Conical Extinction Curves: A New Universal Stage Technique1

N. Joel and F. E. Tocher
Centro de Investigaciones de Cristalografía, Instituto de Física y Matemáticas, Universidad de Chile, Casilla 2777, Santiago, Chile
Dept. of Geology and Mineralogy, University of Aberdeen, Aberdeen, Scotland.
1This technique was evolved independently and almost simultaneously by the two authors who have agreed on a joint presentation.

Summary: New generalized extinction curves, derived from wave-normals located on a circular cone, are presented. They may be used with the universal stage for the accurate location of up to all three of the indicatrix axes, α, β, γ, of any biaxial crystal, or the optic axis of any uniaxial crystal.

Mineralogical Magazine; June 1964 v. 33; no. 265; p. 853-867; DOI: 10.1180/minmag.1964.033.265.03
© 1964, The Mineralogical Society
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