. Geology and Mineralogy of the Ape.x 

Germanium-Gallium Mine, 

Washington County, Utah 

Geology and Mineralogy of the Apex 

Germanium-Gallium Mine, 

Washington County, Utah 

By LAWRENCE R. BERNSTEIN 

U.S. GEOLOGICAL SURVEY BULLETIN 1577 
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1986 

For sale by the 

Distribution Branch, Text Products Section 

U.S. Geological Survey 

604 South Pickett St. 

Alexandria, VA 22304 

Library of Congress Cataloging-in-Publication Data 

Bernstein, Lawrence R. 

Geology and mineralogy of the Apex GermaniumGallium mine, Washington County, Utah 

(U.S. Geological Survey Bulletin 1577) 

Bibliography: p. 9 

Supt. of Docs. no.: I 19.3:1577 

1. Mines and mineral resources-Utah-Washington 

County. 2. Mineralogy-Utah-Washington 

County. 3. Geology-Utah-Wasington County. 

I. Title. II. Series: United States. 

Geological Survey. Bulletin 1577. 

QE75.B9 no. 1577 557.3 s 85-600355 

[TN24. U8] [553' .09792'48] 
CONTENTS 

Abstract 1 

Introduction 1 

Germanium and gallium 1 

Apex Mine 1 

Acknowledgments 3 

Methods 3 

Geologic setting 3 

Regional geology 3 

Local geology 3 

Ore geology 4 

Mineralogy 5 

Primary ore 5 

Supergene ore 5 

Discussion and conclusions 7 

Primary ore deposition 7. 

Supergene alteration 8 

Implications 8 

References 8 

FIGURES 

1. Map showing location of Apex Mine and generalized 

geology of surrounding region 2 

2. Photograph showing main adit of Apex Mine and gently 

dipping beds of the Callville Limestone 3 

3. Geologic map showing locations of Apex and Paymaster 

mines and Apex fault zone 4 

4. Scanning electron photomicrograph showing plumbian 

jarosite crystals from the 1,601-m level, Apex Mine 6 

TABLES 

1. Chemical analyses of some representative ore samples 

from the Apex Mine 5 

2. Chemical analyses of some nearly monomineralic samples 

from the Apex Mine 6 

lll 
Any use of trade names and trademarks in this publication is 

for descriptive purposes only and does not constitute endorsement 

by the U.S. Geological Survey. 
Geology and Mineralogy of the Apex Germanium-Gallium 

Mine, Washington County, Utah 

By Lawrence R. Bernstein 

Abstract 

The Apex Mine, in Washington County, 

southwestern Utah, is the first mine in the world to be 

operated primarily for germanium and gallium. The 

ore, consisting of goethite, limonite, hematite, jarosite, 

azurite, malachite, conichalcite, and several other 

metal oxides, carbonates, arsenates, and sulfates, is 

thoroughly oxidized to at least 42 5 m below the 

surface. Most of the copper-rich ore was removed 

during previous mining operations, leaving behind the 

iron-rich minerals that contain most of the germanium 

and gallium. Germanium is concentrated chiefly in 

goethite (as much as 0.5 percent), hematite (as much as 

0. 7 percent), and limonite (as much as 0. 5 percent), 

while gallium is concentrated mostly in jarosite (as 

much as 0. 7 percent) and in some limonite (as much as 2 

percent). Copper minerals are concentrated in and 

adjacent to carbonate rock, apparently replacing it. 

The ore at the Apex Mine forms an irregular, branching, 

chimney-like body (or bodies) in fault breccia, gouge, 

and fissures associated with steeply dipping subparallel 

fault zones in the Pennsylvanian Callville Limestone. 

Within and immediately adjacent to the fault zones, 

limestone has been dolomitized and locally silicified. 

Only a few small pieces of unreplaced primary sulfide 

ore have been found; these contain pyrite, galena, 

sphalerite, chalcopyrite, quartz, and traces of barite. 

The abundance of copper, germanium, gallium, and 

arsenic in the supergene ore implies the former 

presence of sulfides and sulfosalts containing these 

metals in the primary ore, which would make it similar 

to dolomite-hosted ores at Kipushi, Zaire; Tsumeb, 

Namibia; and Ruby Creek, Alaska. High concentrations 

of germanium and gallium should be looked for in 

gossans and other oxidized zones of copper-rich, 

arsenic-bearing sulfide deposits, particularly those in 

carbonate host rocks. 

INTRODUCTION 

Germanium and Gallium 

The rare elements germanium and gallium are of 

increasing use in a variety of high-technology products. 

Germanium, atomic number 32, is a semiconducting 

metalloid that has a gray color, metallic luster, and 

conchoidal fracture. It was used to make the first 

transistor in 1948, and it continues to be an industrially 

important electronic material. The primary electronic 

applications of germanium at present are in X-ray and 

gamma-ray detectors and in high-frequency integrated 

circuits. Germanium is most used, however, in infrared 

optical components. The element's transparency to 

infrared radiation (with wavelengths longer than 2 J.tm) 

permits it to be fashioned into the lenses and windows 

of infrared detection devices, such as night-viewing 

instruments and some medical diagnostic equipment. 

Germanium is also being used increasingly in fiber 

optics, in superconducting alloys, as a catalyst in the 

production of polyester, in experimental anticarcinogenic drugs, and as a hardening agent in copper, aluminum, and magnesium alloys. 

Gallium, atomic number 31, is a semi-metal with 

a melting point of 30 oc, just above room temperature. 

The use of the semiconducting compound gallium arsenide is rapidly increasing as a photovoltaic material and 

in integrated circuits. Gallium arsenide integrated 

circuits can be operated at frequencies five to ten 

times higher than silicon integrated circuits, with less 

damage from high temperatures and from ionizing radiation. Other gallium compounds, such as GaAlAs and 

GaP, are used to make light-emitting diodes, lasers, and 

other electronic devices. 

