Kaolin (derived from "kao-ling", that is "high hill", the name of a locality in Jiangxi province, China, where white clays) were originally mined) is an argillaceous rock mainly composed of kaolinite-group clay minerals (kaolinite, halloysite or dickite), with such impurities as quartz, potash feldspar, muscovite, and montmorillonite. As a commercial mineral, white or pale-coloured kaolins have the highest value, having a low content of dark-coloured mineral components represented by iron and titanium oxides. Modern industrial production is primarily oriented towards using materials with a maximum content of kaolinite minerals. Therefore, most of the mined natural kaolins undergo enrichment (removal of the impurities largely contained within the sand and silt fraction) to obtain a concentrate of kaolinite minerals close to monomineralic.
Kaolins are characterized by their inertness to acidic and alkaline solutions, high refractoriness, the ability to form a plastic mixture with water, high dry mechanical strength, and high fired whiteness. These properties determine the use of kaolin as a raw material to produce fine, household, sanitary, electro, and radio ceramics, refractory products, silumin, glass, ultramarine, aluminium salts. High dispersability, a white colour, dielectric properties, chemical inertness, good detachability, and wettability are properties which determine the wide use of kaolins as a universal filler in the manufacture of paper, rubber, cables, plastic, and perfume products.