Parapierrotite from the Vorontsovskoe gold deposit, Northem Urals, Russia: crystal structure and chemical composition
Plâsil J., Kasatkin A. V., Skoda R., Stepanov S. Yu.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2018. V. 147. N 1. P. 68-78
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Language: English
Abstract
We report data on the chemical composition and crystal structure of parapierrotite, TlSb5S8, recently found at the Vorontsovskoe gold deposit (Sverdlovskaya Oblast’, Northern Urals, Russia). It forms there short prismatic crystals up to 1 mm across embedded in a calcite-quartz matrix in association with orpiment, prehnite and baryte. Electron microprobe analysis yields the empirical formula (calculated on the basis of sum of 14 atoms) Tl1.01(Sb4.75As0.28)S5.03S7.95. Crystal structure of parapierrotite was solved at the first time. It is determined from single-crystal X-ray diffraction data and refined to R = 0.0536 for 4643 observed reflections with I > 3(σ). Parapierrotite is monoclinic, space group Pn, with unit-cell parameters a = 8.0832(5), b = 19.4057(11), c = 9.0465(5) Å, β = 91.908(6)°, V = 1418.25(1) Å3 and Z = 4. The structure of parapierrotite is identical to previously reported structure of synthetic TlSb5S8.
Key words: parapierrotite, synthetic TlSb5S8, As admixture, Vorontsovskoe gold ore deposit, the Urals.
