石膏(Gypsum)

        主要化学成分是硫酸钙的水合物，可分为生石膏（化学式为 CaSO₄・2H₂O）和硬石膏（无水硫酸钙 CaSO₄）。生石膏呈白色、浅黄色等，硬度较低，莫氏硬度为 1.5 - 2，加热后会失去结晶水变成熟石膏，广泛用于建筑材料、医药、食品等行业。

Its main chemical component is the hydrate of calcium sulfate, which can be divided into gypsum (with the chemical formula of CaSO₄·2H₂O) and anhydrite (anhydrous calcium sulfate, CaSO₄). Gypsum is usually white, light yellow, etc., and has a relatively low hardness, with a Mohs hardness of 1.5 to 2. When heated, it will lose its crystal water and turn into plaster of Paris. It is widely used in industries such as building materials, medicine, and food.