gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1970.037.290.18 Short Communications Hydrogrossular: Ca₃Al₂ (H₄O₄)₃ Versus Ca₃[Al(OH)₆]₂ McConnell Duncan College of Dentistry, The Ohio State University Columbus, Ohio 43210 6 1970 37 290 738 739 17 7 1969 Copyright © 1970, The Mineralogical Society 1970