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Biagioni, C., Pasero, M., Moelo, Y., Zaccarini, F. & Paar, W. H. (2018) Lead-antimony sulfosalts from Tuscany (Italy). XXII. Marcobaldiite, similar to Pb-12(Sb3As2Bi)(Sigma 6)S-21, a new member of the jordanite homologous series from the Pollone mine, Valdicastello Carducci. European Journal of Mineralogy, 30 581–592.
Added by: Richard Baschera (2018-10-04 15:04:06) Last edited by: Richard Baschera (2018-10-04 15:07:02) |
| Type de référence: Article DOI: 10.1127/ejm/2018/0030-2710 Clé BibTeX: Biagioni2018a Voir tous les détails bibliographiques  |
Catégories: IMN, INTERNATIONAL Créateurs: Biagioni, Moelo, Paar, Pasero, Zaccarini Collection: European Journal of Mineralogy |
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| Résumé |
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{The new mineral species marcobaldiite, similar to Pb-12(Sb3As2Bi)(Sigma 6)S-21, has been discovered in a single specimen collected in a quartz vein embedded in tourmaline-bearing schist from the Pollone mine, Valdicastello Carducci, Pietrasanta, Apuan Alps, Tuscany, Italy. It occurs as a black blocky prismatic crystal, up to 1 cm in size, with a metallic luster, associated with Sb-rich tennantite. Under the ore microscope, marcobaldiite is white, with a distinct anisotropism, with grey to bluish-grey rotation tints. Polysynthetic lamellar twinning is common and characteristic. Reflectance percentages for the four COM wavelengths are [R-min, R-max (%), (lambda)]: 31.6, 40.1 (470 nm), 30.9, 39.6 (546 nm), 30.4, 38.5 (589 nm), and 30.0, 37.6 (650 nm). Electron microprobe analyses gave (average of 10 spot analyses -in wt%): Pb 64.05(34), Bi 4.24(6), Sb 9.10(14), As 4.51(8), S 17.24(19), total 99.14(53). On the basis of Sigma Me = 18 apfu, the empirical formula is Pb11.98(4)Sb2.90(3)angstrom s(2.33(3))Bi(0.79(1))S(20.80(20)). The main diffraction lines, corresponding to multiple hkl indices, are [d in angstrom (relative visual intensity)]: 3.568 (ms), 3.202 (ms), 3.016 (ms), 2.885 (ms), 2.233 (vs), 2.125 (s), 1.848 (s), and 1.775 (s). The crystal structure study gives a triclinic unit cell, space group P (1) over bar, with a = 8.9248(9)
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