gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1982.046.339.07 The Occurrence of Uranium in Association with Cassiterite, Wolframite, and Sulphide Mineralization in South-West England Swart P. K. * Moore F. † Department of Geology, King's College, University of London, London WC2R 2LS

Present address: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge.

Present address: Department of Geology, University of Shiraz, Shiraz, Iran.

 6 1982 46 339 211 215 13 8 1981 Copyright © 1982, The Mineralogical Society 1982 Abstract

The U content of cassiterite (SnO2), wolframite (Fe,Mn)WO4, and various sulphides from two localities in the Cornubian batholiths of south-west England has been investigated. Cassiterites showed concentrations of U between 0 and 6 ppm with the higher concentrations corresponding to the darker colour bands. Sulphides contained no detectable U using the fissiontrack method, but high concentrations relate to micro- veining. This veining was also evident in associated wolframite and appeared to have a composition similar to an iron-arsenate mineral associated with the alteration of arsenopyrite. Wolframite exhibited a wide range of U concentrations with sharp zonation and several generations of ore deposition within one crystal. The U was not, however, associated with either the iron- or manganese-rich phases.