Consider a tropical area with warm weather and abundant rainfall. Weathering and leaching are getting to be extreme, and even clay minerals may decompose. Normally soluble elements, and even relatively insoluble silica, are getting to be dissolved and carried away . The remaining material, called a residual deposit, is usually composed primarily of aluminum oxides and hydroxides, the smallest amount soluble of all common minerals. We term such deposits laterites (if not lithified) or bauxites. they're our most vital source of aluminum. The mineralogy of a laterite depends on the composition of rocks weathered to provide it; laterites can also be important sources of iron, manganese, cobalt, and nickel, all of which have low solubilities in water.
Most laterites are aluminous. the foremost important aluminum ore in laterites is bauxite, a mixture of several minerals, including the polymorphs boehmite and diaspore, AlO(OH), and gibbsite, Bauxite is mined in large amounts in Australia and Indonesia, and in smaller quantities within the Americas and in Europe. In some places, relatively young laterites produce ore, but in Australia economical laterite deposits are quite 65 million years old.