Both germanium and gallium have been produced 

only as byproducts of ore processing-germanium mostly from sphalerite-rich ores, and gallium mostly from 

bauxite. Because of increasing demand for these two 

elements, new sources are being sought. The Apex 

Mine is the first in the world to be operated primarily 

for germanium and gallium, and is the first to mine 

oxidized sulfide ore for these elements. 

Apex Mine 

The Apex Mine (also called the Dixie Mine) is 

located on the east flank of the Beaver Dam Mountains 

in Washington County, Utah, about 22.5 km west of St. 

George and 9 km north of the Arizona border (fig. 1). 

The main adit is at an elevation of 1f656 m, lat 3704'11" 

N. and long 113048'14" w. (NE~ SW4 sw! sec. 6, T. 43 

S., R. 17 W.). Before it was reopened in 1985 for 

germanium and gallium, the mine was operated intermittently from 1884 to 1962, producing over 7,000 mt 

of copper, 400 mt of lead, 180,000 troy oz of silver, and 

minor zinc and gold (Perry and McCarthy, 1977, p. 516-

52 5). The ore at the Apex Mine consists of goethite, 

limonite, hematite, azurite, malachite, conichalcite, 

jarosite, and minor amounts of other metal carbonates, 

oxides, sulfates, and arsenates. These minerals occur in 

dolomitized and silicified breccia, gouge, and fissures in 

steeply dipping fault zones within the gently dipping 

Pennsylvanian Callville Limestone. Germanium is concentrated mostly in the goethite, hematite, and limonite, whereas gallium is concentrated chiefly in jarosite 

and in some limonite. These iron-rich minerals were 

1 
113°45'00" 113°37'30" 

37°07'30" 

2 

0 5 10 KILOMETERS 

EXPLANATION 

Surficial deposits and sedimentary rocks 

(Quaternary and Tertiary) 

Volcanic rocks (Quaternary and Tertiary) 

-Basaltic lava flows 

G Sedimentary rocks (Jurassic and Triassic) 

ITJWl Sedimentary rocks (Permian) 

~ Callville Limestone (Pennsylvanian) 

~ Redwall Limestone (Mississippian) 

Sedimentary rocks (Devonian to Cambrian) 

Gneiss, schist, and granitic rocks (Precambrian) 

____ Contact-Dashed where inferred 

o Fault-Dashed where inferred. U, upthrown 

--u-- side; D, down thrown side 

• • Thrust fault-Sawteeth on upper plate 

•1111-+-- Anticline-Showing direction of plunge 

--+-- Syncline 

Figure 1. Location of Apex Mine, Washington County, Utah, and generalized geology of surrounding 

region. Geology modified from Cook (1960). 
generally rejected as waste during the previous mining 

operations. Copper, iron, lead, zinc, an~ ~ilver are 

recovered as byproducts from the current mmmg operations. 

This report provides an outline of the geology and 

mineralogy at the Apex Mine as known to October 1985. 

Possible analogies to other deposits, and a proposed 

model for the genesis of the ore, are also described. 

ACKNOWLEDGMENTS 

I am very grateful to Bernard Dewonck of Musto 

Explorations Limited for guiding me through the Apex 

Mine, permitting me to take samples, allowing me to 

use some assay data acquired by Musto, and discussing 

the deposit. I also thank J.E. Dutrizac of CANMET in 

Ottawa, Canada, for sending a preprint of his paper on 

gallium and germanium host minerals at the Apex Mine. 

Funding for this project was provided in part by a Shell 

Foundation grant through Stanford University. 

METHODS 

The Apex Mine was visited by the author for four 

days in mid-April 1985. Underground workings, including a decline ramp and four crosscuts down to the 

1,601-m level, were examined and sampled. The 

collapsed shaft and adit of the much smaller Paymaster 

Mine, 275 m south-southeast of the Apex Mine on the 

same fault zone, were examined at the surface. Other 

outcrops of the ore zone and host rocks were also 

observed and sampled, as were the extensive tailings 

from the old mine workings. Several additional samples 

were obtained from diamond-drill cores at the Apex 

Mine. The samples were analyzed using an automated 

Rigaku powder X-ray diffractometer at Stanford 

University, and a Cambridge Stereoscan scanning 

electron microscope (SEM) with an energy-dispersive 

X-ray elemental analyzer at the U.S. Geological 

Survey, Menlo Park, California. 

Assays of several ore samples were performed by 

Acme Analytical Laboratories of Vancouver, Canada, 

who used inductively coupled argon plasma analysis 

UCP) to measure the concentrations of Cu, Pb, Zn, Ag, 

Co, Ni, Mo, Bi, As, Sb, Cd, W, Au, and Si in samples 

fused with lithium metaborate. Germanium and gallium 

were measured, with a detection limit of 1 ppm, by 

graphite furnace atomic absorption spectroscopy on 

samples dissolved in hot aqua-regia and hydrofluoric 

acid in a pressure bomb. Carbon dioxide was measured 

by infrared spectroscopy of gas released during heating 

in a furnace; carbon not present as carbonate was determined by taking the difference in measurements 

between untreated samples and samples that had been 

leached in acid to release all the C02. 

Semiquantitative emission spectrographic analyses were performed on seven additional samples by 

Richard Lerner of the U.S. Geological Survey. These 

analyses were made on hand-picked' samples, about 500 

mg each, of homogeneous-appearing ore material. 

Elements Ge and In were analyzed by a 6-step visual 

semiquantitative procedure using glass plates, whereas 

the other elements were analyzed using a directreading emission spectrophotometer. Owing to their 

high iron content, the samples were diluted with 

material containing Si, Al, and K to minimize interferences; this raised detection limits, and also made 

measurements for Si, Al, and K less accurate (standard 

deviations of 30-50 percent of the recorded value, 

versus 10-20 percent for the other elements). 

