Numerous classification schemes have been proposed for bauxite but, as of 1982, there was no consensus. Vadász distinguished lateritic bauxites from karst bauxite ores :
The lateritic bauxites are found mostly in the countries of the tropics. They were formed by lateritization of various silicate rocks such as granite, gneiss, basalt, syenite, and shale. In comparison with the iron-rich laterites, the formation of bauxites depends even more on intense weathering conditions in a location with very good drainage. This enables the dissolution of the kaolinite and the precipitation of the gibbsite. Zones with highest aluminium content are frequently located below a ferruginoussurface layer. The aluminium hydroxide in the lateritic bauxite deposits is almost exclusively gibbsite.
In the case of Jamaica, recent analysis of the soils showed elevated levels of cadmium, suggesting that the bauxite originates from recent Mioceneash deposits from episodes of significant volcanism in Central America.
Bauxite is usually strip mined because it is almost always found near the surface of the terrain, with little or no overburden., approximately 70% to 80% of the world's dry bauxite production is processed first into alumina and then into aluminium by electrolysis. Bauxite rocks are typically classified according to their intended commercial application: metallurgical, abrasive, cement, chemical, and refractory. Usually, bauxite ore is heated in a pressure vessel along with a sodium hydroxide solution at a temperature of. At these temperatures, the aluminium is dissolved as sodium aluminate. The aluminium compounds in the bauxite may be present as gibbsite, boehmite or diaspore; the different forms of the aluminium component will dictate the extraction conditions. The undissolved waste, bauxite tailings, after the aluminium compounds are extracted contains iron oxides, silica, calcia, titania and some un-reacted alumina. After separation of the residue by filtering, pure gibbsite is precipitated when the liquid is cooled, and then seeded with fine-grained aluminium hydroxide. The gibbsite is usually converted into aluminium oxide, Al2O3, by heating in rotary kilns or fluid flash calciners to a temperature in excess of. This aluminium oxide is dissolved at a temperature of about in molten cryolite. Next, this molten substance can yield metallic aluminium by passing an electric current through it in the process of electrolysis, which is called the Hall–Héroult process, named after its American and French discoverers. Prior to the invention of this process, and prior to the Deville process, aluminium ore was refined by heating ore along with elemental sodium or potassium in a vacuum. The method was complicated and consumed materials that were themselves expensive at that time. This made early elemental aluminium more expensive than gold.
