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American Mineralogist, Volume63, pages 720-724, 1978
weissbergite,Tlsbs2er n€wmineralfrom the carlin golddeposit,Nevada
FneNr W. DrcxsoN
Departmentof Geology,Stanford Uniuersity
Stanford, Calfo rnia 94305
eNoAnrsun S. Reorrn
U.S. GeologicalSuruey
Menlo Park, Calfornia 94025
Abstract
weissbergite,Tlsbsr, occursas irregular,broken or fracturedgrains,0.5 mm in maximum
dimension,in silicified,brecciated,
dolomiticcarbonaterocksin the eastpit of the Carlin gold
deposit,Nevada. weissbergiteis opaque,steel-grayin thick plates,and bright metallfuin
luster on fresh surfaces.The mineral is triclinic and apparentlylacksa centeiof symmetry.
A p p r o x i m a t e c e l l c o n s t a n t s alrl e
. 8a,=r : 6 . 4 , c : 6 . 1 A ; a : 1 0 9 . 9 " , g : g l . g . , a n d 7 :
105.4o;Z : 4; cell volume : 420As.StrongestX-ray diffraction lines and their relative
intensities
(subjectto strongpreferredorientation)are:2.971
(100),3.5g3(9), 3.651(9), and
2.839(7);40 lineswereobserved.Weissbergite
displaysseveralcleavages:
one, perfect;two,
excellent;and at leastone,good. Its Vickershardnessis about 35 kg mrn-, (Mohs hardness,
about 1.5).The measured
densityof syntheticTlSbS,is 5.79(5)g c;-'; calculated
densityis
6.1 g cm-e' In reflectedlight the mineral is creamywhite, weakiybireflectant,and strongly
anisotropic,with polarization colors of blue-green,blue-black,orange-brown,uno grly.
Reflectances
(i) in air are:650nm: 32.1-33.g;
sggnr = 34.5-35.g;
546nm: 3s.0-30.a;
ano
470nm: 36.0-38.4.Thin platesin transmittedlight showpleochroismin deepcolors,ranging
from red to orange-redand yellow-orange.Weissbergite
ls essentiallypure TlSbSr;eleciron
microprobeanalyses
gave Tl 52.7,sb 31.2,s 16.4,sum 100.3weight percent.The most
abundanttrace elements,determinedby emissionspectrographic
analysis,are 300 ppm As
and 200 ppm Fe. The mineral is named in honor tr o.. ny.on G. weissberg,chernistry
Division,D.S.I.R.,New Zealand.
butions to the geochemistryof epithermalhydrothermal processes.He was the first to point to a
similarity in the heavy-element
geochemistryamong
the Carlin-typegold depositsand to show that the
same elementsoccur in some hot-spring sinters of
New Zealand(Weissberg,1969).The mineral name
and designationasa newmineralhavebeenapproved
by the Commissionof New Minerals and Mineral
Namesof the InternationalMineralogicalAssociation.
Type materialis depositedin the EpithermalMinerals Collection,Departmentof Geology,Stanford
University,Stanford,California.
'Mineral name
and designation as a new mineral approved by
Commission of New Minerals and Mineral Names, International
Mineralogical Association, December 1977.
0003-N4X/ 78/0708-0720$02.00
720
Occurrence
Weissbergite
occursin small amountswith stibnite
and quartz in silicified dolomitic carbonaterocks
DICKSON AND RADTKE: WEISSBERGITE' A NEW MINERAL
721
and syntheticTlSbS,
of weissbergite
Table l. Reflectivities
alongbrecciazonesand high-anglefaultsthroughthe
upper part of the Roberts Mountains Formation in
(m)
wavelength
Phase
the eastore zoneof the Carlin gold deposit.Individual weissbergitegrains ranging in size from about
650
470
0.005 to 0.5 mm in length are locked within small
massesof quartz, and locally are in contact with
36.0-38.4 35.0-36.8 34.5-35.8 32.1-33.8
wel6sberglte
length;
in
most
largerstibnitegrains,up to l2 mm in
27.r-33.4
29.5'36.9
33,0-39,3
31.1-40,2
TlsbSz
synthetlc
stibnite,and quartzappearto
placesthe weissbergite,
have formed in open spacesbetweenbreccia fragments.