GEOLOGIC SETTING 

Regional Geology 

The Apex Mine is on the east slope of the Beaver 

Dam Mountains, a northwest-trending uplift at the 

boundary between the Basin and Range province to the 

west and the Colorado Plateau to the east. The 

Pennsylvanian Callville Limestone, which hosts the ore, 

crops out on the eastern and sou~h~rn. sl?pes of the 

mountains, where it rests on MISSISSippian Redwall 

Limestone and is overlain by Permian Pakoon Limestone (Cook, 1960; Steed, 1980). In the Beaver Dam 

Mountains and Virgin River Gorge (about 11 km southsouthwest of the Apex Mine) the shallow-marine Callville is 200-210 m thick (Steed, 1980). Igneous rocks 

are not known in the vicinity of the Apex Mine, though 

fresh-looking Quaternary basaltic lava flows occur 

13 km to the north-northeast near Shivwits. 

Local Geology 

In the vicinity of the mine, the Callville Limestone consists of gently dipping beds typically a few 

centimeters thick Uig. 2), though locally they are as 

much as 6 m thick. The bedding generally dips 5° to 

100 E. to N., with local warps producing dips up to 5° 

Figure 2. Main adit to Apex Mine, Washington Cou~ty, 

Utah, showing gently dipping beds of the Callville 

Limestone. 

3 
w., and is commonly irregular and discontinuous. Irregular chert nodules as much as 50 em across, which 

locally form short discontinuous layers, are abundant; 

quartz in these nodules is commonly recrystallized to 

grains as much as several millimeters across. Rounded 

quartz grains as much as a few millimeters across are 

locally common in the limestone, and discontinuous 

sandstone beds as much as several meters thick occur 1n 

places. Scattered shaly beds, as much as a few 

centimeters thick, are also present, as are some dolomitic zones. Poorly preserved fossil horn corals are 

locally common. Solution cavities that range from vugs 

a few centimeters across to caves several meters 

across are found in the mine; these generally contain 

small stalactites or euhedral calcite crystals. 

The most prominent structural feature near the 

mine is the Apex fault, which strikes north-northwest 

and dips 640 to 71 o W. Uig. 3). The fault is readily 

observed at the shafts of the Apex and Paymaster 

mines where the sheared and brecciated zone is 5-7 m 

wide, but elsewhere it is covered by slopewash and is 

apparently narrower. The fault can be approximately 

traced at the surface by the sporadic presence of iron 

oxides, azurite, and malachite in the slopewash. At the 

Apex and Paymaster shafts, the fault zone consists of 

limonite- and goethite-impregnated gouge that contains 

small amounts of malachite and azurite, with dolomite 

breccia in the footwall and apparently unaffected limestone in the hanging wall. The dolomite breccia 

observed at the surface has angular to subrounded 

dolomite clasts in a fine-grained dolomite matrix, 

whereas that in the mine commonly has a limonitegoethite matrix. Evidence on the direction of displacement for the fault was not observed. Kinkel U 951) 

mapped a distinctive sandstone bed and proposed the 

fault to be reverse with a vertical displacement of 

about 75 m. 

Ore Geology 

The ore at the Apex Mine is defined as a goethitelimonite-hematite zone that contains local concentrations of jarosite, azurite, malachite, and other supergene copper, iron, lead, and zinc minerals. This zone 

forms a highly irregular, branching, chimney-like body 

(or bodies) within breccia, gouge, and fissures 

associated with numerous subparallel faults in the footwall of the Apex fault. Mining and drilling data are 

currently insufficient to define the irregular shape of 

the ore zone or zones, but ore thicknesses of 1 to about 

20 m can be observed, with a northwest strike length of 

at least 107m confirmed by drilling (Lalonde, 1983). 

The texture of the ore zone varies considerably. 

Most of the ore consists of broken fragments and 

stringers of goethite or hematite in a matrix of limonite lhere used to denote soft iron oxides and hydroxides that give a weak to non-existent powder X-ray 

diffraction pattern). In places only limonite is present, 

whereas in other places (generally at the footwall of 

the ore zone) hard, vuggy goethite is present. Vugs in 

this goethite range in size from a few millimeters to 

several centimeters across, and commonly contain 

botryoidal crusts or euhedral crystals of azurite, malachite, conichalcite, rosasite, or brochantite. In appearance, such ore resembles the gossans of many sulfide 

deposits, particularly those that contain arsenates such 

as that at Mapimi, Mexico (Hoffmann, 1968). Limonitematrix dolomite breccia occurs in places, and the 

4 

I 

I /:J! 

0../ 

1750 <::I:J 

--,_/ 0 5/ 

Paymaster "'~'__...Collapsed 

Mine 11 ,'l shaft. '/8'!, and ad1t ' "',',',' 1700 

/ 

/ 

t5 

0 50 100 150 200"METERS 

CONTOUR INTERVAL 50 M ETERS 

EXPLANATION 

D Callville Limestone (Pennsylvanian)- Contains 

chert nodules, sparse sandy and shaly beds 

6f-- Fault Zone - Sheared, brecciated, showing dip; 

dashed where inferred; queried where uncertain 

To Strike and dip of bedding 

/{i!Nr\\\ Tailings 

Figure 3. Locations of Apex and Paymaster mines and 

Apex fault zone, Washington County, Utah. Compiled 

from Kinkel (1951) and field work by L.R. Bernstein, 

April, 1985. Most of. the tailings shown on this map 

were hauled to the mill site, about 9 km to the northnortheast, during the summer of 1985. 
dolomite clasts commonly have a rim of malachite or 

azurite. Jarosite occurs as discrete mustard-yellow to 

brownish-yellow, sparkly zones as much as 1. 5 m thick. 

It also occurs in the matrix of some dolomite breccia, 

and is disseminated in small amounts throughout much 

of the ore. The copper minerals appear to be concentrated toward the hanging wall of the ore zone adjacent 

to dolomite. They also replace dolomite fragments 

within limonite-goethite ore, and are disseminated 

through much of the ore in small quantities. Contacts 

between the ore and wall rocks are commonly gradational, with fracture coatings of limonite extending 

several meters into the wall rocks. 

