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 as- sessed. 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 ob- served. 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 asso- ciated 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 pre- cession photographs, with Cu K<r radiatiou they were refined by least-squaresrnethods on the basis of the X-ray powder-diffraction data, '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.