Al₂O₃ is the chemical formula of bauxite?

The most common metal on Earth is aluminium, but it is costly, mainly because of the amount of energy required in the production process. Bauxite (Al₂O₃) is called aluminium ore. The bauxite is purified to yield a white powder from which aluminium can be extracted-aluminium oxide (also known as alumina).

By the Bayer Process, the bauxite is purified. The ore is first combined with a hot, condensed sodium hydroxide solution. Aluminum and silicon oxides, but not other impurities such as iron oxides, can be dissolved by NaOH, which remains insoluble. By filtration, the insoluble materials are removed.

The typical ore of aluminium is bauxite (Al₂O₃.2H₂O). Amphoteric oxides are also classified as metal oxides that react with both acids as well as bases to create salts and water. Al₂O₃ is, for example, an amphoteric oxide. An amphoteric compound is a molecule or ion that may react to create salt and water from both an acid and a base.