L421. The Canadian M ineralo g ist VoI. 35, pp. 1,421,-1430(1,997)

CHLORINE.POORANALOGUES OF DJERFISHERITE. THALFENISITE FROM NORITSK,SIBERIA AND SALMAGORSKY.KOLA PENINSULA, RUSSIA

ANDREI Y. BARKOVI. KAUKO V.O. LAAJOKI AND SEPPO A. GEHOR Instiute of Geosciences,University of Oulu, FIN-90570 Oulu, Finland

YT]RIN.YAKOWEY

Research Production Center, Kola Superdeep Borehol.e, 17 fiibileinaya Street, 184415 kpolyamy, Russia

OLAVITAIKINA-AHO Instituteof ElectronOptics, University of Oulu,FIN-90570 Oulu, Finland.

ABSTRAC"T

Chlorine-poor (A4.2 wt.VoCl) potassium-thallium-lead sulfides (analoguesof djerfisherite-xhalfenisite,ADZ) occur as minute (5 - 30 pm) subhedralinclusions in chalcopyrite, in a galena-rich massivesulfide ore from the Oktyabrsky deposit Noril'sk, Siberia. The ore contains froodite, Ag- and Pb-tellurides, Fe-rich argentopentlanditeand cassiterite. There is an extensivesolid-solution series between the K-rich [(K,Tl,Pb)eGe,Ni,Cu)25S27]and Tl-rich [(Tl,K,Pb)e(Fe,Ni'Cu)zsSzr] end-members.Tfvo principal substitutionsare suggested:(l) K* - Tl*, and (2) Pba*+52-+ K{(I'l+) + Cl-. Another occurrence of the Cl-poor analogueof djerfisherite,AD (0.03 - 0.72 wt.VoCl), is from the $almagelsky qlkaline ultramafic complex, in northwesternRussi4 where it is associatedwith base-metalsulfides, BMS, alid a Cu-rich djerfisherite (up to 21.9 txt.VoC:u), Unlike the latter, the AD shows ar essentialdecrease in K and an increasein Ni, the total of transition elementsand S: the empirical valuesS (S + Cl) are -27 atomsper formula unit, apfu.\\e compositionsimply that the incorporation of S instead of Cl may haveinvolved the incorporationof Ni in the K site, accordingto the coupledsubstitution: Niz* + Sz-+ K* + Cl-. The data suggestthat (l) Cl-free analoguesof djerfisherite and thalfenisite exist; there are (!) rrnlimited Tl-for-K substitutionand (3) firll Cl site occupancyby S ir the membersof the djerfisheritegoup, and (4) to maintain chargebalance, the incorporation of S insteadof Cl requiresthe substitution of a divalent cation (e.g., Pb and Ni) for a monovalentcation (K and Tl).

Keywords:potassiun sulfide, thallium sulfide, lead-bearingsulfide, base-metalsulfide, djerfisheritegroup, argentopentlandite, Cu-Ni ore, alkaline ultramaic complex, Oktyabrsky,Noril'sk, Salmagorsky,Kola Peniasula,Russia.

SonaMens

Nous avons d6couvertdes sulftres de potassium- thallium - plomb d faible teneur en chlore (04.2Vo en poids), phases atalogues d la s6rie djerfisherite-thalfenisite, en grains infimes (5-30 pm) sub-idiomorphesinclus dansla chalcopyrite,dans un minerai riche en galdneprovenant du gisementde Oktyabrsky,h Noril'sk, en Sib6rie. Le minerai contient la froodite, des tellurures de Ag et Pb, I'argentopentlanditeriche en fer, et la cassitdrite.Il y a une 6tendueimportante de solution solide entre les pOlesriches en K t6,Tl,Pb)6Ge,Ni,Cu)r5S7l et en Tl [(It,K,Pb)oGe,Nr,Cu)xSa]. Deux principarx sch6masde substitution semblentimportants: (1) K' + Tl', et (2) Pbp.+ Sz-* K'(Tl') + Cl-. Un autre d6couverte,d'un analoguede la djerfisherite b faible teneur en Cl (0.03 - 0.72VoCl, en poids), provient du complexe alcalin ultramafique de Salmagorsky,dans le secteur nord-ouestde la Russie.Ce min6ral, qui est associ6i des sulfures de m6taux de baseet une djerfisherite cuprifbre (usqu'i 2l.9Vo Cu, par poids),montre une diminution en K et une augmentationen teneursde Ni, 6l6mentsde transitionet S. Les teneursobserv6es en S + Cl sont d'environ2T atomespar unitd formulaire. Les compositionsindiquent que I'incorporation du S i la place du Cl pourrait €fte 1i6ei I'incorporation du Ni dansle site K, selon le sch6made substitutioncoupl6e: Ni2+ + 52- * K* + C1-.Irs donn6esfont penserque (1) des anatoguessans chlore de la djerfisherite et de la thalfenisite existent,(2) il y a possibilit6 de solution solide compldteentre le p6les Tl et Iq (3) il est possiblede trouver un taux d'occupation complet du site Cl par le S dansles rnembresdu groupede la djerfisherite,et (4) il est n6cessaire,pour maintenirl'6lectroneuralit6, d'imftquer, avecle S dansle site Cl, des ions bivalents (e.g.,Pb et Ni) i la place des cations monovalents(K et Tl). Clraduit par la R6daction)

