American Mineralogist, Volume 71, pages210-221, 1986 Renierite, CuroZnGerFeoSru-CurrGeAsFeoSr6: a coupledsolid solution series LRwRTNcB R. BenNsrerN U.S. Geological Survey 345 Middlefreld Road, Mail Stop 984 Menlo Park, Califurnia 94025 Abstract The composition of renierite is found to be Cu,o(Zn,--Cu)Ger-"AqFeaS16(0 = x < l), with continuous solid solution between the zincian and arsenian endmembers, Cu,lnGerFeoS,. and Cu,,GeAsFeoS,u,through the coupled substitution Zn(II) + Ge(IV) + Cu(I) + As(V). This is the first reported example of extensivecoupled solid solution in a sulfide mineral. The renierite structure is a tetragonal, pseudoisometric derivative of the sphalerite structure type, with space group P42m. There are two of the above formula units per unit cell,which hasdimensions a: 10.622(DA and c : 10.551(l)A for zincian renierite, and a:10.60(l) A and c : 10.45(l) A for arsenianrenierite. Mdssbauer spec- troscopy indicates magneticallyordered Fe(II! in three distinct sites.The presenceof bulk magnetism, together with magnetic susceptibility dala, indicate that the magnetic ordering is anisotropic and is slightly uncompensated antiferromagnetic (weakly ferrimagnetic). Electrical measurementsshow that renierite is a p-type semiconductor. Arsenian renierite, not previously characteitzed, is similar to zincian renierite il polished section, with a slightly redder color and lower anisotropy. It is reddish-orangewith relief very similar to that of bornite, though it is harder (VHrs : 286) and does not tarnish in air. It is slightly bireflective, with colors varying from orange-yellowto reddish-orangein nearly crossed polarizers. The strongest powder X-ray diffraction lines are (d(I/1.)(hkl)): 3.042(100)(222),r.86r(29)(044), 1.869(16)(440),1.594(l r)(622), and 1.017(10)(10.2.2). The calculateddensity is 4.50 g/cm3.Specimens have beenfound at the Ruby Creek copper deposit,Alaska, where zincian renierite also occurs,and at the Inexco #1 mine, Jamestown, Colorado. At Ruby Creek, arsenian renierite occurs as sparse grains 20-50 pm across together with bornite, chalcopyrite, pyrite, tennantite-tetrahedrite, chalcocite, and ger- manite. In the ore at Jamestownit occursas rounded grains up to 75 pm acrossassociated with galena,chalcopyrite, sphalerite,bornite, tennantite, fluorite, geocronite,and possibly germanite. Renierite is of widespread occurrencein Cu-Zn-Pb ores throughout the world and is particularly characteristicof dolomite-hosted Cu-Zn-Pb sulfide deposits. Small grains of what appears to be bornite or "orange bornite" in sulfide ores should be carefully examined to determine if thev are in fact renierite. Introduction chemical formulas are shown in Table l. An apparent Renierite was first describedas a distinct mineral from deficiency of sulfur was often reported when a metal-to- the Cu-Pb-Zn deposit at Kipushi, Zaire, where it had for- sulfur ratio of one was assumed.The role of the small merly been called "orange bornite" (Vaes, 1948). It has amounts of As and Zn found in the analyseswas not subsequentlybeen found at Tsumeb, Namibia, and at known. Powder X-ray diffraction data were found to be numerous Cu-Pb-Zn deposits throughout the world. The very similar to those of chalcopyrite and stannite, and a present study was begun when renierite was found by the similar sphalerite-derivative structure was presumed, author during investigations of samples from the Ruby either isometric or tetragonal (Murdoch, 1953; Lambot, Creek copper deposit, southern Brooks Range, Alaska. 