Canodian MineralogistYol.26, pp. 355-376 (1988)

COEXISTING GALENA, PbSo AND SULFOSALTS: EVIDENCE FOR MULTIPLEEPISODES OF MINERALIZATION IN THE ROUND MOUNTAIN AND

MANHARAN GOLD DISTRICTS. NEVADA

EUGENE E. FOORD AND DANIEL R.M.S. 905, U.S. Geological Suney, Box 25046, Denver Federal Cmter,

NANCY M. CONKLINM.S. 928, U.S. Geological Sumey, Box 25M6, Denver Federal Center,

SHAWELakewood, Colorado 80225, U.S.A.

Lokewood, Colorado 80225, U.S.A.

ABSTRACT

Studies of galena and Pb-Bi Ag-Cu(I{g) sulfosalts ofvaried compositions in the Round Mountain and Manhat-tan gold districts of Nevada corroborate the occurrence ofseveral distinct mineralized systems characterized by differ-ent mineral compositions and assemblages. The differentepisodes of mineralization are related to different Creta-ceous and Tertiary magnatic-hydrotiermal events,although the assignment of specific mineral compositionsand associations with dated mineralized systems is stillincomplete. At the Fairview mine, galena associated withPb-Bi-Ag sulfosalts and simple sulfides @curs as inter-growths of discretely different composition controlled bysilver and bismuth content. A galena-type phase @bSo)with solid solution toward matildite, fuBi$ (compositionGal6sMatao) was found. If silver and, to a lesser extent,bismuth are absent, the galena formed will be almost purePbS. Some minor antimony may substitute for bismuth.This study confirms a linear relationship between a cell edgeand Ag-Bi(Sb) content for galena containing less than about15 wt. 9o Ag and B(Sb). Other Pb-Bi-Ag-Cu(Hg) sulfidesand sulfosalts identified from the districts are bismuthinile,galenobismutite, lillianite-gustavite, aikinite, friedrichit{?),hammarite, ourayite, and berryite(?). Phases X and Y,mercury-bearing Pb-Bi-Ag-Cu sulfosalts (most likely newspecies), and coloradoite were recognized from the Out-law prospect southeast of Round Montain. Multiple epi-sodes of mineralization are supported by: (i) coexistinggalena, PbSo and complex sulfosalts of widely varied com-positions and with textures that indicate successive replace-ment; (ii) a characteristic but commonly incomplete para-genesis of mineral species (early hiibnerite, molybdenite,galena, sphalerite, and chalcopyrite; intermediate galenaand Pb-Bi-Ag sulfosalts; late tetrahedrite-tennantite,galena(?), chalcopyrite(?), covellite, and mercurianminerals), some of which can be geologically or geochem-ically correlated with dated deposits; and (iii) mineral com-positions as indicators of temperature of deposition (Sb:Bi<0.06, T 2m-3@'C; Sb:Bi >6.0-13, f 100-160'C).

Keywords: galena, PbSo, Pb-Bi Ag-Cu(Hg) sulfosalts,Round Mountain, Manhattan, Nevada.

SoMMAIRE

Nos €tudes de galbne et des sulfosels de Pb-Bi-Ag-

CuSIg) i composition variable, provenant des disfiicts auri-fbres de Round Mountaitr et de Manhattan, au Nevada,confirment la pr€sence de plusieurs 6pisodes distincts demindralisation, dont temoiguent les diff€rents champs decomposition et assemblages de min€raux. Si les dpisodesde mindralisation sont li6s d divers 6v6nementsmagmatiques-hydrothermaux, d'6ge cr6tac6 i tertiaire, enrevanche I'attribution de compositions et d'associationssp6cifiques d des 6v6nements de min6ralisation d'6ge connudemeure incomplEte. A la mine Fairview, la galOne associ€eaux sulfosels Pb-Bi-Ag et aux sulfures simples se trouvee! intercroissances dont la composition globale d6finit desft€roupsments €Nr termes de teneur en argent et en bismuth.Nous avons trouvd une composition intermddiaire de galine(PbSs, Gal60Mata6) enrichie dans Ie terme matilditeAgBiq. Si l'argent et, i un degrd moindre, le bismuth sontabsents, la galbne form6e par exsolution est par contrepresque stoechiom6trique. L'antimoine, en faibles quan-titds, peut remplacer le bismuth. Ces r&ultats confirmentla relation lindaire entre le param€tre rdticulaire a et laproportion de Ag-Bi(Sb) dans la galbne pour des teneurs(en poids) infdrieures i l5Vo Ag + Bi(Sb) environ. On apu identifio d'autres sulfures et sulfosels de Pb-Bi-Ag-CUGIg)r bismuthinite, galenobismutite, lillianire-gustavite,aikinite, friedrichite(?), hammarite, ourayite, et berryite(?).On siguale la pr€sence des phases Xet I, sulfosels de Pb-Bi-fu-Cu mercurifdres, qui sont probablement de nouvellesespece$, ainsi que la coloradoite, dans I'indice min6ralisdde Outlaw, au sud-est de Round Mountain. Les facteurssuivants indiquent qu'il s'agit d'une multiplicit6 d'6pisodesde mindralisationl (i) une coexistence de galCne, de PbSo,et de sulfosels complexes d compositions trbs variables ete textures qui indiquent une succession d'6pisodes de rem-plac€rnent; (ii) une paragen&e caract6ri$tique mais typique-ment incompldte de min€raux: hubnerite, molybd6nite,galdne, sphal6rite et chalcopyrite (prdcoces), galdne et sul-fosels Pb-Bi-Ag (intermdiaire), et tetraedrite-tennantite,galbne(?), chalcopyrite(?), covelline et min€raux de mer-cure (tardifs); dans cerlains cas, dc corr6lations g6ologiqueset g6ochimiques sont possible avec des gftes min€raux dontl'6ge est connu; et (iii) les indicateurs de tempdrature deformation i partir des compositions min6rales (Sb:Bi<0.06, T 200-3@oC; Sb:Bi > 6.0-13, T 100-160'C).

(fraduit par la Rddaction)

Mots-clds: galEne, PbSo, sulfosels Pb-Bi-Ag-Cu(Hg),Round Mountaia, Menhattan, Nevada.

355

356 THE CANADIAN MINERALOCIST

I 17000'

38037',30"

Ftc. l. Simplified geologic map of the Round Mountain quadrangle, showing locations of areas studied. Qa, Quater-nary alluvium; Tv, Tertiaryvolcanicrccks (-24-27 Ma); Tg, Tertiarygranodioritestock (35 Ma); Tr, Tertiary rhyolitedykes (35 Ma); Kg, Cretaceous granite (-80-95 Ma); Pzsm, Paleozoic sedimentary and metamorphic rocks.

NEVAOA

ElvRound a

\\ Manhdan

a

f c o n t a c t

-z- ovu.

a S a m o l e l o c a l l t Y

8 O - 3 0 a n d n u m D e r

ROUND MOUNIAIN

Fatvts mhe

Romd Mostalngold nlne

MOUNT JEMRSON CALDERA

7+'142ab7918

km

'ffiih

ROUND MOUNTAIN LOBE OFfiE

GRANITE OF SHOSHONE MOUNTAIN

I -.----...\cAlvYoil \.., i

_, \-.s..j_..-' '-...-

i;.r/ \-._-..._..._..\.q,ng:..

MINERALIZATION IN GOLD DISTRICTS' NEVADA 357

INTRoDUCTIoN

As a part of the detailed geological mapping andmineral resoruce appraisal of the southern ToquimaRange, Nye County, Nevada, the mineralogy andparageneses of the sulfides and coexisting Pb-Bi-Ag-Cu sulfosalts from many of the mines andprospects in the area were investigated @igs. l, 2).Physically and chemically different generations ofgalena and sulfosalts have been recognized. In addi-tion, field mapping, radiometric dating, and petro-graphic and geochemical studies indicate a complexsequence of igneous activity and multiple episodesof mineralization (Shawe 1985, 1986, Shawe et al.1986). These studies collectively have clarified thegeological history of several mineral deposits in thearea, in particular the large gold-silver deposit atRound Mountain.

GEoLocY oF THE Locettttss STuPtBo

The southern Toquima Range, in which the RoundMountain and Manhattan gold districts occur, is anarea of complex geology that evolved over a longperiod of time. Paleozoic marine sedimentary rocksconsist of Cambrian and Ordovician mostly transi-tional facies argillite, quartzite, and carbonate thatwere fault-thrust eastward as the Roberts Mountainsallochthon during the late Devonian to MississippianAntler orogeny. Other thrust-fault events followedin later Paleozoic and Mesozoic times, and they ter-minated when granitic plutons were emplaced intothe sedimentary rocks in the Cretaceous. Tertiaryigneous activity involved emplacement of stocks anddykes, and formation of several calderas accompa-nied by eruption of voluminous silicic ash-flow tuffs.Hydrothermal mineral deposits were formed or

lrrfnl''3SsJ,grr-

0 I MltSF----lJ

O 'I KTOMETER

MANI.IATTAN CALI'E8A

Frc. 2. Simplified map of the Manhattan quadrangje, showing locations of areasstudied. Legend as on Figure l.

358 THE CANADIAN MINERALOCIST

remineralized in association with emplacement of thevarious igneous bodies. Locations of each of themines and prospects examined are shown on FiguresI and 2.

Following emplacement of granite plutons, a var-iety of small, mosfly uneconomic base- and precious-metal veins and tungsten-bearing tactite and veindeposits formed at 75-80 Ma in the granite and innearby Paleozoic carbonate and clastic rocks. Thetactite and vein deposits characteristically containpyrite, sphalerite, galena, and chalcopyrite as initialcomponents. Other sulfide and sulfosalt minerals inthe deposits appear to be the products of youngermineralizing events on the basis of textural critera.For example, tetrahedrite-tennantite typically fillsvugs in quartz, is molded around earty sumdeminerals, or fills fractures in broken sulfide mineralgrains in some of the quartz veins. Tungsten-bearingveins in granite were remineralized with copper, leadzinc, arsenic, and antimony in the vicinity of a 35Ma granodiorite stock and associated rhyolite dyke-swarm. Tourmaline mineralization of granite andrhyolite dykes accompanied emplacement of thestock. The main gold-silver mineralization at RoundMountain occurred at 25 Ma within a rhyolitic ash-flow tuff. An economically significant gold-silvermineralizing event at Manhattan took ptace at 16 Mawithin Paleozoic phyllitic argillite, quartzite, and car-bonate along the south margin of the Manhattan cal-dera. A separate but undated Tertiary mineralizingevent introduced mercury, antimony, and arsenicminerals into the eastern part of the Manhattan belt.The mercury mineralization produced a few smallmineable deposits; it was widespread, and overlappedolder zones of base- and precious-metal veins-.-

Fainiew mine

The Fairview mine lies at the eastern edge of amineralized zone in rhyolitic tuff that contains theLarge2S Ma gold-silver deposit at Round Mountain.The Fairview mine produced gold mostly from thinstringers in sheared rock parallel to a west-northwesr-striking fault, not far above a depositional contacrof tuff on granite and Paleozoic rocks. These oxi-dized bodies contained gold associated with ironoxides (from pyrite) in drusy quartz, as well as goldplates interspersed in mosaic-textured vein quartz(Ferguson l92l). Judged from materials on the wastedumps at the Fairview mine, mining extended down-ward from veins and stringers in rhyolitic luff intothe underlying granite, where thin quartz veins wereencountered. The vein material, texturally like nearby80-Ma base- and precious-metal and tungsten-bearingveins in granite (Shawe et ol. 1984), contains hiib-nerite, molybdenite, pyrite, multiple generations ofcovellite, bismuthinite, and ourayite, all as fillingsof vugs and fractures in mosaic-textured to druiv

quarfz,. Pyrite contains sparse tiny cubes of galena,and galena likewise contains rare tiny cubes of pyrite,suggesting possible contemporaneous formation ofthe minerals. Sulfosalt minerals are molded aroundbroken grains of pyrite and molybdenite flakes.Covellite occurs as a replacement of and a fracturefilling in galena. Muscovite fills shears in quartz andlines vein margins, and sparse hiibnerite occurs as1iny, l- to 2-mmJong crystals embedded in massivewhite vein quartz. Limonite is a cornmon alterationmineral a1 the Fairview mine. Anglesite and cerus-site are weathering products of galena.

