Manganese than one minute. The primary decay mode before the most abundant stable isotope, Mn, is electron capture and the primary mode after is beta decay. Manganese also has three meta states. Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. Mn decays to Cr with a half-life of 3.7 million years. Because of its relatively short half-life, Mn is relatively rare, produced by cosmic rays impact on iron. Manganese isotopic contents are typically combined with chromium isotopic contents and have found application in isotope geology and
Manganese until 2000, the only United States coin to use manganese was the from 1942 to 1945. An alloy of 75% copper and 25% nickel was traditionally used for the production of nickel coins. However, because of shortage of nickel metal during the war, it was substituted by more available silver and manganese, thus resulting in an alloy of 56% copper, 35% silver and 9% manganese. Since 2000, dollar coins, for example the Sacagawea dollar and the Presidential $1 coins, are made from a brass containing 7% of manganese with a pure copper core. In both cases of nickel and dollar,