A typical piece of the rock BAUXITE showing pisolitic structure.
Bauxite is NOT A MINERAL but is included in this list because it is often discussed with economically important minerals.
Bauxite is a coherent clay mixture of various aluminum and iron oxides and hydroxides. The aluminum components are commonly:
GIBBSITE - Al(OH)3 BOEHMITE - AlO(OH) DIASPORE - HAlO2
These minerals are typically mixed with silicate clay and commonly form a pisolitic structure. Bauxite forms as a residual deposit in tropical or subtropical climates by the process of extensive leaching of aluminum-rich parent rocks.