The first known natural occurrence of calcium monoaluminate, in a calcium-aluminum-rich inclusion from the CH chondrite Northwest Africa 470

Abstract

Natural calcium monoaluminate, CaAl2O4, has been found in a grossite-rich calcium-aluminum-rich inclusion (CAI) from the CH chondrite Northwest Africa 470. The calcium monoaluminate occurs as colorless ∼10 μm subhedral grains intergrown with grossite, perovskite, and melilite. Nebular condensation is the most likely origin for the precursor materials of this CAI, but calculations suggest that dust/gas ratios substantially enhanced over solar are required to stabilize CaAl2O4.