Canadian MineralogistYol,2l, pp. 137-143 (1983)

AssrRAcr

Specimens from the Ashley gold deposit, Ban-nockburn Township, Ontario dontain tellurideminerals not previously reported from this locality.These minerals are tellurobismuthite, volynskite,rucklidgeite, calaverite, hessite, tellurite and kura-nakhite. This is the first reported occurrence ofvolynskite and kuranakhite in Canada. An uniden-tified secondary gold-bearing phase is also present.

Keywords: tellurides, volynskite, rucklidgeite, ku-ranakhite, Ashley gold deposit, Ontario.

Soutr.leng

Des 6chantillons du gisement aurifdre d'Ashley(canton de Bannockburn, Ontario) contiennent lesmin6raux de tellurium suivants non encore signal6sd cet endroit: tellurobismutite, volynskite, rucklid-g6ite, calav6rite, hessite, tellurite et kuranakhirc,C'est la premiire trouvaille de volynskite et dekuranakhile au Canada. Un min6ral aurifdre secon-daire reste non-identifi6.

(Traduit par la R6daction)

Mots-cles: tellurides, volynskite, rucklidg6ite, ku-ranakhite, gisement aurifire de Ashley, Ontario.

INtnonuctroN

The Ashley property, a former gold producerin Bannockburn Township, Ontario, is locatedapproximately 20 km west-northwest of Mata-chewan at latitude 48'01,N and longitude8Oo54'W, NTS 42Al2W (Fig. l). The depositwas mined in the 1930s and produced 1,558,996grams of gold and 237,754 grams of silver from143,007 tonnes of ore (Gordon et al. 1979)According to Rickaby (1932), the orebody con-sisted of a narrow system of subparallel, inter-connected auriferous quartz veins or lenses,referred to collecitvely as the Ashley vein. Thevein system is approximately 0.6 m wide, strikes170" and dips 30 to 50o west. The principal hostrocks are tholeiitic basalt flows, in places pil-lowed, that are intruded by dykes of porphyriticgranite and lamprophyre (Fig. 2). In the imme-diate vicinity of the quartz veins, the basaltic

TETLURIDE MINERALS FROM THE ASHTEY DEPOSIT,BANNOCKBURN TOWNSHIP, ONTARIO

D. C. HARRIS, W. D. SINCLAIR AND R. I. THORPEGeological Survey of Canada,60I Booth Strcet, Ottawa, Ontatio KIA 1Eg

host rocks are altered to an assemblage ofquartz, carbonate and pyrite (Rickaby 1932).

Thomson (1932) conducted a mineralographicstudy of the Ashley vein and identified thefollowing ten metallic minerals: pyrite, galena,native gold, altaite, chalcopyrite, sphalerite,hematite, krennerite, magnetite and pyrrhotite,in decreasing order of relative abundance. Thiswas the first reported occurrence of tellurideminerals in the Matachewan area. At present,little evidence remains of the former miningactivity. The headframe and other mine build-ings have been reduced to their cement founda-tions, and much of the area is overgrown withtrees and bushes. The original Ashley vein,exposed in surface trenches at the time ofRickaby's visit in 193 1, is now covered by thewaste dump and other surface workings.

The specimens that we studied were takenfrom a set of subparallel quartz veins east of theAshley vein (Fig. 2). Where exposed in a shortadit at the north end and in surface trenches,this vein system is 1.5 to 2.0 m wide, strikes170" and dips 45o to the west. Individual veinswithin the system are I to 2 cm wide and areI to l0 cm apart (Fig. 3). A thin selvage ofK-feldspar, stained red by very fine grainedhematite, is commonly present at the margins ofthe quartz veins, and fine-grained carbonate andpyrite typically replace the basaltic host-rocksadjacent to the veins over widths of approx-imately O.5 to 2 cm. Metallic minerals dissem-inated in the quartz veins, visible in handspecimen, include pyrite, galena, sphalerite,chalcopyrite, native gold and altaite.

MtNen,eLoctcAI- DEscRIprIoN

Most of the metallic minerals reported byThomson are present in our specimens; onlypyrrhotite and krennerite were not found. Theabsence of these two minerals appears to dis-tinguish the vein presently exposed at surfacefrom the Ashley vein, although it may be anoffshoot.

Altaite PbTe, the most abundant of the tellu-

t37

138 THE CANADIAN MINERALOGIST

Ftc. 1. Location map for the Ashley Mine.

ride minerals, is easily recognizable. In polishedsection, it is found as anhedral grains typicallyassociated with galena, pyrite and native gold;it commonly contains inclusions of tellurobis-muthite, volynskite and rucklidgeite.

