Bauxite

Hydrated aluminium oxides mixture (primarily gibbsite, boehmite, and diaspore)

Hardness varies from 1 to 3 on the Mohs scale depending on composition; color ranges from reddish-brown, pink, white, to yellowish-brown; luster is dull, earthy; lacks distinct crystal structure as it is typically amorphous or pisolitic (composed of rounded bean-like grains); specific gravity is 2.0 to 2.5.