanning the 

large numbers of samples collected duringgeochemical prospecting. 

Miscellaneous Researcl} 

Gold and platinum content of U.S. Geological Survey 

standard rocks.-The gold content an'i platinum content of eight U.S. Geological Survey standard rocks 

have been determined by the most accurate methods 

now available. Gold was determined by radioactivation 

analysis (at least four determinations on each rock), 

and platinum metals (platinum, palladium, and rhodium) by a combined fire assay-spectrochemical solution method. Results are as followE'; all values are 

in parts per billion: 

Rock No. ~ Gold Palladium Platinum Rhodium 

G-1 Granite 2.6 0.4 <4 <10 <5 

W-1 Basalt 3.5 .6 14, 14 16, 22 <5 

G-2 Granite .8 .1 <4 <1 0 <5 

GSP-1 Granodiorite 1.2 .5 <4 <10 <5 

AGV-1 Andesite .5 .3 <4 <10 <5 

BCR-1 Basalt .6 .2 <4 <10 <5 

PCC-1 Peridotite .7 .2 7, 7 IS, 15 <5 

DTS-1 Dunite .7 .2 <4 11,<10 <5 

22 
Nineteen determinations of the gold content of Standard Rock G-2 have now been made. Ofthese analyses, 

17 are between 0.6 and 1.0 ppb, the other two analyses 

gave 2.0 ppb. 

Vein quartz in s t rea m gravels as a prospecting 

tool.-Analyses of vein quartz collected in situ from 

gold mines and also from stream gravel presumably 

derived from outcrops at the same mines gave comparable results in two areas--Dahlonega, Ga. (4 

mines), and Kershaw, S.C. (4 mines). None of the samples contained visible gold. Analysis of stream gravel 

material appears therefore to be a potentially useful 

prospecting tool in the Southeastern United States. 

Geology and geochemistry of manganese.-A comprehensive study of manganese deposits in the Southwestern United States as indicators of possible occurrence of silver and base metal deposits at depth 

was made and results, including suggestions for anumber of exploration targets, will be published in 1968. 

Economic geology of platinum.-A comprehensive 

report on the economic geology of the platinum metals 

was completed and will be published in 1968. The report includes a general discussion of the geology of 

platinum and descriptions of all the major platinum 

deposits of the world. 

Hydraulic equivalences of placer minerals.-A report on the hydraulic equivalence of grains of quartz, 

magnetite, silver, and gold, and on settling velocities 

of spheres and flakes of gold in water, bromoform 

(density 2.89) and methylene iodide (density 3.325) 

was prepared for distribution to workers in the program. 

Geobotanical prospecting for gold.-A restudy of 

Equisetum samples from mineralized areas in the 

United States shows the maximum gold content to be 

only 0.4 ppm. Higher values reported many years ago 

are believed to have been caused by contaminated assay 

equipment. 

Field detectors for heavy metals.-A gamma-ray 

spectrometer system designed for airborne use has 

been mounted in a van and tested in the Shoshone, 

Tojyabe, Tuscarora, and Cortez Mountains in central 

Nevada. Traverses were made over areas of altered 

and mineralized rock in order to evaluate the response 

of the system to surficial concentrations of potassium, 

uranium, and thorium. Results may be summarized as 

follows: 

1. In Buckhorn mine area, gold-silver mineralization in basaltic andesites is associated with significant radioactive anomalies caused by potassium 

and uranium. 

2. In the Cortez district, kaolinitic alteration in chert 

results in reduced radioactivity owing to depletion 

of potassium. During this work a uranium anomaly 

was discovered in altered chert along a fault. 

3. Both sericitic (potassium addition) and kaolinitic 

(potassium depletion) alteration are associated 

with gold deposits in chert in rhe Tenato district 

of the Shoshone Range, and potassium anomalies 

are therefore difficult to interpret. Further work 

is required to evaluate the data. 

4. Both potassium and uranium anomalies werefound 

at the Carlin mine in the Tuscarora Moun<:ains. Additional work is planned. 

