Laterite and bauxite deposits
These deposits can be observed in those tropical areas that are characterized by seasonal rainfalls, such as some large areas in Asia, Africa, Brazil and Cuba. They form as a consequence of high temperatures and the high quantity of bacteria that completely decompose the soil organic material. As a consequence, the soil does not contain acid substances and rainwater does not manage to remove iron and aluminium oxides and hydroxides. In these cases the iron deposits and the soil is covered by a thick red laterite crust. Instead, if the soil does not contain a lot of iron but contains lots of aluminium hydroxides, bauxite white deposits are formed.