Micromineralogy of 

Galena Ores, Burgin Mine 

East Tintic District 

Utah

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-A

Micromineralogy of 

Galena Ores, Burgin Mine 

East Tintic District 

Utah

By ARTHUR S. RADTKE, CHARLES M. TAYLOR, and HAL T. MORRIS 

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-A

A study of the distribution of a variety 

of chemical elements in the major and minor 

minerals of a silver-rich lead a?id%inc 

replacement ore body

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 40 cents (paper cover)
CONTENTS

Abstract_ _ ____-_______--____---___

Introduction ____________-_____--_-_.

Acknowledgments___ _ _______________

Purpose and procedure_______________

Mineralogy and chemistry ____________

Galena.________________________

Polybasite- _____________________

Tetrahedrite ____________________

Jalpaite ___-_____________--__._.

Lead-antimony oxide or carbonate. 

Sphalerite. _ _ ___-_-___--______.

Page

Al

1

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2

3

3

5

8

8

Mineralogy and chemistry Continued 

Pyrite and chalcopyrite-___-_____.

Mimetite. _--____-______-_--_--.

Cerussite- _____________-_--_--_.

Silver sulfide-___________________

Hematite- _ _______-___-_--__--_.

Calcite and anglesite(?)_________

Barite and quartz___-_____---_-_-

Element distribution._-_____-___-_-_.

Summary and conclusions._______._.

References cited-____________________

ILLUSTRATIONS

Fage

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[All Illustrations are photomicrographs]

FIGURE 1. Chainlike series of polybasite and tetrahedrite inclusions in galena._____________________________________

2. Large grain of tetrahedrite locked in fine-grained galena._______________________________________________

3. Granular intergrowth of jalpaite and galena surrounded and replaced by cerussite.______-__--___-________.

4. Mimetite forming along a microfracture in galena.___________________________________________________

5. Replacement of remnant grains of sphalerite, quartz, and barite by galena,_______________________________

6. Veinlet of late(?) barite containing fragments of pyrite, chalcopyrite, sphalerite, and galena cutting across quartz.

7. Mimetite along contact between galena and barite gangue______________________________________________

8. Alteration of galena to cerussite localized along cleavage planes________________-_______-_---_-_-________-

9. Fine-grained secondary silver sulfide dispersed in secondary cerussite.-_________-___--__-_-_-___-___-__-_-

10. Replacement of remnant quartz and segmented barite by galena, which was subsequently altered to cerussite- _ _

11. Alteration of galena to cerussite.____________________________________________________________________

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TABLES

TABLE 1. Minerals in the galena ores of the Burgin mine._________________

2. Chemical and spectrographic analyses of galena ores, Burgin mine. 

3-7. Analyses of 

3. Polybasite-__________________________________________

4. Tetrahedrite-________________________________________

5. Jalpaite__--_-_-_____-______-__-_-____-_____________

6. Sphalerite_-_-_-_--__-__--______--__-__-___________.

7. Mimetite__________________________________________

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3

3

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in

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

MICROMINERALOGY OF GALENA ORES, BURGIN MINE, EAST TINTIC DISTRICT, UTAH

By ARTHUR S. KADTKE, CHARLES M. TAYLOR, and HAL T. MORRIS

ABSTRACT

Analyses of argentiferous galena ores from the Burgin mine, 

Utah, by electron microprobe, emission spectograph, and wet 

chemical method indicate distinctly different amounts of silver 

in two general types of galena. Massive coarse-grained galena 

contains an average 0.22 percent silver by weight (approximately 64 ounces per ton), whereas fine-grained galena has less 

than 0.04 weight-percent silver (approximately 12 ounces per 

ton). The primary silver minerals dispersed in the galenas include polybasite, tetrahedrite, and jalpaite. Secondary silver 

sulfides, including argentite (or acanthite) and jalpaite, are 

concentrated in cerussite along fractures.

INTRODUCTION

The Burgin mine, in the East Tintic mining district, 

Utah, has recently become a major source of lead, zinc, 

and silver ores in an area that is widely known for rich 

and extensive replacement deposits (Lovering and 

Morris, 1960, p. 1116-1147; Bush and Cook, 1960, 

p. 1507-1540). The principal ore body in the mine, from 

which the samples described in this report were taken, 

is localized in sheared and brecciated rocks near the 

sole of the East Tintic thrust fault. This ore body is 

reported to contain more than 1,250,000 tons of ore with 

an average content of 10 ounces of silver per ton, 15 

percent lead, and 12 percent zinc (Mining Congress 

Journal, 1961). Several times this amount of lower 

grade ore forms a casing around the high-grade ore 

body, and other ore bodies, estimated to contain an even 

larger quantity of medium- and low-grade ore, have 

been discovered nearby. In general, the ores consist of 

various proportions of argentiferous galena, sphalerite, 

pyrite, and minor quantities of other metallic minerals 

in a gangue of rhodochrosite and baritic jasperoid. 

These minerals replace brecciated masses of Cambrian 

limestone that have been overturned and thrust over 

argillaceous limestones of Ordovician age. All the Paleozoic rocks in the mine area are concealed beneath altered quartz latite lavas of Eocene age that postdate the 

structural events but predate ore deposition.