Mots-cl6s: sulfure de potassium,sulfure de thallium, sulfure de plomb, sulfire de m6taux de base,groupe de la djerfisherite' argentopentlandite,minsrai de Cu-Ni, complexe alcalin ultramafique, Oktyabrsky,Noril'sk, Salm6ge6$r, pdninsulede Kola- Russie.

I E-mail address:barkov@ sveka.oulu.fi L422 TIIE CANADIAN MINERAL@IST

INTRoDUc'roN TABLE I. MINERALSIN POTASSIIJM.THALUTIM{IAD) STJI,FIDE. B&{RING ORFSFROM NORJL'SK SIBERIA Djerfisherite, a complex cubic potassium sulfide [ideally IQ@e,Cu,Ni)r5S26Cl],was first discovered This dudy. Rrdasblky d al, (1979).. by Fuchs (1966) in meteorites (enstatite chondrites). The first terrestrial occurence of djerfisherite was cfuloopyrite x(-80-85vol7o) x(60-65voL7o) describedby Genktnet al. (1969)from a Cu-Ni sulfide gsl€os x(3 l07o) x(25Yo) ore,Talnakh deposi! Noril'sk (Siberi4 northemRussia). pdlandito x (s 1 7o) x(5 -7 W Since tlen, it has been reported from a number of pyrrhotito x(s3Yo) x(2-3o/o) cobaoits x rt.r. various occturences(Clarke et al. L994,and references nsgn€dto x x tlerein). Featuresof the djerfisherite structure were sryedop€dlandito x x characterizedby Dmitrieva & Ilyukhin (1975) and Ag-Aualoys x x Dmitrieva (1976). The crystal strucfure of an h€ssite x x altaite x x electrochemicallyprepared djerfi sherite-likeinorganic paolovito nf x compound, K6LiFezS26Clnwas characterized by kotuldrits nl x Tani (L977).The thallium analogueof djerfisherite, monc.heits nl x thalfenisite tideally TleGe,Ni,Cu)25S25C11,was discov- ftoodits x !Lr. oassitsiie x !Lr. ered by Rudashevskyet al. (L979) in the Oktyabrsky nectinawite x 11f. deposrt Noril'sk. The Noril'sk complexappears to host gaogue x(ores typically host large ally analogousto djerfisherite.The discoveryofthe aggregatesof platinum-group minerals and various Cl-free memberof the djerfisheritegroup suggeststhat tellurides (Rudashevsky et al. 1979, Getllrin et al. other Cl-free membersmay also occur in nature. 1981).In termsof modal composition(Table 1), the ore In 1995,during an examinationof sulfide oresfrom examinedin this study clearly resemblestlat from Noril'sk, we found a numberof small (<30 pm across) Oktyabrsky in which thalfenisite was discoveredby subhedral crystals of K-Tl-Pb-bearing Fe-Ni-Cu Rudashevskyet al. (1979).The ore containingtheADZ sulfides,which stronglyresemble intermediate members is principally composedof chalcopyriteand galena. of the djerfisherite-thalfenisiteseries, but chlorine was Pentlandite and pyrrhotite axepresent in subordinate not detectedin tle minerals,In tle srme year, we amounts.The otler minerals,listed in Table 1, are discovered a new occurrence of a djerfisherite-like, accessories. Froodite and Ag- and Pb-tellurides Cl-deficient sulfide in the Salmagorskyalkaline ulta- (hessite and altaite, respectively) form large (up to mafic complex, in northwesternRussia, northeastern -1 mm), elongate,composite intergrowths with galen4 FennoscandianShield, where it occurs in intimate Ag-Au alloy (Ag63.6,6a.zAu:s.s:e.o)and, more rarely, associationwith the normal, Cl-bearing djerfisherite. argentopentlandite.The latter mineral also occursas (1) Owing to the small grain-size,no X-ray studiescould individual irregular gtains, commonly up to -Q.l mm be caried out on this material. However,tlese occur- across, (2) a thin (-10 pm) rim around the ADT rencesprovide an excellentopportunity to characterize (Fig. la) and, occasionally,(3) small, nearlytriangular the chemistry and substitutions in the Cl-deficient (in cross section) grains, which may represent a phases,which appear to be Cl-poor analoguesof pseudomorphafter the ADT. The argentopentlandite djerfi sherite(AD ) anddjerfi sherite-thalfenisite(ADZ) rims are of particular interest, sln6s similar relation- and, tlerefore, probable new mineral species.In this ships were not previously reported for members of paper,we report the data obtained. the djerfisherite group from other localities, although Genkin et al. (1,98I) describedrims of sphaleriteand Occup.nsNcEs,cNDAssocrATED MnleRAI,s someplatinum-goup minemllsaround djerfisherite from Talnakh.Cassiterite (identified by electron-microprobe Noril'sk analysis) is a trace constituent oftle ore. It occurs as small (-J pm to <0.1 mm) subhedralto anhedral The ADIoccur in massivegalena-rich sulfide ore grains, located mostly at the border between from the Oktyabrsky deposit,which forms part of the chalcopyriteand galena,and as minute crystalsassoci- Noril'sk complex. Galena-rich copper sulflde ores at ated with theADT (Fie. 1a).This seemsto be the first CI-POOR ANALOGUES OF DJERFISHERITE - THAFENISITE L423

