any of various earthy substances yielding alum or alumina.

The name given in Sri Lanka to a reddish gneissoid building-stone, soft when quarried but hardening by exposure to the air; laterite.

A red, porous, clay-like material constituting the top geological layer in many tropical and subtropical regions, subsequently understood to be an…

A hardened soil or duricrust consisting of fragmentary rock or mineral matter cemented by iron compounds, esp. ferric oxide. Frequently attributive.

A hard dry lateritic material associated with soils having impeded drainage in tropical Africa, used locally as road metal. Frequently attributive.

earth of the kind in which opal is found.

A lateritic soil or residual rock that is rich in alumina; (originally, now disused) spec. one in which the ratio of silica to alumina by weight is…

A soil of an order comprising stable, highly weathered tropical mineral soils with oxic horizons.