1950; L6vy and Prouvost, 1957; Viaene and Moreau, Due to its close resemblanceto bornite in the reflecting 1968). microscope,renierite is easily overlooked and appearsto During the course of this investigation it became ap- be a widespread mineral in copper-rich sulfide ore de- parent that various renierite compositions reflect signifi- posits. cant solid solution, particularly towards a high-As, high- The composition of renierite has remained in dispute Cu, low-Zn and low-Ge endmember. The discovery of sincethe discovery of the mineral. Some of the proposed grainshaving compositions closeto this new endmember 0003{04xl86/0r02{210$02.00 2r0 BERNSTEIN: RENIERITE 2tl Table L Proposed chemical formulas for renierite (arsenian renierite) from Ruby Creek, and particularly (Cu,Fe,Ge,zn,As,Sds vae$ 1948 from Jamestown,Colorado, confirmed its existence.The (Cu,Fe)3(Fe,ce,Zn,SnXS,As)n Lambot, 1950 composition of renierite can be expressedas Curo(Znr-*- Cu6FegGeSI0 Viaeneand Moreau,1968 CuJ(Ger-,As)FeoS,u,where 0 < x = 0.5 for zincian re- (Cu,ce,ca,As,Fe,Zn)So.95 Springer.1969 nierite and 0.5 < x < I for arsenianrenierite. Cu3(Fe,Ge,znxs,As)4 Fleischer, 1983 Table 2. Occurrencesof renierite Ge, Ga StaEe or Deposlt Sulfide Associated Country Province Locality l{ost Rock Descriptlon Mlnerals Mlnerals References Bulgaria Pazard- Radka andesite-daci te Cu-Zn-Pb-As am,m, pyrenrcprbn,cv, Tzonev, 1982 zhlk deposit volcanic lastic s sulfldes in large ge,bri, col, tn, ld , dg, cc , and dlkes velns, stockworks, gI st,Au,Agrbt,ra, and beds be,sy,td,f1 Bulgarla Sofiya Chelopech andeslte-dacite ? rn,gl en,luz,Ln,py,fm, Terziyev, 1965; depos it col,ist,hmu,cp, 1966 bn, cv, dg,Au Congo MrPassa, I50 Iate Precambrian Cu-Zn-Pb nineral- rn,ge cp,bn,tn,cc,gn, Picot et al. ' km W of calcareous dolo- ization in faults sp,py 1963 RtazzavlLLe niEe and fracEures Cuba Pinar NII part of Jurassic schists ore in faulted, rn,ge, cp,sp,py,tn,cc, Tvalchrelldze del Rlo provlnce brecciaEed zones gI asprcarb and Holmgren, 197r Italy Sardinia San Giovannl Canbrlan dolo- ore ln carbonates m sprgn;Iesser ba, Lauzac, I965 Pb-Zn nine nite, ls; Silur at contac! with PY lan schist schist Japan Akita Shakanal Miocene dacite- Kuroko-tyPe am cp,py,sp,gn,bn, Miyazaki et nlne basalt volcani-. s t ratifom dg,cv,eI,str,fu a1., 1978- clastics & dikes NaEi.bla Tsumeb Eine Iate Precanbrian large, lrregular ge,rn, cp,bn,sp,tn,cc, Sdhnge, 1963; dolonlte ,b recc ia , pipe; see text brl,gl gn Sclar and pseudoapli te" Geier,1957 USA Alaska Ruby Creek Devonlan dolo- Cu-rlch sulflde rn,arn, cp,bn,py,tn,cc, thls study deposiE, mite, dolonitlc ore in dolonite ge dg,car Bornlt.e breccla breccial see text USA Colorado Inexco /ll granltlc rocks, pipe-like sulfide arn, gn,sp,cp,tn,td, Iowe, 1975; trine, James- gneiss, schist, bodyi see text ge(?) bn,cc,gc,f1 Jenkins,1979; tom migMtite this study USSR Arkhan- Vaygach carbonates ( ?) ? rn, ge, sp,bn,py,cp,gn, Silaev,1980 gelsk, arg ba,fl RSFSR USSR Amenian AkhEala ?rn tn,gn,bn,sp,cp Kodzhoyan, ssR 1962 USSR Caucasus Urup deposit volcanics within