Chromium in Corundum: Ultra-high Contents Under Reducing Conditions

exploration project recovered a variety of gemstone minerals from Cretaceous pyroclastic vents and associated alluvial deposits at Mt these are several types of corundum (Al 2 O 3 ), including rubies with <2 wt% Cr 2 O 3 and sapphires in a variety of colours from yellows through to greens, blues and purples, with a range of chemical impurities e.g. Ti, Fe, V, Ga. The most scientifically interesting type of corundum is the inclusion-rich ‘Carmel Sapphire TM ’, which contains a variety of mineral phases; some of these have only been seen in meteorites previously, e.g. tistarite (Ti 2 O 3 ) and others not previously been described, e.g. carmeltazite (ZrAl 2 4 11 minerals very low oxygen fugacities, at least 7 log units below the Iron-Wustite ( IW-7), and are interpreted CH 4 +H 2 -rich of fluid transfer and redox conditions in the crust and 2