34.6kg mm-2(10 determinations);
Weissbergitein this associationhas beenfound in 37.1and averaged
samplescollectedat two localities in the east ore the hardnessof syntheticTlSbS,measuredundersimzone;theseareasare nearminecoordinates23,000N, ilar conditionsrangedfrom 28'0to 40.6and averaged
Theseaverageval19,800E, 6450bench,and 23,850N, 22,700E, 6350 35.3kg mm-2 (8 determinations).
of about l-5. The
to a Mohs hardness
uescorrespond
bench(Radtke,1973).
densityof syntheticTlSbS,determinedon a Berman
Physicaland optical ProPerties
balanceis 5.79 + 0.05g cm-s;grainsof weissbergite
Weissbergiteoccurs as irregular grains, many of suitable for density measurementwere not found.
which are broken or fractured(Fig. l). A few of the The densitycalculatedfrom unit'cell parametersis
is opaque,steel-grayin
grainswereprismaticor tabular in form and showed 6.1 g cm-3. Weissbergite
luster' The streakis
metallic
striations parallel to the long dimension.Synthetic color, and has a bright
reflectedlight for
properties
in
TlSbS,grainsusuallyare equantto tabular in shape, dark gray. Optical
are similar. In
weissbergite
for
and
of pedions. syntheticTlSbS,
andareboundedby simplecombinations
white, weakly
creamy
is
mineral
the
light
Brokengrainsofweissbergitedisplayseveralcleav- reflected
Polarization
anisotropic'
strongly
and
ageswhich we werenot ableto relateto crystalforms. bireflectant,
orange-brown,
blue-black,
blue-green,
include
perfect,
and
colors
two excellent,
includeone
The cleavages
and synat leastonegood. Cleavedfragmentswhich lie on the and gray. Reflectivitydata for weissbergite
l.
given
in
Table
are
TlSbS2
thetic
thickness
increased
perfect cleavageshow steps of
Optical propertiesin transmittedlight were diffitypical of micaceousminerals.The tracesof someof
intercult
to measurebecauseof the deep color and high
cleavage
the
micaceous
on
the other cleavages
of refraction. One thin crystal displayedan
angles
true
indices
(57'
but
the
and
67o),
acute
angles
sectat
acutebisectrixfigurewith a 2V of about70", and was
could not be measured.
betweencleavages
The Vickershardnessmeasuredwith a Leitz hardnessindentor with a 25 g load rangedfrom 26.0 to
Fig. 1. Grains of weissbergitefrom the Carlin gold dePosit.
White and colorlessgrainsare quartz.
CrYstallograPhY
and
X-ray powderdiffractiondata for weissbergite
prestrong
which
showed
of
syntheticTlSbSr,both
ferred orientation,are given in Table 2' The agreement betweenthe d spacingsof the mineral and synthetic TlSbS,is excellent.Our data do not agreewith
the data of Semiletevand Man (1959)or of Palatnick
et at. (1972),who reportedcubic and hexagonalmodificationsof thin films of TlSbSz.Thin, rapidly deposited TlSbSzis perhapsmetastableor possiblya polymorphicform.
of the unit-cell conApproximate measurements
stants were made by Dr' Kevin Brown, Chemistry
Division. D.S.I.R.,New Zealand.He used a single
722
DICKSON AND RADTKE: WEISSBERGITE, A NEW MINERAL
Table 2. X-ray diffractionpowder data for weissbergite
and synthetic TlSbS"
Table 3. Microprobechemicalanalysesof weissbergite
Grain
Welssbergite
Carlin,
Nevada
Tlsbs2
obs. d (i)
<1
3.811
3 . 74 3
3.708
3 ,6 5 1
)
5
9
l_1"
3.058
2 . 9 7L
9
7
I
4
Z.IOL
t Lo
;-.,,
<l
2.449
2.360
2,35L
z.zt5
I
5
5
2.095
2.054
2.0t2
t.979
I
I
1
q
I.964
1 012
I. YU)
I .843
1.830
1.801
L . 78 7
1.687
r.647
L.)IJ
1.519
J- . )Ub
L.486
I.CD/
<1
<l
1
1
2
4.44L
3.822
3.752
3.1L2
1
4
J. O)U
8
7
<1
<1
2
100*
2.839
7
1
6
<I
I
z. tJ6
2.7L8
2.609
t
<11
2.448
2.362
2.35L
2 . 2 74
2.223
2.209
2.096
2,0s6
2.OL3
1.980
1.963
r. 910
1. 903
1. 845
1. 831
<1
<1
1
I
<1
1,518
r.505
J
L.+6t
I
r.463
L.428
1
I
I
L.255
1. 200
1.130
TotaI
30.8
3 1 .3
16.4
9 9, 8
52.3
52.9
52.9
to. J
qoo
Jr.
