A New Universal Stage Extinction Technique: The Determination of 2V When Neither Optic Axis Is Directly Observable

F. E. Tocher
Department of Geology and Mineralogy, University of Aberdeen

Summary: A new universal stage extinction technique is presented. It is based on the special case of coplanar and conical extinction curves where an optic axis lies on the wave-normal locus. It may be used in favourable circumstances to determine 2V when neither optic axis is directly observable.

Mineralogical Magazine; September 1964 v. 33; no. 266; p. 1038-1054; DOI: 10.1180/minmag.1964.033.266.12
© 1964, The Mineralogical Society
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