Gibbsite (Al(OH)): The primary aluminum mineral.
Boehmite (-AlO(OH)) and Diaspore (±-AlO(OH)): Other aluminum-bearing minerals.
Iron Oxides: Goethite (FeO(OH)) and haematite (FeO).
Clay Mineral: Kaolinite (AlSiO(OH)).
Small amounts of anatase (TiO) and ilmenite (FeTiO or FeO·TiO).