Kaolinite is a clay mineral with the chemical composition Al 2 Si 2 O 5 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