Frc. l. (a) Chlorine-poor djerfisherite-(thalfenisite)-related sulfide (dj), mantled by argentopentlandite(apn); ccp: host chalcopyrite, cs: cassiterite; Oktyabrsky deposit, Noril'sk. (b) Djerfisherite rim (dj) around pyrrhotite (po) ir the Srlmagemftl' somplex. Sil: silicate. Back-scatt€redelectron images. Scale bar is equivalentto l0 pm in a, 100 pm in b.

record of cassiterite in sin in the Noril'sk ores. rim of argentopentlandite(Ftg. 2) are homogeneous. heviously Batyreva(1972) noted the presenceof tace For this reason,results ofelectron-microprobe analyses amountsof cassiteriteandmoissanite in "samplesfrom of the latter only arereported. In addition, crystalsof a the Noril'sk area" (no exact locality was reported), lead-rich mineral (probably galena), which are which were identified by X-ray diffraction and a laser submicrometricin size, may occur in abundanceat the (spectrum)micro-analysis. border between the ADT and the host chalcopyrite In addition to chalcopyrite, tlere are various (Figs.2a b). chalcopyrite-like minerals at Noril'sk: talnakhite Culs@e,Ni)16Srr,haycockite CurFe1sS16,mooihoekite Salmagorslq CuelFqSt6and putoranite CurGrs(Fe,Ni)r3-1eS32(Cabri 1967, Cabi & Haris 1971,Filimonova et al. L980" The Salmagorsky (Salmagorskii or Salmagora) Genkin et al. L98L). The base-metal sulfide (BMS), nlkalineultramafic complex forms part of the Khabozero containing inclusions of tbe ADT at Oktyabrsky, has groupofintrusions (Kukharenkoet aL.7965,Kogarko the composition(basis: S = 16) Cu7.eFq.1S16oideally et al. L995),Kola Peninsula,nortlwestern Russia.The Cu6FqS16or CuFeS2,strongly suggestingtlat it is estimatedU-Pb age (schorlomite)of 375 Ma (cited in chalcopyrite. Kogarko et al. L995) for the complex is in good T\e ADT appearas small (5-30 pm), subhedralto agreementwith Rb--Sr ages of 380 - 360 Ma for all euhedralgrains, typically triangular in cross-section, alkaline magmatism in the Kola - Finnish province enclosedwithin chalcopyrite (Figs. 2a,c). This crystal (Kramm et al. 1993).The complex representsa nearly habit is similar to that reported by Geo&in et al. circular, zoned intrusion (-20 kd), emplaced in (1981) for djerfisherite from Talnakh,where regularly Archean gneisses.A recent re-examinationof tle oriented,triangular grainsof djerfisheriteare observed complex (Murmansk Geological Survey and as inclusions in talnakhite. Djerfisherite from the GEOLKOM: unpublisheddata) significantly extended Elwin Bay kimberlite also occurs as subhedralgrains our knowledge of its geological structure and ore (Clarke et a|.1,994), whereasboth thalfenisitefrom potential. At the contact with wallrocks, fenites and Oktyabrskyand owensitefromWellgreen are anhedral fenitized rocks are developed.The outermost, obvi- @udashevskyet al. 1979,Laflamme et al. L995). ously discontinuous zone comprises otvine-bearing It should be noted tlat tle ADT wilh a rim of clinopyroxenites.The next concantic zone (towardthe argentopentlandite (Fig. la) typically show strong center)is predominantlycomposed of dunite; this zone intergranular semFositional variations, whereas the was not previously recognized (cf. Kogatko et al. single grains(predominantly 5-8 1r"tnacross) without a 1995). A discontinuous zone of melilitic rocks is 1424 TIIE CANADIAN MINERALOGIST