The two ore types described in this report are representative of two major varieties of lead ore in the central part of the main Burgin ore body. Samples of both 

were collected by H.T. Morris in November 1965 from 

the 1,200-foot level of the mine shortly after the main 

ore body was first reached on this level. Type 1 ora is 

massive coarse-grained galena which forms a lead-rich 

zone near the f ootwall of the deposit. Type 2 ore is somewhat finer grained galena that is intergrown with minor 

sphalerite near the hanging wall of the deposit. T^he 

contact between the two types of galena ore is abrupt 

and apparently indicates.either a change in the composition of the ore solutions during deposition or postdepositional leaching and recrystallization of part of the ore 

body.

ACKNOWLEDGMENTS

The writers thank Mr. Gale Hansen, former mine superintendent, and Mr. William M. Shepard, mine geologist, for permission to sample the ore body of the Burgin mine. Dr. Victor Macres, President, Materials 

Analysis Co., generously permitted the use of Model 

400 electron-beam microprobe analyzers and other facilities at the company laboratories in Palo Alto, Calif.

PURPOSE AND PROCEDURE

Examination of the galena ores from the Burgin mine 

was undertaken to (1) study the distribution of silver, 

(2) identify all ore and gangue minerals, (3) study textural and physical relationships of the minerals, p,nd 

(4) study chemistry and element distribution of the 

minerals.

Mineral identifications were made by using the combined techniques of electron microprobe analysis, Xray powder diffraction, and microscopy. The extremely 

small grain size of many of the phases necessitated extensive use of the electron microprobe analyzer. Sample 

preparation wais done by Radtke and Taylor in the 

laboratories of the Materials Analysis Co., Palo Alto, 

Calif., and the U.S. Geological Survey, Menlo Park, 

Calif. All analytical work was done with Materials

Al
A2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Analysis Co. Model 400 two-channel and three-channel 

electron-beam microprobe analyzers.

Mineral textures and physical relationships were 

studied in polished section and, to a lesser extent, in 

hand specimen and are shown in numerous photomicrographs. The polished sections were made by mounting 

thin wafers of ore in epoxy casting resin set in stainless 

steel rings. The surfaces selected for study were ground, 

impregnated, and polished following the method described by Taylor and Kadtke (1965). Use of the stainless steel mounting ring and careful sample preparation resulted in virtually no loss or plucking of galena 

and other minerals from the surface, as well as in extremely low relief between galena and quartz.

Bulk samples of the galena ores were analyzed by 

standard wet-chemical and spectrographic techniques. 

The chemical compositions of all minerals were determined with the electron microprobe analyzer. Certain 

aspects studied in detail include chemical zoning within 

minerals and element-concentration gradients across 

mineral boundaries. Numerous electron-beam scanning 

(EBS) X-ray images illustrate element distribution 

between and within phases.

Instrument geometry for the Materials Analysis Co. 

Model 400 electron-beam microprobe includes (1) electron incident angle, phi (<£) = 62.5°; (2) X-ray takeoff angle, theta (0) = 33.5°; and (3) geometric factor 

for absorption corrections is esc (0) -sin(0) =1.6071.

Operating potentials (excitation potentials) used in 

semiquantitative and quantitative analyses were 30 kv 

(kilovolts), zinc and copper; 25 kv, iron and manganese; 20 kv, indium, sulfur, cadmium, antimony, lead, 

silver, calcium, and chlorine; 15 kv, arsenic; 7 kv, oxygen. All electron-beam X-ray scanning images were 

made at 20 kv operating potential except oxygen, which 

was made at 7 kv. The Ka characteristic lines were used 

for oxygen, silicon, sulfur, chlorine, calcium, iron, copper, and zinc; La characteristic lines were used for 

arsenic, strontium, silver, cadmium, antimony, and 

barium; the Ma characteristic line was used for lead.

Pure-element and compound standards used in the 

quantitative analyses included Fe, Cu, Zn, Ag, Cd, SiO2 , 

NaCl, GaAs, SrSO,, BaSO,, PbCO3 , PbS, and apatite. 

X-ray mass-absorption coefficients were taken from 

Heinrich (1966) and from unpublished data assembled 

by Metals Research, Ltd., Melbourn Boyston Herts, 

England. In the reduction of electron microprobe X-ray 

intensity data, corrections were made for (1) drift in 

the incident electron-beam current; (2) background 

from the continuous spectrum; (3) absorption effects; 

and (4) atomic-number effects. Atomic-number and 

absorption corrections were taken from tables by 

Adler and Goldstein (1965), calculated from absorption corrections by Philibert (1963), and the Dmcumb 

and Shields' (1966) overvoltage correction.

MINERALOGY AND CHEMISTRY

The first of the two types of ore, designate:! ''type 

1," is coarsely crystalline galena with thin coatings of 

secondary minerals. The second, designated "type 2," 

is massive fine-grained crystalline galena with minor 

amounts of sphalerite and abundant overgrowths of 

secondary minerals.

All minerals identified in the ore samples ar°> listed 

with their compositions in table 1.

