GEOLOGICAL SURVEY CIRCULAR 623 

Gold-Bearing Jasperoid 

in the Drum Mountains 

Juab and Millard Counties 

Utah 

Gold-Bearing Jasperoid 

in the Drum Mountains 

Juab and Millard Counties 

Utah 

By J. H. McCarthy, Jr., R. E. Learned, J. M. Botbol, 

T. G. Lovering, J. R. Watterson, and R. L. Turner 

G E 0 l 0 G I C A l S U R V E Y C I R C U l A R 623 

Washington 1969 
United States Department of the Interior 

WALTER J. HICKEL, Secretary 

Geological Survey 

William T. Pecora, Director 

Free on application to the U.S. Geological Survey, Washington, D.C. 20242 
CONTENTS 

Page 

Abstract---------------------------------------------------- 1 

Introduction------------------------------------------------- 1 

Geology and ore deposits------------------------------------- 1 

Geochemical sampling --------------------------------------- 1 

Character and distribution of jasperoid bodies ------------------ 2 

Petrographic description of gold-bearing jasperoid samples------ 2 

Abundance and distribution of gold------- ---------------------- 2 

Other elements in jasperoids --------------------------------- 4 

Analytical methods ---------------"'" -------------------------- 4 

Discussion-------------------------------------------------- 4 

References ------------------------------------------------- 4 

ILLUSTRATIONS 

Figure 1. Geochemical map showing distribution of gold in 

outcrop samples of jasperoid, Drum Mountains, 

Page 

Utah-------------------------------------------- 3 

2. Map showing gold content of chip samples of 

jasperoid at sites 200 and 240---------------------- 4 

TABLE 

Page 

Table 1. Average gold content of jasperoid samples by 

stratigraphic unit--------------------------------- 3 

III 

Gold-Bearing Jasperoid in the Drum Mountains 

Juab and Millard Counties, Utah 

By J. H. McCarthy, Jr., R. E. learned, J. M. Botbol, 

T. G. Lovering, J. R. Watterson, and R. l. Turner 

ABSTRACT 

Geochemical sampling in the Drum Mountains of Utah has revealed anomalous concentrations of gold in jasperoid outcrops. 

One jasperoid sample contains 100 parts per million of gold, and 

20 samples from an outcrop about 50 feet wide and 300 feet long 

average about lO parts per million gold, The gold-bearing jasperoids also contain anomalous amounts of other ore-stage metals 

and may be useful guides to further exploration. 

INTRODUCTION 

Several samples of jasperoid similar to that which 

is commonly found in highly productive mining districts were collected in the Drum Mountains of Utah 

in 1963 as part of a study of the significance of jasperoid related to ore deposits (Lovering and Hamilton, 

1962). Later chemical analysis revealed that some of 

these samples contain as much as one-fourth of an 

ounce of gold per ton (Lovering and others, 1968) as 

well as anomalous concentrations of other met a Is. 

Earlier reports (Butler and others, 1920; Crittenden 

and others, 1961) indicated that gold production in the 

area was largely confined to the jasperoid. Additional 

sampling has revealed high concentrations of gold in 

a number of jasperoid bodies in the district. In this 

report the distribution of gold in jasperoid is shown 

and briefly discussed. The geochemical anomalies for 

gold may be useful as guides to further exploration, 

and some of the jasperoid bodies, if they extend to 

reasonable depths, may in themselves, const-itute 

marginal-grade ore bodies. 

GEOLOGY AND ORE DEPOSITS 

The Detroit mining district s t r add 1 e s the JuabMillard County line in the Drum Mountains, approximately 25 miles northwest of Delta, Utah. The geology 

and the manganese deposits of this district have been 

described by Crittenden, Straczek, and Roberts ( 1961). 

The range forms a westward-dipping monocline, in 

which about 10,000 feet of Cambrian quartzite is overlain by 3,000 feet of Cambrian limestone and dolomite. 

In the mineralized area, these rocks are cut by many 

eastward- to northeastward-trending steeply dipping 

normal and reverse faults. Lower Paleozoic carbonate 

rocks are cut off on the north by the Joy fault, which 

has a displacement of about 2,000 feet and strikes eastward across the district but changes to a northwestward strike just west of it. This fault is traceable for 

many miles northwest of the district but is concealed 

by alluvium on the east. North of the Joy fault the sedimentary rocks are concealed by alluvium and Tertiary 

volcanic rocks. 