' :! -i:l I t '11! E,J

FIc. 2. (a) and (b) Subhedralcrystals of Cl-poor djerfisherite-(thalfenisite)-related sulfides (dj), associatedwith a lead-rich minsml, probably galena@b). Note that the latter is located at the border with the host chalcopyrite (ccp). (c) A typical triangular crystal of the Cl-poor djerfisherite-flalfenisite analogue(dj) enclosedwithin chalcopyrite (ccp). (d) Subhedral inclusion ofthe djerfisherixe-thalfenisite analogue(dj) within chalcopyrite (ccp). Oktyabrsky deposit. Back-scattered electronimages. Scale bar is equal to 1 pm in eachcase. observedcloser to the center.The core of the complex acrosswithin djerfisherite. The lat0ertypically occurs is predominantlyformed by melteigite and ijolite. An as a rim around pyrrhotite (Fig. 1b). Veinlets of irregular body of carbonatite and a BMS-apatite secondarymagnetite and manganoanilmenite (up to orebody are situated at the center. T\e BMS are 3.6 wt.Vo MnO) locally cut grains of djerfisherite. pyrrhotite, cubanite or isocubanite (or both), Minute grainsof barite (1G-20 pm) arc etrcounteredin chalcopyrite, pyrite, cobalt pentlandite and galena a closespatial association with the djerfisherite-bearing (Barkov et al.,ttrrpvbl. data).In places,djerfisherite mineralization. representsan essentialore mineral. T\e AD was identified in a BMS-bearng CoN{PosnroNs (6-8 modal Eo) melteigite tlat consists of *75-80Vo clinopyroxene (Woaa.1j5.7En2e.r-:z.sFsur.;_zo.o),

TABLEZCHBMICAL tillAr,octE|or as standards.Counting periods were 100 s. The most finely focused besm was applied. The spectra were Veigbl7o 4t6 processedby Link ISIS (version3.fi)) or ZAF-4 on-line programs.The estimatederrors in the EDS analysesfor 'r.83 K J.?9 t63 !.60 411 332 432 332 22 0.(B Cl are

!&u n.ca !&6 t&0, 18.t0 l&ti l8.(n l&(x 17.96 lr.6 F9 REI.ATE) ld 1is 4.$ 4S' 4J3 4.r2 4.93 3.03 J,ot 4.ql 6Vt TABLE4. CHEMICALCOIIIPOSITION'OFD'ERF$HENXTEA{D COMPLK Cu /6 239 2-9, 2A Lrr 2-t4 2-tt 2t5 t.12 0.94 CHIORJNE.P@RPI'ASES FROM TIIE SAI.I\{AGORSKY t 2493 24JO 21:t9 21''/5 2u3 2322 23.tt 25 23.01 2t.t2 s 26.9) 26,89 2fi4 16,9 :ro 2fit 2631 x.q, 2637 '55? lleidtuo/o o - 0.t3 0.13 0.13 - 0.81 t23456789s t 2n.n na 2614 23.9 75.m 25.7t 25.64 2nS2 25Jl n34

. aS ekd@dsfd(.edalyeq e6tu@lttl€10@. A@Iys@|Mh@ K 9.00 9.04 9.06 t.80 &9 t.l? 7.67 7.70 IJO dh@lhgtnalh ffi 4d. - dtt@d Fe 34.tXl 333t g2l 3330 32.X 3.&l 3r.60 3J.'19 35.71 A@1. C I - 9: 6is ddyi @L S lO turrifr (f,ldasloiEty a ar. 1979). M 0.91 l2l 0.t9 L8 0.t6 1.78 239 2"45 237 C! 21.45 2lg3 2137 m$g 21.43 20.60 lE.l3 l83l 1E.63 s 32.o? 32,n !254 3l.n 32 3325 32.72 32.4 33.60 (x rJo 125 1,32 126 124 0,7t 0.16 0.06 0.(B 98.04 Finland, to obtain the compositional data. Owing to stJM 98.7J 9924 9439 X.67 n.9 99.35 96.61 96.65 the small grain-sizeof theADZ, EDS was usedto avoid lilodo pnpodo (l am' 58) (or, at least, to minimize) interference from the host K i.99 5.98 5.9E 5.99 6.0,f 5.i10 521 523 5.15 Fo 15.&4 15.43 l5.El 1J.87 15.33 16.12 16.93 16.E9 16:12 chalcopyrite. For comparison, EDS also was used M 0.lo 0.53 0.39 0J4 039 0.78 1.05 l.ll 1.06 to analyzedjerfisherite from Salmagorsky.The quanti- Cu 8.78 E.9B 8.6E 8.?J E.E7 t.3t 7J8 7.6 1.el tlilcr. 25.02 24.89 24.88 25.16 24.59 2528 25.56 8,6 25.45 tative EDS analyses(Tables 2,3 and5) were caried s 26.02 2622 26.1E 25.91 26.45 2S.EO lLrc n.6 n39 out at 15 kV and I.2 nA, using a JEOL JSM-6400 (] 0.96 0.91 0.96 0.94 0.n 052 0.12 0.05 0.02 s+cl 26.98 nJ3 n)4 26.85 n37 n32 n2 n.ll n.4l ssanning-electronmicroscope equipped with a LINK eXL energy-dispersionspectrometer. Pure elementso rStDS el!.dddiswdoboolre JEoI-?33 dslooiqwroberdfd@lytiBl orthoclase,pyrite, syntheticPbTe and NaCl c@dni@ were used qArwgodtmolle.

