Terrywallaceite, AgPb(Sb,Bi)3S6, isotypic with gustavite, a new mineral from Mina Herminia, Julcani Mining District, Huancavelica, Peru
2013; Mineralogical Society of America; Volume: 98; Issue: 7 Linguagem: Inglês
10.2138/am.2013.4423
ISSN1945-3027
AutoresHaibo Yang, R. T. Downs, S. H. Evans, W. W. Pinch,
Tópico(s)Mineralogy and Gemology Studies
ResumoA new mineral species, terrywallaceite, ideally AgPb(Sb,Bi)3S6, has been found in Mina Herminia, Julcani Mining District, Huancavelica, Peru. It is associated with tetrahedrite, gustavite, barite, and pyrite. Terrywallaceite crystals are lath-shaped, metallic-black, with striations parallel to the elongated direction (the c axis). The mineral is opaque with black streak and metallic luster. It is brittle and has a Mohs hardness of ~4; cleavage is good on {010} and no parting was observed. Twinning is pervasive on (100). The calculated density is 6.005 g/cm3. Optically, terrywallaceite is grayish white in polished thin section, with weak bireflectance, weak pleochroism (white to pale gray), and weak anisotropy (gray with bluish tint to bluish black in air). An electron microprobe analysis yielded an empirical formula, based on 6 (S+As) apfu, Ag1.02Pb0.87(Sb1.53Bi1.47)Σ=3.00(S5.94As0.06)Σ=6.00.
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