Lead-Silver King prospect

The Lead-Silver King prospect Iies in a zone ofbase- and precious-metal mineral deposits along thesouthwestern margin of the Mount Jefferson caldera.An intensely sheared, mineralized zone a few metersyrd9, 4gng a northwest-trending fault that separaresOrdovician carbonate rocks from a large horse ofTertiary rhyolite tuff, is about l(D m outside the cal_dera. Irregular, thin quartz veins in the sheared zonecontain galena as irregular masses as much as severalcm long, either as fillings of sheared milky quanz,or as crudely tabular masses in quartz-lined vugs. Thequartz in vugs comrnonly is broken and healed.Cleavage surfaces of some galena masses are nora-bly curved. As seen in polished section, some galenadisplays minute veinlets of marcasite, mosi com-monly oriented along the cleavage planes. Oxidationproducts in the galena-bearing quartz veins includelimonite, beudantite, and cerussite.

Prospect southeost of Round MountainAn unnamed prospect shaft in granite of the

Round Mountain lobe of the granite of ShoshoneMountain (Shawe l98la) about 2 km southeast ofRound Mountain exposes 3 or 4 closely spacednortheast-trending nearly vertical quartz veinsl-20 cm wide. The quartz-vein material, in appear-ance typical of the 80 Ma veins, contains pyr.ite,sphalerite, stibnite, and aikinite. Veinlets of covel-Iite occur in the sulfides and sulfosalts. Alterationproducts of aikinite are abundant medium-yellowocherous bismutite and minor anglesite. Locally,tabular masses of limonite derived from pyrite areas much as 3 cm thick and line vein margins. Serici-tized granite wallrock contains small disseminatedgrains of pyrite and molybdenite, and sparse thinveinlets of pyrite. The prospect lies within 80 m ofa northeast-trending rhyolite dyke of the 35 Maswann.

Fission-track ages determined on accessory zirconand apatite from pyrite-bearing granite collected nearthe quartz veins are about 43-44 Ma and 20 Ma,respectively (Shawe et ql. 1986). The ages are inter-

MINERALIZATION IN GOLD DISTRICTS, NEVADA

preted to reflect partial annealing of zircon during gue minerals along with qrrartz. Anglesite is aemplacement of the 35 Ma dykes, and annealing of weathering product of galena. Addition of sulfidesapitite probably during both the 35 Ma event and to the vein, and alteration of hiibnerite to scheelite,during the 25 Ma mineralization at nearby Round are thought to have occurred during a younger

Mountain, followed by slow cooling to about Z) Ma (35 Ma?) event following the initial (80 Ma) episodeat which time apatite had passed throueh the anneal- of hiibnerite-bearing quartz vein mineralizationing threshold. Remineralization of the quartz veins (Shawe et al. 1984).may have occurred during either or both of theseevents. Prospect north of Mariposa Canyon

A prospect pit about 1.5 km north of MariposaCanyon and 6.5 km south of Round Mountaineiposes a quartz vein, in granite, that strikes Nl5"Eand dips steeply west. A similar parallel vein lies l0m west of the pit. The veins pinch and swell to a max-imum thickness of about 0.5 m. They consist ofmostly massive white quartz, but in places muchvuggy quartz is evident. In one place a central frac-ture in the white massive quartz vein is lined withlate vuggy quaftz. Some vugs are lined or filled withchalcedony (Shawe et al. 1984, Fig. 25).

The veins contains sparse htbnerite embedded inmassive quartz. Abundant sphalerite and lesseramounts of pyrite, galena, tetrahedrite-tennantite,and pyrrhotite(?) are concentrated in vugs in quafiz,or are strung out in quartz close to or in prominentshears in the veins. The sphalerite contains tinyexsolved blebs of chalcopyrite (Shawe et at. 1984,Fie, Zl). Chalcedony locally veins broken sphaleritecrystals, and a late stage of quartz-chalcedony filledsome vugs lined with quartz and pyrite crystals(Shawe et ol. L984, Figs. 24,25). Tetrahedrite-tennantite, paragenetically younger than the earlysulfides, shows late-stage alteration to chalcocite,acanthite, stromeyerite, covellite, and stibiconite(?)(shawe et al. l9M, Fig. 28).

A quartz vein, which is in granite and is similarto the two veins at the prospect north of MariposaCanyon and about 2.2 lm to the northwest, andanother one about 0.9 km to the north, have beendated as 78 and 79 Ma, respectively. Another quartzvein 0.5 km to the northwest, dated as 83 Ma, wassheared, brecciated, and remineralized in Tertiarytime with chalcedony, barite, and cinnabar (datafrom Shawe et al. D$A.

Prospects north of White CaPs mine

Prospects 0.7 km north-northeast of the WhiteCaps mine east of Manhattan expose a set of quartzveins in Ordovician limestone on the south flank ofSalisbury Peak. The veins are witlin about 3fi) mof the south margin of the Manhattan caldera, andthey lie about 3 km norttr of a Cretaceous granitepluton, referred to as the gpanite of Pipe Spring(Shawe lgSlb). Thin veins of white bull quartz a fewcrn to perhaps I m wide, generally northeast-trendingand steeply dipping, occur where limestone is jasper-ized, calcsilicated, and iron-mineralized. Quartz is

359

The Shale Pit

The Shale Pit is a small gold mine in Ordoviciancarbonaceous argillite and limestone about 3 kmsouth of the Round Mountain gold-silver mine. Goldmineralization occurred mostly in argillite just belowa thrust fault that places limestone above the argil-lite. Yery fine-grained gold is disseminated in silici-fied argillite where iron oxides (altered from pyrite)are abundant. Anomalous amounts of arsenic,antimony, mercury, and silver, along with otlermetals, suggest a kinship with Carlin-type golddeposits.

At the Shale Pit a pod of milky-white quartz about2 m long occurs in strongly deformed silicified andiron-mineralized argillite about 3-5 m below thethrust fault that forms the sole of overlying lime-stone. The pod contains abundant masses ofgalenaseveral cm long, interconnected by numerous thinanastomosing veinlets of galena. The galena displayssomewhat curved cleavage surfaces. Thin veinlets ingalena that are filled with cerussite contain sparsetiny grains of arsenopyrite. The quartz mass isstrongly sheared and fractured, and locally it con-tains vugs lined with drusy quartz. The milky-whitequartz of the pod appears typical of that in the 80Ma veins; the drusy quartz is typicat of the Tertiarygold-bearing deposits in tle southern ToquimaRange.

Prospect near the head of Kelsey Canyon

A prospect shaft 5 km southeast of Round Moun-tain near the head of Kelsey Canyon expos€s a quartzvein, in granite, t,'lpical of the 80 Ma group of veins.The vein, of undetermined thickness, strikes north-east and dips steeply southeast. Yein material con-sists of massive milky-white quartz, but with locallyabundant vugs into which less-milky quartz crystalsextend.

Hiibnerite occurs as isolated crystals in quartz andis partly altered to scheelite. Pyrite, galena, covel-lite, and tetrahedrite are seen mainly as vug fillingsin quartz, and in inegular pockets formed in shearedquartz. Covellite forms irrqular replacement patchesand fills cleavages along crystallographic planes ingalena (Shawe et ol. l98y', Fig. 2O, and tetrahedriteis molded around pyrite and galena crystals. Mus-covite, barite, and fluorite occur as additional gan-

360 THE CANADIAN MINERALOGIST

mostly massive and mosaic-textured, though locallyit is wggy. The quartz veins commonty exiriUit ttrinselvages of muscovite, and in places potassium feld-spar occurs with muscovite in vein selvages andextends into the cores of veins, forming a rock simi_lar -to .pegmatite. Locally a few light-brown_weathering clots of calcite, no more than icm across,and thin fracture fillings of calcite can be seen inwhite quartz. Sparse, small tabular masses of pb-Bi-Agsulfosalts along with minor chalcopyrite andgalenobismutite occur in sheared quartz. tiiimitell;,bismutite(?), or daubreeite-bismoclite(?) are altera_tion products of the sulfosalts.

The quartz veins at the prospects nofih of theWhite Caps mine are typical of veins associated withthe granite plutons, though they show evidence ofremineralization with complex sulfosalts. Similarquartz veins nearby have been dated at about 75 Ma.AIso, the quartz veins at the prospects lie within anoftheast-trending zone of Tertiary mercury miner_alization centered on the White Caps mini.

Greenfield claim

Shallow prospect pits at the Greenfield claim about2 km west-southwest of Manhattan expose thin

irregular quartz veins in quartzite ofthe OrdovicianToquima Formation. The veins are about 2 kmsouthwest of the margin of the Manhattan calderaand about 4 km northwest of the main mass of thegranite of Pipe Spring (Shawe l98lb) south of Man-hattan.

Silver- and bismuth-bearing galena occurs inquartz as well as in small (l cm) masses along poorlydefined inegular fractures in quartzite. Galena is theonly sulfide mineral identified at this occurrence,although limonite in some of the vein material sug-gests the presence of pyrite at deeper levels wherethe rock has not been weathered. Cerussite is an alter-ation product of galena.

The Greenfield claim lies about I km south of theeast-trending Manhattan belt of gold mineralization,and about 2 km west ofthe principal gold-producingzone on Gold Hill. Muscovite in quartz-mineralizedrock at Gold Hill has been dated as 75 Ma, whereasadularia associated with gold at the samelocality hasan age of 16 Ma (Shawe et al. 1986't.

Outlaw prospect

The Outlaw prospect, long known (Shannon 1924,Nuffield 1953, 1954, 195, Karup-M gller lTl2, 1977,

TABLE 1. SEUIq'AITITATXVE B'IXSSIOI{-SPECTSOCRAPHXC DATA FOi CALEIIA AI{D PbS.. SIT'PI,SSFRot{ rBE RouItD r.toul{TAlr AND MAr{rurtAr coLD DrsrRrcrs, r{!E courfry, rwAoe. ""

Falf- Load-Sl.lyer Shale

Looal l tv vlew KlnS pposp. ptt- nlne

Prospeot,head ofKelsey

_- Ceyon Csyon

sarple DRS DRS- DRS- DiS- DSlt_ DRS_ DRS- Dns- DBI'_nu-uer !l-: 74- 79- ?8- '14' 74- 74' 'l\- 80-

224 42a 1g ,122 221 219 252a 252b \gpbses pbsse pbs pbsss pbg pbs pbsss pbsss pbsss

0.7r o.2t 1, O.3 '7 30 T0 'to

>2t .03t 1,51 O.3 '150 150 150 m0l{10 il10 Il0 rtto

Prospeot Oson-north of fletdItaPl,pos olaln

0.3t 't.5t 4 2t15 30 30 3oo0.3t 1.5, 2$ >2'

x10 300 't0 r50t{10 lt10 l{10 150

Fe 2000 1 500 3000u8 <50 <10 <10Ca 100 30 <AOrr r{1 lfl l{1!1r 150 5 30

r50 30 50 <10 .t50 70

<10 <10 100 <10 <10 .10<20 30 <20 30 70 2011 r{l 20 [1 l{,t l{l1 5 ' t ' , t o 2 5 5

Ag 7'Ea foBt. >5rcd t{10qo N10

c r lcu 3ooof,l r10lto 3000Pb !l

sb 7000 lrl0o 15oOsn 70 [10 20g r l { 5 3 0 t 5v l { t { ts t 3 , <10 <10A1 lO <.10 <10t{a l{500 $00 r5OO

7000 n100 1100l{10 [10 50

5 X 5 5 03 0 [ 3 0

1.5 ' 3000 1500'r 0 <10 <,10n500 200 [500

r{1 0 t{l 0 t{l 0 l{1 0 llt 011 1 .5 ' 1 .5 t 1 .5 ' 700

!110 [10 !t10 nlo 15x 5 x 5 7 7 N 5M U i l n i l

ltl 050

x t0il5t{

3000

t50

t r u<20

$00

x10 L101 0 2 0

M O M Ox5 l{5U M

?00 200l{10 l{10

1 5 1 0r { N

3000 5000150 3000

x500 x500

llotes: N not deisoted a! ltnit, of.dotsrnlnatlon. !f liaJor. HlBh Cu va1ue6 ln saEplosDRL-74-?2|, DnS-74-219, 7\-252a 8d, DRS-74-252b ar€ due io adrl;ed oovelltte. nfeil SrElues ln ihese s&e four mplga plus DRS-gO-qg and DRS-?3-229 ane due to adnlxeiqq"!l:,!. u. Conklln, ealys!.. Htgh yaluos of Fo 1n mtteo DRS-?3-2?8, DRS_f4_1tl2a,and-Dis-79-18 aro due to pJrlie (or moastte, on !otn) mnt ot6ttoa; htih yalue of '

l{o tn-mplo DBS-73-aaB ls due to dolyb<lsntts'oontelmtlon, md hf.8h'Al in tuptsDRs-74-219 ls duo !o oonlernairo! ly'ninor feldspr. values aro in parta psr mrlltonexoept for lhooe lndloatod 1n t.

