This inorganic mineral is rich in calcium, and is more readily identified as a calcium oxide or calcium hydroxide. Lime is also used to refer to the naturally occurring mineral that results as a result of coal seam fires, and can also be found in the altered limestone xenoliths formed from volcanic ejecta. Mass quantities of lime are used in the production and manufacturing of cement, concrete, and mortar, and as a chemical feedstock in sugar refining. Combined with ferrous sulfate, lime is also used to treat wastewater. The primary composition of lime is calcium carbonate, which can be cut, pulverized, crushed, or chemically altered. Crushed limestone is used primarily in agriculture, whereas calcination, or burning, of calcium carbonate in lime kilns creates the highly caustic substance known as quicklime. Water is often added to quicklime as a means of reducing its highly caustic nature, and is called slaked lime or hydrated lime.