3r.4
1 6 .5
1 6 .3
100,5
1 0 0 .6
Average
\1
3L.2
1 6. 4
100.2
TlSbS2
52.37
31.20
16.43
100.00
7
t
q
3.583
3.336
3,181
3.058
1. 802
L . 78 9
1.684
1.543
r.)/)
J
J
L.428
L.256
1.I99
1.130
Percent
Sb
1
L3.7
1 0 .7
9.4
5.88
4.798
100*
2.839
z.
Weight
TI
obs. d (l)
o,
5.87
4.8L2
no,
Synthetlc
1
o
<1
<1
I
1
1
2
2
3
5
1
1
I
2
I
5
2
a
1
1
1
Dlffractoneter
patterna
obtained with Nl-filtered
Cu
radlatlon,
I Cu Ib1, = 1.54051 A, 51 used as an
internal
standard,
scannlng speed 0.25c 20 per Elnute.
*IntenaLtLea
are affected
by strong
preferred
orLentatlon.
crystal of synthetic weissbergite;natural materials
provedunsuitablefor study.Unfortunately,only one
of the severalcrystalsexaminedyielded an ordered
pattern. This crystal was so small that the uncertaintiesin the cell measurements
werelarge.Attempts
to index the X-ray diffractionpowder data using the
approximatecell constantswerenot successful.
Both
the singlecrystal data and the crystal morphologies
are consistentwith triclinic symmetry.The approximatecell constants
ate:a: 11.8,, : 6.4,and c :
6.lAl' a : 109.9",0 : 81.8",andy : 105.4".The
unit-cell volume is 420As and Z : 4. The mineral
apparentlylacksa centerof symmetry,judging from
the absenceof parallel equivalentfaceson the syntheticeuhedralsinglecrystals,and thusit may belong
to the rare triclinic pedial class.
Chemicalcomposition
Microprobe analysesshow that weissbergiteis
TlSbSr. Resultsof chemicalanalysesof 4 grains of
the mineralusingsyntheticTlSbS,as a standardare
shownin Table3. An emissionspectrographic
analysis for a compositesampleof 5 grainsof weissbergite
indicatesthat the only elementspresentin other than
trace amountsare arsenic(300 ppm) and iron (200
ppm) (Table4).
Synthesis
Syntheticweissbergite
can be preparedby heating
Tl, Sb and S, or TlzS and SbrSr,in stoichiometric
proportionsin sealedevacuatedpyrextubesat 3500C
or higher for severaldays. Cooling melted TtSbS,
commonly produces rnassive buttons of polycrystallineweissbergite,which can be broken with
easeinto cleavagefragments.The deformation accompanyingthe cleavageprocessapparentlydisrupts
the crystal structure,causingcleavagefragmentsto
be uselessfor single-crystalstudy.
723
DICKSON AND RADTKE: WEISSBERGITE' A NEW MINERAL
The single crystals examined during the X-ray
by subjectingpure powdered
study were synthesized
TlSbS,in a horizontalsealedevacuatedpyrextube to
a slight vertical temperaturegradient in a Globar
furnaceheld at about 450"C for 6 days.The gradient
resultedfrom a flux of heat supplied by radiation
from above.Tiny (lessthan about0.03mm) equant
grew on the upper part of the
crystalsof weissbergite
glass tube; X-ray diffraction examination of powderedcrystalsshowedthat they had atomic spacings
identicalto the natural and massivesyntheticweissbergite. Four euhedral crystals were studied by
single-crystaltechniquesin efforts to measurecell
parameters;threeofthe crystalsproduceddisordered
patterns,and one gavean orderedbut faint pattern.
