The Descloizite-Mottramite Series of Vanadates from the Otavi Mountain Land, South West Africa: An X-Ray Study

W. A. van der Westhuizen, H. de Bruiyn, E. A. W. Tordiffe and B. J. V. Botha
Department of Geology, University of the Orange Free State, PO Box 339, Bloemfontein, South Africa

Abstract: Descloizite, cuprian descloizite, and mottramite from most of the known prospects and mines in the Otavi Mountain Land were sampled and subsequently analysed chemically and by X-ray diffraction. Unit cell parameters were refined with the aid of a computer program. It was found that, contrary to previous opinion, chemical parameters of these vanadates can be deduced from their X-ray powder data according to the equations (correlation coefficients in parenthesis):

ZnO = 75.369c−0.119b−31.177a−456.512(0.9634)

Zn2+ = 369.568c + 236.583b − 146.42a − 3726.344 (0.9642)

CuO = − 74.991c + 0.086b + 29.419a + 486.204 (0.9649)

Cu2+ = − 369.568c − 236.583b + 146.420c + 3826.344 (0.9642).

Keywords: descloizite • mottramite • X-ray data • Otavi Mountain Land • South West Africa

Mineralogical Magazine; March 1986 v. 50; no. 355; p. 137-140; DOI: 10.1180/minmag.1986.050.355.18
© 1986, The Mineralogical Society
Mineralogical Society (