TABLE 1. Minerals in the galena ores of the Bur gin mine

.___.. PbS 

______ ZnS

.__... FeS2 

______ CuFeS,

._._-_ (Cu, Zn, Ag) 12 (Sb, As) 4 S» 

______ (Ag, Cu) 16 Sb2 Sn

______ CU0 .46 Agj.54 S

------ Ag2 S

Sphalerite_

Chalcopyrite_ _ _ _ _ .

Tetrahedrite- _____

Polybasite- _______

Jalpaite. _________

Silver sulfide* 

Lead-antimony

oxide-carbonate. 

Cerussite. -__--__. 

Calcite_ __-______.

Mimetite. ________

Hematite. ________

Quartz. ___-_____.

Barite.. _________

Anglesite(?) ______

(Pb-Sb-C-0) f

PbC03

CaCO3

Pb5 (As04) 3 Cl

Fe2O3

SiO2

BaS04

PbS04

*Acanthite or arpentite.

f Precise composition not dptermined.

Small bulk samples of both type 1 and type 2 ores 

were crushed and ground for analysis. Chemical analyses for total lead and complete semiquantitative spectrographic analyses of galena ores are given in table 2.

GALENA

The coarsely crystalline galena of the type 1 ore contains small amounts of dispersed and associated gangue 

minerals, including quartz, barite, and calcite. Small 

rounded or oval grains of polybasite, tetrahedrite, and 

jalpaite are also dispersed through the galena; no acanthite or argentine was identified as primary inclusions or 

as exsolution blebs in the galena, and sphalerite is extremely rare.

In contrast to type 1, the fine-grained crystalline 

galena of the type 2 ore contains slightly greater 

amounts of quartz, barite, and calcite gangue minerals. 

Minor amounts of pyrite, tetrahedrite, and cl alcopyrite are associated with the gangue minerals, and sphalerite is locally abundant. Compared with the coarsegrained type 1 galena, the fine-grained variety is relatively free of dispersed rounded grains or inclusions 

that are commonly attributed to exsolution. Tv<?> most
MICROMINERALOGY OF GALENA ORES, BURGIN MINE, EAST TINTIC DISTRICT. UTAH A3

abundant inclusions are tetrahedrite. Jalpaite is minor, 

and no polybasite was noted.

TABLE 2. Chemical and spectrographic analyses of galena ores, 

Burgin mine

[Spectrographic analyses by Chris Heropoulos. Values in weight percent]

Element

Pb* 

Si..... . ..

Al_ -._-_-

Fe . .

Mg___ .......

Ca--- 

Ti... .... _._-

Mn. . .....

Ag_.. -

Massive

coarsely

crystalline

galena

(type 1)

85.3

.06

.006

.005

.0002

.005

0

.0015

.2

Massive

fine-grained

crystalline

galena

(type 2)

75.0

2.0

.02

.01

.0007

.01

.007

.0007

.15

Element

Ba 

Cd ....

Cr ...

Cu_____-_._-

In .- ..

Ni ---

Sb... .____-_-

ST.... ...... -

Zn_________.

Massive

coarsely

crystalline

galena

(type 1)

0.0007

.007

.00015

.02

0

.0005

.5

.005

0

Massive

fine-grained

crystalline

galena

(type 2)

0.2

.03

.0003

.07

.005

.0005

.03

.01

.5

 Determined by chemical gravimetric technique.

Note: Spectrographic results are reported in percent to the nearest number in the 

series 1, 0.7, 0.5, 0.3, 0.2, 0.15, 0.1, . . . , which represent approximate midpoints 

of interval data on a geometric scale. The assigned interval for semiquantitative 

results will include the quantitative value about 30 percent of the time. Tested 

for but not found in spectrographic analysis: Na, K, P, As, Au, B, Be, Bi, Ce, Co, 

Eu, Ga, Ge, Hf, Hg, La, Li, Mo, Nb, Pd, Pt, Re, Sc, Sn, Ta, Te, Th, Tl, U, V, 

W, Y, Yb, Zr.

The two types of galena show distinct differences in 

silver and antimony contents. The fine-grained galena 

does not contain detectable amounts of either silver or 

antimony in the mineral structure. The limit of detection for both elements in PbS by electron-beam microprobe analyses is 0.04 percent. In contrast, the coarsely 

crystalline galena has an approximate average content 

of 0.22+0.02 weight-percent silver and 0.25+0.02 

weight-percent antimony. The value for silver is considerably higher than the 0.16 weight-percent reported 

byTaylor (1967) for galena-clausthalite associated with 

rich silver ores from Republic, Wash.

Small increases in both the silver and the antimony 

content in galena are apparent within 100 microns of 

polybasite inclusions. Such increases were not found 

within corresponding distances from the tetrahedrite inclusions. Other elements such as copper, zinc, iron, cadmium, arsenic in tetrahedrite, and copper in polybasite show no concentration in galena near these two 

minerals.

POLYBASITE

The small oval grains of polybasite dispersed in the 

massive coarsely crystalline galena of type 1 occur both 

singly and as a series of grains in a chainlike or linear 

orientation (fig. 1). The general composition of these 

grains in the galena host is given in table 3.

