Alumina is a common material, actually has its ingredient in many products!
Alumina is aluminum and oxygen compounds, chemical formula for Al2O3.In the mining industry, ceramics industry, and materials science is also known as alumina.
Ruby, sapphire, the main ingredients of alumina, because other impurities present different colour and lustre, containing iron oxide and titanium oxide and a blue sapphire.
Principal component in aluminium, iron, bauxite the highest content of alumina.Industry, iron and aluminum oxide writing by Bayer process and purification for alumina, again by Hall - Heroult process into aluminum metal.
Alumina is quite practical materials!