gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1978.042.321.12 Hydrous Cordierite with Isotopically Light Oxygen from Granulites, Strangways Range, Central Australia Wilson Allan F. Department of Geology and Mineralogy, University of Queensland, St. Lucia (Brisbane), Queensland, Australia, 4067 3 1978 42 321 89 92 13 12 1976 16 6 1977 Copyright © 1978, The Mineralogical Society 1978 Summary

Two new analyses of magnesian cordierites (MgO ∼ 12 %) reveal about 1% by weight of H2O +, and one sample contains 15 × 10−5 cm3STP/gm argon, which is twenty times in excess of argon expected for its age. Host granulites contain unexpectedly light oxygen, and three cordierites have δ 18O values of 2·0, 2·8, and 3·1 ‰, respectively.