Aluminium oxide

Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formulaAl₂O₃. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly called alumina and may also be called aloxide, aloxite, ALOX or alundum in various forms and applications. Alumina is refined from bauxite. It occurs naturally in its crystalline polymorphicphase α-Al₂O₃ as the mineralcorundum, varieties of which form the precious gemstonesruby and sapphire, which have an alumina content approaching 100%. Al₂O₃ is used as feedstock to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.