A New Occurrenge and Crystal Chemistry

Canadian Mineralogist Vol. 19, pp. 423-427 (198t)

COLU$ITE:A NEWOCCURRENGE AND CRYSTALCHEMISTRY

PAOLO ORLANDI rNn STEFANO MERLINO Istituto di Mineralogia e Petrografiadell'Universitd, via S. Maria 53,56100 Pisa, Italy

GIUSEPPE DUCHI Istituto di Geologiae Paleontologiadell'Universitd, via S. Maria 53,56100 Pisa,Italv

GIOVANNA VEZZALINI Istitutodi Mineralogiae PetrografiadellUniversitti, Iargo S. Eufemia 19,41100Modena, Italy

ABSTRACT occur in the marble formation of the Apuan Alps. To date, forty-seven mineral specieshave A new occurrence of colusite in vugs of the been observed inside vugs in the marble' The marble quarried at Lorano, near Carrara. Apuan minerals are all well crystallized; many species. bronze- Alps, Italy, is reported. The tetrahedral such as famatinite, sulvanite, zinckenite, bou- are cubic. space group P43n, Two brown crystals langerite, seligmannite, wurtzite' sphalerite, tet- of colusite were studied bv X-rav- different crystals covellitei enargite' jordanite, geo- and electron-microprobe methods- The ruGdtit", diffraction belong to the sulfosalt first crvstal, with cell edge a - 10.538(6) A. has cronite and colusite,' (Orlandi 1980)' a composition corresponding to CuznVzAs"$2, and sulfide groups et al. whereasthe secondcrvstal, with a - 10.621(6) A, Colusite was found in'the Lorano quarry, in has the composition CurnVzAsaSnzS;rz.Published ana- the Carrara area, where carbonate rocks (Het- lwical data have been recalculaled on a basis of tangian marbles) are found forming part of the 66 atoms per unit cell. Reflectance, measured at 470, metamorphic Tuscan Series. Colusite is a rare and 546" 589 and 650 nm. varies between 26.7 sulfide of copper, vanadium, arsenic and tin' 13.3 and l7.9Vo in oil. 32Vo in air and between first describea fto- Butte, Montana by Landon VHN,^n is in the range 342-350. & Mogilnor (1933). Nelson (1939) rePortedly Keywords; colusite, sulfosalt. Carrara, Italv. marble. observ"edthis mineral, associatedwith enargite' in a sample from Red Mountain, Colorado' SourrrlnE However, he did not describe any of -the propeftie; of the mineral from this locality' Nous d6crivons un nouvel exemple de colusite, Arnong the various attthors who described form6e dans les cavit6s du marbre de la carridre and itudied colusite from Butte, Berman de Lorano (r6gion de Carrare, alpes Apouennes, & Gonyer (1939) presented correct chemical et bronze-brun, Italie). Les cristaux. t6tra6driques indicating that vanadium is an es- groupe spatial ?43n. Deux cnstaux data sont cubigues, Dangel & Wuensch (1970) 6tudi6s par diffraction X et par microsonde sential component. ont 6t6 and, on the basis Le premier. qui possddeune maille reviewed the whole literature 6lectronique. colusite d'ar6te a : 10.538(6) A, a la composition Cu,"Yt of new X-ray-diffraction data, indicated As"Sy: le second, qul donn" a - 10.621(6) A. to be isometric, with space group P43m' a r6pond i la composition Cu2oV2AsnSnnS"".Pour les 10.62,,A, and characterized by a sphaleriteJike colusites analys6es ant6rieurement, les formules ont arrangementof atoms. 6t6 recalcul6es pour 66 atomes par maille. La Further occurrencesof colusite were reported r6flectance de la colusite. mesur6e d 470. 546, 589 from Chizeuil, Sa6ne-et-Loire@icot et al- 1963) ' I dans I'air et et 650 nm. varie entre 26.7 32Vo from the Kounrad copper deposit (Gazuova & 13.3 it l7.9Vo dans I'huile; sa duret6 VHNno entre Yarenskaya 1966), from the copper deposit of est de 342 i 350. Chelopech, Bulgaria (Ierziev 1966) and from (Traduit Par la R6daction) the day copper-zinc deposit in the southern Mots-cl6s; colusite. sulfosel, Carrare, Italie, marbre. Urals (PshenichnYiet al. 1974). This paper presents new data on colusite, and gives chemical and INrnooucttoN describesits occurrence crystallographic data for two varieties. On the We are presently studying the minerals that basis of-these data and structural results, the 423 424 THE CANADIAN MINERALOGIST crystal chemistry of colusite is revised and assessed.