TABLE 3. CHEMICALCOMPO$IION' OF DJERFIIIHERITE THE SALMAGORSKYCOMPI.EL KOT,APENINSUIA FROM Cl -p oo r analogae s of d.je ffi she rit e-+halfeni s it efro m Steigb% Noril'sk 1234567 Initial (WDS: mOL733 microprobe)analyses of cobalt K 9.18 9.r7 9.2t 9.15 9.09 927 9.30 tbe ADT gave concentrationsof chlorine and Fs 17.25 37.6 37.Vt 36.9E 37.15 37.1t 37.16 below the detectionlimits; Cl also was soughqbut not Cu 1t.32 18.16 18.63 1t.35 18.52 18.6? 1t.57 detected, witl a Cameca electron microprobe (Ya. Ni r39 0.E2 t.vt l.l5 0.82 0.95 l.u Pakhomovskii, pers. commun.). Tlpically, chlorine s 33.00 32.6 32.7t 32.78 ?2.76 32.t9 32.94 cl 1.34 1.42 1.3t l.4l 138 1.37 1.38 doesnot occur in the phases(Iable 2), atd only a few suM 100.$ 99.39 1m.07 9.a w.72 100.33 100.45 of more than twenty ADlcrystals analyzedwith EDS imFly tle possiblepresence of minor chlorine (<0.2 emtproeodw (t *ons= 58) wt.7aCl). This materialconhasts with djerfisheriteand K 5.n 6.V2 6.02 5.99 5.96 6.04 6.05 thalfenisite,which both invariably contain essentialCl Fo 16.96 t1.M 16.96 16.94 L7.M 16.96 16.92 (Clarke et al. L994,Rudashevsky et al. 1979).As ate^st Cu 7.33 7.34 7.49 7.39 7.{' 7.8 7.4? the sameEDS procedurewas applied (almost simulta- 0.41 0./A Ni 0.60 0.,10 O.47 0.50 0.36 djerfisherite,which gave XMeL 24.89 24.78 24.92 24.83 24.tt 24.t5 24.E3 neously) 161[s $r'lmagorsky s 26.17 26.t6 26.V1 26.16 26.18 26.13 26.13 the normal level of Cl. The coppr concentrationsin the cl 0.96 1.03 0.99 Lm 1.00 0.9E 0.9 ADT areuniform (4.I-6.3 wt.VoCu), nickel is higher (8.4-9.9 wt.7aNi), and all ttre grains contain lead (4.2 IEDS electrm-microprobeolf'ses;€'vqy anabrsis is o atmageoftm idividnl oatysos.Tb mlf,*os inthis TableandTable 4 r€ftrio n 9.6 wt.VoPb; 0.6-1.3 apfu). The empiical formulae, {ierfirberitoftm diftrcm mineralizedoqurrenoes d SqlmagorsLy. calculatedon the basis of L atoms= 58 (Table 2), 1426

Pb

FIc. 3. Diagramsrllustrating raagesin compositionsofCl-poor djerfisherite-thalfenisite analoguesfrom Oktyabrsky (open symbol; this study), comparedwith thalfenisite (solid symbol; Rudashevskyar al. 1979): (a) K-Tl-Pb and (b) Ni-Fe-Cv (atom. qo).

TABI,E 5. RBPRTSENTATIVE @MPCISTTIONSTOF from datain this study @ig. 3a).Avery strongnegative AR@NTOPENTI,.ANDTTE FR]OMOKTYABRSKY correlation (R = -0.98) between K and Tl in the compositions indicates tlat K is replaced by Tl in Waigb% t2345 the structure. Variations in concentrations of tle transition elementsnthe ADT arerather restricted. In terms of F9 39.55 39.75 39.56 &.32 N.45 tle Fe-Ni-Cu content, the ADT are compaxablewith Ni 15.14 15.73 15.75 15.64 15.65 (Fig. from owensite, AC 13.95 14.01 14.01 13.60 t2.63 thalfenisite 3b) and are distinct s 31.50 3t.47 31.59 ?1.24 31.93 which is Cu-rich. SIJM 100.14 100.% 100.91 100.80 100.66 The compositionof the argentopentlanditethatrims the ADT is close to tlat of the individual grains = Armio propctim (X amr tO (Table 5). The compositions zlrein good agleement Fe 5.76 5.79 5.76 5.E8 5.85 with the ideal formula, @e,Ni)6AgSs.Compared with Ni 2.20 2.18 2.18 2.17 2.15 most examplesof argentopentlanditefrom the literature 7.% 7.n 1.94 t.05 8.00 (Morales-Ruano& FenollHach-All 1996,and references AS 1.05 1.05 1.06 1.03 0.95 therein),the compositionsin this study are noteworttry s 7.9 7.98 8.0I 7.93 8.05 in beingiron-rich: 5.8-5.9 apfuFe (Iable 5).