Polybasite is the antimony-rich end member in the 

polybasite-pearceite isomorphous series. In polished 

section under reflected light, it is pale brownish gray. 

The largest grains observed in the Burgin galenas are 

approximately 8 microns long and 4 mircons wide.

TABLE 3. Analyses of polybasite

Element » Weight 

percent 2

S_ _____ __ _ _--_ 12-16

Sb____ 10-14

As*__ 

Cu 3-4

Ag_________________________ 65-70

1 Determinations by electron microprobe semiquantitative 

analysis.

2 Values represent element abundance ranges. 

*Arsenic tested for but not detected «0.03). No other 

elements detected.

TETRAHEDRITE

Rounded or oval grains of tetrahedrite are dispersed 

through both types of galena (fig. 1) and also occur 

closely associated with gangue minerals in the finegrained type 2 galena. All grains of tetrahedite analyzed contained small and varying amounts of silver, 

indicating that the variety in the Burgin ores should be 

designated as "silver-bearing tetrahedrite." Chemical 

analyses of tetrahedrite dispersed through galena and 

of tetrahedrite associated with gangue minerals show 

small variations in composition (table 4). A photomicrograph of a relatively large grain of tetrahedrite 

in galena is shown in figure 2.

TABLE 4. Analyses of tetrahedrite 

[Values, given in weight percent, represent element abundance ranges]

Element '

S_ 

Sb... ... _ As.. 

Cd 

Dispersed in 

galena

24-28

16-20

3.5-5

.5- .6

With gangue 

in galena

24-28

20-26 3- 4

.6

Element >

Fe- . ...

Ag 

Cu.- ---

Zn . ...

Dispersed in 

galena

0.7

1. 1- 1. 3

35-40

6- 6.5

With gangue 

in galena

0.4

3. 2- 3. 5

35-40

6-6.5

i Determination by electron microprobe semiquantitative analysis. No other 

elements detected.

Chemical analyses of tetrahedrite show the ratio of 

antimony to arsenic, in weight percent, to be about 

4-6:1. Tetrahedrite dispersed through galena compared 

with that associated with gangue contains consistently 

higher contents of arsenic and iron, and lower contents 

of antimony and silver (table 4). Preliminary studies 

show that the silver content in individual grains vary 

randomly up to the limits given in table 4; similar work 

was not done for other elements in tetrahedrite. Large 

amounts of zinc (6.0^6.5 percent) are present in the 

tetrahedrite and are accompanied by significant 

amounts of cadmium. Of the numerous tetrahedrite 

analyses listed by Palache, Berman, and Frondel (1944) 

none contain cadmium, which ranges to half a percent 

or more in the Burgin tetrahedrites.

Tetrahedrite in coarse-grained type 1 galena commonly occurs in relatively large (20-30 micron) grains. 

In contrast, tetrahedrite grains in fine-grained type 2 

galena are much more numerous and much smaller 

(<l-2 microns in diameter). Under reflected light 

tetrahedrite in these ores is pale gray.
A4 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

 ^FIGURE 1. Chainlike series of polybasite 

(Pol) and tetrahedrite (Tet) inclusions in 

galena (Gal). In general, inclusions of these 

two minerals in galena show no preferred 

orientation. Magnification X 445. A-D, Xray scanning images for Sb, Ag, Cu, and Pb 

in the area outlined in figure 1. The symbols 

in the lower left-hand corner indicate the 

element represented by the bright areas of 

the photograph. Magnification X 650.
A5

FIGUEE 2. Large grain of tetrahedrite (Tet) 

locked in fine-grained galena (Gal). Darkgray phase is quartz (Qtz) gangue, and 

dark band along top of figure is mounting 

resin. Magnification X 330. Chemical data 

on this large tetrahedrite grain are given 

in table 4.

JALPAITE

Minor amounts of primary jalpaite were identified in 

coarse-grained type 1 galena as small clusters of round 

grains or inclusions (fig. 3). Although not closely associated with tetrahedrite, jalpiate is commonly present in and near areas of significant amounts of tetrahedrite. (See fig. 4.) The mineral is also secondary in 

origin and occurs in small grains (<l-2 microns in 

diameter) scattered through cerussite. Chemical analysis of jalpaite is given in table 5. The formula for jalpiate, as reported by Skinner (1966), is Cuo.^Agi.ggSi.oo 

or (0.45Cu2 S 1.00Ag2S), having a cation to sulfur ratio

of 2:1. From the analysis given in table 5 for copper 

and silver, and by calculating the atomic ratios and normalizing the cations to 2.00, the formula for jalpaite 

in Burgin ores is Cuo^eAgi^Si.oo or (0.46Cu2S1.54Ag2S).

TABLE 5. Analysis of jalpaite

Element Weight percent 

S__....________.___.-__-_ 15. 5±0. 5

Ag.______.__._..._..__...__-_ 72±1

Cu______ _________ ________ 12. 5±0. 2

100.0

i Determinations by electron microprobe quantitative 

analysis. No other elements detected.

FIGUEE 3. Granular intergrowth of jalpaite 

(Jal) and galena (Gal) surrounded and replaced by cerussite (Cer). Fine-grained 

fragments in cerussite are remnant galena 

(Gal). Magnification X 645.