MINERALIZATION IN GOLD DISTRICTS, NEVADA

TABLE 2. ELECTBOI ]|ICBOPnOBE DAIA FOB CoExrglxrc cALEllAs, Pbsss' Al{D ouBAYrrE FRoU

rflo RormD MolrNTAr[ - MAMtlrra[ AREA, [rE CO.' TSVADA.

36r

Hanis & Chen 1975, 1976, Karup-Mdller & Limonite is a common alteration product, and angle-Makovicky 1979, Makovicky &'Mummi t929, pun- site and bismoclite-daubreeite(?) are present as alter-ning et a/. 1988) as a localiiy for rare and complex ation products of aikinite. Minor amounts of bis-pb-ni-a,g-Cu sulfosalts, is in a quartz vein at a ion- mutite, sulfur, and cerussite also were identified as

tact betieen eranite and schist about 8.5 km alterationproductsof aikinite(Dunning etal. 1988).

southeast of Round Mountain. The schist, reprsent-ing metamorphosed sedimentary rocks of brdovi- Muscovite from the quartz vein at the-Outlawcian(t) age, forms a narrow east-trending screen prospect hry uq age of 8l Ma (Shawe et al. 1986)'

Uetween lwo granite plutons (Shawe l98ia). The indicating that it was formed as part of the miner-principal(?) uein is t-Zh *iOe, itrikes northeast, and alization related to the Late Cretaceous granite plu-

iipr tt".piy nonhwest, following an irregular con- tons. However, the prospect lies in an east-trending

tact t"tr"'Cn granite and schist. fein quartz is milky belt of Tertiary mercury deposits that extends from

white, generaily mosaic-textured, andiocally wggy. south of RoundMountain for more than l0 km east-

The vein has Leen much sheared, and commoniy ward (Shawe 1986). The leached pyrite in the deposit

shows thin lenses of granite or schist sheared into and veining of sulfides by sulfosalts suggest that at

the vein margins. Muicovite forms thin selvages on some time following formation -of t!t" base-metal

the vein walli, as well as irregular lenses andbleh deposit, additional hydrothermal activity-occured.within quartz. SmAt tourmaline crystals line shears The presence of tourmaline suggests that the miner-

in quart locally near tourmaline schist wallrock. alization is related to the 35 Ma igneous episode.Fluorite, pyrite, and rare rutile are intergrown withirregular masses of muscovite within quartz, or they _ loccur as isolated crystals in quartz. The pyrite localy MINERALoGIcAL DATAis granular to porous (or spongy), giving the appear-anie of having tein ioriiraea ana teiCtred. Resultsofourstudiesareorganizedinthefollow-Sphalerite, galeni, molybdenite, and several Pb-Bi- ing pages on the basis of mineral species agd groups.

Ag-Cu suliosalts occur as euhedral crystals and Material from several localities in the Round Moun-in:egular masses in sheared vein quartz, and as fill- tain and Manhattan golddistricts provided data onings in vugs in quartz. The pyrite, iphalerite, galena, galena, galeaa solid-solution (PbSJ' and other sul-

anO motylaeniie commoniy are fractured, and the fides specifically associated with the galena, on bis-fracturei filed with sulfosalts. According to Shan- muthinite, galenobismutite, and berryile(?), onnon (l9Z) chalcopyrite fills thin veidJts in ben- lillianite-gustavite and on tetrahedrite-tennantite.jaminite. A late gineration of Hg-bearing Pb-Bi- The Outlaw prospect near Round Moudtain is dis-Ag-Cu sulfosaltJ and coloradoite is also present. cussed separately in considerable detail because of

Lsallty FalrYl€l Blne

Prospeot Prosp€ct a,@n-,shate hqd of north of f leld

Pti Kelsoy i{ariPom olatn_ csvon -!4!.9-

L9adStIYor

Klng--999p99!-

sampls DBS-?3-228 DnS- DRS- DBS- DBS- D8S- DRS-

n*ijn phaas prtaee ptraoo ?4- T9- 78- 7\: 74- 7\'t 2 3 1rl2b 18 122 219 221 252b

[o. ofe a l . 6 2 2 5potnte

DRS80-49

nlo.nano

sbhrsPb

0 . 00,90 . 0

1 6 . 039.5

33.39 . 60 . 0

99.5

B I

AA

ToiaI

oraylbe Pbsas Pbgs€

0 . 0 0 . 00 . 1 0 . 20 . 0 0 . 0

1r t .3 1 ,1 .9?0.8 56.7

9 . 1 1 8 . 54 . E 9 . 40 . 0 0 . 20 . 0 0 . 0

0 . 0 1 . 6 3 . 1o . 2 0 . 9 1 . 70 . 0 0 . 0 0 . 00 . 0 0 . 0 0 . 0

Pbs Pbs PNus PbS Pbs Pbsss Pbsss

o . o O , O O . O 0 . 0 0 . 0 0 . 0 0 : 00 . 1 0 . 3 0 . 3 o . o 0 . 1 0 . 0 o ' lo . o 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 1

1 3 . r 1 r g . r r ! 3 . q r 3 . 5 1 3 . 3 1 3 . 5 1 3 . 8e6.s a6 .z 8? .0 87 .5 85 .5 83 .3 81 .2

0 . 0 0 . 10 . 0 0 . 00 . o 0 . 0

o . 2 0 . 00 . 5 0 . 10 . 0 0 . 00 .0 0 i0

99.1 gg .g 10o. l l 1oo .o 101.4 101.1 99 .1 99 .3 100 '0

!lo!o, Mo ed ltg sought ln smple DRS-80-il9 sd foud to be b91ot the deteotlon

iirii. s"rpr" ins-25'rza al$ oontalns o.lf se and 0.03, Ie bassd on enlaslon

cpeotrographto amlysle. -- trot delenmlnod. r

362 Tlm cANADTAN MrNERALocrsr

TASla 3' CorlBrts 0F cttALcoPFrLE 8lIt.l8!lrs FoR SELECISD SAT.IPLES TABLE 4. COrrEltrS trOi SXLVER, Brst{Ultl, A{D Am!Ol|! Irl CA!,E!II8.OT OALE}IA.

ItoopeoiShale PIC head ofpfoop€ct KElset

Csyon

Sa[ple no.{d localttJ

Bl./Aa nailo (xt.)(fr@ qu&t.speo. data)

Ele@nt oongsntB1tooallti I€ad-Sllver Kl.ng

proap9ct

Sarple!@bor

Aa

lu

BI

cd

sbTE

u\

T}

ng

S€

Dns-?rl-l 42a

Dns-?9- r q

Dns-?8-t22 Dns-?rt

-22'l

1 400

fi300)

DRS-?9-18Lqd-S11yefKlng P.osp.

DnS-?q-142atdad-SllYefKlng Fosp.

DRS-?q-1!2bl€ad-St1Y9rKtng Prosp.

Dns-?8-1 22Shale Plt

DR9-74-21 9Prospeot,h@d of trekotCanyon

1?o ,li33i'

(rcne) (2600)

&<10

l l l r . z ) '

roo(150) r

3oo (r)r

20

<20 ([) r

<l 00<100

500<500

t 0 2 0 ? o

<0.2 <0 .2 <0 .4eoo( r to ) ' >o .e t (0 . :o ) . rsoo(a3oo) .1oo( l5o)+ r5o( r5o) , 4 ( f , ) i

r r l0o(1500) r >0 .2 f (0 .3 ) r {oo(?oo) .15 300 1oo

6(n) r roo( r ) t qo(11) r

7 t < 2< 1 1 0 2B A F

ao 1000 loo

6too laooo lroo'.(300) -

( - - _ , t - - _ , ( - - - ,

(200) (<200) (800)15@ 700

52OO 5600 3OOO*-( >2000 )

-(5roo) (3300) (2600)

(1200) (200) (400)

[ote6:. Values ss Blven tn ppE, ed rherg statod, fn l t . , .! E rncopronenoe. For oarpls DRli_?I_tlt2a and DRIt_?g_l22 theu8ul 1lBlts ot detootlon do no! appLy b€oause of tire Of.futtonraotor. ChEl@lhtle sl@ent speotrosraptlr.o analyaga bv C.Heropoutos (uscs). r - varuee iqtsroin.e ;; ;;;;i;;"i;-;;"apoot.ographlo anatyatg (tr. u. conkltn, uifysi). * _ ofulud€terolned by qwbttatlye eotoslon-sp6ctrograpt f o *"f yuti--(f. !-1. Conklttr, aulys!).

its historical importance and the wealth of minera-Iogical data that has been acquired for that locality.A brief section deals with alteration products of somesulfides and sulfosalts in the Round Mountain -Manhattan area.

Galena and galena solid-solutionGalena and PbSs from the Round Mountain -

Manhattan area show a large variation in trace- and

DRs-i4-221 2zoo 23oo ?oo'_Proapeot, (coo)'traad of (1800) (a00) (600)Keley Csyo!

DRs-7\-252a 75oo 1q000 ?000"Proepeot (9000) (15?00) (400)norlh olUalpos Canyon

DRs-80-q9 21ooo !5ooo [too"cr@nfreld (17100) (31300) (600)olalo

!{otss- val.uoa foa Ag and Bl not ttr parsnghegea rs th@detsrolnsd by q@bttattre €U-step eateslor speotrography (f. U.conklln, aulyot). t - yaluoa 1n ps.engbeme ior so-oi itroedqtorElngd by quilt,ttattvs ohaloolthtlo gl@nt, speotrcgraphy (C.Heropouloa,

-ualyst,). - l{torop.obe Elues Btven f i, par.itirlulu'- -

\E, L. r@o, elyat) . + - valu@ detemlned by fogulr atretop &oi. g@bttabtve eota6lo! apeoerogralhy tll.

- ll. Lnf f f n,

''

malyst). Dtsreparcy tn !toroprobo .oa ip6oinoff"pf,to'".i,i""of Sb ln €eple DRS-7tl-252a uaooouged foi,. 1-i- 1' - snpiu-ooteE0losd by otoroprobg.

a(A)

5 . 9 4 0

5 . 9 3 0

5 . 9 2 0

5 . 9 1 0

\ {€ - - - - - - - -o

-\

3 4 5 6 7 w t . %

EAg+Bi+SbFtc. 3. Relation of a versas summation of sb+Ag+Bi for galena from the Round

Mountain - Manhanan area (1, DRS-74-142b; 2, T9-lg; 3, 7L219; 4,7g_l?2; 5,7L221; 6, 74-142a; 7 , 74-252b; 8, 14-252a;9, 8G49). Solid circle, ty etectron_'nicroprobe; open circle, by quantitative emission spectrography. An'additionaldata p-oint--(from Karup Mdller &"Makovicky lggl), is sh-own

"r * op.n lri*_

gle. AII cell dimensions r0.0o2 A. Micropiobe data arc r0.4 $.g;.

MINERALIZATION IN GOLD DISTRICTS, NEVADA 363

minor-element contents. Discrete coexisting galenaand PbSo with different compositions have beenidentified from two localities (Lead-Silver Kingprospect and Fairview mine dump) and probablyexist elsewhere as well @oord et al. 1985). Telluriumand selenium substitution for sulfur in galena (altaiteand clausthalite components, respectively) was deter-mined to be nearly nil. Results of spectrographic andelectron-microprobe analyses are given in Tables Iand 2, respectively. Concentrations of chalcophileelements are shown in Table 3; those.of silver, bis-muth, and antimony in selected galena samples aregiven in Table 4.

Back-scattered electron @SE) imaging of thegalena from the Greenfield Claim (DRS-8049)showed homogeneous-appearing galena, an unusualproperty for galena with such high content of bis-muth and silver.

An almost linear correlation may be seen betweenthe a cell edge and the sum of silver, bismuth, and

antimony contents in galena samples (Fig. 3). Datafrom the literature are included for comparison.Fieure 4 showns the compositions determined byelectron microprobe and plotted along the galena-matildite join. It can been seen on this figure thatsome of the points show a slight excess in bismuth.This phenomenon suggested to Karup-Mdller (1977)that the Bi-excess in galena may be due to domain-type structures similar to those in the lillianite homo-logues.