t EDS elecfrm-mio:roprobeamlyt€s. # l-3: Dj erfi sh,e rit e{rom Salma g o r slq irreguhr individuslgrain4 # 4: noarlytiangular edn (pseuAomrpna$er Cl+oor amloeueof with respect (?); * 5: rim Djerfisheritemay be nonstoichiometric dj€rfilhsrite-.th.1ft0ftite arond (Fe, Cl+oor malogueof derfishsits-thlftoisib. to transition elements:ftom23 to 24 Ni, Cu, Co) apfu arc reported in the literature (Clarke et al. L994, and referencestherein). In conbast the Salmagorsky correspondto the stoichiometrSrof owensite;the latter djerfisherite is remarkably stoichiometric,as revealed alsocontains lead (up to 5.2wt.VoPb;I-aflammeet al. by both EDSand WDS analyses(Iables 3, 4), andclosely 1995).An extensivesolid-solution seriesbetween the correspondsto tle formula K6(Fe,Cu,Ni)25S26C1.A K- andTl-rich end members,(KT1"Pb)6GeJ.[i,Cu)zsSz narrowrange of Cl content(1.24-L.42wt%o;0.91-1.03 and CIl,KPb)6(Fe,Ni,Cu)25Sr,respectively, is evident apfu CL)is characteristicofthis djerfisherite. CI-POOR ANAI,OGUES OF DJERFISHERITE - THALFENISITE 1427

ol 62 3 .g L4 +o x6 +7 o8 0.6 17

d ZB

0.5 0.9

_1 t 5 Ni+Co Atom.% d g 0.6

Flc. 4. Ni (+Co)- Fe- Cuplot of djerfisheriGcompositions 0 0.1 0.3 0.4 fromvarious terrestial occurrences; 1:from Salmagorsky (djerfisheriteand AD; this study),2: from alkalinerocks E g and carbonatitesat Khibi:ra, Kovdor, Lovozeroand E Murun(Ifantopulo et aL,1978,Balabonin et al,1980, , s6 Dobrovol'skayaet al. 1980),3:from serpentiniteand I peridotiteat Kovdorand Inagli (Balabonin et a|.1980, Yeremeevet al. 1982),4: fromkimberlites and xenoliths 0.1 in kimberlites,Yakutia (Dobrovol'skaya et al. L975, Distleret a|.1987)and Elwin Bay,Northwest Territories (Clarke et al. 1994), 5: fron eclogite (xenolith in 5 kimberlite),Yakutia (Ctovorov et a|.1984), 6: fromCu-Ni E

sulfideores at Noril'sk (Genkinet aI. l98l),7: from I

magnesianskarns in theYokc-Dovyren layered intrusion, 0.1 0.3 0.4 0.5 0.6 0.7 0,4 0.9 Pribaikal'e(Kislov er aI. 1994),8: from a skarnat cnoBG (rF(4 Tazheran,Siberia (Konev et aL l'972).

Frc. 5. Plot of chlorine versttscopper, iron, nickel, potassium Figure 4 showscompositional data for djerfisherite and sulfur contents(apfu;2 atoms= 58) in djerfisherite from various terrestrial occlurences, comparedwith (open symbol) and associated Cl-poor analogue of (solid the SalmagorskSt that from Salmag66ly. In general, examFles of djerfisherite symbol) from djerfisherite from alkaline rocks display the highest complex. concentrationsof copper.However, djerfisherite from ulnama.ficrocks in alkaline ulfiamalic complexesmay be very Cu-poor (Balabonin et al. L98O,Yeremeev e, a\.1982). The Salmagorskydjerfisherite is particularly rich in Cu (up to 21.9 wt.Vo),berngamong the richest known to date.Lesser amounts of Cu are reportedfor djerfisherite from Noril'sk (up to 16.6 wt.Vo Cu: Genkin et al. L98L) and the Murun alkaline complex, Cl-poor analogueof djerfi.sherttefrom Salmagorslcy Siberia (16.4 wt.VoCu: Dobrovol'skayaet al. 1980). Djerfisherite from other occlurences, including Comparedwith the djerfisheritefrom Sa}nagorsky, kimberlites, xenoliths in kimberlites and skarns, are the coexistingAD is characterizedby:(1) low Cl (0.03- typically poor in Cu (Fig. 4). Djerfisherite from O.72wt VoC|, 0.O2452 apfu Cl), (2) low K (3) higher kimberlites and xenoliths in kimberlites (Clatke et aI. Ni and Fe, (4) lower Cu, (5) higher totals of hansition L977, 1994,Clarke 199), alongwith djerfisheritefrom elementsoand (6) hieher S Clable4). Thesedistinctions the disseminatedpyrrhotite-rich Noril'sk ores (Genkin are illustrated in Figures 5 and 6. If calculatedon the et al. l98l), show the highestlevel of enrichmentin Ni basis of X, atoms= 58, the total of S and Cl is close to (Fig.4).Djerfisherite associatedwith various skarnsis 27 apfu in both djerfisherite and Cl-deficient sulfide characteristicallyFe-rich (Konev et al. 1972,Orsoev et Clables3,4). This imFlies the existenceof the S-for-Cl al. I993,I3slov et al. 1994). substitution,as previously noted inADTfrom Noril'sk" r428 THE CANADIAN MINERALOGIST