Gal

317-359 O - 69 - 2

..».

m

/ T

FIGURE 4. Mimetite (Mim) forming along a microfracture in galena (Gal). Large dark areas are quartz (Qtz) gangue. Two large grains of tetrahedrite (Tet) and one 

small jalpaite (Jal) grain are locked in galena. Note two areas of microintergrowths in galena on right side of photograph. In these areas the darkest phase 

is mimetite, the lighter gray phase is tetrahedrite, and another gray phase (slightly darker than tetrahedrite) is a lead-antimony oxide or carbonate. Magnification x 330. A-K, X-ray scanning images for Si, O, Fe, Cu, Zn, Ag, Pb, S, As, Sb, and Cl in the area outlined in figure 4. The symbols in the lower left-hand corner 

indicate the element represented by the bright areas of the photograph. Magnification X 400.
A8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

LEAD-ANTIMONY OXIDE OB CARBONATE

An unknown secondary mineral containing large 

amounts of lead, antimony, and oxygen, plus a significant amount of iron, is closely associated with mimetite 

in the ore. Although the mineral is present in both types 

of galena ore, it is much more abundant in the finegrained ore. In the massive coarse-grained galena ore, 

it is confined to, and dissemintaed through the cerussite 

coatings on galena. In the fine-grained galena ore, too, 

the mineral is confined to, and dispersed in, cerussite 

coatings on galena but is also common with mimetite 

and cerussite along microfractures in the galena (fig. 4) 

and as a thin (<1 micron) selvage between quartz 

grains and galena. Although the mineral is abundant, it 

everywhere is present only as particles 2-4 mircons in 

diameter.

Detailed quantitative electron microprobe study indicates that the mineral contains approximately 40 percent lead, 22 percent antimony, 2.2 percent iron, and 0.4 

percent calcium. Sulfur is not present, and wavelengthshift studies on Sk« show no sulfate (SCXf2 ) to be 

present near the mineral. Behavior of the mineral under 

electron bombardment strongly suggests that it is anhydrous. Since the antimony, lead, iron, and calcium 

contents, when converted to oxides, are considerably less 

than 100 percent, and the mineral is confined to cerussite 

or a system rich in CO3~2 molecule, it seems likely that 

the carbonate, or bicarbonate, is present. If the mineral 

is a carbonate, a general formula close to the following 

would be reasonable on the basis of known data:

3 (Pb,Fe,Ca) CO3 Sb2O3 , or 

3(Pb,Fe,Ca) (HCO3 ) 2 -Sb2O3

The small particle size and interference from carbon 

and oxygen in cerussite surrounding the mineral prevented accurate carbon and oxygen analyses.

SPHALERITE

Sphalerite was not observed in the coarse-grained 

type 1 ore, but it is abundant as small grains interlocked 

within galena in the fine-grained type 2 ore. Locally, it is 

concentrated with quartz and barite, commonly rimmed 

by galena, which clearly replaces the earlier sphalerite 

crystals (fig. 5).

Chemical analyses of sphalerite grains are given in 

table 6. Numerous analyses were made on sphalerite 

grains, and the general discussion on composition of 

sphalerite given here incorporates data obtained from 

all analyses on the samples studied.

TABLE 6. Analyses of sphalerite

Weight 

percent" 

0.5-1.0 

.02- .3 

.09

1 Determinations by electron microprobe semiquantitative analysis. No other 

elements detected.

2 Values represent element abundance ranges.

Continuous quantitative analyses for iron, cadmium, 

and indium were made along traverses across numerous sphalerite grains. The concentration of iron in 

most of the sphalerite grains is below the limit of 

detection (0.02 percent). The maximum amount found 

was 0.07 percent, but the minor concentrations apparently vary widely between grains and even within individual grains. In all the traverses the cadmium content 

varied directly with that of iron, and the maximum 

amount of cadmium found, 1.0 percent, was in the area

Element >

Zn_. ....................

Fe .. 

Weight 

percent " 

30 -35

60 -70

<.02- .07

Element '

In..... ...... .........

Cu-_ ....................

FIGURE 5. Replacement of remnant grains 

of sphalerite (Sph), quartz (Qtz), and barite 

(Bar) by galena (Gal). Note alteration of 

galena to cerussite (Cer) near center of figure. The mineralogy and chemistry of microintergrowth areas in galena, outlined in the 

figure, are shown in detail in figures 4, 4AK, and 11, UA-K. Mimetite formed along 

microfractures is present in both outlined 

areas. Magnification X 80.
MICROMINERALOGY OF GALENA ORES, BURGIN MINE, EAST TINTIC DISTRICT, UTAH A9

containing 0.07 percent iron. In contrast, the distribution and abundance of indium in sphalerite does not 

correspond to that of iron or cadmium. The highest 

indium content found was 0.3 percent, and the average 

is estimated to be 0.04 percent. Other elements specifically tested for in sphalerite but not found include silver, 

manganese, mercury, tin, gallium, and thallium.

