Manganese easy to oxidize. Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen. Naturally occurring manganese is composed of one stable isotope, Mn. Eighteen radioisotopes have been isolated and described, ranging in atomic weight from 46 u (Mn) to 65 u (Mn). The most stable are Mn with a half-life of 3.7 million years, Mn with a half-life of 312.3 days, and Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives of less than three hours, and the majority of less
Manganese still known as Hadfield steel (mangalloy). It was used for British military steel helmets and later by the U.S. military. The second largest application for manganese is in aluminium alloys. Aluminium with roughly 1.5% manganese has increased resistance to corrosion through grains that absorb impurities which would lead to galvanic corrosion. The corrosion-resistant aluminium alloys 3004 and 3104 (0.8 to 1.5% manganese) are used for most beverage cans. Before 2000, more than 1.6 million tonnes of those alloys were used; at 1% manganese, this consumed 16,000 tonnes of manganese. Methylcyclopentadienyl manganese tricarbonyl is used as an additive in unleaded gasoline