Because of the extremely small amount of PbSoand associated sulfides and sulfosalts collected fromthe Fairview mine dump, all data (X-ray, emissionspectrographic and microprobe) could not beobtained on exactly the same grain or grains ofmaterial. A 114-mm diameter Gandolfi X-ray pat-tern made from a somewhat brittle silvery-white sul-fide or sulfosalt associated with visible molybdeniteand quartz in veins within hydrothermally alterederanite (sample DRS-73-228, Fairview mine) shows

Ag(Gu,Hg) PbFrc. 4. Triangular plot in terms of Pb, Bi(Sb), and AeGu,Hd, showing the com-

positions (atomic) of galena and associated sulfosalts from the Round Mountarn- Manhattan area. Selected data from the literature are also shown. Symbols: opencircle, known minerals and ideal compositions; solid circle, samples from RoundMountain and Manhattan; open square, Karup Mdller (1977); open triangle, Fina-slir et al. (1981), Herbert & Mumme (1981); +, phase X; solid square' phaseY; b, bismuthinite; u, ustarasite; ip, ideal pavonite; ib, ideal benjaminite; ub' unsub-stituted benjaminite; k, kitaibelite; gb, galenobismutite; gu, gustavite; abh, Ag-Biheyrovskyite; mu, mummeite; cp, cupropavonite; o1qo, ourayiteljgi op, P<enteredourayite; t, treasurite; un, unnamed; c, cosalite; v, vikingite; iber, ideal berryite;m, matildite; e, eskimoite; o, ourayite (B-centered); s, schirmerite; l, lillianite;x, xilingoite; h, heyrovskyite; a, aschamalmite; g, galena.

Bi(sb)

( 1 9 8 1

364 TIIE CANADIAN MINERALOGIST

lines that could be indexed on two discrete galena-type cells. However, after the discovery of anggrante composition (Ours) as well as that ofPbS"" by microprobe analysis of additionalmaterial, and BSE imaging indicated an intergrowth

of two minerals, it was realized that one of thegalenas was ourayite. Additional X-ray powder-diffraction studies of material from the preparedpolished section also indicated the presence ofourayite. The X-ray-diffraction pattern of ourayite

Ftc. 5. Back-Scattered Electron (BSE) photograph of Gal66-Mat4q (medium grey) and host pyrite (white) from theFairview mine, Round Mountain, Nevada. Samprc Off,S-ZlZi6.

Ftc. 6. BSE, and element dot.maps for an aggregate of minerals in sample DRS-73-228 (Fairview mine). (a) BSE image:pyrite' black cube; ourayite(?), dark grey; PbS* light grey. (b) PbMa dot map, same are{l ag on 6a. (c) BiMcv dotmap' same area as 6a and 6b. (d) BSE image: pyrite, black; ourayite(?), medium grey; PbSo, light grey. (e) AgZcudot map, same area as 6d.

MINERALIZATION IN GOLD DISTRICTS, NEVADA 365

(Karup-Mdller 1977, Makovicky & Karup-Mdller1984) is simil4l to that of galena, owing to thepresence of dominantly galena-type layers with rela-tively few bismuthinite-type layers. Single-crystalstudies will be necessary to confirm.whether theourayite is 3-centered or P-centered (Makovicky &Karup-Mdller 1984) or if it is another mineral spe-cies having a value of N equal to ll. A lillianitehomologue can be characterized by the number ofoctahedra (N) in the octahedral chains in each of twotypes of layers Makovicky & Karup-Mdller lW7 a,b).On the basis of electron-microprobe analyses andSEM studies, two galena-type phases (phases 2 and3) were found along with a dominant third phase(phase l) compositionally most closely lsgsrnuingourayite. X-ray-diffraction studies of this materialidentified phases I and 2 as ourayite and galena,respectively. An insufficient amount of phase 3(highest Ag- and Bi-containing galena) was presentfor detection by X-ray diffraction. However, care-ful examination of phase 3 (CafuMatao) at highmagnification using SEM BSE imaging techniquesshowed no traces of any other intergrown or exsolvedmineral phase (Fig. 5).

Annealing studies of two samples of the hand-picked fragments selected for spectrographic analy-sis, and which were initially determined to have twogalena-type phases present (subsequently identifiedas an intergrowth of galena and ourayite), whenheated at 5ffioC in vacuo for 1 week producedmaterial that gave a sharper single galena-type pat-tern along with a faint pattern for ourayite. We con-clude that the untreated sample contained, in addi-tion to ourayite(?), two discrete compositions ofgalena, both of which contain abundant matilditein solid-solution (PbSJ. Upon heating, the twodifferent compositions of galena were homogenized,and the ourayite-like mineral was converted to theartificial equivalent of ourayite sensu stricto.

Figures 6a to G show BSE and selected-elementdot maps for phases I (Our53) and 2 (Gal*Mat2') inDRS-73-228 from the Fairview dump (Fig. l). Simul-taneous srystallization of ourayite, PbSo, and pyriteseems indicated; compositional boundaries betweendifferent minerals are sharp and no exsolution-typetextures are visible. Phase 3 (GaleoMat*) is totallyenclosed within a grain of pyrite @ig. 5).

An emission-spectrographic analysis of hand-picked fragments yielded the composition for DRS-73-228 eiverr in Table 1. Three thousand ppmmolybdenum are present, indicating somewhat lessthan 190 molybdenite contamination. X-ray-diffraction studies confirm the presence of minoramounts of 3R molybdenite and quaxtz. Three dis-tinct sulfide and sulfosalt phases in addition to pyrite(Iable 2, Fig. 4) were determined to be present basedon optical and electrou-microprobe studies.

Bismuthinite, galenobismutite, gustav ite,and berryite(?)

A lead-bearing bismuthinite was identified in onesample (DRS-81-201c), collected from the Fairviewmine dump south of Round Mountain @ig. l). Thegrey, metallic bismuthinite is associated with quartzand pyrite. A six-step semiquantitative emission-spectrographic analysis (by NMC) showed: Fe0.1590, Mg <10 ppm, Ca (20 ppm, Ag 70 ppm'Bi major, Cu 0.790, Nb 15 ppm, Pb 2t/0, Sb 0.390'Zr 20 ppm, Si 0.390, and Al < l0 ppm. Other ele-ments were not detected at their respective limits ofdetermination. Chalcophile elements were also deter-mined (by C. Heropoulos, USGS) for the samplewith the following results (in ppm): As 1()0' Au<0.3, Bi > 1000, Cd 4, Sb 200, Te 200' Zn 26, P<1, T l <1, Hg <1, Se 1300.

An average of six electron-microprobe analysesgave: Bi 79.22wt.r/0,Pb2.23, S 18.47, total99.92.A structural formula calculated on the basis of twocations is (Bi,.nrPbo.or)S2.e5, or if calculated on thebasis of 3 sulfur atoms is (Bi1.e7Pb0.06)Sr. This bis-

-'*i;il .&Frc. 7a. BSE photograph of intergrowth of gustavite, laths

of bismuthinite and sparse patches of alterationproducts, prospect north of the White Caps mine @RS-8G56). white, bismuthinite; light gey, gustavite; darkgrey, galena. 7b. BSE closeup-photograph of 7a.

!E]E

*:$:r*S

:rfr ii:ii Si.i:l@-; 'b,S . r b : 1

366 THE CANADIAN MINERALOCIST

muthinite is similar in composition to others reportedin the literature @ig. 4). BSE photographs show thebismuthinite to be monomineralic.

One polished section (DRS-80-56) of vein quarrzfrom one of the prospects north of the White Capsmine contains an intergrowth of pb-Bi-Ag-Cu_Sbsulfosalts; X-ray, spectrographic, and ilectron-microprobe analyses show these to consist chieflv ofbismuthinite, galenobismutite, and gustavite withlesser amounts of berryite(?). Cerussite, bismutire,bismite, and other alteration products are alsopresent. BSE-imaging and EDS analysis of the finergrained part of the intergrowth show the presenceof major gustavite enclosing randomly oriented lathsof bismuthinite and scattered, extremely smallanhedral blebs, patches and veinlets of alierationproducts within the gustavite @ig. 7a). The bis_muthinite laths are 5-10 pm long and 2-3 p m wide.AJteration patches of cerussite and/or angiesite, andBibearing minerals are typically 2 pm aCross @gs.7a,b). Another part of the same polished section con_tains a coarser grained (50-100 pm across) inter-grofih of euhedral crystals of bismuthinite andgalenobismutite without guslavite. A six_stepemission-spectrographic analysis (NMC) of the mix_ture_qlve: Fe 700 ppm, Mg l0 ppm, Ca 200 ppm,Ag2Vo,Ba200 ppm, Be2 ppm, Di >l0go, CIIOO!pT: 90 ? ppm, Cu 1.590, Ni 7 ppm, pb >l0go,Sb 5000 ppm, Si 1.590, and Al < l0ppm. Other ele-msnts were not detected at their respective limits ofdetermination (Table 5). The Si is fiom quartz con-tamination. Chalcophile elements determined spec_trographicallyby C. Heropoulos, USGS, are: As-560g!g, Au <1.6 ppm, Bi )lgo, Cd 4m ppm, Sb1600 ppm,-Te 240 ppm, Zn 80 ppm, p < l-ppm, Tl16 ppm, Hg 15 ppm, Se Z@ ppm.

IABLE 5. .APPTOXIMAIE LOXER LII,lIlS OF DET8ft{1I,IATIOI{ FOE EL&,I8I{TSDETERI,III{ED B1 6.SISP SPSCTBOOMPMC UEIIIOD (IIi PETCEI{T AtrD PPM)

An average of three microprobe analyses of thegalenobismutite gave: Cu 0.2, Sb 0.1, S l?.1, pb27 .5, Bi 56.2, total 101. I wt. 90. Zinc, arsenic, ilon,and silver were sought but were found to be belowthe limits of detection. This material is normalgalenobismutite; its composition is plotted onFigure 4.

An average of six electron-microprobe analyses ofthe bismuthinite gave: Bi 80.63, Pb 1.45, S 18.42,total 100.50 wt.9o. A calculated structural formulabased on 3 S atoms is: (Bir.efb6.srS3.

The gustavite matrix enclosing laths of bis-muthinite is uniform in appearance @SE images) andis homogeneous in composition. An average of sixmicroprobe analyses is given in Table 6.

A fourth mineral, which may be berryite, isassociated with the gustavite, bismuthinite, andgalenobismutite in DRS-8G56. The chemical formulaof berryite still is uncertain, and the extent of solid-solution between copper and silver end-members isvariable. An electron-microprobe analysis of onegrain of the berryite(?) gave: Cu 5.11, Sb 0.86, S16.55, Pb 24.61, Bi 42.32, Ag 10.09, total99.54 wt.t/o. Zinc, arsenic, and iron were sought butnot detected. If the data are recast on the basis of16 S atoms, the formula is: Pbr.r(Agr.oCuz.o)(Bi6.4Sb0JSr6; on the basis of ll S atoms, the for-mula is: Pbr.6(Ag2.oCu1.8XBi4.4Sb0.rS,,. If themineral is berryite then some minor substitution ofantimony for bismuth is likely. No X-ray-diffractionstudies on pure material were done because of thesmall grain-size. A Gandolfi film for a sample ofbulk material showed major bismuthinite, lessergalenobismutite and gustavite, plus additional faintlines that are close to those of berryite. The compo-sition of the probe-analyzed berryite(?) material isshown on Figure 4. Ideal benyite is also plotted onthe Figure. Other analyzed samples (Nuffield &Harris 1966, Karup-Mdller 1966, 1917, Borodayev&Mozgova 1971, Harris & Owens 1973) are shownon Figure 8. Berryite is the only phase that is closein composition to our analyzed material.

TABT.E 6. ELECTRON MICROPROBE OATA FOB LILLIAIITTE IITDcuslAyrlE FRox UAInATTAI, lrBgApA

Dffr-8o-55ALl11lutta

Dns-80-56Custaylis

'I ppnl

5050

r00

slA I

Ms

Ne

T 1

Un

A8A8Au

BA

B9B i

Co

CrC uDtBr8u

0.002t,001.001,002.002

cdG€Hfgo

1nIN

LU

!{ol{bl{dlll,09

PbPdPTPtRe

RhRusbScSn

5 pp!501 0

1 0 020

AYoragg ofArera8s ofT

qr c nnh

so 100ta 200Tb 200!e 2000

th 200 ppn

to 20u 500t 7

r 100 pp!

Zr\ 200Zr 100

sb

Pb

B i18ASTO

Toial

,05,, 7.0002. 2.0001

10 ppq503O5030

3 ppo1 0

50

10 ppo

'I00

3030

2 ppm1 0

1 0

1000202o

1 ppD

?0150

0 . 0

16.3\2 .3

39,2

0 . 1o , 2

1 0 0 . 4

. 316.453 1 . 9

47.8

-?:o. 1

I 02 .05

lotor Zn ed Fe s@ght but noi degeoted. --- notdgiernlned.

MINERALIZATION IN COLD DISTRICTS, NEVADA 367

Lil lianit e- gust av it e series

Studies of members of the lillianite-gustavite(Pb3Bi2S6 - PbAgBi3S) series (e.9., Nedachi e/ d/.1973, Makovicky & Karup-Mdller 1977b, Finashinet al. I98l) have indicated a solid-solution seriesbetween the two minerals vrith a miscibility gap inthe series between about Gusr6 and Gus65.

