Sapphirine in the Sittampundi Complex, India

摘要

D ti RING recent work on the Sittampundi anorthosite intrusion, Salem District, Tamil Nadu (Madras) State, India (Subramaniam, 1956) we discovered a plagioclase(c. An73)- rich rock with colourless gedrite (2V), 821 and nearly colourless clinoamphibole, corundum, chrome spine!, rare prismatic sillimanite, rare phlogopite, and a little pale granular sapphirine, a mineral not previously recorded from this intrusion. The sample occurs between chromitite layers 2 km north-east of Pamandapalaiyam. The corundum is a vermicular, skeletal ruby that occurs mostly in association with the perfectly fresh plagioclase, sometimes as thin strips following the plagioclase grain boundaries, but a few skeletal grains also occur inside the amphibole. The sapphirine has 2V,, 50±2°, occurs in isolated granules or prismatic crystals that are sometimes skeletal, is usually associated with the plagioclase, and has a very pale sapphire to colourless pleochroism. The rock contains some late chlorite, especially replacing the gedrite, and patches of an unidentified colourless mica-like mineral occurring in aggregates that sometimes are radiating.