Tellurobismuthite Bi;lex, the second mostcommon telluride, forms irregular grains asso-ciated with,altaite. Most

lath-shaped inclusions in,inclusions are less than

10 x 20 y.m, with a few up to 70 x 400 p.m.The larger laths contain inclusions of hessite(Fig. 4). Electron-microprobe analysis gave52.3Vo Bi and 47.5Vo Te: total 99.8 wt.Vo orBir.e0Tea.oo. A synthetic bismuth telluride withthe composition Biz.orTes was used as a standard.

Volynskite AgBiTe: is a rare telluride thatwas first reported as an unnamed silver bismuthtelluride by Bezsmertnaya & Soboleva (1963) ingold ores of Armenia. Subsequently, in 1965, themineral was fully characterized and named bythese authors. In the Ashley specimens, volyn-skite was observed in several polished sectionsas irregular grains up to 200 pm across associatedwith tellurobismuthite, rucklidgeite, altaite andgalena. It also occurs as small inclusions inrucklidgeite. In reflected light under oil immer-sion, volynskite is weakly anisotropic, varyingfrom pale pink to grey. Against altaite, it has aslightly purplish tint. It is readily distinguishablefrom rucklidgeite, which is strongly bireflectantwith shades of pink, and strongly anisotropicvarying frorp creamy to pale blue. Electron-

microprobe analysis gave l8.0Vo Ag,36.6Vo Biand 45.2Vo Te, total 99.8 wt' 7o, correspondingto Agr.oBir.oTez.oo. Synthetic Bi:.otTeg and puresilver were used as standards. X'ray powder-diffraction data are in close agreement withthose reported in the literature, but there areslight discrepancies in estimated intensities.These differences could be due to preferredorientation of the Powder mount.

Rucklidgeite (BiPb)Jee was first reported asan unidentified Pb-Bi telluride from the Robb-Montbray deposit, Quebec (Rucklidge 1969).Subsequently, the mineral was reported at twolocalities in Russia by Zav'yalov & Begizov(1977), who characterized and named the species.Rucklidgeite was identified in several polishedsections of samples from the Ashley deposit,particularly those rich in tellurobismuthite andvolynskite. The largest grain is 200 p.m in dia-meter; the mineral commonly occurs as inter-growths with volynskite and altaite (Fig. 5).Rarely, it is in contact with native gold, galenaand pyrite. Electron-microprobe analysis gave39.9Vo Bi, 13.3Vo Pb,45.5Vo Te, total 98.7 wt.Eo, cortesPonding to Pbo.":Bir.tJer.oo. SyntheticBir.o,Te" and synthetic PbTe were used asstandards. The X-ray powder-diffraction dataare in agreement with the published values.

Hessite AgzTe is rare in the specimens exam-ined. The largest grains (20 X 30 p.m) forminclusions in tellurobismuthite (Fig. 4). Identifi-cation was based on a semiquantitative micro-

or asof the

TELLURIDE MINERALS FROM THE ASHLEY DEPOSIT. ONTARIO

Flc. 2. sketch map of the Ashley property (based on an unpublished map by W. MacRae, 19g0).

probe analysis and on optical properties.Calaverite AuTe, is rare, present mainly as

isolated grains in the quartz-carbonate veinmaterial. A few grains were observed in contactwith altaite. Electron-microprobe analysis gave44.4Vo Au, O,6Vo Ag, 55.4Vo Te, total 100.4wt. Vo or Aur.oaAgo.orTe*.u0. The standard usedwas a synthetic phase with the compositionAuo.enAgo.rsTez.oo. An X-ray-diffraction studyproved the gold telluride to be calaverite.

Aa unidentified gold-bearing phase occurs asa replacement of the calaverite grains, rarely as

139

inclusions in altaite and as isolated grains inquartz-carbonate gangue. It has distilct opticalproperties, which resemble those of the valleriite-fype miner,als. Its color is yellowish brown tobronze with areas of red, and it exhibits strongbireflectance and very strong anisotropism vary-ing from brilliant yellow to fiery orange toreddish brown. Many of the grains or rims showrhythmic banding, whereas others have acolloidal-looking texture (Figs. 6, 7). Close ex-amination of this phase with an optical micro-scope and a scanning electron microscope indi-

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t40 THE CANADIAN MINERALOGIST

Frc. 3. Subparallel quartz veinlets cutting basalt as exposed in the adit. The quartz veinlets are enclosed

by typical carbonate-pyrite alteration envelopes. GSC 203882'

cates that in some places it contains microscopicinclusions of gold, but elsewhere it commonlyconsists of interlayers of tellurite and kurana-khitg. Microprobe analysis of the areas rimmingcalaverite gave Ag 0.8, Au 48.5, Te 4O.7, total90.0 wt Vo. Other fragments with no visibleassociated telluride or oxide minerals gavecompositions for three grains of Au 83.5, 87.7,90.7 and Fe 4.7, 5.1, 0.4, respectively. Otherelements with atomic number greater than so-dium were not detected. An X-ray powderpattern of these grains is similar !o that ofnative gold. In view of their consistent andunique optical properties, this X-ray result wasunexpected and remains inexplicable.

