calcium carbonateChalk. Composition: Chalk is a form of calcium carbonate, having the same chemical composition as ground calcium carbonate, limestone, marble, and precipitated calcium carbonate (PCC). In fact, all of the calcium carbonates listed in the previous sentence have the same crystal form, calcite.
Calcium carbonateBlackboard chalk originally contained Calcium carbonate typically bound with kaolin clay, Oleic acid, and Sodium hydroxide. A wide variety of formulations are now used, most of which are made from calcium sulfate hemihydrate (Plaster of Paris), which reacts with water to form Gypsum.Apr 29, 2016
biochemical sedimentaryChalk is a biochemical sedimentary rock formed by the accumulation of microscopic marine calcite fossils. The fine-grained nature and white color of the calcite are used in the recognition of chalk.
Gypsum is composed of calcium sulphate (CaSO4) and water (H2O). Its chemical name is calcium sulphate dihydrate (CaSO4. 2H2O).