MANGANESE

Mn. Atomic Weight 64:93. A hard, brittle metal, having the color and appearance of cast iron, with a specific gravity of 8:0. It is readily attacked by the oxygen of the air, so that it must be kept under oil in sealed containers. It melts at about 1245°O, It decomposes water with the evolution of hydrogen, and di olves readily in all dilute acids. It occurs abundantly, the ores Of commerce being obtained chiefl \from India, Brazil and Ru ia, althoug' many minerals containing manganese are found throughout the United States and Canada. The most important one is the dioxide, MnO:, known as pyrolusite. Others are braunite, Mn.Os, O;, H:0, and psilomelane, a compound oxide of barum and manganese. There are also various sulphides, carbonates and _ silicates, the best known being rhodonite, a silicate found in the Ural Mountains, used as an ornamental stone because of its red color. The metal is obtained from its ores either by reduction with aluminum or by means of the electric furnace. The metal is largely used in metallurgy for the preparation of various alloys, such as manganese bronze, alloys with aluminum, antimony, tin, and bismuth, and the well-known manganese steels. [Iron alloys with manganese in all proportions, the presence of manganese increasing the tenacity of steel and improving its working properties. Manganese steel, containing about 10 per cent. manganese, is very hard and tough, and is used for jaws of rock breakers, and other machinery.