A general term for burned (or calcined) limestone, also known as quicklime, hydrated lime, and unslaked or slaked lime. Use of lime as a building material in mortar and plaster coincides with earliest recorded history. However, since development of the chemical process industries, its predominant usage is as a basic industrial chemical, where it ranks second to sulfuric acid in tonnage. It still enjoys its traditional building uses, but more than 90% is used as a chemical. Uses in order of decreasing size are steel fluxing, water treatment, nonferrous metals (alumina, magnesium, copper, and others), pulp and paper, refractories, soil stabilization, sewage and trade waste treatment, chemicals, and glass manufacture.