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

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.