Corundum is the mineral aluminum oxide crystallized in a hard form. Ruby and sapphire are forms of corundum. Artificial Corundum could be made on the moon by purifying aluminum oxide, melting it, and recrystallizing it. It is useful as grit for abrasive machining. Corundum can have a hardness of 9 Mohs. So, it should be useful for abrading cast basalt, iron, and steel.