The Lattice Parameters of High-Temperature Triclinic Sodic Feldspars

I. S. E. Carmichael1 and W. S. Mackenzie
Department of Geology, Imperial College of Science London, S.W. 7
Department of Geology, The University, Manchester, 13
1Present address: Dept. of Geology and Geophysics, Univ. of California, Berkeley.

Summary: The lattice parameters of twenty calcium-bearing anorthoclases and potassium-bearing acid plagioclases have been determined by powder methods. The 201¯ spacing of the homogenized anorthoclases gives a good measure of the Or content irrespective of the amount of calcium present ; this spacing combined with α* (010): (001) may be used to determine the ternary composition of homogeneous feldspars more potassic than approximately Or15. The lattice parameters of feldspars less potassic than Or15 cannot be used for the determination of their ternary composition.

Mineralogical Magazine; September 1964 v. 33; no. 266; p. 949-962; DOI: 10.1180/minmag.1964.033.266.03
© 1964, The Mineralogical Society
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