A Sakhaite-Like Mineral from the Kombat Mine in Namibia

Pete J. Dunn, Donald R. Peacor, Joseph A. Nelen, Robert A. Ramik and John Innes
Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20560, USA
Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20560, USA
Department of Mineralogy, Royal Ontario Museum, Toronto, Ontario, Canada M5S 2C6
CSIRO Institute of Minerals, Energy, and Construction Division of Exploration Geoscience, Private Bag P.O., Wembley, W.A. 6014, Australia

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

Mineralogical Magazine; March 1990 v. 54; no. 374; p. 105-108; DOI: 10.1180/minmag.1990.054.374.11
© 1990, The Mineralogical Society
Mineralogical Society (www.minersoc.org)