Cranswickite — a rare tetrahydrate sulfate of magnesium MgSO4 ∙ 4H2O, the new find in Yakutia

Zayakina N. V.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2019. V. 148. N 1. P. 49-53

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Language: Russian 


Cranswickite — a rare tetrahydrate magnesium sulfate, MgSO4 ∙ 4H2O, has been discovered in the Malo-Tarynskoe gold ore deposit in Yakutia. It is its third find in the world, the second in Yakutia. The mineral is soft, it forms a crust of white and slightly grayish color on the rock surface. It associates with mica, chlorite, quartz, gypsum and pentahydrite. Its study has been carried out by X-ray phase and electron microprobe analyses. Its chemical composition is MgO — 20.12, SO3 — 43.50, H2O — 36.37 wt %. The empirical crystal chemical formula of the mineral is Mg0.99(SO4)1.08·4.02H2O. The mineral is hypergenic, it is formed probably due to oxidation of pyrite in sulfidized rocks. It is sufficiently stable while stored in laboratory conditions. The photograph and X-ray diffraction pattern of the sample are given in the paper.

Key words: cranswickite, β-starkeyite, magnesium sulfates, X-ray phase, electron probe analyses,Yakutia