1. Bauxite
2. Removal of earthy impurities (gangue) from bauxite ore and separation of metallic aluminium is called extraction of aluminium.
3. Bauxite is treated with NaOH solution and sodium meta aluminate is formed. The aluminate solution is neutralised by passing CO2 gas and hydrated Al2O3 is precipitated by seeding with freshly prepared samples of hydrated Al2O3. Hydrated alumina is filtered, dried and heated to obtain pure Al2O3