Manganese is a transistion metal like chromium and iron, it has an atomic number of 25 and an aproximate atomic weight of 55. Different variations and compounds of Manganese (Such as Manganese dioxide) have been used since ancient times by glass makers. Though scientists knew by the mid-18th century that manganese-dioxide contained an element that had not yet been discovered, however Johan Gottlieb Gahn was the first to isolate an impure sample of manganese in 1774. is used to strengthen steel and to prevent rust and corrosion. Most types of enzymes contain manganese, and it is essential to most living organisms as it strengthens bones. Manganese is the 5th most common metal in the earths crust.
Sources:
https://en.m.wikipedia.org/wiki/Manganese#History
http://www.rsc.org/periodic-table/element/25/manganese
