Abstract
Ilmenite from East Ongul Island, Antarctica, is described. It was found in microcline pegmatite, is in single crystals up to 5cm in diameter, and is associated with small amounts of biotite and quartz. Its mineral composition determined by X-ray, chemical and magnetic methods is hematite, Fe2O3, 46mol%; ilmenite, l0Fe2O3•90TiFeO3, 49mol%; magnetite, Fe3O4, 5mol%. The specific gravity is 4.976 at 17°C. The specimen is ferromagnetic and shows natural remanent magnetism. It shows exsolution inter-growth texture of ilmenite and hematite, and in the lamellae of each mineral are contained minute rod-like crystals of the other kind, regularly arranged in a certain crystallographic direction. The chemical compositions of both minerals do not vary with grain size. The exothermic reaction observed in the differential thermal analysis curve seems to be understood mainly as oxidation of ilmenite.