Of particular interest is the cathodoluminescence of 

the sphalerite in the Burgin ores, which is apparently 

dependent on the minor element content. Under highenergy electron bombardment, the cadmium-bearing 

sphalerite emits radiation in the visible spectrum range 

that apparently varies with the concentration of cadmium in the following way: (1) >0.08 percent Cd, faint 

yellow white; (2) 0.05-0.07 percent Cd, faint greenish 

yellow; (3) 0.03-0.05 percent Cd, pale blue; (4) <0.03 

percent Cd, pale red.

Since the iron content varies directly with the cadmium content, these color variations may also reflect 

small differences in the abundance of iron. Other elements considered to influence cathodoluminescence in 

sphalerite, such as manganese, may affect it. However, 

if present, such elements occur in amounts below the 

limit of detection in the samples studied.

PYBITE AND CHALCOPYBITE

Rare grains of both pyrite and chalcopyrite are 

present in the fine-grained type 2 ore, but are absent in 

the coarsely crystalline type 1 ore. Both minerals commonly occur in grains less than 10 microns in length. 

(See fig. 6.) No complete chemical analyses were made 

on these phases.

MIMETITE

Mimetite in small amounts was also identified in type 

2 ore. It occurs with cerussite, minor amounts of anglesite ( ? ) , and calcite as a coating or overgrowth on galena. 

Commonly, it fills minor voids between the quartz or 

barite grains and the galena (fig. 7), as well as the microfractures within galena (fig. 4). Other secondary 

minerals commonly associated elsewhere with mimetite, 

such as smithsonite, hemimorphite, and wulf enite, were 

not identified. Their absence may reflect the general low 

abundance of iron, zinc, vanadium, and copper in the 

galena ores. The general low abundance of mimetite in 

the ore also doubtless reflects the low concentration of 

arsenic in the Burgin galena ores.

A complete chemical analysis of mimetite in the Burgin ores is given in table 7.

TABLE 7. Analysis of mimetite

Element '

Pb.

percent 

69 ±2

. 4± . 1 

15 ±1 

2. 8± .2 

13 ±2

Total_____________ 100.2

i Determinations by electron microprobe quantitative 

analysis. No other elements detected.

CEBUSSITE

Large amounts of cerussite are present in both types 

of ore, both as surface coatings and along fractures and 

cleavage directions in galena. The cerussite commonly 

contains intergrowths of mimetite, jalpaite, secondary 

silver sulfide, secondary lead-antimony oxide or carbonate, and minor amounts of hematite, calcite and anglesite^). The typical alteration of galena to cerussite 

along galena cleavage planes is shown in figure 8. Even 

in areas where this alteration is massive and virtually 

complete, numerous small inclusions of remnant galena 

remain. Although minor amounts of anglesite may be

FIGURE 6. Veinlet of late(?) barite (Bar) 

containing fragments of pyrite (Py), chalcopyrite (Cpy), sphalerite (Sph), and galena 

(Gal) cutting across quartz (Qtz). Note tiny 

inclusions of tetrahedrite (Tet) and sphalerite in galena fragments, and cerussite (Cer) 

along margin of veinlet. Magnification X 

330.
A10 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Gal

7. Mimetite (Mim) along contact between galena 

(Gal) and barite (Bar) gangue. Small amounts of cerussite (Cer) are also present. Small white grains in mimetite are remnant galena grains. Magnification X 1,290. 

A-F, X-ray scanning images for Cl, As, O, Ba, Pb, and S 

in the area outlined in figure 7. The symbols in the 

lower left-hand corner indicate the element represented 

by the bright areas of the photograph. Magnification 

X 1,500.

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MICROMINERALOGY OF GALENA ORES, BURGIN MINE, EAST TINTIC DISTRICT, UTAH All

present with cerussite, no typical intermediate zone of 

lead sulphate was observed between the lead carbonate 

and the lead sulfide.

SILVER SULFIDE

Large amounts of argentite or acanthite of secondary 

or supergene origin containing minor amounts of copper (0.5-0.8 weight-percent Cu) are admixed with, and 

dispersed through, cerussite (fig. 9). The extremely 

small size of individual silver sulfide grains (<l-2 microns) precluded obtaining either the optical data or 

the X-ray diffraction data necessary for positive identification. Aggregates of granular grains that formed 

contemporaneously with cerussite are shown in X-ray 

scanning images (fig. 9A-E).

No primary argentite (or acanthite) was identified 

with the galena either as an individual intergrown mineral or in dispersed rounded exsolution-type grains.

HEMATITE

Minor amounts of hematite are present with cerussite in areas of extensive alteration of galena to the lead 

carbonate. The low abudance and erratic distribution 

of hematite reflects the corresponding occurrence of 

primary iron-bearing sulfides. X-ray scanning images 

for oxygen (fig. 115) and for iron (fig. 11(7) show 

the close association between hematite, cerussite, and 

the other alteration products.

