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 or kaolin.
The name is derived from Gaolin 高岭("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 is one of the most common minerals; it is mined, as kaolin, in Brazil, France, United Kingdom, Germany, India, Australia, Korea , the People's Republic of China, and the southeastern U.S. states of Georgia, Florida, and, to a lesser extent, South Carolina.
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.