Gypsum
Appearance
Gypsum is a soft sulfate mineral (CaSO₄·2H₂O) mined globally, primarily used for making drywall (plasterboard) and plaster, but also as a soil conditioner for calcium and sulfur, in cement, and for decorative items like alabaster and selenite crystals. It forms from evaporated seawater, often with salt deposits, and its commercial forms include fire-resistant Type X drywall and Plaster of Paris (bassanite), a dehydrated form used in construction and arts.