<P> Laterite is a soil and rock type rich in iron and aluminium, and is commonly considered to have formed in hot and wet tropical areas . Nearly all laterites are of rusty - red coloration, because of high iron oxide content . They develop by intensive and prolonged weathering of the underlying parent rock . Tropical weathering (laterization) is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils . The majority of the land area containing laterites is between the tropics of Cancer and Capricorn . </P> <P> Laterite has commonly been referred to as a soil type as well as being a rock type . This and further variation in the modes of conceptualizing about laterite (e.g. also as a complete weathering profile or theory about weathering) has led to calls for the term to be abandoned altogether . At least a few researchers specializing in regolith development have considered that hopeless confusion has evolved around the name . There is no likelihood, however, that the name will ever be abandoned; for material that looks highly similar to the Indian laterite occurs abundantly worldwide, and it is reasonable to call such material laterite . </P> <P> Historically, laterite was cut into brick - like shapes and used in monument - building . After 1000 CE, construction at Angkor Wat and other southeast Asian sites changed to rectangular temple enclosures made of laterite, brick and stone . Since the mid-1970s, some trial sections of bituminous - surfaced, low - volume roads have used laterite in place of stone as a base course . Thick laterite layers are porous and slightly permeable, so the layers can function as aquifers in rural areas . Locally available laterites have been used in an acid solution, followed by precipitation to remove phosphorus and heavy metals at sewage - treatment facilities . </P>

How many percentage of laterite soil in india