s@wl djerfisherite(Rudashevsky et al. 1979, Clarke et al...... 8 I 1994, and referencestherein). The presenceof Pb2' g substitutingfor K' and T1*in the ADZ structureseeurs to be of considerablesignificance in order to compen- sate tle chargeimbalance in the probable S!-for-Cl- substifution.Thus, the following coupled substitution 5.1 &3 6A 5.5 5.8 8.7 5.8 5.S is suggestedto occur:Pb2* * Sl + K(Il). + C1-.This is POTAS9m GpFt,) not inconsistent with owensite. which is Cl-free and 17 containsonly divalent cationsin the Ba site. The other imFortant F substitution in the ADT is homovalent: 3 Kt - T1'. 210 oa In spiteof &e fact that theADToccurin a copper-rich environment (chalcopyrite-rich ore) and form as inclusions in chalcopyriteothey are rather poor in Cu 6.1 a3 &4 5.5 6.8 5.7 5.8 6-J rcTASAUU NPFU) (4.L-6.3 wt.Vo Cu). This feature suggeststhat a factor(s) otler than tle extent of Cu-(Ni-Fe) enrich- menthas controlled their composition.

I The rims of argentopentlandite(Fig. 1a) deserve g attention,since similar textureshave not previously d g o.u been reported, and similarities exist between tlre djerfisherite and argentopentlanditestructures. Prob- ably, silver was an incompatible element during 8.1 6.2 5.3 5.4 6.6 rcrAaguu tpFq growth of the ADT crystals, and becamesufficiently concentratedat the border to form argentopentlandite. Since the latter is only stableup to 455'C (Mandziuk FIG. 6. Plot of potassium yers&J copper, iron and nickel & Scott 1977), the rims presumablywere formed contents(apfu;Z atoms= 58) in djerfisherite(open below this temperature.Morales-Ruano & Fenoll symbol)and associated Cl-poor analogueof djerfisherite Hach-Ali (1996)proposed a generalizedformula for (solidsymbol) from theSalmagorsky complex. argentopentlandite:(Fer"6.77Ni:$.zs)xoAgrrySs&, with 0 <.r< 0.30,0 crystal structure of the ADT wder the conditions of Rudashevskyet al. l979,Clarkeet a|.1994).However, growth, and was precipitated separately.Although the a synthetic Cl-free djerfisherite-like compound has ADT contain as much as 2l mol.Voof a hypothetical beenreported by Gorbachev& Nekrasov(1980). lead-richend-member Pb6@e,Ni,Cu)2rSy, the observed In accordance with the oo50%orule" in mineral solid-solutionseries essentially does not extendtoward nomenclature (a.9., Nickel 1"992), the Cl-poor the Pb end-member(Fig. 3a). However,this fact cannot djerfisherite and thalfenisite analogueswith S > Cl in be takenas evidencefor the absenceof a moreextensive the Cl site can be proposedto representnew mineral solid-solution seriesinvolving K-, Tl- and Pb end species. Unfortunately, no X-ray sfudies could be members.A lead-richbase-metal sulfide. shadlunite carried out because of the small grain-size of the (and related manganese-shadlunite),which occurs at Cl-poor phases at Noril'sk and Salmagorsky.By Noril'sk, is reportedto belong to the pentlanditegroup analogy with (Cl-free) owensite, these and related @vstigneevaet al. 1,973).However, it is also possible phases also appeax to be structurally similar to that theseminerals are akin to the djerfisherite group. djerfisherite and belong to the djerfisherite group. It is noteworthy that initial interpretation of tle owensitestoichiometry was MeeS8,and it was only Evilence from Noril'sk possible to understandthe true stoichiometryafter the crystal-structure study (Laflamme et al. 1995, T\e ADT from Noril'sk are distinct from Szymadski 1995).Assuming an essentialMez+-for-Pb djerfisherite-thalfenisite in tlat they are Cl-deficient substitution in shadlunite,the representativecompo- andinvariably containessentiallead (4.2-9.6 wt.EoPb1, sition given in Evstigneevaet al. (1973) and Genkin er 0.6-1.3 apfu), which is absent in thalfenisite and al. (I98I), i.e.,Pb 16.6,Cd 3.9, Cu 27.5, Fe 24.1.,S CI.POOR ANALOGUES OF DJERFISTIER.ITE _ THALFEMSITE 1429

