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Lead-antimony sulfosalts from Tuscany (Italy); I, Scainiite, Pb (sub 14) Sb (sub 30) S (sub 54) O (sub 5) , the first Pb-Sb oxy-sulfosalt, from Buca della Vena Mine

Paolo Orlandi, Yves Moelo, Alain Meerschaut and Pierre Palvadeau
Lead-antimony sulfosalts from Tuscany (Italy); I, Scainiite, Pb (sub 14) Sb (sub 30) S (sub 54) O (sub 5) , the first Pb-Sb oxy-sulfosalt, from Buca della Vena Mine
European Journal of Mineralogy (December 1999) 11 (6): 949-954

Abstract

The new mineral scainiite, Pb (sub 14) Sb (sub 30) S (sub 54) O (sub 5) , the first lead oxy-sulfosalt, has been found at Buca della Vena mine in the Apuan Alpes, northern Tuscany, Italy. Scainiite occurs as black acicular crystals with bluish metallic lustre, elongated [010], up to 2 mm long and 0.2 mm thick. The mineral is brittle, opaque; VHN (sub 20) = 192 kg/mm (super 2) , d (sub calc) = 5.56 g/cm (super 3) . In reflected light it shows a low anisotropy and bireflectance, and rare red internal reflections. Its ideal chemical formula, derived from electron-microprobe data and from crystal structure refinement, is Pb (sub 14) Sb (sub 30) S (sub 54) O (sub 5) . Scainiite is monoclinic, space group C2/m, a = 52.00(2), b = 8.148(2), c = 24.31(6) Aa, beta = 104.09(4) degrees , Z = 4. The strongest five lines of the X-ray powder diffraction pattern are [d in Aa(I)(hkl)]: 3.472(100)(14 0 4), 2.956(54) (6 2 4, 12 2 1), 2.052(46)(14 0 8, 24 0 1), 3.041(35)(4 0 8), 2.228(22)(22 0 1, 22 0 6, 8 2 9). Scainiite is a structural derivative of synthetic hexagonal Ba (sub approximately 12) Bi (sub approximately 24) S (sub 48) , a member of cyclically twinned sulfosalt structures (zinkenite group). Scainiite crystallized in small fractures of dolomitic lenses in massive Fe-Ba ore, together with many Pb-Sb sulfosalts. The formation of this unique lead oxy-sulfosalt is related to narrow fO (sub 2) -fS (sub 2) conditions, corresponding to the magnetite-hematite-pyrite buffer at relatively high temperature (>300 degrees C).


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 11
Serial Issue: 6
Title: Lead-antimony sulfosalts from Tuscany (Italy); I, Scainiite, Pb (sub 14) Sb (sub 30) S (sub 54) O (sub 5) , the first Pb-Sb oxy-sulfosalt, from Buca della Vena Mine
Affiliation: Universita di Pisa, Dipartimento di Scienze della Terra, Pisa, Italy
Pages: 949-954
Published: 199912
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 21
Accession Number: 2000-026828
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Secondary Affiliation: CNRS Laboratoire de Chimie des Solides, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200009
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