The main alumina containing minerals that occur in bauxites are:

  • Gibbsite
  • Boehmite and
  • Diaspore

Other gangue or impurity minerals typically found in bauxites include:

  • Clays, typically kaolinite
  • Quartz
  • Iron oxide andiron hydroxy-oxide (hematite and Goethite)
  • Titanium dioxide in the form of anatase or rutile.

The mineralogy is very important as it dictates the refining conditions that must be used and has a large bearing on the economics of processing a particular bauxite.

Source: World Bauxite Resources, USGS, CMGroup