gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1992.056.384.14 Crystal Structures The Crystal Structure of Klyuchevskite, K3Cu3(Fe,Al)O2(SO4)4, a New Mineral from Kamchatka Volcanic Sublimates Gorskaya M. G. * Filatov S. K. * Rozhdestvenskaya I. V. † Vergasova L. P. ‡ State University Russia LPO ‘Burevestnik’ Russia St.-Petersburg Institute of Volcanology, Academy of Sciences, Russia Petropavlovsk-Kamchatsky, Russia 9 1992 56 384 411 416 20 11 1990 1 11 1991 Copyright © 1992, The Mineralogical Society 1992 Abstract

The crystal structure of klyuchevskite, K3Cu3(Fe3+,Al)O2(SO4)4, was determined in space group 12 using the total of 715 independent reflections up to R 0.12. Klyuchevskite is a structural analogue of piypite (caratiite) K4Cu4O2(SO4)4MeCl with the substitution K+ + Cu2+ → (Fe3+,Al) + MeCl. Compared to piypite, the ordering of Cu2+ and Fe3+ cations in the klyuchevskite structure results in the distortion of the unit cell and in lowering the symmetry of the chains to 1.

This brings about a more compact packing of the chains. The chain-like arrangement of the structure determines physical properties of the mineral, its acicular habit, perfect cleavage, strong anisotropy of optical properties and orientation of optical indicatrix.

 Keywords klyuchevskite crystal structure piypite Tolbachik volcano Russia