Limestone within the ore zone has been converted 

to dolomite or microcrystalline quartz, and the effects 

of dolomitization and silicification locally extend 1-2 m 

into the wall rocks. Dolomitization was pervasive 

throughout the ore and fault zones, whereas silicification appears to have been most intense toward the 

hanging wall and at depth. 

As the extent of the ore zone has not yet been 

fully defined, particularly at depth, grade and tonnage 

estimates are preliminary. The ore defined as of 

October 1983 is estimated by Lalonde (1983) to be 

242,768 short tons containing 0.064 percent Ge, 0.032 

percent Ga, 1. 63 percent Cu, 0. 77 percent Pb, 1. 58 

percent Zn, 0.50 percent As, 16.73 percent Fe, and 1.21 

troy oz/short ton (38 ppm) Ag. In addition, the surface 

dump from the old mine is estimated (Lalonde, 1983) to 

contain about 50,000 short tons with 0.037 percent Ge, 

0.019 percent Ga, and 1.55 percent Cu. Chemical 

analyses of some representative ore samples are 

presented in table 1; chemical analyses of some homogeneous-appearing, nearly monomineralic samples are 

presented in table 2. 

MINERALOGY 

Primary Ore 

The ore has been thoroughly oxidized to at least 

425 m below the surface (the maximum depth of the old 

workings), and only a few fragments of sulfide minerals 

have been found. Several pieces of coarsely crystallized galena, as much as 10 em across, have been found 

on the old dump, embedded in and largely replaced by 

anglesite. Within the galena and adjacent anglesite are 

masses of fine-grained pyrite, as much as 1 em across, 

sooty black covellite that replaces pre-existing Cubearing sulfides, and very scarce grains of residual 

chalcopyrite up to 100 ,urn across. Lalonde (1983) 

reported very fine grained galena disseminated in a 

mustard yellow mud (plumbian jarosite) in drill-hole 83-

16 at 48.8 m (160 ft). He also reported dark-gray to 

black quartz-pyrite-sphalerite stringers in limonitic 

zones in drill-holes 83-20 and 83-25. In drill-hole 85-1 

at 28.3 m (93 ft) a layer of fine-grained pyrite, 4 em 

thick, was found in the center of a mass of dense 

goethite. Small amounts of barite and quartz are 

intergrown with the pyrite. In the SEM, scarce scattered grains of galena 1-10 ,urn across were observed, 

as were a few grains of an unidentified 

Pb- As- Cu- S-rich mineral, 1-5 ,urn across. Approximately 75 ppm Ni and 15 ppm Co were detected in this 

pyrite (table 2). In drill-hole 85-36 at 67.1 m (220 ft) 

friable masses of marcasite several centimeters across 

occur, together with veinlets and b1ebs of covellite as 

much as one millimeter wide. The marcasite occurs in 

Table 1. Chemical analyses of some representative ore samples from Apex 

Mine, Washington County, Utah 

[Compositions determined by inductively coupled argon plasma analysis 

for Cu, Pb, Zn, As, Bi, Cd, Co, Mo, Ni, Sb, Fe, Ag, Ca, Mg, and Si; 

atomic absorption for Ge and Ga; and infrared spectroscopy for C02. 

Analyses performed by Acme Analytical Laboratories, Vancouver, Canada; 

provided through the courtesy of Musto Explorations Ltd.] 

Sample 1 No.--

Weight percent 

Ge---------

Ga---------

Cu---------

Pb---------

Zn---------

As---------

0.026 0.198 0.460 0. 382 0.108 0.224 0.065 0.092 

B i ---------

Cd---------

Co---------

Mo---------

Ni ---------

Sb---------

Fe---------

Ca---------

Mg---------

Si02-------

COz--------

Ag---------

.032 

3.08 

.09 

1. 59 

.09 

0.001 

.00 

.01 

.004 

.03 

.001 

26.18 

1. 73 

1. 23 

41.58 

5. 54 

.033 

.65 

.51 

1.06 

1. 10 

0.01 

.01 

.01 

.032 

.02 

.012 

40.70 

.16 

.06 

25.24 

.49 

.086 .148 .119 

.16 12.00 .10 

.10 .42 • 74 

• 33 • 62 .13 

2.10 4. 38 • 70 

0.01 0.001 0.01 

.01 .01 .00 

.01 .04 .00 

.027 .038 .039 

.02 .06 .01 

.089 .077 .055 

31.92 19.20 12.12 

.42 1. 31 .11 

• 09 .07 .06 

37.04 41.23 69.48 

.33 4. 36 • 37 

Parts per million 

77 161 97 

.086 .040 .087 

.31 .17 1.42 

5.48 4.10 .87 

• 26 .12 .53 

2. 74 1.03 2. 71 

0.001 0.004 0.053 

.001 .001 .00 

.001 .001 .01 

.013 .043 .057 

.01 .01 .01 

.037 .143 .257 

25.43 22.36 14.05 

.35 .14 .58 

.04 .02 .05 

30.12 28.95 65.74 

.24 .14 .61 

197 235 674 

lsample descriptions (some quartz is present in all the samples): 

1. Dense, vuggy goethite with some limonite. 1,630-m (5,347-ft) level, 

N. rib. 2. Mainly dense, vuggy goethite. DDH85-9, near 29m (96 ft). 

3. Mixed, fractured goethite, hematite, limonite. DDH85-9, 45-47 m 

(148.5-155 ft). 4. Friable goethite with azurite, conichalcite, and 

some plumbian jarosite. 1.625-m (5,330-ft) level, S. rib. 5. Mixed 

friable goethite, limonite, and a little plumbian jarosite. DDH85-9, 

44-45 m (143.5-148.5 ft). 6. Laminated, earthy, red-brown limonite and 

yellow plumbian jarosite. 1,601-m (5,253-ft) level, N. rib. 7. Mostly 

plumbian jarosite. 1,601-m (5,253-ft) level, N. rib. 8. Mostly slightly 

plumbian jarosite. 1,625-m (5,330-ft) level, S. rib. 

two habits: intergrown euhedral tabular to lozengeshaped crystals, 0.1-0. 7 mm long, and spongy, anhedral 

material filling interstices between the euhedral 

crystals. It is not clear whether the marcasite is of 

hypogene or supergene origin. 

