Gypsum Fluorspar Rock Phosphate Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4ยท2H2O Rock phosphate is a general term for rock that contains a high concentration of phosphate minerals, which commonly belong to the apatite group. Phosphate rock minerals are the only significant global resources of phosphorus. Phosphorus is an essential element for plant and animal nutrition.