Gold and copper were discovered in the Drum Mountains in 1872, and from 1904 to 1917, gold, silver, and 

copper, having a total value of about $46,000 (Butler 

and others, 1920, p. 464), were produced from siliceous 

replacement fissure deposits in limestone and dolomite. Manganese ore has been mined sporadically since 

1924, with peak production during World War II. Total 

production of manganese ore from 1924 to 1954 was 

72,462 tons (Crittendenandothers, 1961,p. 508). There 

appears to have been little activity in the district in 

recent years other than sporadic prospecting. Manganese deposits and copper-gold deposits, though apparently related in origin, are distinct in occurrence. 

The manganes-e ore bodies are largely in the I ower 

carbonate beds above the basal quartzite, and contain 

little copper or gold (Crittenden and others, 1961, p. 

507-.508). The copper-gold ore is chiefly associated 

with ferruginous jasperoid bodies that replaced carbonate beds higher in the section along fa u 1 t s and 

fractures; it contains little manganese (Butler and 

others, 1920, p. 464). 

GEOCHEMICAL SAMPLING 

During the present study, approximately 600 rock 

samples were collected in the area. Most of the samples were collected from jasperoid outcrops. More 

than one sample was collected from many of the localities shown, but only the highest gola content from the 

outcrop is plotted in figure 1. Plotting the highest gold 

content emphasizes the geochemical distribution of 

gold in the district and may indicate local areas in 

which mineralization was more intense. 
CHARACTER AND DISTRIBUTION OF 

JASPEROID BODIES 

Masses of jasperoid are widely distributed through 

the carbonate rocks of the region. Most of them are 

localized along faults and fractures where they have 

replaced the adjacent host rock and commonly form 

prominent dike like bodies locally called IT reefs. IT Some 

jasperoid bodies are small pods a few feet in diameter, 

and others are masses several hundred feet long and as 

much as a hundred feet wide. The jasperoid ranges in 

color from gray through various shades of red and 

brown. Some varieties are dense and aphanitic, resembling chert; others are vuggy with a saccharoidal 

texture resembling quartzite. Most of the 1 a r g e r 

masses consist of several distinctive varieties, each 

with different colors and textures. High gold contents 

are not restricted to any one particular type of jasperoid; some of the brown vuggy saccharoidal varieties 

contain appreciable amounts of gold, but some dense 

gray varieties contain even more. Many of the jasperoid samples have characteristics similar to those 

of jasperoid found in the Bingham, Tintic, and Ely mining districts. 

PETROGRAPHIC DESCRIPTION OF GOLD-BEARING 

JASPEROID SAMPLES 

Petrographic examination of thin sections cut from 

several jasperoid samples that assay more than 10 

ppm (parts per m i 11 ion) gold shows that they vary 

greatly both in mineralogy and microtexture. Most of 

the samples examined exhibit an older generation of 

presumably hypogene quartz withxenomorphic texture 

and average grain diameter ranging from about 0.02 

mm to 0.08 mm. This quartz typically contains abundant inclusions of hematite, ilmenite, goethite, and unidentified opaque mineral particles all averaging about 

5 microns in diameter. Microvugs, ranging from a 

fraction of millimeter to several millimeters in diameter, are also characteristic; the larger vugs are 

associated with the coarser grained quartz. In some 

samples these microvugs form open voids, in others 

they are filled with supergene hydrous iron oxides, 

jarosite, and malachite, or with a late generation of 

aphanitic quartz. Although some samples containing 

abundant dark-brown limonite, jarosite, andmalachite 

yield relatively high gold assays, others that do not 

contain these oxidation products contain even higher 

concentrations of gold. The richest gold-bearing jasperoid sample analyzed thus far assays 100 ppm in 

gold. It is a medium gray fine-grained dense rock, 

whose only visible indication of mineralization is that 

it weathers to a dark chocolate brown on the outcrop. 

