An accurate determination of the cell dimensions of bultfonteinite, Ca4Si2O10H6F2

Abstract

Bultfonteinite from Bultfontein mine, Kimberley, South Africa, is a hydrated fluorine-containing calcium silicate, of approximate composition Ca₄Si₂O₁₀H₆F₂. It was first described in 1932 by Parry, Williams, and Wright,1 who gave an account of its morphology, optical properties, composition, and chemical relationships. It is triclinic but markedly pseudo-orthorhombic. The present work consists primarily of a determination of the unit-cell dimensions, involving a more accurate evaluation of the interaxial angles than the earlier one; this is followed by some tentative suggestions about the structure.