Manganese
Manganese, a hard, brittle, gray-white metallic element. It is chemically active; it corrodes readily in air and is soluble in water and dilute acids. Small amounts of manganese are considered essential to plant and animal life.
Most of the manganese produced in the world is used in the steel industry. Small amounts are required to remove sulfur and oxygen impurities from molten steel. The addition of larger amounts of manganese produces a hard steel that cannot be magnetized. The manganese added to steel is usually contained in an alloy, ferroman-ganese, consisting of about 20 per cent iron and 80 per cent manganese.
Manganese is also used in several nonferrous alloys and in the production of some chemicals. The compound manganese dioxide is used in dry-cell batteries to prevent the accumulation of hydrogen.
The most common sources of manganese are oxide and carbonate ores such as pyrolu-site, rhodochrosite, and manganite. Pure manganese is obtained mainly by electrolysis. Ukraine, South Africa, Gabon, Australia, and Brazil are the leading manganese-producing nations, usually accounting for about three-fourths of the world output. Other major producers are China, the Republic of Georgia, and India. The United States has manganese deposits, but they are of too low a grade to be mined profitably. Deposits of manganese in the form of nodules that also contain copper, nickel, and cobalt cover extensive areas of the ocean floor. They have not yet been exploited commercially.
Symbol: Mn. Atomic number: 25. Atomic weight: 54.9380. Specific gravity: 7.43. Hardness: 5.0. Melting point: 2,273 F. (1,245 C). Boiling point: 3,564 F. (1.962 C.). Manganese has one natural isotope, Mn-55. Manganese belongs to Group VII-B of the Periodic Table and can have a valence of +1, 2, 3, 4, 6, or 7.