Chemical formula: Al₂O₃
Uses: Ruby, sapphire main ingredients are all aluminum, as other impurities present different color, sapphire is iron oxide and titanium oxide and blue. Synthetic gemstones, smelting, rust, abrasive materials, color layer media analyte, glass, refractories, ceramics, laser materials, adsorbents, flame retardant. Emery hardness can be used as abrasives, polishing powder, high-temperature sintering of alumina, said artificial corundum or synthetic stones, can be prepared by mechanical bearings or diamond timepiece. Alumina is also used as a high temperature refractory material, made bricks, crucibles, porcelain, artificial gems, etc., aluminum is aluminum raw materials.