Blades of lillianite enclosed in quartz comprisesample DRS-80-55a from one of the prospects northof the White Caps mine. An average of sevenmicroprobe analyses is shown in Table 6. Five114 mm Gandolfi X-ray-diffraction films of the lil-lianite in DRS-80-55a showed the material to bemostly rilli4aile, with a trace of galena. The galenawas not found during the microprobe analyses of thelillianite. The lillianite in DRS-80-55a ranges in com-position from LTaGuq6 to L76Gus2 (Fig. 4), follow-

ing the nomenclature of Makovicky & Karup-Mdller(1977a,b). The calculated N..* is equal to 3.99.The gustavite from DRS-80-56 has an average com-position of L3eGus61 and appears to be composi-tionally homogeneous (Table 6).

As stated by Makovicky & Karup-Mdller (1977b),natural phases belonging to the lillimils-gu51ayi1gseries, PbrBirS6 - PbAgBi3S6, &re- homogeneousbetween Gus,* and Gusr, (the 8-A phases) andagain between Gusrs and Guse (the 4-A phases;e.9., Ontoyev et al. 1982). High-temperature phaseswith compositions situated in the compositional gapshow exsolution phenomena. The lillianite in DRS-8G55a is homogeneous and represents lower temper-atures of crystallization thar the crest of the solvus.Because the gustavite in sample DRS-80-56 appearshomogeneous (BSE imaging) even at high magnifi-cation (2000 x ), it may have cooled rapidly enough

pe

une

g l o

I e o k o

r . rd h 9 ' 8 tA A :

r { nuo on",

6 @ a

Frc. 8. Triangular plot in terms of Cu(Ag), Pb, arid BilSDl showing the composi-tions (atomic) of aikinite-bismuthinite series minerals and others. Solid circle'compositions of minerals from Round Mountain - Manhattan; plus sign' averageof cornposidons of seven samples from the Outlaw prosp€ct; open circle with cross'aikinite-bismuthinite series; open circle, ot[er natural minerals; open triangle,unknown structure; open square, Karup Mdller (1977);b, bismuthinite; p, pek-oite; u, ustarasite; un, unnamed; gl, gladite; r, rezbanyite; n, nordstromite; j'junoite; k, krupkaite; gb, galenobismutite; pa, paderaite; ho, hodrushite; cb'cuprobismutite; e, ernplectite; l, lindstrdmite; ip, ideal paderaite; h, hammarite;ber, berryite; ko, kobellite; pr, proudite; c, cannizarite; co, cosalite; bur(?)' bur-saite; lil, lillianite; xil, xilingoiie; bon(?), bonchevite; hey, heyrovskyite; asc,aschamalmite; g, galena; w, wittichenite; la, larosite; cc, chalcocite; f, friedrichite;s, soucekite; a, aikinite; nu, nuffieldite; ne, neyite; solid squares, giessenite. Bonche-vite and bursaite are inadequately'described minerals.

368 THE CANADIAN MINERALOGIST

SffpLs nos.

TABLE 7. CIIALCOPIIILE ELEMEIIT CONCEITRITIONS IN TIIREESAI,IPLES OF TE'IRAHSDRIIE F'ROU TNE BOUND !,IOIJI{TAIN AREA

Dns-?8-l Dns-78-2 DnS-?q-243(Fon rboaurons rc shawe eu afllSSIT-

microprobe. The maximum amount of silver deter-mined by electron-microprobe analysis to be presentin any of the six examined tetrahedrite-tennantitesamples from the Round Mountain - Manhattanarea is about 390.

Sulfusolts and suffides from the Outlaw prospect,northeast of Manhotton

Table 8 is a summary of minerals identified fromthis prospect. Despite the complexity and degree ofdifficulty in positively identifying the various sul-fosalts that are present, only one mineral that wasfirst identified as one species (pavonite) has beeir sub-sequently re-identified as another (benjaminite)(Karup-Mdller 1972, 1977). Re-examination of var-ious samples through the years has resulted in addi-tional species being identified (e.9., Nuffield 1953,LeTs).

The aikinite-bismuthinite series. Four of the ninecurrently known members of the aikinite-bismuthinite series (oikinite, friedrichite, hammarite,lindstrdmite,krupkaite, gladite, unnamed member,pekoite, ar;d bismuthinite) have been identified fromthe Manhattan-Round Mountain area. Details of thecompositional and structural variations in the serieshave been provided only recently (Synedek & Hybler1974, ZAk et ol. 1974, Mumme 1975, Harris & Chen1976, Mumme & Watts 1976, Mumme et al. 1976,Chang & Hoda 1977, Horiuchi & Wuensch 1977,Chen et al. 1978, Makovicky & rrVlakovicky" 1978,Mozgova 1978, Prachal 1979, Zitk 1980, Zek &Hybler 198l,ZAk & Prachai l98l). Whereas a com-plete solid solution exists between aikinite and bis-muthinite, there are distinct structural differencesamong different members of the series. Stoichiomer-ric and nonstoichiometric compositions are com-posed of various cells of bismuthinite-type,krupkaite-type, and aikinite-type structural ribbons(Kostov & Minleva-Stefanova 1982). Various mem-bers of the series, e.g., pekoite and hammarite, maybe seleniferous (e.g., Mumme & Watts 1976,Kovalenker el al. 1984, Chekalova & Slyusarev 1974).

Aikinite. In this study, aikinite and possiblyfriedrichite(?) were identified from seven differentsamples from the Outlaw prospect. Electron-microprobe data on the aikinite and friedrichite(?)in all of these samples are given in Table 9. The com-positions given in Table 9 and the average (of 7 sam-ples) are plotted on Figure 8. Whereas some of theanalytical points cluster around ideal friedrichite @b30.5, Bi 43.1, Cu9.4, S 17.0 wt.9o), and other pointsare closer to ideal friedrichite than to ideal aikinite(Pb 36.0, Bi 36.3, Cu 11.0, S 16.7 wt.9o), single-crystal precession-camera studies (of DRS-79-84a)confirmed that some material is nonstoichiometricaikinite wirh 4 l l.3l(l), , l l .6t(l), c 4.02Q) A.Figure 9 is a photograph of a kinked (twinned) sin-

Elonant

ASAuB t

sb

Za

T1HgSe

>20000 . 5

200>1 000>2000

>2000<0.2

>2000

OM 11Bl-PtsFg-A8-tu

stfd8 I(Pb@ x)

U@ 11Br-Pbng:&-Cu

olfodl 2(tu i)

&lof&1te 11. 12c 4 @ 1 b t o , l t , 1 2Anglestt€ 10, 11, 12B l @ l r r 1 0 , 1 1 , t 2

tuube1t6

al@tlh 12tul@hlb 12hk1!e 72E€rrhtydi6 120o€h1& 12Jf@lb 12xoslblb 12$lfa 12

rr @p6lLlo s EtEn t6 MD ol ll!'@lb rah€f tu hDdb.Fl"I" l9:"-- !1)-q" ' ,1"1 (19?I), (2) xf f lerd(1953), (3) bnFutr+ (112),(4) Xuff lerd (1975), (5) ht6 a tun (r9?5), (5) br ls & ci len t1976). t7)hrFbt lr (r9?7), (8) Hovloky & @ ( l97g), (9) kutsrrrbr &

' ' '

! , t : !9v, loky (19?9), 00) S. A..r l l r t@, p6. @., r98r, ( i t ) mrs sUay,(12) MIG gq *, ( ln pros+

100>200

<1

20

t00>200

<1<t

<5

700

>l 000>1 000>2000

1 0 0>200

<1

<5

Amlyst, C. Horopouloa (U.S. caologtoal Supyoy). Daiaobbalned by onlsslotr speobrography.

to prevent exsolution at a scale large enough to bevisible.

Te t r q h e d r it e- t ennan t it e

Arsenic-poor to moderately arsenic-bearing tetra-hedrite, as determined by electron-microprobe anal-ysis, is a minor but widespread constituent of manyof the 80 Ma quartz-hiibnerite-muscovite veins,which were remineralized by later hydrothermalevents in the Round Mountain - Manhattan area(Shawe et ol. 1984). Concentrations of chalcophileelement for three tetrahedrite grains are given inTable 7. One sample of antimony-bearing tennan-tite (DRS-80-48b), which is from a mineralized thrustzone2km southwest of Manhattan associated withquartz, pyrite, galena, and secondary covellite andstibiconite(?) also was examined by electron

TSU 8. fif8urcol OF Tm OUTUr pmpmt, nnpogA cmx, mqjm nAi@,NtrOA

lln6fal Fof3ren@s nn@al nddm€s

Q u s t z 1 , 2 , 5 , 1 1Fluof l t€ 1, 2, 11I e o r t b 1 , 2 , l tlor@l lne t 1tutlle 11P r r l e 1 , 1 1 , 1 2C h a l @ y f t b 1 , 2 , 3 , 5 , 6 , 9 , 1 1 , 1 2tul@tb 1, 12

&rolltb 6, 12bltxontle 1, 1tSPhalerllo 10Glem 11

A r t h t b 1 . 2 , \ , 5 ! 1 1 , 1 2hJelnl te 1, 2, 3, 4, 6, 7, 8, 9ht l& 2, 6, 7, 8kt1ldt& 2, 7LldEtrod& 2,9Bl@lhtnlb 4

Mrlb 6, l , 11trqpbl ler. 7,8, 9, 12tubrlb 7, 8, 9, 12

MINERALIZATION IN GOLD DISTRICTS, NEVADA 369

gle crystal of aikinite (DRS-79-8zla) elongared on cand striated parallel to [c]. Reddish brown internalreflections are present in oblique incident light. Ourinvestigation showed only aikinite, friedrichite(?),and hammarite to be present as representative of theaikinite-bisrnuthinite series. Other investigators havereported lindstrOmite, krupkaite, and bismuthiniteas well (Table 8). The composition of krupkaite(average of seven points) reported by Karup-Mdller(1977) and Karup-Mdller & Makovicky (1979) is justabout identical to that reported by Harris & Chen(1976) as hammarite. Compositionally, the averageof the seven points plots close to ideal hammariteand is quite removed from ideal krupkaite.

One specimen @C-Benj) of material labelled "ben-jaminite, Outlaw Mine, Mariposa Canyon, Nye Co.,Nev." was obtained from F. Cureton. This samplewas collected in the 1920s from the Outlaw prospect.As viewed megascopically, the specimen consists ofmilky quartz containing muscovite, molybdenite,pyrite, and a bronze-tarnishing sulfosalt. Examina-tion of the sulfosalt by electron microprobe showedthe presence of a member of the aikinite-bismuthinite series having a composition nearly iden-tical to that of ideal friedrichite (Table 9, Fig. 8).The mineral, however, may be nonstoichiometricaikinite, as was found in some of the other samplesexamined in this study (Table 9, Fig. 8). One com-position (Table 9, Fig. 8) lies midway betweenfriedrichite and hammarite, which is probably a non-stoichiometric hammarite. One area examined bymicroprobe contains a 20-pm-wide veinlet of amercury-bearing Bi-Pb-Ag-Cu sulfosalt (phase X),which is most likely a new species. Material of simi-lar composition was found in two additional sam-ples @RS-7343b and DRS-73-43d); additionaldetails are given later.

One sample (DRS-7343a) of aikinite from theOutlaw prospect contains 100 ppm As, 150 ppm Sb,200 ppm Se, 50 ppm Hg, 100 ppm Te, and 7 ppm

Frc. 9. Photograph of kinked, elongate, striated crystal ofaikinite in quartz from the Outlaw prospect (DRS-79-84a), Mariposa Canyon, Toquima Range, Nevada. Scaledivisions are I mm.

Tl (emission-spectrographic determination of chal-cophile elements by C. Heropoulos, USGS). Six-stepsemiquantitative emission-spectrographic analysis(NMC) of another split of this sample showed: Fe0.1590, Ag 3000 ppm, Ba 15 ppm, Bi major, Cumajor, Pb major, Cr 7 ppm, Ni 10 ppm, Mo 500ppm, Sb 7@ ppm, and 1.590 Si. No other elementswere detected.

What is most likely aikinite, with a slight excessof bismuth, is present in DRS-8G38a (prospect 2 kmsoutheast of Round Mountain; Table 9) associatedwith sphalerite, pyrite, and quartz. An emission-spectrographic analysis (NMC) of the aikinite(?) thatcontains minor sphalerite and pyrite shows 300 ppmAg and 3000 ppm Sb. Among the chalcophile ele-ments (analyst: C. Heropoulos), the sample contains50 ppm As, < I ppm Hg, 2 ppm Tl, 70 ppm Te, 700ppm Se, 500 ppm Sb, and < 0.2 PPm Au. Theassociated sphalerite (containing about 490 aikinite)contarns 0.590 Fe, 0.390 Mn, 1.590 Cd' 50 ppm Iqand 7 ppm As.