FIGURE 8. Alteration of galena (Gal) to 

cerussite (Cer) localized along cleavage 

planes. Note remnant galena grains in cerussite. Small black spots are micropits produced in sample preparation. Magnification 

X 80.
A12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

FIGURE 9

FIGTTEE 9. (Explanation on next page.)
MICROMINERALOGY OF GALENA ORES, BTJRGIN MINE, EAST TINTIC DISTRICT, UTAH A13

CALCITE AND ANGLESITE(P)

Minor amounts of both calcite and anglesite(?) are 

present with cerussite in both types of ore in areas 

where alteration of galena to cerussite is relatively complete. The calcite is commonly associated with mimetite and anglesite( ?). As previously noted, anglesite is 

not concentrated along galena-cerussite contacts.

BARITE AND QUARTZ

Small amounts of barite and quartz form the gangue 

minerals in fine-grained type 2 ore. Only a few scattered 

grains of each were recognized in coarse-grained type 1 

ore. Both minerals are dispersed through galena, and 

textural evidence clearly shows replacement of the early 

gangue minerals by galena (figs. 5, 10). The elongated 

and segmented appearance of barite crystals shown in 

figure 10 is common in the fine-grained ore. Barite generally occurs with quartz, although the reverse is not 

necessarily true.

Small veinlets of barite cutting galena and quartz 

suggest a second generation of late postore bariite. These 

veinlets commonly contain numerous fragmental inclusions of early sulfide minerals (fig. 6).

ELEMENT DISTRIBUTION

Electron-beam scanning techniques allow graphic 

portrayal of the distribution of many key elements in 

the galena ores. These EBS X-ray scanning images are 

presented throughout the report.

Silver. In the primary minerals silver is present in 

polybasite jalpaite, and tetrahedrite, although in tetrahedrite the silver content is far below the 17-19 percent 

apparent maximum level for freibergite. The two types 

of galena contain different amounts of silver. In areas

FIGURE 9. Fine-grained secondary silver sulfide 

(Arg) dispersed in secondary cerussite (Cer). Note 

argentite or acanthite concentrated in narrow zone 

between galena (Gal) and inclusion-free cerussite. 

Black areas are micropits in cerussite. Magnification X 160. A-C, X-ray scanning images for Ag, S, 

and Pb in the area outlined in figure 9, Magnification X 240. D and E, X-ray scanning images for Ag 

and S at high magnification, showing typical finegrained (<2 microns) silver sulfide dispersed 

through the lead carbonate matrix. Magnification 

X 1,300.

FIGURE 10. Replacement of remanant quartz (Qtz) 

and segmented barite (Bar) by galena (Gal), which 

was subsequently altered to cerussite (Cer). Small 

white grains in cerussite are remnant galena and 

secondary silver sulfide (Arg). Magnification X 80.

near the polybasite inclusions, silver occurs as a small 

but definite concentration. Argentite, commonly reported to be intergrown with, or dispersed in, "silverbearing galena," was not identified in the galena of the 

samples studied. Jalpaite and argentite (or acanthite) 

of supergene or secondary origin apparently formed 

with cerussite. This is particularly evident in figure 9 

and in the X-ray scanning images for silver, sulfur, and 

lead distributions in figure 9A-E. A minimum of 50 

percent of the total silver in the samples studied was 

represented by this latter occurrence.

Antimony. The distribution and concentration of 

antimony in primary minerals in the ore is similar to 

that of silver with antimony concentrated in polybasite 

and tetrahedrite and in coarse-grained galena. The distribution of antimony, silver, copper, and lead between 

polybasite and tetrahedrite locked in galena are shown 

in X-ray scanning images (fig. 1A-D).

During oxidation and alteration of galena, antimony 

is concentrated in the secondary lead-antimony oxide or 

carbonate phase in cerussite. No antimony is present in 

the cerussite itself, with the limit of detection for antimony in lead carbonate of 0.04 percent.

Copper. The minor amount of copper in primary 

sulfide ores is closely associated with silver and antimony in polybasite and tetrahedrite, and associated 

with silver in jalpaite. Only trace amounts of chalcopyrite were observed, and no simple sulfides of copper were 

recognized. The paucity of secondary or supergene 

copper minerals reflects the apparent general low abundance of copper compared with lead in the ore body. 

Jalpaite, the silver copper sulfide, was the only secondary copper mineral identified. The concentration of copper in sulfosalt minerals in galena is shown in X-ray 

scanning images (figs. W, 4Z>, 11Z>).

Gal

FIGURE 10
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A*1

JT

ATT

KV

FIGUBE 11. Alteration of galena (Gal) to cerussite (Cer). Note tetrahedrite (Tet) intergrown and locked in galena. Magnification X 645. A-K, X-ray scanning images 

for Si, O, Fe, Cu, Zn, Pb, Sb, As, Cd, S, and Cl in the area outlined in figure 11. The symbols in the lower left-hand corner indicate the element represented by 

the bright areas of the photograph. Magnification X 400. Several minerals not included in the area shown in figure 11 but shown in X-ray scanning images include mimetite (11B, oxygen, F, lead, H, arsenic, K, chlorine), sphalerite (E, zinc, 7, cadmium), and hematite (B, oxygen, C, iron).

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I

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M GOoOr
A16 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Arsenic. In contrast to antimony, the concentration 

of arsenic is low in primary galena ores (table 2). No 

arsenic sulfides or arsenic-rich sulfosalt minerals were 

identified. Mimetite has formed near contacts between 

gangue and galena (fig. 7) and along microfractures in 

galena (fig. 4). X-ray scanning images for arsenic in 

corresponding areas are given in figures 47 and 77?. 

