Theoretical composition (wB%): CaO 32.5, SO3 46.6, H2O+ 20.9. The composition does not vary much. Often have clay, organic matter and other mechanical mixing materials. Sometimes contains SiO2, Al2O3, Fe2O3, MgO, Na2O, CO2, Cl and other impurities. It is widely used in construction, building materials, industrial molds and art models, chemical industry and agriculture, food processing and medicine and beauty and many other applications, is an important industrial raw materials. Different uses of gypsum powder to buy in different places, such as for construction, criminal investigation, go to the building materials market, for the treatment of disease go to the Chinese medicine store