China Clay

China Clay or Kaolin is one of the purest form of clays, composed chiefly of the mineral kaolinite, usually formed when granite is changed by hydrothermal metamorphism. Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6) octahedra.

Kaolinite has a low shrink - swell capacity and a low cation-exchange capacity (1–15 meq/100 g). 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 colors. Commercial grades of kaolin are supplied and transported as dry powder, semi-dry noodle or as liquid slurry.

Salient Features

Contributes in improving the chemical resistance, electrical properties and reduction in water absorption
Lowers the crack tendency in the finished products
Improves shock resistance as well as surface quality