Gypsum is the primary mineral used to make drywall plaster and chalk. Gypsum is a naturally occurring mineral composed primarily of calcium sulfate dihydrate (CaSO4·2H2O). When heated to a specific temperature, gypsum undergoes a chemical change known as calcination, which results in the formation of calcium sulfate hemihydrate (CaSO4·1/2H2O) and water vapor. This process creates a powdery material known as plaster of Paris, which is the main component of drywall plaster.

In the production of drywall plaster, plaster of Paris is mixed with water and various additives to create a smooth, workable paste. This paste is then applied to drywall boards or other surfaces to form a smooth, hard finish.

In the production of chalk, gypsum is finely ground and mixed with a binder, such as clay or chalk, to create a solid, stick-like form. This mixture is then pressed into molds and allowed to dry, resulting in the familiar pieces of chalk used for writing and drawing.

Additionally, gypsum is also used in the manufacturing of cement, paint, tiles, and other construction materials.