gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1998.62A.1.148 Hydrogen in α-Alumina and Water Softening of Polycrystals and of Sapphire Between 600°C and 1000°C Castaing J. Laboratoire de recherches des musées de France, CNRS UMR 171; 6 rue des Pyramides, 75041 Paris cedex 01, France Kronenberg A. Department of Geology and Geophysiscs, Texas A & M University, College Station, TX77843-3113, USA Kirby S. H. U.S. Geological Survey, Mail Stop 977, 345 Middlefield Road, Menlo Park, California 94025, USA 1998 62A 1 280 281 Copyright © 1998, The Mineralogical Society 1998