Kaolinization

the high temperature hydrothermal alteration and breakdown of FELDSPARS to form KAOLINITE. The process can proceed in granites to the point where the rock literally falls apart and the only recognizable, original mineral is quartz.

Taken from Dictionary of Science

Kaolinite

aluminium silicate with water in its structure which occurs as an alteration product in IGNEOUS ROCKS, GNEISSES and a weathering and hydrothermal reaction product in sedimentary products. It is used in ceramics and as a coating and filler in the paper industry.

Taken from Dictionary of Science

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Kaolinite is a clay mineral with the chemical composition Al₂Si₂O₅(OH)₄. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra. Rocks that are rich in kaolinite are known as china clay, white clay, or kaolin.

The name is derived from Gaoling or Kao-Ling (高嶺; "High Hill") in Jingdezhen, Jiangxi province, China. Kaolinite was first described as a mineral species in 1867 for an occurrence in the Jari River basin of Brazil.

Kaolinite has a low shrink-swell capacity and a low cation exchange capacity (1-15 meq/100g.) It is a soft, earthy, usually white mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world, it is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lighter concentrations yield white, yellow or light orange colours. Alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, USA.

Taken from Wikipedia