Bauxite, an aluminium ore, is the world's main source of aluminium. Approximately 70% to 80% of the world's dry bauxite production is processed first into alumina, and then into aluminium by electrolysis as of 2010. Bauxite rocks are typically classified according to their intended commercial application: metallurgical, abrasive, cement, chemical, and refractory.
Bauxite is not a mineral. It is a rock formed from a laterite soil that has been severely leached of silica and other soluble materials in a wet tropical or subtropical climate. It is the primary ore of aluminum. Almost all of the aluminum that has ever been produced has been extracted from bauxite.
Calcined alumina is a synthetic corundum, which is a very hard material. Calcined alumina is crushed, separated by size and used as an abrasive. Aluminum oxide sandpaper, polishing powders and polishing suspensions are made from calcined alumina.