OccunnENcr eNp pnopnntrps

Numerous quarriesof the well-known marble can be found in the surroundings of Carrara. Colusite was found only in the Lorano quarry, which is five kilometres from the town. Colusite occurs as small (l mm3) crystals that show a characteristic habit (Fig. I ); the most frequent form is the tetrahedron, often associated with the tristetrahedron {21 1} and rarely with the cube. The snow-white matrix of the marble makes a considerable contrast for the epitactic overgrowths of the mineral on sphalerite or on wurtzite individuals; this feature makes these specimensparticularly beautiful. -/ oil The colusite crystals are bronze-brown with metallic lustre. No definite cleavage was observed. The specific gravity was not measured becauseof the very small quantity of material. All the physical and chemical studies were made on two small crystals found in vugs in two different blocks of marble; both have a AO &O &O tuM tetrahedral habit and are much smaller than Frc. 2. Reflectancesat various wavelengtis.Con- the crystal represented in Figure l. Crystal I tinuous and dashedlines refer to crystals I and was found associatedwith quartz, albite, fluorite 2, respectively, and dolomite, whereascrystal 2 was found associated with quartz, dolomite and sulvanite. In reflected light, colusite appearscream co- nffii',!lir$+++t{,-{gffilored in polished sections.Internal reflections, zonal structures or heterogeneities were not observed. Reflectance was measured using tungsten-titanium carbide No. 144 (Zeiss) as a standard(Fig. 2). Values at the four standard wavelengths are listed in Table l. The range of micro-indentation hardness was found to be 342-350 kg/mm' for a 100-9 load. The cell parameters of the two crystals of colusite were obtained by Weissenbergand precession photographs, with Cu K

'I. TABLE REFLECTANCEMEASUREMENTS lN AlR ANDIN OIL

(1) (2) l nm R(a'ir) R(oll) R(alr) R(oil) 470 28.2y" 14.9% 26.7% 13.3% 546 32.0 17.4 29.7 t5.6 589 32.9 17.9 31.3 17,0 650 32.0 17.5 3t,7 l7.l

'l) Crystal No. l: ce1l dimensiona=10.532i 2) Crystal No. 2: cell dimensiona=10.606[ CRYSTAL CHEMISTRY OF COLUSITE 42s

TABLE2. X.RAYPO!,IDER-DIFFRACTION DATA

dlhkl d. d I hkl | 11, nDs {a Ic -sr - {DS ta tc +st {DS hkl 6.15 5 lll 5.25 5.27 w 200 5.32 5.30 w 200 5.34 5 002 ot2 4.70 4.71 w ?10 4.72 4.74 w 210 4.77 'I 4.30 4.30 w 2lI 4.30 4.33 w 211 4.35 l0 l2 J,J4 J.JJ W 310 3.37 3.35 w 310 3.04 3.04 s 3.06 3.06 s 222 3.07 100 222 2.82 2.81 w 321 2.84 2.83 vr 321 2.86 5 tzJ 2.63 2,63 w 400 2.65 2,65 w 400 20 004 2.48 2.48 w 330 2.51 5 033,ll4 a.J7t 4.Jt9 W 420 2.38 2.37 w 420 2.38 5 0?4 2.245 2.245 || 33? 2.255 2,26't w 332 t26 5 233 2.065 ?.066 w 431 2.083 2.080vw 431 2.08 5 015,134 1.952 1.956vw 432 I .977 I .970 vw 43? 1.973 5 0?5,?.34 'I.881 L860 1.862 s 440 t,tt' ':ttt 440 044 '1.806 1.806vw 433 t./5f t./Dl w 442 : : 1.709 1.709 vw 532 '1.586 '1.601 I .588mg 622 1.599ms 622 1.600 40 226 1,554 1.553vw 631 - t.i/t 136 1.520 I.520 w 444 - L54n 5 444 1.462 1.461 640 '1.434 vw 1.433w 552 1.338 oll '1.3171.338 w 1.324 20 008 '1.209 1.317m 800 1.325 1.326 w 800 1.208m 662 1.215 1.217 m 662 1.2?2 30 266 1.178 1.178m 840 1.184 1.816 w 840 1.183 l0 048 '1.074 '1 'f.085 1.075m 844 .081 1.083 ns 844 30 448 1.012 I.013m 10,2.? 1.020 1.021 m 10.?..2 1.024 20 666 0.931 0.931m 880 0.938 0.937 m 880 0,940 I 0 088 0.898 20 2.6,10 0.841 l0 0.4.12 0.81I 5 6.6.l0