In thin section it is seen to consist largely of xenomorphic quartz grains with diameters averaging about 0.02 

mm and containing numerous mineral particle inclusions; the jasperoid also contains many open microvugs approximately 0. 3 mm in diameter. Examination 

of a polished section under a metalographic microscrape reveals the presence of free gold particles imbedded in the quartz and hem at i t e (B. F. Leonard, 

written commun., 1968). The presence of native gold 

2 

has been further confirmed by electron microprobe 

analysis, which also showed a few small grains of pyrite in addition to the iron oxides (G. A. Desborough, 

written commun., 1968). An area about 0. 6 square 

centimeter of the p o 1 ish e d section was examined 

microscopically to determine the size and distribution 

of gold particles. Of 4,000 particles of gold counted, 

all but 12 were found to be less than 1 micron indiameter; the largest particle is 6 microns in diameter. 

Thus, the gold in this sample would escape detection 

unless examined microscopically or assayed. The 

small size of the gold particles in this sample is similar to that found in the gold deposit at Carlin, Nev., 

where no pannable gold was found in samples containing as much as 4ouncesofgoldper ton (Hardie, 1966). 

ABUNDANCE AND DISTRIBUTION OF GOLD 

J asperoid outcrops containing greater than 5 ppm 

of go 1 d a p p e a r to be c o n f i n e d to an i r r e g u 1 a r 

north-northwestward-trending belt or zone approximately a mile wide and 2~ miles long (fig. I). Within 

this zone, the highest gold contents obtained were in 

jasperoids adjacent to the JoyandStaatsfaults(fig. 1). 

Anomalous gold contents were also obtained from jasperoids localized by the Last Chance and Ibex faults, 

and others near the Copperhead, Martha, EPH, and 

Charm mines. J asperoid outcrops with high gold content appear to be most abundant along faults that have 

east to northeast trends. 

In order to determine the variability of gold content 

of individual jasperoid outcrops, two of these bodies 

were sampled at about IS-foot intervals. These sites 

are near Joy townsite in sec. 26, T. 14 S., R. 11 E. The 

gold content of each sample is shown in figure 2. The 

average gold content of the 20 samples at site 200 is 

9. 9 ppm with individual values ranging from 0. 7 to 100 

ppm gold. The average gold content of the six samples 

at site 240 is 6. 9 ppm with individual values ranging 

from 2.0 to 19 ppm gold. The variability in gold content of these as well as other outcrops shows that the 

gold is erratically distributed. 

Although structural localization of mineralization is 

apparent, some stratigraphic control may be indicated 

because most of the gold-bearing outcrops occur in four 

stratigraphic units as mapped by Crittenden, Straczek, 

and Roberts ( 1961). The average gold content of jasperoid samples within the mapped area is shown by 

stratigraphic unit in table. 

Other rock types sampled included quartz monzonite 

dikes and quartz diorite plugs. Although most of these 

bodies were moderately to strongly altered and some 

are rich in pyrite, their gold content is < 0.04 ppm. 

Some samples of strongly altered quartz 1 at it e and 

andesite, collected north of the Joy fault (fig. 1), also 

contain <0.04 ppm gold. 

The highest gold content was found in samples of 

jasperoid that replaces limestones e and f, which are 

equivalent to the Dome Li:r11estone and Swazey Formation. J asperoids replacing dolomite h and limestone i, 
R. II E. 

0 I MILE 

L-----------------------------~ 

EXPLANATION >-

~ Alluvium H 

:~ 

ru :::> 

0 + 

Porphyritic rocks 

>-

~ "' <( 

i= 

ffi Volcanic rocks 1-

0 

}I Limestone, dolomite, ond shale 

B 

Prospect Mountain Quartzite 

Faults (from Crittenden and others, 1961 l 

Doffed where conceoled by ol/uvium 

Linear features as seen an aerie I photographs by J. H. Me Car thy and C.L. Pi lmore 

Gold in outcrop samples of jasperoid 

(parts per million) 

X 

<0.1 

0 

0.1- 1.0 

e 1.0-10 

• >10 

Areas where jasperoid outcrops have 

samples Jhat con tal n > 5 ppm Au 

Map locot ion 

Figure 1.--Geochemical map showing distribution of gold in outcrop samples of jasperoid, 

Drum Mountains, Utah. 

