High-alumina refractories are made from bauxite, a naturally occurring material containing aluminum hydroxide (Al[OH]3) and kaolinitic clays. These raw materials are roasted to produce a mixture of synthetic alumina and mullite (an aluminosilicate mineral with the chemical formula 3Al2O3 · 2SiO2). High Alumina bricks are refractory bricks which has Alumina content of more than 50% . These are generally made from calcined bauxite or material having high alumina content .