l) coluslte No. 1 fion Loranoauarry (a=10.532i) 2i Colusite No. 2 from Loranoquarry (a=10.606[) 3i coluslte fron Butte, JcPDscard ilo. 9-10. The reflection at 6..|5 tr was not ohserved ln colusite fron Lorano, lt is absent also in x-ray Dowderoattern renorted bv LAvv (1967)for colusite from Butte. Theasslqned indices lll are not connatihlewith snace grouo P43n, collected using the Gandolfi camera, with Cu of the mineral during extremely long exposures. Ka radiation. Table 2 compares the X-ray B.J. Wuensch(pers. comm. 1980) independently powder patterns for t}|e two crystals of colusite determined that the extra reflections can be from Lorano with that of colusite from Butte considered spurious and also concluded that the (PDF 9-10). The cell parametersare a 1O.532Q), correct space group is P43n. Single-crystal dif- 10.606(7) A for crystals 1 and 2, respectively. fractometer data were collected on crystals I the systematicabsences (&/ll absent f.or l=2n* and 2 to solve their crystal structures. These 1), determined by means of Weissenberg and data confirmed the choice of space group P43n precession photographs, indicated Pm3n or and gave unit-cell parameters a 10'538(6) P-43n spacegroups. However, only P43n is con- A and 10.621(6) A for crystals I and 2, re- sistent with the 43m point group indicated by a spectively. morphological study of the crystals; therefore, The microprobe analytical data obtained for this space group is assumed to be the correct one the two crystals of colusite previously studied for the mineral. Dangel & Wuensch (1970) pro- by X-ray methods are given in Table 3. The posed the space group P43m for colusite from analysis was done with an ARL-SEMQ electron Butte, mainly on the basis of some very weak microprobe at 15 kV and 0.2O pA specimen hhl (l=2n*l) reflections,such as 333,993,773 current. The following standards were used: and 555, observed in its diffraction pattern. galena for sulfur, chalcopyrite for copper, syn- Such reflections have not been observed at all thetic sulfides of antimony and arsenic for these in the diffraction pattern of colusite from elements,and metals for vanadium, tin and ger- Irorano, even with Weissenberg and precession manium. The data were computed onJine using photographs obtained from very small fragments the program Magic 4 (Colby 1968). 42.6 THE CANADIAN MINERALOGIST

TABLE3. CHEMICALDATA, COLUSITES FROM LORANO TABLE4. UNIT.CELLCONTTI{TS FOR COLUSITE FRO}I VAEIOUS SOURCES

l.lt.%(1 v'tt.1,(2) ) Cu 25.63 25.30 26.24 25.96 26.61 '1 v 2.11 2.03 .50 2.06 1.74 2.16 2.31 V 3.3 3.I o:uu ':" 0.42 0.30 LU 50.I 49.5 Zn- : 0.29 0.19 ?,1 7 Ge 0.28 0.50 1.27 1.31 sb 1.4 0.92 Sn 0.07 I.85 I .89 2.O2 2.48 0.95 0.89 Sn 0.26 6.6 As 5.90 3.92 4,27 3,76 2.96 3.09 3,62 Ge t.t sb 0.38 0.25 0.05 - 0.48 As AR Te- 0.33 s 31.63 31.44 32.01 32.38 30.91 Tota l I00.49 100.22 1,2 - Sn-poorand sn-.lch coluslte from Carra.a (thJs study) 3 - Colusite fron Butte (Beman & oonyer 1939) 4 - Coluslte frcd Butte (L6vy 1967) (1) CrystalNo. I: 5 - Colu3lte from ChJzeull (Levy 1967) celI dimensiona=.l0.532i 6,7 - Colusite fmn 4ay (Pshenlchnyig! g!.1974) (2) CrystalNo. 2: celI dimensiona=10.606i Cnysrer CHE,tr4rsrny or Cor,usrte colusitefrom Butte (no. 3, Table 4), or the (As. Sn) site, as shown by colusite from Gay (nos. The crystal structure of colusite was solved 6 and 7, Table 4). Germanium may also sub- by one of us and will be fully described and stitutefor (As,Sn),as in colusitefrom Gay. discussedelsewhere (S. Merlino, in prep.). We Murdoch (1953) claimed colusite and ger- are concerned here only with the main features manite to be isostructural. If this claim can be of the structure, as they provide a sound basis proved, colusite from Gay will represent on which the crystal chemistry of colusite may an be assessed. intermediate member, together with the vanadium arsenic germanate studied by Mitryaeva The structure of colusite can be easilv de_ et al. (1968), compositionally between colusite scribed as derivative from that of sphalerite by and germanite, as suggestedby Pshenichnyi et aI. substitution and insertion. fne ICuSol and [(As, (1974). However, the whole problem of the Sn)Sal tetrahedra are connected in three di- relationship of structure crystal mensions by corner-sharing in a sphalerite-like and chemistry among colusite, germanite and renierite deserves structure. Two vanadium atoms are stuffed in a closere-examination and will be discussed tetrahedralsites at 0, 0, 0 and r/2, Yz, Vz.The else- where. [VSal tetrahedron shares six edges with the [CuSa] tetrahedra, as in the crystil structure of sulvanite (Pauling I 965, Trojer 1966). The struc- ACKNOWLEDGEMENTS tures of the colusites found at Lorano quarry were refined to reliability values of 0.070 and Editor Dr. L.J. Cabri. Associate Editor Pro- 0.054 for crystals I and 2 (the Sn-rich variety), fessor B.J. Wuensch and the referees of the respectively. The crystal-chemical formulae ob- paper are kindly acknowledged for their con- tained as a result of the refinements are CuruV, structive criticism and many useful suggestions. AsoSsaand Cur"VzAsaSn:Sre(crystals I and 2, Support from the Consiglio Nazionale delle respectively). Ricerche, C.N.R. (Roma, Italy) is acknowledged. We note that, in contrast to the generally acceptedassumption of 64 atoms in the unit cell. RrrrneNcEs with a metal:sulfur ratio equal to one, the structural study indicates a unit-cell content of BERMAN,H. & GoNvsn, F.A. (1939): Re-examina- 66 atoms, with 26 copper atoms and a total tion of colusite. Amer. Mineral. 24, 377-381. of 34 metal atoms. Colnv, J.W. (1968): Quantitative microprobe anal- We recalculated the unit-cell contents of col- ysis of thin insulating flields.Adv. X-ray Anal. tL, usites from various sources on the basis of 66 287-305. [See also Magic 4. A Computer Program atoms in the unit cell, as indicated by the for Quantitative Electron Microprobe Analysis. structural results (Table 4). An ideal crystal- Bell Telephone Labs., Allentown, Pa.l chemical formula for colusite is CuroVr(As,Sn)u DANcEL,P.N. & WuENscH, B.J. (1970): The crys- Su. The data reported in Table 4 indicate that tallography of colusite. Amer. Mineral.55, 1787- iron may enter either the V site, as shown by t79t. CRYSTAL CHEMISTRY OF COLUSITE 427

