Kaolinite (/ˈkeɪəlɪnaɪt/) 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 (SiO
4) linked through oxygen atoms to one octahedral sheet of alumina (AlO
6) octahedra. Rocks that are rich in kaolinite are known as kaolin /ˈkeɪəlɪn/ or china clay.