gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1967.036.279.01 A New Polytype of Taaffeite—A Rare Beryllium Mineral from the Granulites of Central Australia Hudson D. R. Wilson Allan F. Department of Geology and Mineralogy, University of Queensland, St. Lucia, Queensland, Australia Threadgold Ian M. Department of Geology and Geophysics, University of Sydney, Sydney, New South Wales, Australia 9 1967 36 279 305 310 22 11 1966 31 3 1967 Copyright © 1967, The Mineralogical Society 1967 Summary

Chemical and single crystal X-ray studies have shown the existence of a 9-layer polytype of taaffeite. The parameters of the hexagonal unit-cell are a 5·675 Å, c 41·096 Å (arh 14·085 Å, α 23·24°). The oxide composition of the mineral is Al2O3 71·44, MgO 15·76, FeO 6·78, BeO 5·50%. It is pale olive green, with refractive indices ω = 1·739, ε = 1·735, and a specific gravity of 3·68.