gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1960.032.250.05 The Biaxial Ray Surface Tocher F. E. B.Sc., Ph.D. Dept. of Geology and Mineralogy, University of Aberdeen. 9 1960 32 250 558 566 Copyright © 1960, The Mineralogical Society 1960 Summary

Existing descriptions of the biaxial ray surface are, in general, misleading. A more accurate description, stressing the simplicity of the surface, is proposed and this is supported by numerous sections drawn through or near the singular points.