(o
o
ro
lr
tt,
c{
@
ll
!,
600
-566
L('
o
oa
-
oc
6
4o4ts2-
NT
400
it+ L
, -422
400
Prl
'-392
w+L
342 324-
-322
P +S t
w+P
w+<
Clc
200
o
Tl2S
20
40
60
80
Mol Percent Sb2S3
200
100
Sb2S3
as a functionof temperatureand bulk
Fig. 2. SystemTlrS-SbrSB
Phaserelations
comfosition, at the vapor pressure;slightlymodified,after Bohac
The phase relationshipsof weissbergiteto other ,t oi. 19ln1. Symbols:C : carlinite,TtS; a : TLSbS'; W =
TlSbSz;P : parapierrotite,TlSbuS';St = stibnite;
as determined weissbergite,
solid phasesin the systemTl2S-Sb2Ss,
:liquid,
Tl,S-Sb,Ss.
L
by Bohacet al. (1974)by differentialthermalanalysis and
(DTA) methods,are shownin Figure2. Weissbergite
melts congruentlyat 484'C. It showsa eutecticwith
TlSbS, reacts with TlAsSz(lorandite) to form a
and seriesof solid solutions(Dickson, 1976,unpublished
Tl'SbSs(a) at322'C and 30 molepercentSbzSs,
with TlSbuSs(parapierrotite;Johan et al., 1975)at data). The compoundsshow d spacingsthat vary
The a phase, from thoseof weissbergite
392"Cand about 73 molepercentSbzSg.
(pure TlSbSr)to a modiTlsSbSs,hasnot beenfound in nature,but it appears fied weissbergite
pattern at 50 mole percentTlSbSr.
likely that it existsat the Carlin deposit,judging from Inasmuchasloranditeis monoclinicand weissbergite
the occurrencethere of two minerals,carlinite(TlrS) is triclinic,an unlocatedstructuraldiscontinuitymust
and weissbergite(TlSbSr),with compositionsalong existin this systemsomewhere
between50 and 0 mole
join. The DTA studies percentTlSbSr.
the carlinite-a-weissbergite
revealedno evidencesof significantsolid solution.
imPlications
Geochemical
Bohac et al. (1974) used materialsof high purity,
melting
processed
refining;
their
by
zone
originally
Weissbergiteis another member of the suite of
temperaturesfor two other mineralphasesthat occur uniquemineralsformed in the Carlin gold depositby
on the diagram,carlinite (TlrS), 452"C, and stibnite late-stageprocesses
(Dickson and Radtke, 1977).In
(Sbrsr),566oC,are somewhathigherthan valuesre- addition to weissbergite,thallium minerals found
portedbefore,attestingto the purity of their phases. only at Carlin include carlinite, Tl2S; christite,
TlHgAsSr; and ellisite, TlaAsSg,a recently-named
Table 4. Semiquantitative spectrographic analysis of weissbergite
mineral. Rare minerals include lorandite, TlAsSz;
galkhaite,Hg(As,Sb,Tl)S;getchellite,SbAsS'; and
I.lelght
PercenE
EIeDent
WeighE Percent
Elenent
avicennite,TlrO, (Radtke et al., 1978a).Common
minerals are stibnite, SbrSs;orpiment, nearly pure
0,0001
Mn
0.0005
AC
or with someTl in solid solution;realgar,AsS;
0.0002
As2Ss,
Mo
0.03
As
0.005
Nl
0.0015
B
and cinnabar,HgS.
0.005
Pb
0.005
Ba
l4aJot
sb
0.00015
Bi
The vein mineralsformed during the latter part of
0
.
0
0
0
3
S
n
0
.
0
0
1
5
the hydrothermal episodewhen the solutions were
Co
0.0003
Tl
0.001
cr
j
boiling (Radtke et al., 1978b)and changingin coml.Ia or
Tl
0.002
Cu
0.0003
v
0.02
Fe
position.They lost COz,HzS, and HzO, and became
more alkaline and concentrated.Little is known of
of wels6bergite
of 5 grains
Analysis
G
a
,
G
e
'
H
f
'
C
e
,
E
u
,
B
e
'
C
a
,
C
d
,
the solubility behavior of thallium sulfosaltsunder
A
I
,
A
u
,
not
found:
[Sought but
In, K, La, Li' Ug' Na' Nb, P, Pd, Pt, Re, Sc, Sl, sr' Ta, Te, Th,
theseconditions, and specificprecipitation mechaU.S. Geological
Chris l{eropoulos,
Atralyst:
U, W, Y, \b, Zn, Zt.l
Survey.
