Kaolin, or China Clay, a pure, fine, white clay composed primarily of the mineral kaolinite, with small amounts of similar minerals. Kaolinite is chiefly aluminum silicate. Because kaolin is extremely free of impurities, it can withstand very high temperatures without cracking, flaking, or discoloring. Kaolin was named after Kaoling, a hill in China where it was first obtained.
Kaolin has long been used to make porcelain and other ceramics. A major use of the clay is as a coating material and filler to make white printing paper that is smooth and opaque. The clay is also used as filler in plastics, rubber, and paints, and it is made into fire brick and face brick.