gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1993.057.388.19 Mineralogical Note 1992 Mineralogical Society—Schlumberger Award Presentation, by Professor C. M. B. Henderson, to Professor Ian S. E. Carmichael, 16 December 1992, at University of Manchester 9 1993 57 388 545 548 Copyright © 1993, The Mineralogical Society 1993