A Former Association of Enstatite and Kyanite

G. A. Chinner and T. R. Sweatman1
Department of Mineralogy and Petrology, Cambridge
1Permanent address: C.S.I.R.O. Division of Soils, Adelaide, South Australia.

Summary: An enstatite-cordierite-sillimanite-quartz rock from a pyroxenegranulite facies terrain in southern Rhodesia gives evidence of at least two stages of recrystallization : an early, high-pressure recrystallization to form the assemblage enstatite-kyanite-quartz, and a later, ‘retrogressive’ recrystallization during which kyanite inverted to sillimanite, and cordierite was formed by reaction. The rock itself has ratios of R2+ : Al : Si that are virtually those of cordierite ; the recent data of Schreyer (1967) may thus be applied to the occurrence. The early kyanite-enstatite recrystallization occurred under pressures in excess of 10 kb, corresponding to depths greater than those of the continental Moho.

Mineralogical Magazine; December 1968 v. 36; no. 284; p. 1052-1060; DOI: 10.1180/minmag.1968.036.284.03
© 1968, The Mineralogical Society
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