Characteristics: Pure manganese is a hard, very brittle metal which cannot be fabricated. Like iron, it will tarnish in air and rusts in the presence of moisture. Due to its reactivity, it is easily oxidized, decomposes in water and readily dissolves in dilute mineral acids. Pure manganese is not found as a free element in nature, but is found in many minerals, principally pyrolusite, braunite, and psilomelane. Manganese is considered essential for plant and animal life.
Applications: The largest use of manganese is in metal alloys. Manganese is used in many steel alloys and aluminum alloys to improve strength, malleability and corrosion resistance. A manganese alloy is even used in some US one dollar coins. Manganese compounds are used as gasoline additives, as a reagent in organic chemistry, and in batteries. Manganese dioxide has been used in the manufacture of glass to remove color caused by iron impurities and as a pigment in glass, ceramics and paint. Manganese oxides have been used as a pigment since prehistoric times.
Hazards: Chronic inhalation of high levels of manganese may result in a syndrome called manganism with symptoms similar to Parkinson’s disease. Dust or powder is flammable. Use dry chemical to extinguish. Exposure limits: ACGIH/TLV: elemental and inorganic compounds 0.02 mg/m3 (respirable), OSHA: compounds and fume, 5 mg/m3 (ceiling).