Laterite

In short

Laterite is a rust-red weathering product, rich in iron and aluminium oxides, formed when rocks break down over a long time in hot, wet tropical climates. It is something between soil and stone: soft where it lies, cut into blocks, and hardening when it dries in the open air. Its name comes from a Latin word meaning “brick”. It matters as a building material and as the source of metals such as bauxite (aluminium ore) and nickel, and it covers about a third of the continents.

Photos

How to recognise it

1. 1

   It is rust-red, reddish brown or orange, with a porous, rough surface.

2. 2

   In place it is soft and can be cut into brick-shaped blocks; it hardens when it dries in the open air.

3. 3

   It does not fizz in dilute acid, because it holds iron and aluminium oxides and clay, not lime.

4. 4

   In the tropics it forms a thick cover or crust close to the surface.

Myths and misconceptions

• MythThe red soil under rainforests is very fertile.

  FactLaterite soils are poor in humus because heavy rain washes the nutrients out; the lush look of the forest comes from plant litter that rots and is reused quickly. With manure and irrigation, crops such as oil palm, tea, coffee and cashew can be grown.

• MythLaterite is a kind of soil, not a stone.

  FactIn place laterite is like soil and soft, but once exposed to air it hardens and makes a building stone that stands up to the weather. The temples of Kerala and Cambodia are examples.

Did you know?

Where is it found?

• Angadipuram, Malappuram, Kerala, India · Type localityFrancis Buchanan-Hamilton described laterite in southern India in 1807 and named it from the Latin later, “brick”, because the stone could be cut into brick-shaped blocks. The Angadipuram Laterite is today a notified geo-heritage monument.
• Basilica of Bom Jesus, Old Goa, India · Historic sourceThe basilica, built by the Portuguese in the 16th century, is laid in local laterite blocks. The stone's durability depends more on keeping water out than on its strength.
• Angkor Wat, Siem Reap, Cambodia · Historic sourceThe visible parts are sandstone, while the outer wall and hidden structural parts are laterite. After about 1000 CE, laterite, brick and stone were used together in the temple enclosures at Angkor.
• New Caledonia (Houaïlou and Canala area) · Major depositLateritic and saprolitic nickel ores formed by the tropical weathering of ultramafic rocks such as peridotite hold about 21% of the world's nickel laterite resources; nickel was found in 1864 and wide-scale mining began in 1875.
• Sorowako, South Sulawesi, Indonesia · Known localityIn the Verbeek Mountains a large open pit mines nickel laterite formed by the weathering of ultramafic rocks.
• Moa Bay, Holguín, Cuba · Known localityA reference area where oxide-type nickel-laterite profiles developed from partly serpentinised peridotite have been studied.
• Çaldağ, Turgutlu area, Manisa, Türkiye · Known localityThe nickel-cobalt deposit at Çaldağ is a reddish-brown laterite cover formed by the intense tropical weathering of peridotites, developed in two stages: as transported iron crust (ferricrete) in the late Paleocene–middle Eocene, and by in-place lateritisation in the Oligocene. Theses report an ore reserve of 33–40 million tonnes.

Locations are approximate to protect sites. Red dots mark places in Türkiye. Open in the big map →