On the Existence of Monoclinic NaAlSi3O8 at Elevated Temperatures

H. D. Grundy, W. L. Brown and W. S. Mackenzie
Department of Geology, The University, Manchester 13

Summary: Measurements from powder diffraction patterns recorded at temperatures up to 950° C for the supposed equilibrium forms of albite synthesized at 800°, 900°, and 1000° C by MacKenzie (1957) indicate that only the form synthesized at 1000° C becomes monoclinic. Single-crystal measurements on heated pure natural albite (Ab99·26) show that it becomes truly monoclinic, both in geometry and intensity distribution, at 930° C, the same temperature as for the highest-temperature synthetic form. These experiments were carried out in conditions that exclude possible contamination by potassium.

Mineralogical Magazine; March 1967 v. 36; no. 277; p. 83-88; DOI: 10.1180/minmag.1967.036.277.13
© 1967, The Mineralogical Society
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