Manganese

Manganese is a chemical element; it has the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. First isolated in the 1770s, manganese is a transition metal with many industrial alloy uses, particularly in stainless steels in which it improves strength, workability, and resistance to wear. Various manganese oxides are used as oxidising agents, as rubber additives, and in glass making, fertilizers, and ceramics. Manganese sulfate can be used as a fungicide. Manganese is also an essential human dietary element, important in macronutrient metabolism, bone formation, and free radical defense systems. It is a critical component in dozens of proteins and enzymes. It is found mostly in the bones, but also the liver, kidneys, and brain. In the human brain, manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes. Manganese in the form of the deep violet salt potassium permanganate is commonly used in laboratories as an oxidizer. Potassium permanganate is also used as a biocide in water treatment. It occurs at the active sites in some enzymes. Of particular interest is the use of a Mn–O cluster, the oxygen-evolving complex, in the production of oxygen by plants.