Supergene Ore 

Goethite-Goethite is the most abundant mineral 

in the ore zone, and occurs in several habits. It is most 

common as irregular fragments of stringers as much as 

several centimeters across mixed with fine-grained 

quartz, imbedded in limonite or jarosite that form 

yellow-brown locally friable masses. It also occurs as 

zones of hard, dense, brown, vuggy material, particularly toward the footwalL In the SEM, this material is 

found to be intimately admixed with microcrystalline 

quartz, accounting for its hardness. A few masses of 

dense lustrous goethite a few centimeters across having 

a conchoidal fracture were found. 

Goethite is the major host for germanium, and 

contains as much as 5300 ppm Ge (Dutrizac and others, 

in press). In the SEM, no discrete germanium minerals 

were observed, and the germanium appears to be distributed rather uniformly in the goethite itself (either 

within the crystal lattice or in grain boundaries). 

Typical, clean-looking areas of goethite were always 

found to contain as much as several percent of Si, Al, 

Ca, K, As, and Zn, with traces of Pb and Ge. The hard 

5 
Table 2. Chemical analyses of some nearly monomineralic samples from Apex 

Mine, Washington County, Utah 

[Compositions determined by semiquantitative emission spe c troscopy performed 

by R. Lerner of the U.S. Geological Survey. Standard deviations are about 

10-20 perc ent of the indicated value, except for Si, K, and Al, for which 

they are 30-50 perc ent. Elements not detected at the indic ated detection 

limi ts (ppm) for samples 2-7 (detection limits for sample 1 are 40% of 

these, due to less sample dilution): Au(SO),Be(S),Ce(SOO),Cr(SO),Hg(2500), 

In( 7), La( 100), Li( 250) ,Mn( 1000), Nb( 125), P( 1000), Re( 250), Sc (50), Se( 1000), 

Sn(SO), Te(250) ,W(SOO), Y(SO) ,Zr( 100) .] 

Sample1 No.-- 1 

Parts per million 

Ge--------- <7 150 7000 3000 2000 2000 3000 

Ga--------- <20 <SO 150 100 100 200 1SO 

Cu--------- 1900 250 620 1500 >5000 1800 1300 

Pb--------- >SOOO 290 110 >5000 1600 330 5000 

Zn--------- <100 1100 1500 >5000 >SOOO 2600 1000 

As--------- <400 <1000 >SOOO >SOOO >SOOO >5000 >SOOO 

Ag--------- 66 <S 45 100 <S 48 1200 

B---------- <20 <SO 50 <SO (50 50 <SO 

Ba--------- <40 640 150 410 <100 150 420 

B i --------- <20 <SO <SO <SO <SO <SO 80 

Cd--------- <8 <20 50 50 50 100 (20 

Co--------- <2 15 37 70 100 100 70 

Mo--------- <20 <SO 50 <SO <SO 50 950 

Ni --------- 18 7S 130 80 2SO 200 43 

Sb--------- <200 <SOO 1200 <SOO <SOO <SOO 4200 

Sr--------- 610 650 2900 7SO 920 4300 >5000 

Tl--------- <20 <SO <SO <SO <SO <SO 170 

v---------- <20 <SO <SO <SO 55 <SO <SO 

Weight percent 

Fe--------- 0.36 so. 34. 45. 46. 29. 20. 

Ti --------- <.04 <.10 .1S <.10 <.10 .15 <.10 Al--------- <. 25 .40 2.0 0.46 .83 2. 3 .85 

Ca--------- <.10 <. 25 .40 1.2 • 25 .80 <. 25 

Mg--------- <. 20 • 70 .65 • 70 • 70 .60 <.50 

K---------- <.08 .15 1.5 .30 .20 .10 2.0 

Na--------- <. 30 <. 75 <. 75 <. 75 <. 75 <. 75 1.0 

SiOz------- <16. <16. 31. <16. 22. 36. 25. 

1samples: l. Galena with a few percent anglesite. Tailings of old 

workings. 2. Pyrite with a few percent of quartz plus traces of barite and 

galena. DDH85-1, 27 m (93 ft). 3. Granular hematite with intimately 

intergrown microcrystalline quartz plus small amounts of jarosite and possibly other minerals. DDH85-9, 45-47 m (148.5-155 ft). 4. Reddish-brown 

limonite with a few percent of jarosite. 1,601-m (5,253-ft) level, N. rib. 

5. Dense, vuggy goethite with microcrystalline quartz plus small amounts of 

jarosite and possibly other minerals. DDH85-9, 29 m (96 ft). 6. Goethite 

with microcrystalline quartz plus small amounts of jarosite and possibly 

other minerals. DDH8S-9, 45-47 m (148.5-155 ft). 7. Slightly plumbian 

jarosite with microcrystalline quartz. 1,625-m (5330-ft) level, S. rib. 

•conchoidal material contains the smallest amounts of 

all these elements. Discrete hexagonal plates of jarosite 5-10 J.Lffi across are dispersed in much of the 

goethite. 

Limonite-The term limonite is used to denote the 

abundant yellow-brown to red-brown, friable, commonly 

earthy mixture of iron-rich oxides, hydroxides, and 

oxysalts that produce only small, broad peaks Uf any) in 

powder X-ray diffraction patterns. Quartz and goethite 

are almost always present, but most of this material is 

either amorphous or is so fine grained that it will not 

produce sharp diffraction peaks. Limonite occurs ll) 

interstitially to goethite and hematite, (2) as the matrix 

of some dolomite breccia, (3) impregnating fault gouge, 

and ( 4) as vug and fracture fillings throughout the ore. 

