The Swedish chemist Johan Gottlieb Gahn discovered the element manganese (symbol Mn, atomic number 25), a gray-white, hard, brittle metallic element, in 1774. Its relationship with man and most other life on Earth has a long history, as it is an essential element. A deficiency of the element causes infertility in mammals as well as bone malformation in growing chicks. It is thought manganese plays a vital part in the metabolism of vitamin B1.
Gahn recovered the element from the mineral pyrolusite made of manganese dioxide and this mineral still provides the majority of the element for industrial use today. To obtain manganese from pyrolusite requires reduction of the mineral usually by burning it with powdered aluminum in a furnace. Sodium or magnesium may be used in place of aluminum. Alternatively, treating the mineral with sulfuric acid forms manganese sulfate and electrolysis of this sulfate yields manganese metal.
Industrially the greatest use of the element is within the steel industry. The addition of manganese to molten steel removes oxygen and sulfur contaminants. The addition of manganese to steel increases its rolling and forging qualities as well as its strength, toughness, stiffness, wear resistance, hardness, hardening ability and resistance to impact. These properties are important in the production of railway tracks, which may contain up to 1.2% manganese.
Manganese also proves valuable in the glass industry. The element imparts an amethyst color to glass and it is responsible for the color of the amethyst gemstone. Manganese dioxide removes the green coloration caused by iron contamination of molten glass.
Another use of manganese dioxide is the preventing the formation of hydrogen in dry cell batteries. It also acts as a drying agent in black paints.
The permanganate is also important. It is a powerful oxidizing agent and as such, it is used in quantitative analysis and medicine.
While not naturally ferromagnetic, manganese when treated and alloyed with aluminum, antimony and copper results in highly ferromagnetic alloys.
Currently much of the world’s supply of the metal comes from Russia, Brazil, Australia, South Africa, Gabon, and India. Because of its economic value, other sources of the element are important. The mineral rhodochrosite also contains manganese. A potential source that may provide economical supplies in the future is the ocean. Nodules containing up to 24% manganese occur on the oceanic floor.
Los Alamos National Laboratory Chemistry Division
Jefferson Laboratories Science Education website