Manganese is used in the production of virtually all steels and cast irons, and its principal use is in iron and steel production. Manganese is essential to iron and steel production because there are no satisfactory substitutes for its uses therein. The traditional function of manganese in steelmaking has been to control oxygen and sulfur so as to make steel workable. Manganese is also added to steel to improve strength, toughness, hardenability, and other properties. Most manganese is utilized as an intermediate form such as ferromanganese into which manganese ore is first smelted. A relatively small amount of manganese is used as an alloying element in several nonferrous metals. The chief one of these is aluminum, the corrosion resistance of which is generally improved by a manganese addition. Minor quantities of manganese are consumed in the chemical industry and to make dry cell batteries, for which certain specific ores are used. Manganese is a brittle metal, which as such has no significant use. This Bureau of Mines report presents comprehensive data on manganese including strategic considerations, problems, technology trends and developments, reserves-resources, supply-demand relationships, operating factors and problems, and outlook to 2000.