This soft sulfate mineral is composed primarily of calcium sulfate dihydrate, is widely used as a fertilizer in agriculture, and is also the main ingredient in plaster, wallboard, and blackboard chalk. The most well-known form of gypsum is the massive, fine-grained white variety called alabaster, and has been used as a sculpting medium in many cultures such as ancient Egypt, Mesopotamia, Medieval England, and the Byzantine Empire. The name gypsum comes from the Greek word gypsos, which means plaster. Gypsum is the main ingredient in plaster of Paris, which was one of the primary casting and construction materials for building interiors for centuries. Today, gypsum is still used in construction materials like drywall, concrete blocks, mortar, and plaster. It is also an additive in baking dough to reduce stickiness, and as a source of dietary calcium, and can be found in foot creams, shampoos, and various other hair products.