Manganese is a gray-white metal, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes cold water slowly. Manganese is widely distributed throughout the animal kingdom. It is an important trace element and may be essential for utilization of vitamin B. Manganese is present in quantity the floor of oceans. It is an important component of steel.
Source: http://www.webelements.com/