Montmorillonite, (Na,Ca) x +  y (H 2O) n {(Al 2− x (Mg,Fe) x ) 2[Si 4− y (Al,Fe) y O 10](OH) 2}, as the main mineral component of bentonite, is a 2:1-type (TOT-type) dioctahedral layer-structured aluminosilicate that is rich in interlayer exchangeable cations and can absorb water and expand. Based on the types and contents of interlayer exchangeable cations, montmorillonite mainly has variants such as calcium montmorillonite (Ca-montmorillonite) and sodium montmorillonite (Na-montmorillonite). The clay rocks with montmorillonite as the main component are respectively called Ca-bentonite and Na-bentonite. In the classification of mineral crystal chemistry, montmorillonite belongs to the silicate class, the layer-structured silicate subclass, the montmorillonite-vermiculite group, and the montmorillonite subgroup. In the structural-functional classification of mineral raw materials in mineral material science, montmorillonite belongs to the category of two-dimensional structural minerals and the subcategory of functional minerals.