Laterite is a soil and rock type rich in iron and aluminum that forms through intense, long-term weathering of the underlying rock, mostly in hot, wet tropical regions.
Nearly all laterites are rusty red because of their high iron oxide content. Because laterite hardens when exposed to air, it has long been cut into blocks for building, and some laterites are mined as ore for aluminum (bauxite) or iron.
Source: Laterite, Wikipedia