A Study Of The Opaque Minerals In The Whitestone Anorthosite, Dunchurch, Ontario

Abstract

<p> A textural and mineralogical study of the magnetite, hemoilmenite and minor sulfide phases of the Whitestone anorthosite, Dunchurch, Ontario, was carried out. The composition of magnetite and hemo-ilmenite was determined by chemical analysis, X-ray diffraction and electron probe microanalysis. A modification of the solvus shape in the hematite-ilmenite system consistent with the composition of hemo-ilmenite lamellae, as well as a mechanism for formation of metamorphic magnetite porphyroblasts from ferrianilmenite is proposed. Buddington and Lindsley's experimental data cannot be used directly to obtain f02 and T of formation of the anorthosite because compositions fall in the highly oxidizing and as yet undetermined portion of their diagram. </p>