nisms cannot be stated.Obviously,some unusual
DICKSON AND RADTKE: I|/EISSBERGITE, A NEW MINERAL
combinationof supplyor depositionalconditionsare
requiredto form the uniquesuiteof minerals.possibly the suite of elementsrequires special kinds of
rocks, suchas carbonates,which can reactwith solutions and causeprecipitation.A hint that the suiteof
elementsmay occur commonlyin hot-springwaters
was given by the observations
of Weissberg
(1969),
who reportedhigh levelsof Tl, Au, Ag, As, Sb, and
Hg in siliceoussinter depositsat Ohaki and other
hot-springoutletsof New Zealand.Dilute watersof
geothermalsystemsmay commonlycarry theseheavy
elements.The elementsprobablydo not precipitatein
observablequantities,exceptwhere they encounter
reactiverockssuchasthe carbonatehost rocks ofthe
Carlin deposit.During boiling, the solutionsbecome
enrichedin the heavyelements.Unusuallyhigh con_
centrationsin solution would causeprecipitationof
minerals,either by replacementof carbonate,or by
depositionin openfractures.
References
Bohac,P., E. Br6nnimannand A. Giiumann(1974)On the ternary
compoundTlSbS,and its photoelectricproperties.Mater. Res.
Bull.,9. 1033-1040.
Dickson,F. W. and A. S. Radtke(1977)Theuniquemineralogy
of
Hg-As-Sb-Tl sulfidesat the Carlin gold deposit,Nevada,and
implicationsasto the origin of the deposit(abstr.).Mineral. Soc.
Am.-Friendsof Mineralogy.3rdJoint Symposium,Tucson,Arizona, 13-14.
Iohan, 2., P. Picot, J. Hak and M. Kvadek (1975) La parapierrotite,un nouveaumin6ralthallifdred'Allchar(yugoslavie).
TschermaksM ineral. Petrogr. Mitt., 22, 200-210.
Palatnick,L. S., L. P. Zozulya,L. F. Zozulyaand L. G. Voinova
(1972)The structureof thin TlSbS,films.IzuestiyaAkad. Nauk
SS^SR,Seria Fizicheskaya, 36, 1986-1989.
Radtke,A. S. (1973)Preliminarygeologicmap of the Carlin gold
mine, Eureka County, Nevada. U.S. Geot.Suru. Misc. Field
StudiesMap MF-537.
and F. W. Dickson (1975)Carlinite,TlzS,a new mineral
from Nevada.Am. Mineral.,60, 559-565.
F. W. Dickson and J. F. Slack (1978a)Occurrenceand
formationof avicennite,TLO', a secondarymineralat the Carlin
gold deposit,Nevada.J. Res.U.S. Geol.Suro.,6, 241-246.
-,
R. O. Rye and F. W. Dickson(1978b)Geologyand stable
isotopegeochemistry
ofthe Carlin gold deposit,Nevada.Econ.
Acknowledgments
Geol.(in review).
The help and encouragement
of the staff of the Carlin Gold
-,
F. W. Dickson,J. F. Slack and K. L. Brown (1927)
Mining Companyand Newmont Mining Corporationis acknowl_
Christite,a new thallium mineralfrom the Carlin gold deposit,
edgedand appreciated.A. J. Ellis, ChemistryDivision,D.S.I.R.,
Nevada.Am. Mineral., 62. 421-425.
-,
C. M. Taylor, R. C. Erd and F. W. Dickson0974) Occurrenceof lorandite.TlAsSr.at the Carlin gold deposit,Nevada.
Econ. Geol.,68, l2l-123.
Semiletov,S. A. and L. I. Man (1959)Electrondiffractionstudyof
the structureof thin films of TlBiSe,and TlSbSr.Kristallogra_
istry Division,D.S.I.R.,New Zealandand R. C. Erd, U.S. Geolog_
4, 414417.
fiya,
ical Survey.The encouragements
and suggestions
given through_
Weissberg,
B. G. (1969)Gold-silver ore-gradeprecipitatesfrom
out our study by Akiro Kato, Natural ScienceMuseum,Tokyo,
New Zealandthermalwaters.Econ.Geo\.,64,95-10g.
Japan,were valuable.The manuscriptbenefitedfrom the critical
reviewsof Gordon E. Brown, StanfordUniversity,and Joan R.
Manuscript receiued,January31, 1978;accepted
Clark and K. J. Murata, of the U.S. GeologicalSurve;.
lor publication,March 21, 1928.