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Bindi, L., Evain, M. & Menchetti, S. (2007) Selenopolybasite, [(Ag,Cu)(6)(Sb,As)(2)(S,Se)(7)][Ag9Cu(S,Se)(2)Se-2], a new member of the pearceite-polybasite group from the De Lamar mine, Owyhee County, Idaho, USA. Can. Mineral. 45 1525–1528.
Added by: Laurent Cournède (2016-03-10 22:02:28) |
| Type de référence: Article DOI: 10.3749/canmin.45.6.1525 Numéro d'identification (ISBN etc.): 0008-4476 Clé BibTeX: Bindi2007 Voir tous les détails bibliographiques  |
Catégories: MIOPS Mots-clés: antimonpearceite, crystal-structure, disorder, polytypism, series Créateurs: Bindi, Evain, Menchetti Collection: Can. Mineral. |
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Indice de consultation : 4% Indice de popularité : 1% |
| Résumé |
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{Selenopolybasite, ideally [(Ag,Cu)(6)(Sb,As)(2)(S,Se)(7)][Ag9Cu(S,Se)(2)Se-2], is a new mineral species from the De Lamar mine, Owyhee County, Idaho, USA. It occurs as black anhedral to subhedral grains up to 400 mu m across, closely associated with naumannite, covellite, pyrite and calcite. Selenopolybasite is opaque with a metallic luster and possesses a black streak. It is brittle, and neither fracture nor cleavage was observed; the Vickers microhardness (VHN100) is 131 kg/mm(2) (range 125-141) (corresponding Mohs hardness: 3-3 1/2). The density could not be measured owing to the small grain-size. The calculated density is 6.548 g/cm(3) (on the basis of the empirical formula). In plane-polarized reflected light, selenopolybasite is light grey, weakly to moderately bireflectant, and weakly pleochroic from grey to a violet-blue grey. Between crossed polars, it is anisotropic, with no characteristic rotation-tints and no internal reflections. Reflectance values (R-min and R-max) for the four standard COM wavelengths are 32.8, 34.1 (471.1 nm), 31.0, 32.9 (548.3 nm), 30.2, 31.8 (586.6 nm), and 29.3, 30.0\% (652.3 nm), respectively. Selenopolybasite is trigonal, space group P (3) over bar m1, with unit-cell parameters: a 7.5950(4), c 12.0731(6) angstrom, V 603.12(5) angstrom(3), c : a 1.5896
Added by: Laurent Cournède |