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|Atomic Number:||25||Atomic Symbol:||Mn|
|Atomic Weight:||54.9380||Electron Configuration:||2-8-13-2|
|Melting Point:||1245oC||Boiling Point:||1962oC|
|Uses:||steel, batteries, ceramics, making plows|
History(L. magnes, magnet, from magnetic properties of pyrolusite; It.
manganese, corrupt form of magnesia)
Recognized by Scheele, Bergman, and others as an element and isolated by
Johann Gahn of Sweden in 1774 by reduction of the dioxide with carbon.
SourcesManganese minerals are widely distributed; oxides, silicates,
and carbonates are the most common. The discovery of large quantities of
manganese nodules on the floor of the oceans may become a source of manganese.
These nodules contain about 24% manganese together with many other elements in
Most manganese today is obtained from ores found in Russia, Brazil,
Australia, Republic of S. Africa, Gabon, and India. Pyrolusite and rhodochrosite
are among the most common manganese minerals. The metal is obtained by reduction
of the oxide with sodium, magnesium,
aluminum, or by elctrolysis.
PropertiesIt is gray-white, resembling iron, but
is harder and very brittle. The metal is reactive chemically, and decomposes
cold water slowly. Manganese is used to form many important alloys. In steel,
manganese improves the rolling and forging qualities, strength, toughness,
stiffness, wear resistance, hardness, and hardenability.
With aluminumand antimony,
especially with small amounts of copper, it forms highly
Manganese metal is ferromagnetic only after special treatment. The pure metal
exists in four allotropic forms. The alpha form is stable at ordinary
temperature; gamma manganese, which changes to alpha at ordinary temperatures,
is said to be flexible, soft, easily cut, and capable of being bent.
UsesThe dioxide (pyrolusite) is used as a depolarizer in dry cells, and
is used to "decolorize" glass that is colored green by impurities of iron.
Manganese by itself colors glass an amethyst color, and is responsible for the
color of true amethyst. The dioxide is also used in the preparation of oxygen
and chlorine, and in drying black paints. The permanganate is a powerful
oxidizing agent and is used in quantitative analysis and in medicine.
Manganese is widely distributed throughout the animal kingdom. It is an
important trace element and may be essential for utilization of vitamin B1.
HandlingExposure to manganese dusts, fume, and compounds should not
exceed the ceiling value of 5 mg/m^3 for even short periods because of the
element's toxicity level.