gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1982.046.338.01 On the New Mineral Theophrastite, a Nickel Hydroxide, from Unst, Shetland, Scotland Livingstone A. Department of Geology, Royal Scottish Museum, Chambers Street, Edinburgh, Scotland Bish D. L. Los Alamos Scientific Laboratory, PO Box 1663, Mail Stop 978, Los Alamos, New Mexico, USA 3 1982 46 338 1 5 1 6 1981 Copyright © 1982, The Mineralogical Society 1982 Abstract

The new mineral theophrastite, Ni(OH)2, from Unst, is Mg-bearing and occurs associated with a very poorly crystalline Ni-containing mixed hydroxide of the pyroaurite type and/or zaratite on chromitite. X-ray powder diffraction data show a shift in d spacing toward brucite compared with pure Ni(OH)2. Infrared, thermal, chemical, optical, and physical data are presented together with indexed powder data for fifteen lines ranging from d 4.66Å to 0.90Å. The solid-solution series brucite-theophrastite is briefly discussed.