Small pieces of chalk have been used by students for over 1000 years for writing on small slates and large classroom panels known as “blackboards”. It is an inexpensive and erasable writing material and the most widely known use of chalk. Much of the early blackboard writing was done with pieces of natural chalk or natural gypsum.

Today pieces of natural chalk and natural gypsum have been replaced by sticks manufactured from natural chalk; sticks manufactured using other sources of calcium carbonate; or sticks manufactured using natural gypsum. Gypsum chalk is the softest and writes smoothest; however, it produces more dust than calcium carbonate chalk. Calcium carbonate chalk is harder, requires more pressure to produce wide marks, and makes less dust. It is sometimes marketed as “dustless chalk” but that description is not quite true. Even though most chalk today is not made from mineral chalk, people still use the name “chalk” for this familiar writing material.