gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1977.041.317.10 New Data on Ktenasite Raade G. Institutt for geologi, Universitetet i Oslo, P.O. Box 1047, Blindern, Oslo 3, Norway Elliott C. J. Fejer E. E. Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, England 3 1977 41 317 65 70 17 5 1976 Copyright © 1977, The Mineralogical Society 1977 Summary

Ktenasite from Glomsrudkollen zinc mine, Modum, Norway, is menoclinic, space group P21/c. The cell dimensions are a 5·598, b 6·121, c 23·762Å, β 95·55° The chemical formula is (Cu3·5Zn1·5)(SO4)2 (OH)6·6H2O with Z = 2; ρcale 2·96 g/cm3, ρobs 2·94 g/cm3. The mineral is biaxial negative with α (colourless) 1·574, β (bluish green) 1·615, γ (light green) 1·628, 2Vα 59°.