Tellurite TeO, forms rims on altaite and isalso associated with the unidentified gold-bearingphase. Its identity was confirmed by X-raypowder diffraction.

Kuranakhite PbMnTeOu is very rare in ourspecimens and was identified only in a polishedsection of a heavy-mineral concentrate as inter-layers with the unidentified gold phase. Itspresence was detected with the scanning electron

microscope equipped with an energy-dispersionanalyzero and its identity was confirmed -byX-ray powder diffraction' The only otherreported occurrence of kuranakhite is in SouthYakutia. USSR (Yablokova et al. 1975).

Drscussrox

Gold-bearing quartz veins on the Ashleyproperty near Matachewan have been found tocontain numerous telluride minerals, includingaltaite, calaverite, tellurobismuthite, rucklidgeite,volynskite, hessite and kuranakhite. This is thefirst reported Canadian locality for volynskiteand kurinakhite, and the second for rucklidgeite.

Rucklidgeite and volynskite are Bi- and Te-bearing minerals that occur with tellurobismu-thite, altaite and galena in the Ashley veins.They are also associated in other ore deposits'For example, in veins cutting the Lunnon andIuan nicliel orebodies, Kambalda, Australia,they occur with palladium-bearing minerals andother tellurides. In the case of the LunnonShoot, associated minerals are altaite, galena,

TELLURIDE MINERALS FROM THE ASHLEY DEPOSIT. ONTARIO r4 l

Flc. 4. Photomicrograph of a tellurobismuthite lath (IEBI) containing aninclusion of hessite (HS) in galena. The large idiomorphic grain is plritewith native gold. Bar scale 100 srm.

Fro-5. Ph.otomicrograph of 1llaite (ALT) containing inclusions of volynskite(V) and_rucklidgeite (R). The dark grey mineral with triangular;ii, i;galena. Bar scale 100 pm.

r42

Frc. 6. Photomicrograph of calaverite (white) partlyreplaced by the unidentified gold phase. Bar scale100 trrm.

hessite, chalcopyrite and trace amounts of gold,michenerite, testibiopalladite, hawleyite (orgreenockite) and melonite (Hudson et al' 1978).Our work on specimens from the Juan Shoot,kindly supplied by J.J. Gresham of Western

MINERALOGIST

Mining Corporation, has revealed relativelyabundant altaite, molybdenite, melonite (Pd- andBi-bearing), pentlandite, pyrrhotite, pyrite andchalcopyrite, and minor volynskite, rucklidgeite,ilmenite, Cd-rich sphalerite, hessite, micheneriteand gold. Rucklidgeite and volynskite also occurin gold ore in the Zod deposit, Armenia, USSR

@av'ylov & Begizov 1977) together with arseno-pyrite, pyrite, boulangerite, gersdorffite, galena,freieslebenite, altaite, gold, quartz and dolomite.Tellurobismuthite and tetradymite occur in otherspecimens from the Zod deposit, but apparentlyare not associated with rucklidgeite and volyn-skite.

Rucklidgeite was first reported from the Robb-Montbray gold deposit, Montbray Township,Quebec (Rucklidge 1969). This deposit consistsmainly of auriferous chalcopyrite, which formsirregular bodies within the chloritized matrixof a breccia zone in silicified rhyolite (Cookeet al. l93l). Rucklidgeite grains, 30 to 40 p.min size. are associated with altaite and arecompletely surrounded by chalcopyrite (Ruck-lidge 1969). Other telluride minerals identifiedfrom the Robb-Montbray deposit are frohber-gite, melonite, tetradymite, tellurobismuthite,krennerite, petzite, coloradoite, montbrayite andcalaverite (Thomson 1928, Peacock & Thomp-son 1946, Thompson 1947, Rucklidge 1969).In contrast, rucklidgeite in the Ashley speci-

THE CANADIAN

Frc. 7. Photomicrograph of the unidentified gold phase (in quartz-carbon-

ate gangue) strowing the optical rhythmic layering' Bar scale 100 pm'

TELLURIDE MINERALS FROM THE AS.HLEY DEPOSIT. ONTARIO t43

mens forms 200 p.m grains intergrown withvolynskite and tellurobismuthite.

