Template:Corundum

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Corundum
Chemical composition Al2O3
Crystal system trigonal
Habit prismatic, tabular
Cleavage poor
Fracture conchoidal
Hardness 9
Optic nature uniaxial -
Refaction index 1.76-1.78
Birefringence 0.008-0.009
Dispersion low, 0.018
Specific gravity 4
Lustre bright vitreous
Pleochroism weak to moderate