Concentration of arsenic in mimetite associated with 

other secondary minerals suggests some migration of 

arsenic in the ore during oxidation and alteration.

Lead. Galena is the dominant primary lead mineral 

in the ore and accounts for more than 95 percent of the 

total lead in the samples studied. No primary lead-bearing sulfosalt minerals were identified in the galena. The 

low lead content (<0.04 percent) in tetrahedrite surrounded by galena suggests a very limited solubility for 

lead in tetrahedrite.

In the sections studied, less than 5 percent of the 

total lead is in the alteration mineral, cerussite. Alteration of galena to cerussite with remnant inclusions of 

galena reflects in situ oxidation of the sulfide ore. The 

apparent tendency for lead sulfide to alter directly to 

lead carbonate without the formation of lead sulfate 

suggests that oxidation took place in a slightly acid to 

alkaline environment with relatively high activity of 

total carbonate species. (See Eh-pH diagram, Garrels 

and Christ, 1965, p. 237, 238.)

Zinc. The dominant part of the zinc in the primary 

sulfide ore is present as sphalerite, although tetrahedrite, relatively rare in the ore, contains significant 

amounts of zinc. Zinc in tetrahedrite and sphalerite are 

shown in X-ray scanning images, figures 47? and 117?, 

respectively. Secondary zinc minerals such as smithsonite and hemimorphite were not identified with cerussite and mimetite, even in those areas showing intense 

alteration. The apparent absence of any zinc carbonate 

or zinc sulfate species may be explained by their much 

greater solubility relative to the corresponding lead 

species.

Cadmium and indium. Both cadmium, and indium 

are concentrated in the sphalerite of the Burgin ore 

body. Significant amounts of cadmium, along with 

large amounts of zinc, are also present in tetrahedrite 

and reflect the similar geochemical behavior of the two 

elements. The binary cadmium sulfide, greenockite, was 

not identified. Indium was identified in sphalerite only. 

Analysis of secondary minerals associated with both 

types of galena ore shows no concentration of either 

cadmium or indium.

Iron. Iron is low in abundance in both types of 

galena ore (table 2). This is reflected mineralogically 

by the very limited amount of pyrite in the ore sample 

studied. Other iron-bearing minerals, including chalcopyrite and tetrahedrite, are minor in abundance, and

the sphalerite is virtually iron free. Secondary minerals 

coating the samples and filling fractures cutting across 

them are also virtually iron free. No iron carbonate was 

found, although small amounts of the iron oxide 

hematite were identified locally. Small amounts of 

hematite, closely associated with cerussite, lie just outside the area shown in figure 11. The iron oxide mineral 

is shown in X-ray scanning images for iron (11#) and 

oxygen (115). Figure 6 shows a photomicrograph of 

pyrite and chalcopyrite in barite.

SUMMARY AND CONCLUSIONS

The mineralogy of massive galena ores of the Burgin 

mine in general is deceptively simple, but in detail it presents many complexities. Substantial mineralogical differences exist between the two general types of ore and 

are reflected in chemical analyses of the bulk ore. The 

massive coarse-grained type 1 ore is chiefly galena, 

whereas the massive fine-grained type 2 ore, although 

dominantly galena, carries significant amounts of 

sphalerite.

The oxidation and alteration of galena to cerussite 

along fractures and cleavage directions is well developed 

in both types of ore. In contrast, sphalerite, identified 

only in the fine-grained ore, is fresh and unaltered.

Compared with the apparently limited movement and 

the lack of zinc enrichment in the ore, silver as a 

constituent of the obviously secondary or supergene 

minerals jalpaite and argentite (or acanthite) is concentrated in, and dispersed through, secondary lead 

carbonate. Although the amount of silver sulfide-rich 

cerussite is small compared with the primary galena in 

the samples studies, more than 50 percent of the total 

silver content is in this form.

Much of the silver in the primary sulfide ore is in 

grains of polybasite and tetrahedrite and in smaller 

amounts of jalpaite dispersed through galena. In many 

"argentiferous galena" ores the small disseminated inclusions commonly assumed to be "exsolution argentite" 

probably are actually complex sulfosalt minerals.

The coarsely crystalline "argentiferous galena" contains detectable amounts of silver in the galena, and 

locally, near the sulfosalt inclusions, there is a notable 

concentration of the element. In contrast, the finegrained galena is very low in silver, containing only 

about one-fifth of the silver found in the coarsely crystalline type. The solubility of silver in galena varies 

directly with that of antimony.

Only minor amounts of zinc-rich tetrahedrite were 

found disseminated through galena. That its occurrence 

is only minor is an advantage, for the presence of larger 

amounts of the mineral would introduce harmful 

amounts of zinc and antimony into any lead concentrate 

produced by flotation milling.
MICROMINERALOGY OF GALENA ORES, BURGIN MINE, EAST TINTIC DISTRICT, UTAH A17

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U.S. GOVERNMENT PRINTING OFFICE: 1969 O 317-359