Laterite is a type of soil produced by intense, prolonged weathering, usually in tropical climates. Abundant oxygen, water, and warmth leach most water-soluble minerals from particles of parent rock and leave a nonsoluble residue enriched in hydroxides of aluminum, iron, magnesium, nickel, and titanium. Laterites high in specific metals are often stripmined as ores.

Laterite rich in aluminum are termed aluminous laterite or bauxite. Aluminous laterite is formed from clay minerals such as kaolinite (Al₄[Si₄O₁₀][OH]₈) by the leaching of silica (SiO₂). The residue left by the leaching of silica, aluminum hydroxide (Al[OH]₃), is termed gibbsite. Gibbsite's dehydrated forms, diaspore and bohemite (both HAlO₂), are also common components of aluminous laterite. Aluminous laterite is the world's primary source of aluminum.

Laterite descended from basalt is rich in iron and nickel and is termed ferruginous laterite. Laterite formed from rocks particularly rich in nickel may contain a high percentage of the mineral garnierite ([NiMg]₆Si₄O₁₀[OH]₈). A continuum of mixed laterites exists between the aluminous and ferruginous extremes. Nickeliferous laterites are an important commercial source of nickel.

See Also

Soil and Soil Horizons; Weathering and Weathering Series