Kaolinite (Al 4[Si 4O 10](OH) 8 or Al 2O 3·2SiO 2·2H 2O), as the main mineral component of kaolin, is an aluminum silicate with a 1:1-type (TO-type) dioctahedral layer structure. In the classification of mineral crystal chemistry, kaolinite belongs to the silicate class, the layer silicate subclass, and the kaolinite group. In the structural-functional classification of mineral raw materials in mineral material science, kaolinite belongs to the category of two-dimensional structural minerals and the subcategory of functional minerals.