Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Résumé Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Borodaev, Y. S. Articles by Vurro, F. Search for Related Content GeoRef GeoRef Citation

RARE SULFOSALTS FROM VULCANO, AEOLIAN ISLANDS, ITALY. V. SELENIAN HEYROVSKITE

Yuri S. Borodaev¹, Anna Garavelli², Carlo Garbarino³, Silvana M. Grillo³, Nadezhda N. Mozgova⁴, Werner H. Paar⁵, Dan Topa⁵ and Filippo Vurro^6,

¹ Department of Geology, Moscow State University, Moscow, 119992, Russia
² Dipartimento Geomineralogico, University of Bari, Via E. Orabona 4, I-70125 Bari, Italy
³ Dipartimento di Geoingegneria e Tecnologie Ambientali, University of Cagliari, Piazza d’Armi, I-09123 Cagliari, Italy
⁴ IGEM RAS, Staromonetny 35, Moscow, 109017, Russia
⁵ Institute of Mineralogy, University of Salzburg, Hellbrunnerstr. 34, A-5020 Salzburg, Austria
⁶ Dipartimento Geomineralogico, University of Bari, Via E. Orabona 4, I-70125 Bari, Italy

E-mail address: f.vurro{at}geomin.uniba.it

Heyrovskite, a rare Pb–Bi sulfosalt, was found around a fumarole of ca. 500°C at the La Fossa crater, Vulcano Island, Italy. The mineral occurs in the thin sulfosalt-rich crust covering the brecciated altered rocks of fumaroles, mainly admixed with selenian varieties of lillianite and cannizzarite, with subordinate galenobismutite and galena. Heyrovskite occurs as thin needle-like crystals up to 300 µm in length and less than 1 µm in width. No traces of a breakdown texture have been noticed in any of the crystals studied. Electron-microprobe analyses show that the heyrovskite from Vulcano has a composition close to the ideal Pb-rich composition of synthetic Phase II, Pb₆Bi₂S₉, obtained by Salanci & Moh in 1969. Particularly interesting is the absence of Ag and Cu, which makes the heyrovskite from Vulcano unique, with respect to cations; only a minor amount of a Cd impurity is present. Like in other sulfosalts from Vulcano, significant Se concentrations are invariably present (0.9–2.5 wt.%). The compositional field of heyrovskite from Vulcano, expressed in terms of the mol.% Bi₂S₃, ranges from ~14.23% (the most Pb-rich composition) up to 15.24% (the most Bi-rich), averaging 14.73 mol.%. This very narrow compositional spread (~1 mol.%) is in the range attributable to analytical error; the composition of heyrovskite from Vulcano is thus quite constant in terms of Pb-for-Bi substitution. The calculated average composition corresponds to the empirical formula (Pb_5.95Cd_0.02)_5.97Bi_2.06(S_8.53Se_0.44)_8.97, which is close to the ideal end-member, Pb₆Bi₂S₉. The cell parameters, resulting from an X-ray powder-diffraction study, are: a 13.734(7), b 31.28(3), c 4.135(3) Å. The reflections having h + l = 2n are indicative of space group Bbmm. The cell parameters of heyrovskite from Vulcano have been compared with those in the literature for heyrovskite from various deposits and with those of synthetic Phase II. There is no general agreement among the data reported by different authors. These data, together with the compositional differences, in terms of mol.% Bi₂S₃, among various natural and synthetic products, suggest that the range occupied by synthetic Phase II consists of many chemically and structurally very similar compounds. In particular, the Pb-rich part of the compositional field of the Phase II might be considered as the synthetic analogue of heyrovskite from Vulcano.

Keywords: selenian heyrovskite, Pb–Bi sulfosalts, fumarole, Vulcano Island, Italy.

This article has been cited by other articles:

				A. M. Callegari and M. Boiocchi Aschamalmite (Pb6Bi2S9): crystal structure and ordering scheme for Pb and Bi atoms Mineralogical Magazine, June 15, 2009; 73(1): 83 - 94. [Abstract] [Full Text] [PDF]

				D. Pinto, T. Balic-Zunic, E. Bonaccorsi, Y. S. Borodaev, A. Garavelli, C. Garbarino, E. Makovicky, N. N. Mozgova, and F. Vurro RARE SULFOSALTS FROM VULCANO, AEOLIAN ISLANDS, ITALY. VII. Cl-BEARING GALENOBISMUTITE Can Mineral, April 1, 2006; 44(2): 443 - 457. [Abstract] [Full Text] [PDF]

				D. Pinto, T. Balic-Zunic, A. Garavelli, E. Makovicky, and F. Vurro COMPARATIVE CRYSTAL-STRUCTURE STUDY OF Ag-FREE LILLIANITE AND GALENOBISMUTITE FROM VULCANO, AEOLIAN ISLANDS, ITALY Can Mineral, February 1, 2006; 44(1): 159 - 175. [Abstract] [Full Text] [PDF]

				I. V. Chaplygin, N. N. Mozgova, L. O. Magazina, O. Yu. Kuznetsova, Y. G. Safonov, I. A. Bryzgalov, E. Makovicky, and T. Balic-Zunic KUDRIAVITE, (Cd,Pb)Bi2S4, A NEW MINERAL SPECIES FROM KUDRIAVY VOLCANO, ITURUP ISLAND, KURILE ARC, RUSSIA Can Mineral, April 1, 2005; 43(2): 695 - 701. [Abstract] [Full Text] [PDF]