What is the main component of chalk?

The main components of chalk are calcium carbonate, calcium sulfate and a small amount of calcium oxide. Calcium carbonate, also known as limestone, is also the main component of animal bones or shells. Calcium sulfate, also known as gypsum, is a kind of white precipitate, the particles are larger than dust, and it is not easy to decompose.

What is chalk?

There are two kinds of chalk: ordinary chalk and dust-free chalk, which are generally used to write on the blackboard. Chalk is made of hydrated calcium sulfate (commonly known as gypsum). You can also add various pigments to make colored chalk. In the production process, raw gypsum is heated to a certain temperature to partially dehydrate to form plaster of Paris, then the plaster of Paris is stirred into paste with water, and then poured into a mold for solidification.

Ancient chalk was usually made of natural chalk, but now it has been replaced by other substances. Dust-free chalk is an improved product of ordinary chalk, aiming at eliminating chalk dust pollution in classrooms. It just adds grease or polyol as binder to ordinary chalk, and then adds filler with high specific gravity. Non-toxic chalk is the healthiest chalk. It is made of pure gypsum, solidified and dried with water, and made of edible gypsum. This kind of chalk has been used in most foreign teaching since primary school.