Kalithallite, K₃Tl³⁺Cl₆⋅2H₂O, a new mineral with trivalent thallium from the Tolbachik volcano, Kamchatka, Russia

Abstract

A new mineral kalithallite, K3Tl 3+ Cl6•2H2O, was found in an active fumarole belonging to the Northern fumarole field at the First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Kalithallite is a product of the relatively low-temperature (70-150°C) interactions involving high-temperature sublimate minerals, volcanic gas and atmospheric water vapour. The associated minerals are cryobostryxite KZnCl3•2H2O, halite, sylvite, opal, and gypsum. Kalithallite forms lamellar to tabular crystals up to 5 × 30 × 40 μm 3 combined in open-work aggregates up to 1 mm across. It is transparent, colourless in individuals and white to pale cream-coloured or pale beige in aggregates, with vitreous lustre. Dcalc = 3.01 g•cm -3 . Kalithallite is optically uniaxial (-), ε = 1.656(3), ω =