Pyroxene Relations in Two Hawaiian Hypersthene-Bearing Basalts

I. D. Muir and J. V. P. Long
Department of Mineralogy and Petrology, Cambridge

Summary: A preliminary account is given of an optical and electron-microprobe investigation into the pyroxene relations of Hawaiian hypersthene-bearing lavas. It is shown that the clinopyroxene jackets to the phenocryst hypersthenes consist of strongly zoned augite, not pigeonite as formerly believed; the compositional range of this pyroxene is approximately the same as that of the groundmass augite phase. Groundmass pyroxene relations are complex; in one case two distinct pyroxene phases, augite and pigeonite occur, in the other all compositions lying between augite and pigeonite are encountered.

Mineralogical Magazine; 1965 v. 34; no. 268; p. 358-369; DOI: 10.1180/minmag.1965.034.268.30
© 1965, The Mineralogical Society
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