Gibbsite and Boehmite in Weathering Crusts of Different Ages Affected by Lateritization: Location and Formation

Abstract The main source of aluminum is bauxite ores and their basic mineral components gibbsite Al(OH)3 and boehmite AlO(OH). Alumina Al2O3 is formed by various methods of decomposition of these components, electrolytically decomposed to pure Al. It has been established that gibbsite is the basic and often the only mineral of aluminum in the Mesozoic and Cenozoic laterite bauxites, representing most of the world’s reserves. Boehmite is formed in laterite-sedimentary bauxites, during lateritization and desilication of albic water-sedimentary continental sediments, as well as the underlying bleached parent rocks. The formation of boehmite is associated with an excess of aluminum generally due to its input from above. Boehmite predominates in the Paleozoic laterites. The formation of aluminum monohydrate is explained by a decrease in the oxidation–reduction potential.