Manganese

Manganese is used in many alloys.   It improves the rolling and forging qualities, strength, toughness, wear resistance, hardness and hardenability of steel.   When alloyed with aluminum, antimony and copper, it forms highly ferromagnetic metals.   Manganese dioxide (pyrolusite) is used to depolarize dry cell batteries, and decolorize green glass colored by iron impurities.   The dioxide also is used to prepare oxygen and chlorine, and in drying black paints.   The permanganate is a powerful oxidizing agent, which is used in chemical quantitative analysis and in medicines. ^{Lide 4-17}

Manganese is essential to life.   It is part of many body enzymes.   It aids food digestion, vitamin activation, healthy bone structure, sex hormone production, nutrition for brain and nervous system.   Sources: nuts, whole grains, fruits and vegetables, tea, instant coffee, cocoa powder.   A human deficiency is not observed.   In animals, it results in in poor reproduction, retarded growth, birth defects, abnormal bone growth. ^{Brody 188, Netzer 802}

In plants, manganese is a part of the enzymes used in photosynthesis, respiration, and nitrogen-fixing.   A deficiency in young leaves may show a network of green veins on a light green background similar to an iron deficiency.   In the advanced stages the light green parts become white, and leaves are shed.   Also, brownish, black, or grayish spots may appear next to the veins.   In neutral or alkaline soils plants often show deficiency symptoms.   In highly acid soils, manganese may be available to the extent that it results in toxicity. ^{Morgan n.p.}

Manganese was recognized as an element by Scheele, Bergman and others, but it was Johan Gahn, a Swedish mineralogist, who isolated it in 1774 by reducing the dioxide with carbon.   Manganese minerals are widely distributed as oxides, silicates, and carbonates.   Pyrolusite, MnO₂, and rhodochrosite, MnCO₃, are the most common manganese minerals.   It is extracted from ores by reducing the oxide with sodium, magnesium or aluminum, or by electrolysis. ^{Lide 4-17}