An area of laminated red-brown, earthy limonite was observed in the north rib of the 1601-m crosscut that 

contains numerous parallel layers, about 1-2 mm thick, 

of yellow plumbian jarosite, suggestive of a banded 

texture in the primary sulfide ore (see analysis 6, table 

1). In the SEM, limonite samples are found to contain 

as much as several percent Si, Ca, Al, K, As, Pb, Cu, 

and Zn. Gallium is not usually detected in the SEM 

( < 500 ppm), but zones of limonite a few tens of micro6 

meters across that contain as much as 2 weight percent 

Ga were observed in the laminated sample {analysis 6, 

table 1). These small zones also contain 1-2 weight 

percent Ca, Pb, As, K, and Al. Germanium is detected 

using the SEM in many limonite samples (500 ppm to 

about 2,000 ppm), but not in others. 

Hematite-Hematite is much less abundant than 

goethite or limonite and occurs as red-brown, hard 

nodules and angular fragments encrusted with limonite 

and jarosite. It is admixed with abundant fine-grained 

( < 1 ,urn) quartz. The hematite contains as much as 

several percent Si, Ca, K, and As, and somewhat more 

Ge than was observed in goethite. Emission spectroscopy detected roughly 7,000 ppm Ge in one specimen 

(table 2). The extreme fine-grained ( < 1 J.LID) nature of 

this material makes the host(s) for these elements 

uncertain. Powder X-ray diffraction detected only 

hematite and quartz. Adsorption of some of the minor 

elements in grain boundaries is a possibility. 

Jarosite-Massive jarosite is bright yellow to 

brownish yellow, slippery feeling, and has a fine-grained 

sparkly appearance. It forms zones at least 1.5 m 

thick, and also occurs in breccia matrix and dispersed in 

smaller quantities throughout much of the ore. Under 

the SEM it is seen to consist of platy hexagonal 

crystals, 5-10 ,urn across, that are always mixed with 

quartz, which is fibrous in some specimens (fig. 4). It 

contains variable amounts of Pb, Na and K, being 

intermediate between jarosite, natrojarosite, and plumbojarosite. Dutrizac and others On press) and the 

current study found the cell parameters, as determined 

by powder X -ray diffraction techniques, to lie between 

those of the two end members, without the doubling of 

the c-axis found for plumbojarosite. Jarosite is a major 

hosC for Ga in the ore, with as much as 0. 70 weight 

percent Ga substituting for Fe according to Dutrizac 

and others (in press). They reported an average composition, based on 11 electron microprobe analyses, to be: 

(Ko. 682 Nao.166Pb0.183Ago.034h. o2t Fe2. 95JZno.016-

Gao.027)3.00(S04)2.00(0H)5.96. Jarosite is a major 

host for Ag, which substitutes for K, Na, and Pb (see 

tables 1 and 2). The cores of many jarosite crystals are occupied by rhombohedral crystals of goyazitesvanbergite 1-10 J.LID across. 

0 10J..Lm 

Figure 4. Scanning electron photomicrograph showing 

tabular, hexagonal jarosite crystals with some acicular 

quartz crystals. Apex Mine, Washington County, Utah, 

1,601-m leveL 
Goyazite-svanbergite-Dutrizac and others Un 

press) report the presence of rhombohedral crystals, 

about 10 J,Lm on edge, of sulfate-bearing goyazite, 

SrAl3tP04)z\OH)5· H20, forming a solid solution with 

svanbergite, SrAl3{P04XS04XOH)6, in two samples of 

jarosite. Measureable quantities of Ge and Ga were not 

detected ( < 300 ppm). Similar crystals were observed 

in this study together with jarosite from the 1,625-m 

level. Most of these goyazite-svanbergite crystals form 

the cores of jarosite crystals. Small amounts of As 

U,000-7,000 ppm) were detected in this mineral under 

the SEM. 

Azurite-From observations of the underground 

workings and of the old dump, azurite, 

Cu3(C03)2tOH)2, appears to be the most abundant 

copper mineral in the ore. However, because most of 

the high-grade copper ore was previously mined out, the 

content of azurite in the original ore may have been 

different. Azurite is most concentrated where it fills 

cavities that are at least several centimeters wide in 

partly silicified dolomite in the hanging walL In these 

cavities it forms botryoidal crusts, as much as 2 em 

thick, covered by drusy crystals, as much as a few 

millimeters across. Azurite also occurs as euhedral 

crystals, as much as a few millimeters across, lining 

vugs in goethite, and as partial replacements of isolated 

dolomite fragments in the limonite-goethite ore. In 

some places azurite is replaced by malachite, and in 

other places it is replaced by X-ray-amorphous lightblue chrysocolla-like materiaL 

Malachite-Malachite, Cu2C03tOH)2, is less 

abundant than azurite, though both minerals occur in 

the same environments. It forms botryoidal crusts of 

radial-fibrous crystals as much as 1 em thick and, 

locally, it replaces azurite. In places, spheres of 

radiating fibrous crystals that are several millimeters across are observed on goethite. 

Conichalcite-Conichalcite, CaCu(As04XOH), is 

nearly as common as malachite. It forms thin emeraldgreen crusts on goethite, generally associated with 

azurite. 

Aurichalcite-Aurichalcite, (Zn,Cu)5tC03)2tOH)6, 

is sparsely found 111 goethite as turquoise-blue radiating 

fibrous crystals as much as 1 em long. It is generally 

not associated with the other copper minerals. 

Rosasite-A few blue-green spheres of radiating 

fibrous crystals of rosasite, (Cu,Zn)2(C03XOH)2, that are several millimeters across were found in vuggy 

goethite with malachite, azurite, and conichalci te. 

Brochantite-Brochantite, Cu4S04(0H)6, was found 111 a sample of hard vuggy goethite on the dump, 

where it forms transparent, green, euhedral crystals 

that are a few millimeters across on a crust of malachite. 

