... approximately 2000 degrees Celsius). Its chemical composition consists mainly of Al2O3 (94,5-97%) and vestigial amounts of TiO2, SiO2, Fe2O3, CaO ... and hardness (9 in Mohs scale). The micro hardness of the material reaches about 1900kG/mm2. Specific gravity (density ... processing durable articles, above all for steel processing, production of abrasive papers and clothes, in fireproof and ceramic industry ...