TASI,E 9. SLBCTIOI UICROPROBE DA1A FOR AIKII{ITE, FiXBDBICFITE(?)' AnD BA}|UARITE FRolil lHEoufLArPRosPEcT, MARXPOSA CIJ{YOII, AllD flt0 PRoSPE0T sourlt oF RoultD !{ouNtAll{' mquIMA RAXOE'NET!"DA

err.*t, o$rl3 DRS-73 DRS-?3-43o -43d

DRS-73 DRS'-73 DRII-79 Fc--tr3e -43f -8qa BBIIJ

Avdags of DBS-8Ooullac -3gampre9

l{o. olpolnta

sbs

B1A8z\te

fotal

( 2 )(4 )

9 . q 9 . C 8 . 50 . 1 0 . 1 0 . 1

16. ' , t 17 .8 16 .831.8 31 ,7 29.',142.3 39 .2 44 .2

-9:t -::' -::'I.D. rf .D. l{.D.

100,3 98.2 99.q

9 . f

't't .132.238,7

- t .0 .

97 .9 98 .0

9 . 1 9 . 5 8 , 70 . 1 0 . 1 0 . r

1 7 . 4 1 6 . 9 1 7 . 03r .5 29 .8 28 .840.8 S4.o 47 .1

-::t -9:t -9:'l f .D . .0 .1

9 9 . 0 1 0 0 . 4 1 0 1 . 9

9 .2 10 .20 .1 0 . l l

1 ' , | .1 1 '1 .330.6 33 .542.S 38 .C50 . 0 0 . 0

0 . 10 .0 [ .D .

99.4 99.95

8 . 90 . 0

1 2 . 4

42.5

-;;.

Xoto! Zn, trg' ed Aa $ughi but no! dsteoled aboYo lln1t of deterBlmtlon ln OutlatpPoopeot'miles. f.D. ' no! deierolned. uo ed tl8 eougtlt bu! oo! foud ln Dls-73-43a'ina ons-rl-4id. Dns-?3-[3a-C3f, DiL-?9-84a' !!-BEl{.t - Out].ar proepoctt DRs-80-38ap!"ospecl south ol Roud Moutatn.

370 THE CANADIAN MINERALOGIST

FIc. 10. BSE photograph of veinlet of unidentified Hg-bearing sulfosalt within aikinite. DRS-7343d, Outlawprospect, Mariposa Canyon, Toquima Range, Nevada.Dark grey aikinite host, light grey Hg-bearing pb-Bi-Ag-Cu sulfosalt.

Results of electron-microprobe analyses of theaikinite(?) are giyen in Table 9. The average of thethree data-sets, plotted on Figure 8, lies between the-oretical aikinite and friedrichite, about l/3 of theway from aikinite to friedrichite. No single-crystalX-ray studies were done on this material; the spe-cies designation is based on chemistry only.

Hammarite. An electron-microprobe analysis ofone area in sample DRS-73-43d (Outlaw prospect)gave a composition very close to that of hammarite:Cu 7.05, Sb 0.22, S 16.74, Pb 26.22, Bi 49.97, Fe0.10, Mo 0.09, Hg 0.23,totil 100.43 @ig. 8). Zinc,silver, and arsenic were sought but not detected. Theresults are in agreement with the findings of Harris& Chen (1976) and Karup-Mdller (1972) on ham-marite from the Outlaw prospect.

Phase X (probably a new Bi-Pb-Hg-Cu sut/osott).Three of the eight polished sections examined fromthe Outlaw prospect (DI{S-73-43b, DRS-7343d, andFC-Benj) contain a mercury-bearing sulfosaltmineral, here called phase X. Phase X has beenobserved only as veinlets that cut nonstoichiometricaikinire (in two samples, FC-benj and DRS-73-43d).The reflectivity and color differences between phaseX and aikinite are very small, but the carbon appliedfor microprobe analysis enhanced these differences.BSE photographs show the intergrowth of themercury-bearing sulfosalt and aikinite very clearly@ig. l0). The mercury-bearing sulfosalt has veinedand replaced the aikinite. The presence of mercuryin the sulfosalt was confirmed by wavelength spec-trometer scans and subsequently by emission-spectrographic analysis (NMC). The presence of mer-cury was noted in the bulk sample of aikinite fromthe Outlaw prospect (DRS-7343), but not in theaikinite(?) from the prospect 2 km southeast ofRound Mountain (DRS-8O.38a). Mercury also has

been detected at low levels (20 to 50 ppm) by spec-trographic determination of the chalcophile elements,in samples of tetrahedrite-tennantite (DRS-78-1,DRS-78-2, DRS 74-243), and in one sample ofsphalerite (DRS-74-252a) from sulfide- and sulfosalt--lnglalized hiibnerite-quartz veins described byshawe et al. (1984). This study also has indicated thepresence of mercury in a sample of sphalerite fromthe prospect 2 km southeast of Round Mountain (20ppm, DRS-8G.38a) and in the composite sulfosaltfrom one of the prospects north of the White Capsmine (15 ppm, DRS-80-5O.

Electron-microprobe data for the mercury-bearingsulfosalt in DRS-7343b and DRS-73-43d for ll ele-ments are given in Table 10. If these compositions(and the average) are plotted on a triangular diagramAg(+Cu)-Bi-Pb (Fig. 4) adding Hg to rhe Ag r-.Cu corner, they fall very near the Nequals 7 line(iy'"h". = 7.16) and lie between eskimoite and hey-rovskyite, but are closer to eskimoite. The metal-to-sulfur ratio for phases along this line is 0.889. TableI I summarizes data on phases lying along this line.

A complete structural formula of phase X basedon 27 sulfur atoms is: (Hg2.rrAg1.aeCur.o:Pbo.:z)(Pb)8.'(Bi,0.7rMoo.*Pbe.qrSbe.0rS27. Single-crystalstudies of the material will be necessary to determineif it is a mercury-substituted heyrovskyite, a mercury-substituted eskimoite, a new member of the lillianitehomologous series, or a new species.

Phose Y (probobly a new Bi-Pb-Hg-Ag-Cu sul-fosalt). Either a compositional variant of phase X(ly' : 7) or, more likely, a new species of similar com-position but with Nequal to ll was found in DRS-7343b. Two microprobe analyses of the mineralgave: Sb 0.02, 0.03; Te 0.04, 0.07; Cu 1.60, l.6l;Hg 10.13, 9.14; S 15.40,15.42; Pb 35.M, 34.71;Bi36.79, 36.95; Ag 2.59, 2.43; total 10l.6l,100.37 wt.9o. Iron, zinc, and arsenic were looked forbut not detected. These compositions are plotted onFigure 4. This mineral forms the bulk of one area(about 200 x 200 pm) in the section, and containslath-like intergrowths of phase X (Table l0), exsolvedblebs and irregular masses of galena, andcoloradoite. Phase Y has been found in only one sec-tion thus far, and may possibly be a mercury- andcopper-substituted ourayite; single-crystal X-ray-diffraction studies will be necessary to completelycharacterize the mineral.

It seems clear that a mercury-rich and, to a lesserextent, a silver-bearing mineral assemblage postdatesan earlier Bi-Pb-Cu-Mo-Fe mineral ?ssemblage atthe Outlaw prospect. Phase X occurs as veinlets inearlier formed minerals but as intergrown laths inthe later generation of mercury-, silver-rich, andcopper-poor minerals.

Coloradoite. Based on microprobe analyses, veryminor amounts of coloradoite, HgTe, were identi-

MINERALIZATION IN GOLD DISTRICTS, NEVADA 37t

fied in sample DRS-7343b. The rnineral occurs asirregular and randomly oriented blebs (grains) asmuch as 15 x 20 pm in size included y'61hin phaseY. Recently, this mineral also has been identifiedfrom the Outlaw prospect by Dunnineet al. (1988).Insufficient amounts were available for X-ray-diffraction studies.

Benjaminite. Benjaminite, frst described (Karup-Mdller & Makovicky 1979, Makovicky & Mumme1979) from the Outlaw prospect, was not found dur-ing this investigation (Table 8). The existence of acopper- and lead-unsubstituted benjaminite fromAustralia was described by Herbert & Mumme(1981).

Golena. Galena, not previously reported from theOutlaw prospect, was found in one sample (DRS-7343b). Some of this galena, however, rather thanhaving the coupled Ag + Bi = 2Pb substitution,appears to illustrate a Hg(Ag) * Bi = 2Pb coupledsubstitution. Two analyses of an elongate inter-erowth of galena in phase Y within DRS-7343bgave: Cu 0.1, 0.1; S 13.3, 13.6; Pb 83.9, 83.3; Bi,0.9, 0.8; Ag 0.45, 0.,10; St 0. I, 0.0; Hg 0. l, 0.0; total98.85, 98.2 wt.9o. No antimony, tellurium, or zincwas detected. The grain shows the normal Ag + Bi= 2Pb coupled substitution. Two other microprobeanalyses of galena from the same sample gave: Cu0.17,0.14; S 13.2, 13.9; Pb 76.3,78.9; Bi 4.3, 4.9;Ag 0.7,0.6; He 5.0, 1.3; totals99.67,99.74wt.0/0.A structural formula based on one sulfur atom,using the average of the two analyses is:@b6.6sBie.qrHgs.ooAgo.or)S.

Alteration products of sulfides and sulfosalts.Identified products of alteration of galena from theFairview mine material are covellite, anglesite, andcerussite. These same minerals are also present at theother galena-bearing localities examined.

A mineral(s) that shows low reflectivity, ismedium-dark grey in reflected light and light tomedium yellow in plane light, occurs as an altera-tion product that coats, fills fractures, and is includedwithin galenobismutite and gustavite in DRS-80-56.Two microprobe analyses showed: Bi 86.0 and86.590 and S 0.0 and 0.190, respectively; totals 86.0and 86.6 fi.90. No other elements above atomicnumber 9 (F) were detected. This mineral is mostlikely bismite, bismutite, or daubreeite-bismoclite.

An emission-spectrographic analysis (NMC) of abismutite-anglesite mixture associated with aikinite,sphalerite, pyrite, and quartz (DRS-80-38a) gave:FeA.2o/0, Mg 0.0190, Ca 1.590, Mn 5 ppm, Ag700 ppm, Ba200 ppm, Bi )1090, Cd 70 ppm, Cr30 ppm, Cu 1000 ppm, Mo 7000 ppm, Ni 15 ppm,Pb > 1090, Sb 3000 ppm, Sr 100 ppm, U 1000 pprn,V 500 ppm, Y 30 ppm, Zn 700 ppm, Si 390, A10.390,and Yb 3 ppm.All other elements were not detectedat respective limits of determination (Table 5). Thehost(s) of the calcium, uranium, vanadium, and

lABla 10. EI.ICTROI UICROPEOBE ANALXSES OF UEBCURY-BE.A8II{GSULTOSALT TROM TIIE OUTUT PROSPECT, IiIARIPOSA CAI|YOI{, TOQUIUAMITOE, I{EVADA

ElsBsnr pns-73-43b tj-:-:1 AYSrago

of 1-3

sbsPbB1

ABl.totlst9

TotaLs

r . 3 1 . 30 . 3 0 . 0

l5 .9 16 .029.8 29.340.3 40 ,6

3 . 4 3 . 6

8 . 3 8 . 40 . 3 0 . 4

99,3 99.3

' | .5 0 .9 1 .3 ' t .2

0 . 1 0 . 1 0 . 1 0 . t1 6 . 0 1 5 . 6 r 5 . 8 r 5 . 830.6 32 .3 31 .8 31 .6\2.',t 39.7 40.5 t10.8

2 . 7 3 . 1 2 . 5 2 , 80 . 0 0 . 2 0 . 1 0 . 19 . 0 7 . 7 7 . 7 8 . 1n .d . n .d . n .d .

