Introduction to Chalk

Chalk is a widely used tool in daily life, generally used for writing on blackboards. Ancient chalk was usually made of natural chalk, but nowadays it is replaced by other substances. The main component of chalk is calcium sulfate, which is a white precipitate, which is not easy to be decomposed, and the particles are larger than dust. The chalks used in China mainly include ordinary chalk and dust-free chalk. The main components are calcium carbonate (limestone) and calcium sulfate (gypsum), or a small amount of calcium oxide.