Irish Osumilite

G. A. Chinner and P. D. Dixon
Department of Mineralogy and Petrology, Cambridge University

Summary: Osumilite of composition closely approaching that of the K,Mg end-member occurs as a significant constituent of tridymite-enstatite-feldspar-cordierite-hematite-magnetite buchites at the contact of the Tertiary dolerite plug of Tieveragh, Co. Antrim; it is proposed that the mineral be known as osumilite-(K,Mg). Despite laboratory demonstration of the metastability of osumilite-(K,Mg) over a wide pressure-temperature range, the unaltered character and apparently constant composition of the Tieveragh osumilites raises the possibility of an osumilite stability field within the system K2O-MgO-FeO-Al2O3-SiO2.

Mineralogical Magazine; June 1973 v. 39; no. 302; p. 189-192; DOI: 10.1180/minmag.1973.039.302.06
© 1973, The Mineralogical Society
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