China clay / Kaolin China Clay is also known as kaolin & white clay. Primary clay formed by natural kaolinization process. The chemical formula for china clay used in mineralogy is Al₂Si₂O₅(OH₄). Silica Sand Silicon dioxide (SiO₂), also known as silica. It is a natural compound made of two of the earth's most abundant materials: silicon (Si) and oxygen (O₂). Silicon dioxide is most often recognized as silica sand. Bentonite Bentonite is a clay mineral, It is an absorbent swelling clay consisting of mineral Montmorillonite. The Bentonite found in the Kutch region of India is of igneous origin.