102.0 99 .6 99 .9

pbe X

l{ote, F9, 46, ed Zn saght bul oot dsgected aboye llolis ofdeterulmllon. n.d., nob deiornlned

lsE 11. trIJauLs uvnc r - 7 IN Ea 8$m Pb - Bt(sb) - 38(c!)((C)

&tdrrsdfot

Ag7?btOBt t 5336 32136 - O,AA9

(sg'Ag'fr'Pb)5PbS(81'rb'8b'b)u827 24127' 0.489

Pb6,Bt2s9 !o Pb19ASB15316

Pb6,81289

A€3Pb5,Bt781g (1@ s, htgb A8; l@ ed) 16/18'0.889

molybdenum have not been established.A white to creamy microcrystalline crust (altera-

tion coating) on aikinite in DRS-79-84b from theOutlaw prospect also was examined. A six-stepemission-spectrographic analysis (NMC) of a 3.3 mgbulk sample gave: Fe 0.0590, Mg0.02t/0, Ca0.l0/0,Mn 5 ppm, Ag 200 ppm, Ba 500 ppm, Bi > 1090,Cu 500 ppm, La 200 ppm, Mo 30 ppm, Pb 290, Sr50 ppm, Al < 150 ppm. All other elements were notdetected (Table 5). Transmitted-light and X-ray-diffraction studies of this material indicate anglesiteand probable bismoclite-daubreeite. Additionalalteration products of sulfides and sulfosalts arelisred in Table 8.

DISCUSSIoN AND CONCLUSIONS

In many natural deposits and in synthetic systemsinvolving lead-bismuth sulfides and sulfosalts, ageneralized paragenetic sequence has been observedin which lead-rich minerals form prior to bismuthrich ones (e.9., Chang & Bever 1973, Czamanske &Hall 1975). Structurally, most bismuth sulfosalts arecomposed of axial-type structures (Kostov &Mindeva-Stefanova 1982). Furthermore, a trendexists from bismuth to antimony to arsenic sulfosaltswith generally decreasing temperature. Antimoniansulfosalts are principally of pseudo-isometric types,and arsenian sulfosalts are principally planar types.This trend, axial - pseudo-isometris - planar, hasa definite bearing on the conditions of crystalliza-tion of the respective sulfosalt minerals. The sulfosaltminerals tend to separate and crystallize after the sul-fide minerals Kostov & Mindeva-Stefanova 1982).

8/9 or 16118 - 0,889

8/9 - 0.889

372 THE CANADIAN MINERALOGIST

However, within the Pb-Bi-Ag-(Cu)-S system,some minerals, such as the crystallization sequencebismuthinite, galenobismutite, lillianite-gustavite,berryite(?), and galena*, which have been inves-tigated in this study, commonly exhibit progressivelead-enrichment or silver-enrichment (or both) withdecreasing temperatur€ (Karup-Mdller 1977).Ontoyev et al. (1982) found similar results in theirstudy of mernbsrs qf ths lillianite-gustavite series andrelated sulfosalts. Silver- and bismuth-rich sulfosaltsformed earliest, then sulfosalts with a moderareamount of these elements, and finally at the end,galena with an insignificant content of silver and bis-muth. As stated by Malakhov (1968) and Karup-Mdller (1977), bismuth-bearing sulfides are gener-ally considered to have crystallized in the high-temperature hydrothermal range, antimony-bearingsulfides in the medium hydrothermal range, whereasarsenic-bearing sulfides generally belong to the low-temperature hydrothermal (epithermal) ranges.Abundant data including phase equilibria (e,g., Crug1967), fluid inclusions (e.g., Nedachi et a/. 1973), sra-

. ble isotopes, and other data indicate that most ofthe mineral parageneses belonging to the pb-Bi-Ag-(Cu)-S system have crystallized at temperaturesbetween 2@ and 400oC. Galena + Pb-Bi-Ag(Cu)sulfosalt assemblages at lvigtut, Greenland are inter-preted to have crystallized between 300 and 550.C(Karup-Mdller 1973,1977, Karup-Mdller & pauly1979). Galena and associated sulfosalts in the Dar-win district, California were interpreted to have crys-tallized at more than 350oC (Czamanske & Hallr97s).

The annealing of samples with high bismuth con-tents (21 to 27 wt.tlo Bi) and that do not lie on thegalena-matildite join (i. e. , being composed of matil-dite, clausthalite, and galena) at 500oC for 5 hoursproduces a galena-type pattern (Czamanske & Hall1975). This is due to reincorporation of the other ele-ments into the high-temperature galena structure.

Galenobismutite has been determined to be sta-ble above about 390oC (Hoda & Chang 1975, Chang& Hoda 197?). Below this temperature, decomposi-tion to bismuthinite and lillianite occurs: 3pbBirsa- 2Bi2S3 + Pb3Bi2S6. Galenobismutite was foundat only one locality (DRS-80-5O examined in rheRound Mountain - Manhattan area. Only bis-muthinite is directly associated (intergrown) with thegalenobismutite. As mentioned in earlier pages,another part of the same polished section containsgustavite and bismuthinite. Deposition of thegalenobismutite and bismuthinlle as interlockingeuhedral crystals indicates that the bismuth( + silver?) mineralization took place above 390oC,if the stability dara of Chang & Hoda (1977) are usedas a geothennometer.

Bismuth and antimony contents of 204 samplesofgalena from 84 deposits representing a depth range

of crystallization from 3@ to 50& m were examinedby Malakhov (1968). He concluded thar the Sb:Biratio principally reflects the temperature of crystal-lization of the galena. Very low Sb:Bi values (<0.06)are characteristic of high-temperature galena (200-300oC and greater), whereas higher Sb:Bi values(>6.0 to 13) are typical of low-temperature galena(100-160.c).

Values of the Sb:Bi ratio in galena from the RoundMountain and Manhattan gold districts range from0.00x to 5 (6-step semiquantitative emission-spectrographic analyses), <0.0m1 to 8 (quantitativeemission-spectrographic analyses), 0.03 to 7(chalcophile-element emission-spectrographic anal-ysis), and from 0.01 to 25 (electron-microprobe anal-ysis). These values are in agreement with the rangeof temperatures and depths of formation estimatedfor these districts from geological and laboratory(fluid-inclusion data) studies: depth about 3 km, tem-perature 300-200oC, to depth less than I km andtemperature less than 200'C (Nash 1972, Shawe etal. 1984). Significantly, the values for galena fromthe Round Mountain and Manhattan districts showwide variation and, moreover, two populations, onewith values greater than 2 and the other with valuesless than 1. Samples of galena from one locality(Lead-Silver King prospect) have two distinct chem-ical compositions, based on major-, minor-, andtrace-element contents, as well as two distinct habirs(fillings in sheared quartz, and as irregular tabularcrystals in quartz vugs). The two samples (DRS-79-18 and DRS-74-142b) have low silver and bismuthcontents and elevated antimony contents relative tothose of DRS-7+142.a, which has high silver and bis-muth and low antimony. Thus, two generations ofgalena appear to be present, a high-temperature formand a low-temperature form.

Khetchikov (1958) found two generations ofgalena in a polymetallic skarn deposit in the SovietFar East: the first is high in bismuth and is early,whereas the second has no bismuth and is late.However, within the first generation of galena, greatheterogeneity (as much as 2wt.t/o Bi difference) wasfound from closely spaced samples within the sametype of ore. This heterogeneity was attributed toinclusions of galenobismutite. The two generationsof galena from the Kti-Tberda deposit, northernCaucasus, U.S.S.R. (Ontoyat et al. 1982), depositedin Paleozoic and Mesozoic time, respectively, areanother example of two distinctly separate episodesof mineralization.

Galena is definitely not always t}le simple mineralthat it commonly is assumed to be. Galena mayunder appropriate conditions contain substantialamounts of silver and bismuth (with lesser antimony)in solid-solution (as much as 25 mol.9o AgBiS),without decomposition to matildite plus silver- andbismuth-free galena. The substitutional scheme

MINERALIZATION IN COLD DISTRICTS, NEVADA 373

2Pb2+ = Bi3+ + Ag+ has been accepted by manyinvestigators to account for the presence of silver andbismuth in galena. However, as noted by Karup-Mdller On7), any surplus of silver over bismuth (insingle-phase galena) would require, in order to main-tain charge balance, the insertion of 2Ag* for eachPbz* removed. One of the two silver atoms wouldtherefore have to be placed in interstitial positionsin the galena structure. However, as also noted byKarup-Mdller (1977), such positions are apparentlynot available, accounting for the apparent impossi-bility of finding more than a few tenths of a mol.9osilver in excess of bismuth. An excess of bismuth isreadily accounted for, because for every 3Pb2*removed, 2Bi3" enter into the galena structure,leaving one lead position empty. If a substantialexcess of bismuth is present, and no other bismuth-bearing minerals are present, then a domain struc-ture may exist. Such domain structures may be simi-lar to those of the lillianite homologues (Karup-Mdller 197). Multiple generations of galena are res-tricted to base- and precious-metal deposits wheresufficient ?mounts of silver and bismuth both arepresent in lead-rich environments. We believe tharthese galenas originate by either incomplete exsolu-tion resulting from rapid sqsling, or by multipleheating (mineralizing) events in varied geochemicalenvironments.

The presence of coexisting galenas with or withoutassociated Pb-Bi-Ag(Cu) sulfosalt assemblages sup-ports the geological and geochronological evidencefor multiple and chemically complex stages of miner-alization in the Round Mountain and Manhattan dis-tricts. They also may be used as crudely approximategeothermometers.

The Round Mountain and Manhattan districts areareas in which several distinct and separate episodesof base- and precious-metal mineralization tookplace over approximately 65 Ma (80 to 15 Ma). Fol-lowing emplacement of granite plutons, a variety ofsmall, mostly uneconomic base- and precious-metalveins and tungrl"n-6garing tactite and vein depositsformed at 80-75 Ma in the granite and in nearbyPaleozoic carbonate and clastic rocks (Shawe el a/.1984, 1986, Shawe 1985, 1986). These deposits arecharacterized by small amounts of simple sulfides:pyrite, sphalerite, chalcopyrite, and galena. Thequartz-hiibnerite veins in granite were subsequentlyremineralized with copper, lead, zinc, arsenic, andantimony in the vicinity of a 35 Ma granodioritestock and associated rhyolite dyke-swarm. Deposi-tion of Pb-Bi-Ag(Cu) snlfides and sulfosalts, as wellas tetrahedrite-tennantite, and the replacement ofgalena by covellite, are thought to have beenassociated with this event. Possibly two separateevents, an early bismuth-rich event (a late phase ofthe hiibnerite epi$ode, at 80 Ma?), and a latetetrahedrite-tennantite event (at 35 Ma), took place.

The mdn gold-silver mineralization at Round Moun-tain occurred x 25 Ma within a rhyolitic ash-flowtuff. This mineralizing event, by modification of anolder (Cretaceous?) vein, may have been responsiblefor production of the two coexisting compositionsof PbSo at the Fairview mine. The two distinctlydifferent compositions of galena found at the Lead-Silver King prospect are probably products of Ter-tiary events younger than the 27 Matuff of MountJefferson that forms one wall of the Lead-Silver Kingvein system. An economically significant gold-silvermineralizing went at Manhattan took place at 16 Mawithin Paleozoic sedimentary rocks along the southmargin of the Manhattan caldera. A separate butundated (probably early) Tertiary mineralizing eventintroduced mercury, antimony, and arsenic mineralsinto the eastern part of the Manhattan belt (anortheast-trending zone centered on the White Capsmine: Shawe 1986). Other centers of mercury,antimony, and arsenic mineralization peripheral tothe Manhattan caldera may have formed conclu-rently. Formation of the mercury-bearing Bi-Pb-Ag-Cu sulfosalts (phases X and Y), coloradoite, andthe mercurian galena in a Cretaceous quartz vein atthe Outlaw prospect is thought to have occurred dur-ing this episode of mineralization.

Thus, we infer a general sequence of depositionof sulfides and sulfosalts in the Round Mountain -Manhattan area, although timing of the sequence isimperfectly known, and similar stages in differentlocalities may not be strictly correlated in time. Iso-topic ages have not been determined on any of thelead minerals. Interpretations of lead-isotope ana-lytical data would of course depend on assumptionsthat may or may not be valid for the complsx mingl-alized environments in the two gold districts. Anearly high-temperature event related to the Creta-ceous granite plutons involved deposition of simplesulfides in tactites and quartz veins. At a later time,a high-temperature bismuth-, silver-rich hydrother-mal activity locally modified these deposits. Proba-bly at about 35 Ma a lower temperature copper-lead-zinc-arsenic-antimony mineralization (charac-terized by covellite replacement of galena andtetrahedrite-tennantite deposition) related to thegranodiorite stock and associated rhyotte dyke-swarm modified some of the Cretaceous veins. Stilllater, at about 25 Ma and at 16 Ma, low-temperaturegold mineralization occurred at Round Mountainand at Manhattan, furtler modifying older depositsin those areas. A Tertiary mercury-arsenic-antimonylow-temperature event also modified older d€positsin the vicinity of the White Caps mine, the Outlawprospect, and at other centers peripheral to the Man-hattan caldera.

