Gypsum is often a tender sulfate mineral composed of calcium sulfate dihydrate, with the chemical system CaSO4·2H2O.[four] It truly is widely mined and is utilized as a fertilizer and as the major constituent in lots of types of plaster, drywall and blackboard or sidewalk chalk. Agates: A kind of quartz https://www.propanraya.com/id/produk/eco-gypsum-ee-4050