Chalk book flagship store. The flagship store of chalk books has all kinds of chalk, including 5000 chalk questions. Chalk is a widely used stationery in daily life, which is generally used to write on the blackboard. Ancient chalk was usually made of natural chalk, but now it has been replaced by other substances. The main component of chalk is calcium sulfate, which is a white precipitate, not easy to decompose, and its particles are larger than dust.