 |
 |
|
Zelenski, M., Garavelli, A., Pinto, D., Vurro, F., Moelo, Y., Bindi, L., Makovicky, E. & Bonaccorsi, E. (2009) Tazieffite, Pb20Cd2(AS,Bi)(22)S50Cl10, a new chloro-sulfosalt from Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. Am. Miner. 94 1312–1324.
Added by: Laurent Cournède (2016-03-10 21:41:23) |
| Type de référence: Article DOI: 10.2138/am.2009.3190 Numéro d'identification (ISBN etc.): 0003-004X Clé BibTeX: Zelenski2009 Voir tous les détails bibliographiques  |
Catégories: CESES Mots-clés: aeolian islands, chloro-sulfosalt, crystal-structure, della vena mine, fossa crater, fumaroles, high-temperature gases, lead-antimony sulfosalts, mount st-helens, Mutnovsky volcano, rare sulfosalts, Tazieffite, thermochemical model, vurroite isotype, x-ray Créateurs: Bindi, Bonaccorsi, Garavelli, Makovicky, Moelo, Pinto, Vurro, Zelenski Collection: Am. Miner. |
Consultations : 1/585
Indice de consultation : 4% Indice de popularité : 1% |
| Résumé |
|
{Tazieffite, ideally Pb20Cd2(As,Bi)(22)S50Cl10, is anew mineral from the high-temperature fumaroles of the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as tiny, slender, needle-shaped crystals, up to 400 mu m long and 10 pm across, generally forming fibrous aggregates. Tazieffite is closely associated with greenockite, galena, mutnovskite, kudriavite, and Cd-rich cannizzarite. Other minerals spatially associated are pyrite, anhydrite, and cristobalite. Tazieffite is silvery-gray in color, occasionally with a magenta tint when it forms aggregates of extremely fine needles. It has a black streak and metallic luster. In plane-polarized incident light, tazieffite is weakly bireflectant and weakly pleochroic from dark gray to a blue-gray. Between crossed polars, the mineral is weakly anisotropic, without characteristic rotation tints. Reflectance percentages measured in air (R-min and R-max) for a single grain are 33.9, 34.1 (471.1 nm), 32.8, 33.0 (548.3 nm), 32.4, 32.6 (586.6 nm), and 30.9, 31.1 (652.3 nm), respectively. Electron microprobe analyses yield the following ranges of concentrations: Pb 41.88-44.14 (avg. 42.90), Cd 0.87-1.16 (avg. 1.03), Sn 0.31-0.69 (avg. 0.48), Bi 20.43-22.94 (avg. 21.90), As 8.64-10.73 (avg. 9.66), S 16.10-17.48 (avg. 16.58), Se 0.82-1.28 (avg. 1.04), Cl 2.39-2.77 (avg. 2.63), Br 0.09-0.15 (avg. 0.12), I 0.27-0.58 (avg. 0.42). The empirical chemical formula, calculated on the basis of 44 cations, is Pb-20.06(Cd0.89Sn0.39In0.02)Sigma(1.30)(As12.49Bi10.15)Sigma(22.64)(S50.08Se1.28)Sigma(51.36)(Cl7.18I0.32Br0.15)Sigma(7.65). Tazieffite is closely related to the halogen-sulfosalt vurroite, Pb20Sn2Bi22S54Cl6, both from a chemical and structural point of view. It represents the (Cd,As)-dominant of vurroite, according to the coupled heterovalent substitution Sn4+ + 2S(2-) -{>} Cd2+ + 2Cl(-). The crystal structure of tazieffite was refined in the space group C2/c to R = 0.0370 for 4271 reflections with I {>} 2 sigma(I). Unit-cell parameters are a = 8.3520(17)
Added by: Laurent Cournède |