SELENITE variety of gypsum, Las Salinas Mine Pisco Province Ica District PERÚ (cabinet)

Gypsum is a soft sulfate mineral made up of calcium sulfate dihydrate, represented by the chemical formula CaSO4·2H2O. It is extensively extracted for use as a fertilizer and serves as a primary ingredient in various products such as plaster, drywall, and chalk for blackboards or sidewalks. Additionally, gypsum can crystallize into translucent selenite crystals. It typically forms as an evaporite mineral or as a hydration product of anhydrite. According to the Mohs scale of mineral hardness, gypsum is rated at a hardness of 2, indicating its relative softness in comparison to other minerals.