Bauxite (boks'aight) a muddy red-ish powderish clay composed of one or more aluminum hydroxide minerals as well as various mixtures of aluminum silicate ( which is clay, etc.), iron oxide (gives it the red colouring), silica, titanium, and other minor impurities. It's principal use in the production of alumina (Al2O3, the oxide of aluminum), which is used mainly in the production of aluminium metal.
Some of the largest reserves of bauxite are found in Australia, where it exists in huge swaths a meter or so under the topsoil. Huge operations are in place to remove the topsoil layer, harvest the bauxite and then replace the topsoil on the substrate below.