Manganese, the chemical symbol is Mn, its atomic number is 25, is a gray white, hard brittle, shiny transition metal, pure manganese metal is slightly softer than iron metal, manganese with a small amount of impurities, strong and brittle, moist place will oxidize. Manganese exists widely in nature, the content of manganese is 0.25% in soil, and more in tea, wheat and hard-shelled fruit. Exposure to manganese operations include gravel, mining, welding, production of dry cells, dye industry and so on.