Laterite

Physical Properties

Hardness: 1-3 (soft when wet, hardens upon drying); Color: rusty red, brown, or yellowish-orange; Luster: dull to earthy; Structure: porous, vesicular, or pisolitic (pea-like grains); Composition: primarily goethite, hematite, and gibbsite.

Formation & Geological History

Formed through intense and long-term weathering (leaching) of underlying parent rock in hot and wet tropical climates. Over time, silica is removed, leaving behind a concentration of iron and aluminum oxides.

Uses & Applications

Extensively used as a building material (bricks), road construction aggregate, and as a major ore for aluminum (bauxite) and iron. Also used in water filtration to remove phosphorus and heavy metals.

Geological Facts

Laterite was named by Francis Buchanan-Hamilton in 1807, derived from the Latin word 'later' meaning brick, because it could easily be cut into brick shapes when moist and would then harden like stone when exposed to air.

Field Identification & Locations

Identify in the field by its distinct reddish-brown color, porous texture, and occurrence in tropical soil profiles. It is commonly found in India, Southeast Asia, Africa, and Brazil. Collectors look for pisolitic specimens showing circular concentrated layers.

Identified on: 4/20/2026

Mode: Standard