The principal conclusions are that significant patterns of radioelement variation are associated with 

hydrothermally altered and mineralized rocks, and 

that radioactivity measurements may be useful in exploring for deposits of nonradioactive minerals. Detailed geologic information is necessary for meaningful interpretation oft he radioactivity data, particularly 

because of the opposing effects of sericitization and 

kaolinization on the magnitude of potassium anomalies. 

The neutron activation heavy-metal detec-:or, Mark 

III, is completed, and preliminary testing was done 

at a site in the gold district of Dahloneg[, Ga. The 

equipment performed well under rugged conditions. 

Several minor modifications were made and testing 

will continue. 

Work also is progressing on a field detector for gold 

and silver using X-ray fluorescence. Despite some 

problems involving back-scatter of initial X-rays, results to date are encouraging. 

Use e:f wool as collector of gold.- Experiments have 

shown that wool is an effective collector of gold in solution. Radiotracer studies have shown complete retention of gold from a 1.5 M HCl solution containing 

5 ppb gold. Gold also is concentrated quantitatively 

from tapwater solutions containing 0.05, 0. 5, and 5 ppb 

gold. The gold content of commercialgradewoolbeing 

used was determined by three methods. All gave the 

same result, 30 ppb gold. The gold content of unprocessed wool is not known as yet. 

In addition to gold, bismuth, antimony, and silver are 

adsorbed from 1 M HCl. Other metals, including copper, zinc, cobalt, iron, and manganese, are not. Work 

continues on the problem of analyzing gold collected on 

wool. Sodium contained in the wool interferes with 

neutron irradiation measurements because of the similarity of its radioactive emission spectrum to that of 

gold. 

Testing of "Gold Saver" heavy mineral concentrator.-The portable heavy-mineral concentrator known 

commercially as "Gold Saver" has been thoroughly 

tested in the Denver Heavy Metals 1 abo rat or y and 

modified for more efficient operation. Modifications 

were necessary because, although recovery of gold in 

the +200 mesh size was complete, recovery in the -200 

+400 size range was only 36 percent, and in the -400 

mesh size, only 2.4 percent. The machine will facilitate 

concentration in the field of large samples of auriferous 

conglomerate from northwest Wyoming and thus help 

to provide much more reliable informatio'1 on such 

factors as gold content and particle size. 

23 
Compilations on Geology and Geochemistry of Gold 

1. A comprehensive bibliography on the geology and 

geochemistry of gold is in preparation. 

2. A 73-page preliminary bibliography on the geology 

of gold deposits of the world was distributed to 

project geologists. 

3. A 70-page summary report on the occurrence of 

gold in i g n eo u s, sedimentary, and metamorphic 

rocks was prepared for use of workers in the 

program. 

4. A 6-page bibliography on prospecting for placer 

deposits by magnetic methods was distributed to 

g eo 1 o gists who are studying areas where such 

deposits might occur. 

Data storage and retrieval. -An interim system for 

storing and retrieving data resulting from the Heavy 

Metals program has been developed pending completion of a comprehensive system. The interim systern can be entered automatically into tb~ final system. 

Specifications for the system have be~n transmitted 

to the Computer Center Division and programming has 

begun. The system has been designated RASS (Rock 

analysis storage system). 

Standard sam p 1 e for gold.-A homogeneous gold 

standard was prepared and is now available for interlaboratory standardization. The standard was made 

using 120 pounds of gold-bearing quartz from the Great 

Falls gold mine, Maryland. Analyses o~ ten 15-g samples of the homogenized standard by the fire assayatomic absorption method ranged from 1.8 to 2.2 ppm, 

with an average of 2 ppm and a standard deviation of 

0.16 ppm. Analyses of seven 10-g sam p 1 e S· by the 

cyanide leach-fluorimetric method ran!ed from 1.9to 

2.3 ppm with an average of 2.2 ppm and a standard 

deviation of 0.14 ppm. 

U.S. GOVERNMENT PRINTING OP"~ICE: 1968 0-2.89~713 

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