Corundum: What are the main component of corundum

Corundum name comes from India, Department of Mineralogy name, gemology gemstone conditions have called on Ruby (Ruby), Sapphire (Sapphire). Isomer like corundum Al2O3 There are three main variants, namely α-Al2O3, β-Al2O3, γ-Al2O3,, according to X-ray diffraction analysis indeed there is η-Al2O3 (equiaxed), ρ-Al2O3 (Crystal Department of uncertainty), χ-Al2O3 (hexagonal system), κ-Al2O3 (hexagonal system), δ-Al2O3 (tetragonal), θ-Al2O3 (monoclinic [1]). Corundum variety of colors, there is a colorless, white, yellow (pigment ion Ni, Cr), yellow (pigment ion Ni), red (pigment ion Cr), blue (pigment ion Ti, Fe), green (pigment ion Co, Ni , V), purple (Ti, Fe, Cr), brown, black (pigment ion Fe, Fe), incandescent violet, purple under fluorescent effect (pigment ion V).
Corundum glass luster, hardness 9. Weighting 395-410. In the high-temperature aluminum-rich C depleted silicon formed under conditions, mainly related magmatism, contact metamorphism and regional metamorphism.
Corundum is bauxite mining as the main raw material refining furnace artificial materials with corundum, green silicon carbide powder. Yu do abrasives and refractories. Called high purity white fused aluminum oxide, a small amount of impurities is called as a brown corundum.