Volynskite in the Ashley ore occurs as dis-crete, irregular grains associated with telluro-bismuthite, rucklidgeite, altaite and galena, andas small inclusions in rucklidgeite. In the goldores of Armenia, it forms complex intergrowthswith tellurobismuthite where the latter containshessite and altaite inclusions (Bezsmertnava &Soboleva 1963).

Kuranakhite in the Ashley specimens is inter-layered with a strongly anisotropic unidentifiedgold phase; these minerals, as well as tellurite,are almost certainly supergene. At the Kuranakhgold deposit, South Yakutia, USSR, kuranakhiteoccurs in quartz-limonite and quartz-hematiteores of an oxidized zone and is associated withsupergene gold, electrum and hydrous iron oxides(Yablokova et al. 1975\.

In summary, this study of specimens from theAshley gold property has resulted in the recog-nition of some rare telluride minerals not re-ported by previous workers. However, futurestudies of telluride minerals associated withother gold deposits of the Canadian Shield willundoubtedly demonstrate a wider distributionof some that now appear to be extremely rare.

ACKNO\)llLEDGEMENTS

The technical assistance of J.J.y. Bourgoin,E.J. Murray and D.R. Owens of CANMET andA.C. Roberts of the Geological Survey ofCanada are gratefully acknowledged. W. Mac-Rae, J.H. Tremblay and D. Sawyer providedinformation on the Ashley property. NguyenKham Kim drafted the figures.

RrrennNces

BrzsupnrxeyA, M.S. & Soror,Eva, L.N. (1963): Anew telluride of bismuth and silver. establishedby the newest micromethods. Trudy Inst. Mineral,,G_eokhim., Kristallokhim, Redkikh. Elementov,1!, ?0 94 (in Russ.; abstr.: Amer. Mineral. (1964)49, 818).

& - (1965): Volynskite, a new tellurideof bismuth and silver. Akad. Nauk S^i^fR, E/csper-irnental'no Metod. Issled, Rudnykh Minerilov,

Moscow 129-141. (in Russ.; Abstr.; Amer. Mine-ral. (1966) 51, 531).

Coore, H.C., Jeues, W.F. & Mewosrrv, J.B. (193 l):Geology and ore deposits of Rouyn-Harricanawregion, Quebec. Geol. Surv. Can., Mem. 168.

GonooN, J.8,, LovrD, H.L., op Gnr.rs, J. & Devrr,,R.F. (1979): Ashley mine. Irr Cold Deposits ofOntario. 2. Part of District of Cochrane. districrsof Muskoka, Nipissing, Parry Sound, Sudbury,Timiskaming, and counties of Southern Ontario.Ont. Geol, Surv. Mineral. Dep. Circ. tB; 125-126,

HuosoN, D.R., RoernsoN, B,W. & Vrcrns, R.B.W.(1978) : Zonod michenerite-testibiopalladite fromKambalda, Western Australia. Can. Minerol. 16,121-126.

Pracocr, M.A. & THovesoN, R.M. (1946): Mont-brayite, a new gold telluride. Amer. Mitreral. l1.,5 15-526.

RICKABv, H.C. (1932): Bannockburn gold area. Ont.Dep. Mines, Ann. Rep.4l, (II).

RUcKLIDGE, l. (1969): Frohbergite, montbrayite, anda new Pb-Bi telluride. Can. Mineral. 9,709-716.

TnouesoN, R.M. (1947): Frohbergite, FeTe,: anew mineral of the marcasite group. Univ.Toronto Stud., Geol. Ser., Contr. Can. Mineral.51. 35-40.

THorusoN, E. (1928): A new telluride occurrencein Quebec. Univ. To: onto Stud., Geol. Scr.,Contr. Can. Mineral. 27, ll-14.

(1932): Metallic minerals of the Ashlevmine, Bannockburn Township, Ontario, Univ. To-ronto Stud., Geol. Ser., Contr. Can. Mineral. 12,27-31.

YlnLorova, S.V,, DurerrNe, L.S., DMITRTK, A.L.& Sororove, G.V. (1975): Kuranakhite, a newsupergene tellurium mineral. Zap. Vses. Mineral.Obshchest. 104, 310-313 (in Russ.; abstr.:, Amer.Mhteral. (1976) 6L, 339).

Ztv'vtrov, Yr.N. & Brcrzov, V.D. (1977): Ruck-lidgeite, (Bi, Pbr)Ter, a new mineral from theZod and Kochkar gold ore deposits, Int. Geol.Rev. lg, 145l-1456.

Received May 28, 1982, revised manuscript acceptedAugttst 27, 1982.