27.4,tota199.5wt%o. may be recalculatedon the basis with the electron-microprobeanalyses and scanning- of L atoms = 58 to the formula (Pb2,olirfebyaCdl.*) electron microscopy, Dr. Yakov Palhomovskii x.sr(Cu,Fe)225.s0S2?.03,whereMe =ps2+stCu.Thefact (GeologicalInstitute, Kola ScienceCentre) for the that Mn can readily replace Pb in the (manganese)- initial electron-microprobedata" and colleaguesfrom shadlunite structure may imFly the possibility of the Murmansk Geological Survey and GEOLKOM Fe-for-Pb substitution in tlese minerals. Since (Apatity, norttrwestern Russia) for their help with shadlunitecan contain up to 9.1 wLVoCd (Karpenkov variousaspects of the studyregarding the Salmagorsky I974;ciledincenkin etal. I98l),theexistenceof the complex. We sincerely thank D.B. Clarke, R.H. Cd-predominantmember also is possible.It seemsthat Mitchell, A.C. Roberts,R.F. Martin andW.H. Maclran all these Noril'sk minerals under discussion may for their valuable comments and improvements to representthe K-, Tl-, Pb-, Mn- and Cd (?)-predominant tle manuscript, but the conclusions remain the sole Cl-free members of the djerfisherite group, akia 1s responsibility of the authors. Thanks go to Kristiina owensite; this possibility should be tested in further Karjalainen(University of Oulu) for draftingthe figures. studies. In addition, the possible incorporation of a transition element (N0 in the K site of a Cl-poor REFEREN.E' djerfisherite-like mineral is implied by the findings from the Salmagorskycomplex. BALAB.NtrT,N.L., VoLosrm{,A.V., pAKsoMovsrn,y.A. & Polvarov, K.I. (1980):The composition of djerfisherite Evidencef'rom Salmagorslq from alkalinecomplexes, Kola Peninsula- Mineral. 7t 2, 90-99(in Russ.). Unlike many compositionsof djerfisheritereported in the literature (Clarke et al. L994, and references Bervnnva, N.N. (1972): On the first find of cassiterite and (Insti- therein), the Salmagorsky examplesare in excellent moissanitein the Noril'sk ores.1z Abstr. I.G.E.M. Mineralogy agteementwith the ideal formula. In conhast the AD tute of Ore Deposits, Geology,Petrography, and Geochemistry; Academy of Sciences) for 1971. differs in composition, and showsa relative depletion IGEM, Moscoril,79(in Russ.). in K, an increasein Ni (andFe), a somewhatlower Cu content. and an excess in total transition elements Cannr,L.J. (1967): A new copper- iron sulfide, Econ. Geol. (Table 4, Figs. 5, 6). The empirical S (+ Cl) values in o,910-925. the formulae areclose to Zl apfu,like thosein theADZ from Noril'sk andin owensite.We concludefrom these & HARRrs,D.C. (1971):New compositionaldata observationsthat (1) thereis a Cl-poor naturalanalogue for talnakhite,Curs(Fe,Ni)r6s32, Econ. Geol, 6, 673'675. of djerfisherite, which is characterizedby significant (1979): djerfisherites (probably nnlimited) S-for-Cl substitution (in the CLARre,D.B. Synthesisof nickeloan and the origin of potassic sulphides at the Frank Smith Cl site); a transitional variety with 0.5 apfu Cl was mine. /n The Mantle Sample: Inclusions in Kimberlites encounteredat Salmagorsky;(2) the incorporation of and otler Volcanics(F.R. Boyd & H.O.A. Meyer, eds.). S instead of Cl into tle structure also involves an Proc. SeconLlnt. KimberliteConf,2,300-307. essentialincrease in the contentof a transition element (Ni) and a decreasein K. A comparison between the Mrrcnuc, R.H., CsapuaN, C.A.T. & MlcKav, Cl-bearingand Cl-deficient compositionsin Table4 R.M. 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Kocanro, LJ.[., KoNoNove,V.A., ORLovA,M.P. & Woor,r,sy, Received June 5, 1997, revised mnnuscript accepted A.R. (1995): Salmagelsffi. /n Alkaline Rocks and November22, 1997.