Manganese is a gray-white metal, resembling iron. It is a hard metal and is very brittle, fusible with difficulty, but easily oxidized. Manganese metal is ferromagnetic only after special treatment.
The most common oxidation states of manganese are +2, +3, +4, +6 and +7, though oxidation states from +1 to +7 are observed. Mn2+ often competes with Mg2+ in biological systems, and manganese compounds where manganese is in oxidation state +7 are powerful oxidizing agents.
Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost stainless steel formulations and certain widely used aluminium alloys. It is also added to gasoline in order to reduce engine knocking. Manganese(IV) oxide (manganese dioxide) is used in the original type of dry cell battery. Manganese dioxide is also used as a catalyst. Manganese is used to decolorize glass (removing the greenish tinge that presence of iron produces) and, in higher concentration, make violet-colored glass. Manganese oxide is a brown pigment that can be used to make paint and is a component of natural umber. Potassium permanganate is a potent oxidizer and used in chemistry and in medicine as a disinfectant. Manganese phosphating is used for rust and corrosion preventation on steel.
The overall level and nature of manganese use in the United States is expected to remain about the same in the near term. No practical technologies exist for replacing manganese with other materials or for using domestic deposits or other accumulations to reduce the complete dependence of the United States on other countries for manganese ore.
Substitutes: Manganese has no satisfactory substitute in its major applications. In minor applications, (e.g., manganese phosphating), zinc and sometimes vanadium are viable substitutes