Additional new mineral species in the Pb-Bi-Ag(Cu) t Hg system continue to be reported. Manyadditional studies remain to be done on this sy$tem

374 THE CANADIAN MINERALOGIST

to further elucidate T, P, and lS, conditions ofmineral deposition in complex natural systems.

AcKNOWLEDGEMENTS

The authors thank C. Heropoulos (U.S. Geolo-gical Survey, Menlo Park, Calif.) for emission-spectrographic analyses for the chalcophile elementson selected minerals and mineral mixtures. We aregrateful to James Craig (V.P.I., Blacksburg, Va.)for sealing some galena and sulfosalt samples inquartz tubes under vacuum and annealing them forus. One sample of 'benjaminite' from the Outlawprospect was provided by Forrest Cureton. The staffof the U.S. Geological Survey library was most help-ful in obtaining many of the Russian language pub-lications used in this work. We gratefullyacknowledge the careful and perceptive reviews ofR. C. Erd, P. J. Modreski, and B. F. Leonard, allof the U.S. Geological Survey. We also acknowledgethe constructive reviews of two anonymous refereesand the editor of the Canadian Mineralogist,R. F. Martin.

RSFERENcSS

Bonooevrv, Yu. S. & Mozcovn, N.N. (1971): Newgroup of the sulfobismuthides of Ag, Pb and Cu.Soc. Mining Geol, lapan, Spec. Issue. (Proc. ofIMA-IAGOD meetings '?0, joint symp.) 2, 344.1.

Cuarc, L. L. Y. & Bevnn, J. E. (1973) Lead sulphosaltminerals: crystal structures, stability relations, andparagenesis. Minerals Sci. Eng.5, l8l-191.

& Hooa, S. N. (1977): Phase relations in the:m PbS-Cu,S-BirSr and the stability ofsystem PbS-Cu2S-Bi2S3 and the stability of

galenobismutite. Amer. Minerql. 62, 346-350.

Cnrranove, K. A. & Sr,wsanrv, A. P. (1974): Find ofseleniferous hammarite in the Orlovskoye deposit,Rudnyy Ntai. Dokl. Acad. Sci. USSR, Eorth Sci.Sect.216, 14+146.

CnrN, T. T., Krncmwn, E. & Paan, W. (1978):Friedrichite, Cu5Pb5Bi7Sls, a new member of theaikinite-bismuthinite series. Can. Mineral. 16,t27-t30.

Cnerc, J. R. (1967): Phase relations and mineralassemblages in the Ag-Bi-Pb-S system, MineraliumDeposita 1,278-306.

Czauarsrn, G. K. & Har.l, W. E. (1975): The Ag-Bi-Pb-Sb-S-Se-Te mineralogy of the Darwin lead-silver-zinc deposit, southern Californta. Econ. Geol.70, r09Lltt0.

DunrNrNc, G. 8., Coornn J. F., Jn. & Moss, G. E.(1988): Rediscovery of the Outlaw mine, NyeCounty, Nevada. Miner. Rec. (in press).

FencusoN, H. G. (1921): The Round Mountain dis-trict, Nevada. U. S. Geol. Sum. 8u11. 12U1, 383 406.

Fnvasnm, V. K., Lrravnnqa, R. F., RoN,raNsNKo, I. M.& Cuueenov, V. M. (1981): On lillianite-gustaviteand the lillianite-gustavite mineral series in tin oresof the Kavalerovsk region. Zap. I/ses. Mineral.Obshch. Ll0, 304-310. (In Russ.).

Foono, E. E., Snawn, D. R. & Corrm, N. M. (1985):Multiple coexisting phases of galena and associatedsulfosalts from the southern Toquima Range,Nevada and the Idarado mine, Ouray, Colorado.Geol. Soc. Amer. Program Abstr. 17,219.

Harnrs, D. C. & CHrN, T. T. (1975): Benjaminite,reinstated as a valid species. Can. Mineral. 13,402401.

& - (1976): Crystal chemistry and re-examination of nomenclature of sulfosalts in theaikinite-bismuthinite series. Can. Mineral. 14.t94-205.

& OwnNs, D. R. (1973): Berryite, a Canadianoccurrence. Can. Mineral. 11, 1016-1018.

Hnnrrnr, H. K. & Muulre, W. G. (1981): Unsub-stituted benjaminite from the AW Mine, NSW: adiscussion of metal substitutions and stability. NeaarJahrb. Mineral. Monatsh., 69-80.

Hona, S. N. & CnaNc, L. L. Y. (1975): Phase rela-tions in the systems PbS lg2S-Sb2S3 and PbS-Ag2S-Bi2S3. Amer. Mineral. 60, 621-633,

HouucHr, H. & WuBNscs , B. J . (1977): Lindstrdmite,Cu3Pb3Bi7S15: its space group and ordering schemefor metal atoms in the crystal structure. Car.Mineral. 15, 527-535.

Kanw-Mor.mn, S. (1966): Berryite from Greenland.Can. Mineral. 8, 414423.

(1972): New data on pavonite, gustavite, andsome related sulfosalt minerals. Neues Jahrb.Mineral. Abh. 117, 19-38.

(1973): A gustavite-cosalite-galena-bearingmineral suite from the cryolite deposit at Ivigtut,South Greenland. Medd. Grdnland 195(51.

-(1977): Mineralogy of some Ag-(Cu)-Pb-Bi sul-phide associations. Bull. Geol. Soc. Denmark 26,4l-68.

& Marovrcrv, E. (1979): On pavonite,cupropavonite, benjaminite and "oversubstituted"gustavite. Bull. Mineral. 102, 351-367.

& - (1981): Ae- and Bi-rich heyrovskltefrom the Bi-W-Mo mineralization at Castlegar,British Columbia. Can. Mineral. 19, 349-353.

MINERALIZATION IN GOLD DISTRICTS, NEVADA 375

& Pnulv, H. (1979): Galena and associated oreminerals from the cryolite deposit at lvigtut, SouthGreenland. Medd. Grdnland, Geosci.,25 pp,

KHercuxov, L. N. (1958): On the question about thecontent of bismuth in galena. SoobshcheniyaDal'nevostoch. Filiala im. V. L. Komarova. u4NCCCP, No. 9, 133-136. Vladivostok. (In Russ.).

Kosrov, I. & MrNlsve-Smrarove, J. (1982): SulphideMinerals - Crystal Chemistry, Parageneses and Sys-tematics. E. Schweizerbart'sche Verlagsbuchhand-lung, Stuttgart, W. Germany.

Kovelpuren, V. A., Marov, V. S., Ynvsrtcr.meva, T.L. & Vvel'sov, L. N. (1984): Junoite and pekoite- first find in the USSR. Zap, Vses. Mineral.Obshch.ll3, 3543.

Maroucrv, E. & Kenup-Morlsn, S. (19?7a): Chemis-try and crystallography of the lillianite homologousseries. I. General propefiies and definitions. NeuesJarhb. Mineral. Abh. L30,2U-287.

& -(1977b): Chemistry and crystallogra-phy of the lillianite homologous series. II. Defini-tion of new minerals: eskimoite, vikingite, ourayiteand treasurite. Redefinition of schirmerite and newdata on the lillianite-gustavite solid solution series.Neues Jahrb. Mineral. Abh. l3l, 56-82.

& - (1984): Ourayite from lvigtut, Green-land, Can. Mineral. ?2, 565-575.

& Marovrcrv, M. (1978): Representation ofcompositions in the bismuthinite-aikinite series.Can. Mineral. 16, 4A5-409.

NxH, J. T. (1972): Fluid-inclusion studres of somegold deposits in Nevada. In Geological SurveyResearch, 1972. U.S. Geol. Sum. Prof. PaperS0nC,cl5-c19.

NsoacHl, M., TareucHr, T,, Yeuaora, K. &TaNrcucHr, M. (1973): Bi .le-Pb-S minerals fromAgenosawa mine, Akita Prefecture, northeasternJapan. Tohoku Univ., Sci. Rep., Third Series, 12,no. l, 69-80.

Nurrrcro, E.W, (1953): Benjaminite. Amer. Mineral.38, 550-552.

- (1954): Studies of mineral sulpho-salts. XVII.Pavonite, a new mineral. Amer. Mineral. 39,4094t5.

(1975): Benjaminite - a re-examination of thetype material. Can. Mineral. 13,3944A1.

& Hannts, D. C. (1966): Studies of mineralsulpho-salts. XX. Berryite, a new species. Care.Mineral. 8, 407413.

ONrovev, D. O., DnuzrnxtN, A. V., TsentN, A. I.,Vval'sov, L. N. & Basove, G. V. (1982): Mineralsof the gustavite-lillianite series from the Kti-Teberdadeposii (northern Caucasus). Int. Geol. Rev.24,659-670.

Pnacrn{, I. (1979): Aikinit z Krupky, CSSR. z4ctaUniv. Carolinae-Geol. No.34, 183-186. (In Czech.).

SsasNoN, E. Y. (1924:): Benjaminite, a new sulphosaltmineral of the klaprothite group. Proc, U.S. Nat.Museam 65, art.24.

Suewr, D. R. (l98la): Geologic map of the RoundMountain quadrangle, Nye County, Nevada. U.S.Geol. Sum. Open-File Rep. 8l-515, scale l:24,000.

- (l98lb): Geologic map of the Manhattan quad-rangle, Nye County, Nevada. U.S. Geol, Sum.OWn-File Rep. 8l-516, scale I :24,@0.

(1985): Multiple episodes of mineralization inthe southern Toquima Range, Nye County, Nevada.,lz USGS Research on Mineral Resources-l985, Pro-eram and Abstracts (K. Krafft, ed,), U.S. Geol.Sum. Circ.949, 4849.

(1986): Complex history of precious metaldeposits, southern Toquima Range, Nevada. U,S,Geol. Sum. Open-File Rep.86-0459.

Foonp, E. E. & CouruN, N. M. (1984): Hueb-nerite veins near Round Mountain, Nye County,Nevada. U.S. Geol. Sum, Prof. Pap. l?37.

-, MenvIN, R. F., Atontessst{, P. A. M.,Msm.rEnr, H. H. & Mennrrt, V. M. (1980: Ages ofigneou3 and hydrothermal events in the RoundMountain and Manhattan gold districts, NyeCounty, Nevada. Econ. Geol.81, 388407.

- & Muut"tp, W. G. (1979): The crystal structureof benjaminite Cus.joPbe.a0Ag2.3sBi6.seS12. Caz.Mineral. 17, 607-618.

Mar-arHov, A. A. (1968): Bismuth and antimony ingalenas as indicators of some conditions of ore for-mation. Geochem. Int. 7, 1055-1068.

Mozoove, N. N. (1979): Nonstoichiometric andhomologous series of sulfosalts. Mineral. Zh. l,93-98. (In Russ.).

Muuun, W. G. (1975): The crystal structure of krup-kaite, CuPbBi3S6, from the Juno mine at TennantCreek, Northern Territory, Australia. Amer.Mineral.60, 300-308.

& Warrs, J. A. (1976): Pekoite, CuPbBi11S16,w member of the bismuthinite-aikinite minerala new member of the bismuthinite-aikinite

series: its crystal $tructure and relationship withnaturally- and synthetically-formed members. Can.Mineral. 14,322-333.

Wrlm, E. & Wu'rNscs, B. J. (1976): Crystalchemistry and proposed nomencliature for sulfosaltsintermediate in the system bismuthinite-aikinite(Bi2S3-CuPbBi\). Amer. Minerol. 61, 15-20.

376 THE CANADIAN MINERALOGIST

SvNetrr, V. & Hrnrnn, J.0974)l. The crystal struc-tures of krupkaite, CuPbBi3S6, and of gladite,CuPbBisSe, and the classification of superstructuresin the bismuthinite-aikinite group. Neues Jahrb.Mineral. Monatsh., 541-560.

ZAK,L. (1980): Isomorphism and polymorphism in thebismuthinite-aikinite group. Neues Jahrb. Mineral.Monatsh., 440448.

& Hrnren, J. (1981): Krupkaite (x = 1.3) fromDobsina, CSSR. Nerres ./a& rb. Mineral. Monotsh.,20G2r4.

- & Pnacuafi., I. (1981): Estimation of chemicalcompositions of the bismuthinite derivatives fromthe lattice parameters. Neues Jahrb. Mineral.Monatsh., 495-544.

-, Srrrdrr, V. & Hvrlrn, J. (1974): Krupkaite,CuPbBi3S6, a new mineral of the bismuthinite-aikinite group. Neues Jahrb. Mineral. Monatsh-,533-541.

Received December 15, 1986; revised manuscriptaccepted June 29, 1987.