gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1990.054.374.11 Silicate Mineralogy A Sakhaite-Like Mineral from the Kombat Mine in Namibia Dunn Pete J. Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20560, USA Peacor Donald R. Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Nelen Joseph A. Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20560, USA Ramik Robert A. Department of Mineralogy, Royal Ontario Museum, Toronto, Ontario, Canada M5S 2C6 Innes John CSIRO Institute of Minerals, Energy, and Construction Division of Exploration Geoscience, Private Bag P.O., Wembley, W.A. 6014, Australia 3 1990 54 374 105 108 20 3 1989 14 9 1989 Copyright © 1990, The Mineralogical Society 1990 Abstract

Sakhaite from the Kombat Mine in Namibia is cubic, with a = 14.749(1)Å; the space group is a subgroup of Fd3m, the density is 2.88 g/cm3, and the index of refraction is n = 1.642(2). It is apparently more highly hydrated than previously described sakhaite, and has more aluminosilicate substitution. The idealized composition is Ca24Mg8(BO3)8[(BO3)y{AlSi4(O,OH)<16}x](CO3)8.< 8H2O with x = 0.73 and y = 5.0.

 Keywords sakhaite Kombat Mine Namibia