G^zrzov^, K.S. & YennNsreve, M.A. (1966): Colu- mifera di Carrara. Atti Soc, Tosc. Sc. Nat. Mem. site from the Kounrad copper deposit. Tr. Inst. 87, 93-t24. Geol. Nauk, Akad. Nauk Kae.,S.S.R. 15, 82-91 (1965): The nature of the chemical (in Russ.). PeurrNc, L. bonds in sulvanite, CusVSa. Tschermaks Mineral. LeNooN, R.E. & MocILNoR, A.H. (1933): Colusite, Petrog. Mitt. 10, 379-384. a new mineral of the sphalerite grottp. Amer. Prcor,. P., T!'orv, G. & VrNcrsNNr, H. (1963): Mineral. 18, 528-533. Pr6cisions nouvelles sur les min6ralisations de LEw, C. (1967): Contribution i la min6ralogie Chizeuil (Sa6ne-et-Loire).,Soc. Frang. Min6ral. des sulfures de cuivre du type CasXSe. Bur. Crist. Bull. 86, 373-375, Rech. G6ol. Minidres M6m. 54. PsnsNrcHr.lvt,G.N., Sneor,uN, T.N., VYAL'sov, L.N. MrrRyAEvA, N.M., YenrNsreva, M.A., KosyAK, & TsnrtN, A.l. (1974): First find of germanium- E.A. & Munerove, D.N. (1968): Vanadium- bearing colusite. Dokl. Akad. Naa& SSSR 221(l), arsenic germanite. Zap, Vses. Mineral. Obshchest. l9l-194 (in Russ.; see also Dokl. Acad, Sci. 97,325-331. USSR, Ea;th Sci. Jecr. 22L, 140'143). Munoocu, J. (1953): X-ray investigation of colusite, Trnztrv, G. ( 1966) : Kostovite, a gold--copper germanite and reni6rite. Amer. Mineral. 98,794- telluride from Bulgaria. A mer. Mineral. 5t, 29'36. 801. Tno.lsn, FJ. (1966): Refinement of the structure NELsoN, R. ( 1939): Colusite - its occurrence, of sulvanite. Atner. Mineral. 51, 890-894. paragenesis and genetic significance. Amer, Mirt- erat. 24, 369-376, Onr-eNor, P., Bneccr, G., Der-Ere, D. & VFTTALTNI, Received August 1980, revised marutscrlpt accepted G. (1980): I minerali della formazione mar- April 1981.