hydroEhemal, epi- rn py,cp,bn,sp,gn, Kachalov- reglon cad i man t. r$ genet ic tn,luz skaya et a1., sequence 1975 USSR Kazakh- ? cartonates hydrothemal ( ?) rnrge sp,bnrtnrcc,gn, Yakovlev and py, en, fn,luz ,ba , Snimov , 1963 USSR Uzbeki- ? carbonates m py,nc,gn,sp,cp, Chebotarev -et s tan ap aI., 1975 Zaire Shaba Prince Leo- Late Precanbrian highlyirregular rn,ge, cp,bn,!n,py,cc, Intionale and pold nine, dolmlte, dolo- pipe along fault; bri,gl sprcar Oosterbosch, Klpushi nltlc shale and see text r974 b reccia Mlneral abbreviations: Ag-silverlarg-argyrodlte;arn-arsenian renierlte;asp-arsenopyriEe;Au-gold;ba-barite; be-beege ri te ; bn-b orni Ee;b ri-b ria rE i Ee;b t-be tekht ini te; ca r-ca rrolli te ; c c-c halcoci te; c oI-c olus it e; c p-chalcoPyri te ; cv-covellite; el-electrum; fn-fana!inlte; fu-furutobelte igc-geocronlte; ge-gemanite 1g1-ga111te; gn-galena; hnu-henusitelld-idaite;isl-isostannite;luz-luzonlte;mc-narcaslte;py-pyriEe;ra-rathite;rn-renleritei sp-sphalerite;st-stanniEe;str-sEromeyerite;sy-sylvanite;td-tetrahedrite;tn-tennanEite 2t2 BERNSTEIN: RENIERITE Fig. l. Arsenian renierite (arn) from Ruby Creek, Alaska. Fig. 3. Rounded grains ofarsenian renierite (arn) from the Associatedminerals are bornite (bn), chalcocite-digeniteinter- Inexco #1 mine, Jamestown,Colorado. Associatedminerals in- growth (cc), and calcite (ca). Plane polarized reflectedlight. clude "crackled" chalcopyrite (cp), fluorite (f), galena (gn), and quartz (q). Plane polarized reflectedlight. In this study, the composition, properties, and structure copyrite, sphalerite,galena, briartite, and gallite. It generallyoc- of renierite were investigated using electron microprobe curs as small (<75 pm) inclusionsin the other sulfidesor as fine- powder analyses, Mdssbauer spectroscopy, X-ray diffrac- grained massesup to at least severalcentimeters across. tion, single-crystal electron diffraction, reflectance spec- The Pb-Zn-Cu deposit at Tsumeb consistsof an irregular pipe- troscopy, and electrical and magnetic measurements. like intrusive within a late-Precambriandolomite sequence.The pipe containsmassive sulfide ore togetherwith breccia,kersanite, Occurrences and associations diabase dikes, and an enigmatic quartz-feldspar rock termed The known occurrencesof renierite are summarized in Table "pseudoaplite" (Stihnge,1964). A summary and bibliography of 2; other occurrencesof "orange bornite" may turn out to be this deposit is given by Wilson (1977). Renierite occurs as mi- renierite aswell. The localities from which renierite was obtained croscopicintergrowths throughout the hypogeneore. It is highly for this study are describedin more detail below. concentratedin Ge-rich zonesfound within high-gradehypogene Renieriteis found most abundantly at Kipushi, Zaire and Tsu- copper ore at various levels in the mine (Sclarand Geier, 1957). meb, Namibia. The Zn-Cu-Pb orebody at Kipushi occursat the The Ge-rich ore zonescontain large amounts ofgermanite (masses faulted boundary betweenbrecciated dolomitic shaleand a ma- weighingup to 28 tons have beenfound (S<ihnge,1960),together rine dolomite sequence.The sulfide ore forms a highly irregular with smaller amounts of the Ge minerals renierite and briartite, subverticalpipe, with sulfide replacementzones extending along and the Ga mineral gallite.