Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4ยท2H2O. It contains calcium, sulfur, oxygen, and water molecules
. It typically forms in sedimentary rock layers as an evaporite mineral, created when mineral-rich water evaporates, leaving behind solid deposits
. Gypsum is widely mined and used in many applications, especially in construction. It is the main component of plaster, drywall (also called wallboard), and blackboard chalk. When heated, gypsum loses water and becomes plaster of Paris, which hardens when mixed with water again
. It is also used in agriculture as a fertilizer, providing sulfur and calcium to plants
. Gypsum occurs in various forms, including:
- Selenite: translucent crystalline form
- Alabaster: fine-grained white or lightly tinted form used historically for sculpture
- Satin spar: fibrous variety with a silky sheen
Gypsum is a very soft mineral, with a Mohs hardness of about 2, and is often found in thick beds or layers associated with other evaporite minerals like rock salt and anhydrite
. In summary, gypsum is a naturally occurring mineral essential for construction materials, agriculture, and various industrial uses, formed mainly by the evaporation of seawater and found worldwide