Cuprite-A lens of cuprite (Cu20), about 

30x23x8 mm, was observed in drill-hole 85-12 at 22.7 m 

(74.5 ft). The cuprite has an average grain size of 

about 0.5 mm. The lens is surrounded by a crust of 

malachite, which is in turn surrounded by a crust of 

azurite, which is enclosed within earthy decomposed 

dolomite containing clay minerals and limonite. Malachite has replaced cuprite within the lens along fractures. 

Anglesite-White, gray, and yellow massive anglesite (PbS04) surrounds and partly replaces galena in a 

sample from the dump. No elements other than Pb and 

S were detected in the SEM. 

Covellite-Sooty bluish-black covellite (CuS) 

masses that are as much as 1 em across occur with 

pyrite, anglesite, and traces of chalcopyrite in a sample 

of coarse-grained galena found on the dump. Small 

amounts of covellite occur in fractures within the 

galena crystals. Veinlets and blebs of covellite, as 

much as one millimeter wide, occur with massive 

marcasite in drill hole 85-36 at 67.1 m {220 ft). 

Black manganese oxides-Thin coatings of black 

manganese oxides occur locally in fractures and vugs in 

goethite. A high concentration of these black oxides 

was noted in goethite at the 1,625-m (5,330-ft) level 

together with azurite and conichalcite. 

Chrysocolla-X-ray-amorphous, light-blue, chalky 

to hard material that have a conchoidal fracture is a common late alteration product of azurite in cavities. 

Other reported minerals-Bullock {1967) reported 

the presence of native copper, cerussite, hydrozincite, 

adamite, and smithsonite from the Apex Mine, though 

these were not observed in the present study. 

DISCUSSION AND CONCLUSIONS 

Primary Ore Deposition 

Deposition of ore at the Apex Mine was confined 

to brecciated, fissured, and sheared zones associated 

with the Apex fault. As only one geologic formation 

(Callville Limestone) is present, structural data on the 

geologic ages of faulting and of ore deposition are not 

available. Kinkel U951) noted that although the limestone has abundant solution cavities, only those directly 

connected with the fault zone were mineralized. Dolomitization and silicification were associated with the 

fault zone, and extended as much as several meters 

beyond the ore into the wallrocks. 

No large examples of primary ore have been found 

at the Apex Mine, but aspects of its composition can be 

inferred. The ore was certainly rich in iron and copper. 

It also contained considerable lead, lesser zinc and 

arsenic, and small amounts of germanium and gallium. 

It is very unlikely that germanium and gallium were 

introduced during supergene alteration, as these 

elements are always highly depleted in carbonate rocks 

(by roughly two orders of magnitude) in relation to their 

average crustal abundance (Bernstein, 1985; Burton and 

others, 1959). The available fragments of primary ore 

show the presence of fine grained pyrite, which was 

probably abundant, coarse and fine grained galena, 

sphalerite, chalcopyrite, and a small amount of barite. 

The abundance of secondary copper minerals now 

observed indicates the former presence of abundant 

copper-bearing sulfides such as bornite, chalcopyrite, 

and chalcocite. The abundance of arsenic in the 

secondary copper and lead minerals strongly suggests 

the former presence of sulfosalts such as tennantite or 

lead-arsenic sulfosalts. Significantly, the relatively 

high concentrations of germanium and gallium indicate 

that sulfides containing these elements were present. 

Such sulfides possibly included renierite 

(CUll-xZnxGe2-xAsxFe4S16), germanite 

(Cull Ge(Cu,Ge,Fe,Zn, W,Mo,As, V)4-6S16), and gallite 

(CuGaS2). The relatively small amount of zinc in the 

ore precludes the possibility that sphalerite was the 

major host for germanium and gallium. 

The inferred primary ore is similar to bornitechalcopyrite-tennantite±galena:sphalerite ore found at 

Tsumeb, Namibia (Sahnge, 1964), Kipushi, Zaire 

7 
Untiomale and Oosterbosch, 1974), and Ruby Creek, 

Alaska (Bernstein and Cox, in press). Ore at these 

deposits is very rich in copper in certain zones, occurs 

in dolomitized carbonate host rocks that are commonly 

brecciated, and contains germanium-bearing copper 

sulfides. The ore zone at the Apex deposit, though 

much smaller, appears to be most like that at Kipushi, 

in the Zaire-Zambia copper belt. The ore body at 

Kipushi forms a highly irregular subvertical pipe at the 

faulted boundary of dolomitic shale and marine dolomite, commonly within breccia zones Untiomale and 

Oosterbosch, 1974; DeVos and others, 1974). Some 

sulfide replacement extends along bedding planes and 

fracture zones. The bulk of the ore consists of the 

assemblages chalcopyrite-pyrite, chalcopyrite-bornitetennanti te, bornite-chalcocite, and sphalerite-pyritegalena. Renierite, with lesser germanite and briartite 

(Cu2(Fe,Zn)GeS4), are locally common in copper-rich 

ore, commonly near zinc-rich ore. Gallite is present in 

small quantities as inclusions in renierite, germanite, 

and sphalerite. 

Supergene Alteration 

At the Apex Mine, supergene alteration of the ore 

has occurred at least down to the 1,230-m level, the 

maximum depth of the old workings. The water table 

had not yet been reached at that level. The thorough 

oxidation of the ore is certainly due to the high 

permeability of the limestone, and particularly of the 

fault zones, which allowed access to air, meteoritic 

water, and Thiobacillus bacteria that can break down 

sulfides (Duncan, 1967). 

It is not clear if the general separation of ironrich and copper-rich ore now observed reflects the 

original distribution of sulfides, or is a product of 

supergene alteration. The occurrence of the richest 

copper ore in and adjacent to carbonate rock, and the 

nearly complete lack of residual primary copper 

minerals, suggest that copper was fairly mobile during 

supergene alteration, and was precipitated mainly by 

reaction with carbonate wallrocks and breccia fragments. The similar distribution of zinc-bearing 

minerals to copper-bearing minerals suggests that zinc 

behaved in much the same way. Lead, however, was 

mainly precipitated in place as sulfates (plumbian jarosite and anglesite). Gallium was concentrated mainly in 

jarosite, where it substituted for iron, and in limonite, 

where it either substituted for iron or was adsorbed 

onto grain and fracture surfaces. Most of the iron in 

the ore was left in a spongy to dense mixture of 

limonite, goethite, and hematite. 

