Co-existing Sapphirine and Quartz in Granulite from Enderby Land, Antarctica

Abstract

SAPPHIRINE and quartz have been found together in nature for the first time in granulite collected by I. R. McLeod, of the Australian Bureau of Mineral Resources, from a small nunatak (66° 57′ S, 51° 31′ E) about 42 miles east of Amundsen Bay, Enderby Land, Antarctica. This rock belongs to a gneiss–granulite–charnockite terrain (personal communication from I. R. McLeod), and was called blue quartzite in the field. In thin section it is seen to consist of rutilated quartz, cordierite-quartz intergrowths, sapphirine as grains up to 2 mm long, and accessory sillimanite, garnet, hypersthene, rutile, chlorite, zircon and biotite; the first three constituents make up about 98 per cent of the rock. Another granulite from the same nunatak contains no sapphirine, though it may formerly have done so; it consists of quartz, garnet, sillimanite, orthoclase microperthite with unusually low 2 V (35° to 40°), and accessory rutile, sericite and zircon.