Caliche

The term caliche is borrowed from Spanish and is originally from the Latin word calx, meaning lime.

[1] Caliche is generally light-colored but can range from white to light pink to reddish-brown, depending on the minerals present.

[2][3] In northern Chile and Peru, caliche also refers to mineral deposits that include nitrate salts.

In addition, it has been used to describe some forms of quartzite, bauxite, kaolinite, laterite, chalcedony, opal, and soda niter.

Plant roots play an important role in caliche formation, by releasing large amounts of carbon dioxide into the A horizon of the soil.

A mixture of calcium carbonate and clay particles accumulates, first forming grains, then small clumps, then a discernible layer, and finally, a thicker, solid bed.

The caliche layer disappears complete in temperate climates if annual rainfall exceeds 100 centimeters (39 in).

[12] Highly indurated (hardened) caliche is known as calcrete, and it gives rise to characteristic landforms in arid environments.

Examples include Mississippian calcretes in South Wales and Pliocene to Pleistocene caprock of the Llano Estacado of Texas, US, and Mormon Mesa, Nevada, US.

[15] The Great House at Casa Grande Ruins National Monument, Arizona, US, was built with walls of caliche.

Although caliche does not generally meet all of the requirements for sugar refining, it is used in areas where another source of calcium carbonate, such as limestone, is not present.

Salitre was an important source of export revenue for Chile until World War I, when Europe began to produce both nitrates industrially in large quantities.

The caliche beds are from 2 cm to several meters thick in alluvial deposits, where the soluble minerals form a cement in unconsolidated regolith.

First, an impermeable caliche layer prevents water from draining properly, which can keep roots from getting enough oxygen.

The basic soil, along with calcium carbonate from the caliche, can prevent plants from getting enough nutrients, especially iron.