Germanium became concentrated mainly in 

goethite, hematite, and limonite, though it is uncertain 

whether it is primarily adsorbed onto grains of these 

minerals or is incorporated into their lattices. Some 

solid solution between magnetite and the related spinel 

brunogeierite (GeFe204) has been reported (Otteman 

and Nuber, 1972), probably through the coupled substitution 2 Fe( III) ~ Ge(IV) + Fe( II). The same or similar 

coupled substitutions may account for the presence of 

germanium in goethite and hematite. Burton and others 

(1959), for example, reported as much as 83 ppm 

germanium in hematite from Cumberland, England. 

Experiments have shown that germanium has a high 

affinity for iron hydroxide: Burton and others U 959) 

found 95 percent of dissolved germanium to be precipitated from seawater by Fe(OH)3, and Pazenkova (1963) 

8 

found 93 percent of dissolved germanium to be precipitated by Fe(OH)3 in waters with a pH greater than 

about 6; less germanium was incorporated from more 

acidic waters. 

Implications 

Future mmmg operations at the Apex Mine may 

eventually reach primary sulfide ore, which would 

permit better comparisons with other deposits and 

would allow a more thorough understanding of the 

supergene alteration that has occurred. Primary ore 

may occur below the current water table, where it 

would not have been exposed to severe oxidizing 

conditions. However, the position of the water table in 

the vicinity of the mine is not known. A flowing spring 

(Cave Spring) is located 4. 9 km east of the mine at an 

elevation of 1,160 m ( 70 m below the deepest workings), 

and the perennial Virgin River is about 11 km to the 

southeast at an elevation of about 750 m (480 m below 

the deepest workings), which would be a minimum level 

for the water table. 

The similarity was previously noted between the 

supergene ore at the Apex Mine and the gossans at 

many sulfide ore deposits, particularly at those containing considerable arsenic. This observation, combined 

with observations that germanium is commonly concentrated in carbonate-hosted copper-rich deposits, many 

of which are associated with organic material 

(Bernstein, 1985), may be useful in the exploration for 

additional germanium deposits. Similarly, the occurrence of gallium in jarosite-group minerals and limonite 

at the Apex Mine provides new directions in the exploration for this metal. 

REFERENCES 

Bernstein, L. R., 1985, Germanium geochemistry and 

mineralogy: Geochimica et Cosmochimica Acta, 

v. 49, p. 2409-2422. 

Bernstein, L.R., and Cox, D.P., in press, Geology and 

sulfide mineralogy of the Number One ore body, 

Ruby Creek copper deposit, Alaska: Economic 

Geology. 

Bullock, K.C., 1967, Minerals of Utah: Utah Geological 

and Mineralogical Survey Bulletin 76, 23 7 p. 

Burton, J.D., Culkin, F., and Riley, J.P., 1959, The 

abundances of gallium and germanium in terrestrial materials: Geochimica et Cosmochimica 

Acta, v. 16, p. 151-180. 

Cook, E.F., 1960, Geologic atlas of Utah, Washington 

County: Utah Geological and Mineralogical Survey Bulletin 70, 119 p. 

DeVos, w., Viaene, W., Moreau, J., and Wautier, J., 

1974, Mineralogie du gisement de Kipushi, Shaba, 

Zaire [The Mineralogy of the Kipushi deposit, 

Shaba, Zaire] : in Bartholome, Paul, ed., Gisements stratiformes et provinces cupriferes: 

Liege, Societe Geologique de Belgique, p. 165-

183. 

Duncan, D. w., 1967, Microbiological leaching of sulfide 

minerals: Australian Mining, v. 59, no. 11, p. 21-

28. 

Dutrizac, J. E., Jambor, J. L., and Chen, T. T., in press, 

Host minerals for the gallium-germanium ores of 

the Apex mine, Utah: Economic Geology. 
Hoffmann, V.J., 1968, The mineralogy of the Mapimi 

mining district, Durango, Mexico: Ph. D. dissertation, University of Arizona, Tucson, 266 p. 

Intiomale, M.M., and Oosterbosch, R., 1974, Geologie et 

geochimie du gisement de Kipushi, Zaire [The 

geology and geochemistry of the Kipushi deposit, 

Zaire]: in Bartholome, Paul, ed., Gisements 

stratiformes et provinces cupriferes: Liege, 

Societe Geologique de Belgique, p. 123-164. 

Kinkel, A.R., Jr., 1951, Preliminary report on the Apex 

and Paymaster mines, Washington County, Utah: 

U.S. Geological Survey open-file report, 9 p. 

Lalonde, C. M., 1983, Report on the 1983 diamond 

drilling program at the Apex Mine, Washington 

County, Utah: Unpublished report of Musto 

Explorations, Ltd., Vancouver, Canada, 20 p. 

GPO 687-049/45009 

Pazenkova, N.I., 1967, Germaniferous limonite-forming 

mechanism: Doklady of the Academy of Sciences 

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translation , v. 173, p. 204-206. 

Perry, L.I., and McCarthy, B.M., 1977, Lead and zinc in 

Utah - 1976: Utah Geological and Mineralogical 

Survey Open-File Report 22, 525 p. 

S8hnge, P.G., 1964, The geology of the Tsumeb Mine, in 

Haughton, S.H., ed., The geology of some ore 

deposits in southern Africa: Geological Society of 

South Africa, Johannesburg, v. 2, p. 367-382. 

Steed, D.A., 1980, Geology of the Virgin River Gorge, 

northwest Arizona: Brigham Young University 

Geology Studies, v. 27, pt. 3, p. 96-115. 

9