Material with low organic matter content, high content of iron- and aluminium-oxides, and low exchangeable cations and nutrients (Ca, Mg, and K). It is formed by mobilization and residual accumulation of iron in the subsoil of floodplains, low-lying areas, and other places of oscilating watertable. Soils containing horizons rich in plinthite are relatively common in the Cerrado. An interesting feature is their irreversible hardening upon air-drying. In a sense, is the the same as bauxite (material containing the aluminium ore) and laterite.

Plinthite (from the Greek plinthos, brick) is an iron-rich, humus-poor mixture of clay with quartz and other minerals.