Table 1.--Average gold content of jasperoid samples by stratigraphic unit 

Stratigraphic unit 

Drum Mountain 1 House Range 1 

Dolomite a------ Howell Formation 

Limestone e----- Dome Limestone 

Limestone f----- Swazey Formation 

Limestone g----- Wheeler Formation 

Dolomite h------ Marjum Limestone 

Limestone i----- ------do--------

Dolomite k------ Weeks Limestone 

Dolomite n------ ------do--------

Number of 

samples 

3 

6 

19 

17 

93 

68 

44 

2 

1 Crittenden, Straczek, and Roberts (1961, p.497). 

3 

Average gold 

content 

(ppm) 

0.04 

4.63 

4.28 

l. 39 

3.26 

3.78 

.18 

.35 
Approximate outline of 

jasperoid outcrops· 

0 100 200 FEET SITE 200 

Figure 2.--Gold content (in parts per million) 

of chip samples of jasperoid at sites 200 

and 240. 

the Marjum Limestone, also contain substantial gold, 

and most of the areas with high gold content are in the 

Marjum. 

OTHER ELEMENTS IN JASPEROIDS 

Several elements other than gold were found to be 

concentrated in the jasperoid samples. Maximum concentrations of other elements detected include: 1,000 

ppm silver, 1 1/2 percent bismuth, 5 percent arsenic, 

2 percent antimony, 1. 5 percent tin, 1 percent lead, 10 

percent copper, >100 ppm mercury, and 700 ppm yttrium. None of these elements correlates strongly with 

the gold on a sample for sample basis. Areally, however, all give distribution patterns similar to that of 

gold. The similarity of geochemical patterns suggests 

a common origin of mineralizing solution or solutions 

throughout the area sampled. 

ANALYTICAL METHODS 

All the samples were analyzed for gold in a mobile 

laboratory by the atomic-absorptionmethodofThompson, Nakagawa, and VanSickle ( 1968). The analysts 

were: R. L. Turner, J. R. Watterson, and Eric Welsch. 

The other elements were determined by a semiquantitative spectrographic method (Ward and others, 1963). 

The analysts were David Grimes, Elwin Mosier, and 

R. T. Hopkins. 

DISCUSSION 

Apparently gold was introduced in the same silicarich solutions that replaced the carbonate rocks to form 

the jasperoid. This persistence of gold in jasperoid 

outcrops suggests a common source of gold-bearing 

solutions throughout the entire area. The similarity in 

geochemical distribution of several elements of dissimilar geochemical behavior also suggests a common 

origin. The association of hypothermal and epithermal 

elements, and apparent lack of zoning, may indicate 

a relatively shallow source. 

The numerous outcrops of gold-bearing jasperoid 

along the Joy fault may indicate that it is a promising 

structure for additional exploration. Several other 

areas in the district, as shown in figure I, are also 

attractive targets for further exploration. 

4 

REFERENCES 

Butler, B. S., Loughlin, G. F., andHeikes, V. C., 1920, 

Ore deposits of Utah: U.S. Geol. Survey Prof. Paper 

111, p. 463-465. 

Crittenden, M. D., Jr., Straczek, J. A., and Roberts, 

R. J., 1961, Manganese deposits in the Drum Mountains, Juab and Millard Counties, Utah: U.S. Geol. 

Survey Bull. 1082-H, p. 493-544. 

Hardie, Byron S., 1966, Carlin gold m:i:ne, Lynn district, Nevada, in Nevada Bureau of Mines Report 

13, Mackay School of Mines, University ofNevada, 

Reno, Nev.: p. 73-83. 

Lovering, T. G., and Hamilton, J. C., 1962, Criteria 

for the recognition of jasperoid associated with 

sulfide ore, in Short papers in geology and hydrology: u .. S. Geol. Survey Prof. Paper 450-C, 

p. C9-C11. 

Lovering, T. G., Lakin, H. W., and Hubert, A. E., 1968, 

Concentration and minor element association of 

gold in ore-related jasperoid samples, in Geological Survey research 1968: U.S. Geol. Survey Prof. 

Paper 600-B, p. Bll2-Bll4. 

Thompson, C. E., Nakagawa, H. M., andVanSickle, 

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

materials, in Geological Survey research 1968: U.S. 

Geol. Survey Prof. Paper 600-B, p. Bl30-B132. 

Ward, F. N., Lakin, H. W., Canney, F. C., and others, 

1963, Analytical methods used in geochemical exploration by the U.S. Geological Survey: U.S. Geol. 

Survey Bull. 1152, 100 p.