Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O
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. Mined rock phosphate is primarily used in the production of phosphate fertilisers for agriculture. Phosphorus from rock phosphate is also used in animal feed supplements, food preservatives, anti-corrosion agents, cosmetics, fungicides, ceramics, water treatment and metallurgy
Phosphorous, nitrogen and potash are the three main plant nutrients. Phosphorous plays an important role in root development and in the synthesis of protein, fats and carbohydrates. Its deficiency in the soil can be made up by adding natural or manufactured phosphorous bearing minerals / rocks. Apatite and rock phosphate are the two important minerals of phosphorous. Apatite is of two types. i.e., chlor-apatite having a composition 3Ca+3 (PO4) 2CaCl2 and fluor-apatite having a composition 3Ca (PO4) 2CaF2.