Chalk is a type of sedimentary rock. It is primarily composed of micro-skeletal shell fragments of calcite-secreting marine organisms called coccoliths.
Sedimentary rocks are natural formations made from the deposition of particle materials through the action of air or water. In terms of the source or sediment variety, sedimentary rocks can be classified into three types: biologic, clastic and chemical. Biologic rocks are produced from the buildup of fossilized organic matter or biological activity.
Chalk is a type of biologic rock characterized by its fine-grained consistency, bright white coloration and low opacity. It is commonly used as a filler in the paper industry. Rich chalk deposits are predominantly found in Europe, particularly England and Denmark.