gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1982.045.337.11 Trace Element Distributions Between the Perthite Phases of Alkali Feldspars from Pegmatites Mason R. A. * Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637 USA

Present address: Department of Earth Sciences, Bullard Laboratories, Madingley Rise, Cambridge CB3 0EZ.

 1982 45 337 101 106 Copyright © 1982, The Mineralogical Society 1982 Abstract

The distribution of various trace elements between the K-feldspar and albite phases of perthites from several pegmatites was determined by ion microprobe. Ranges in distribution coefficients (wt. % in K-feldspar/wt. % in albite) are: Li, 1.2–780; Mg, 0.2–1.1; P, 0.1–17; Ca, 0.02–1.6; Cs, 32–820; Ba, 24–284; Pb, 1.6–30; Fe, 0.3–0.7; Rb, 59–5505; Sr, 1.3–5.1. The trace elements are zoned within the K-feldspar lamellae and the profiles are interpreted as the result of cross coefficients in the diffusion matrix.