manganese

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A gray-white or silvery brittle metallic element, occurring in several allotropic forms, found worldwide, especially in the ores pyrolusite and rhodochrosite and in nodules on the ocean floor. It is alloyed with steel to increase strength, hardness, wear resistance, and other properties and with other metals to form highly ferromagnetic materials. Atomic number 25; atomic weight 54.9380; melting point 1,244°C; boiling point 1,962°C; specific gravity 7.21 to 7.44; valence 1, 2, 3, 4, 6, 7. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, Mn; atomic weight, 55. A metal having a remarkable affinity for, and in some respects a close resemblance to, iron, of which it is an extremely frequent associate. It differs from iron, however, in that it is not used at all by itself in the arts, although of great interest and importance as connected with the manufacture of iron, and as modifying by its presence in small quantity the character of the product obtained. The use of the black oxid of manganese for removing the coloring matters from glass was known to the ancients, and is mentioned by Pliny, but the nature of the material thus used was not understood until quite modern times. This ignorance was shown in the confusion of the oxid of manganese with the magnetic oxid of iron, the lodestone (Latin magnes and magnesius lapis), and the former was called magnesia by chemists in the middle ages, apparently in conformity with Pliny's idea of a dual (masculine and feminine) nature in some metals, manganese not having the attractive power of the magnet, and being on that account considered feminine. Other variants (in the fifteenth and sixteenth centuries) of the name of the ore used by glass-makers were magnosia, mangadesum, and manganensis. After what we now call magnesia had received the name of magnesia alba, apparently from the idea that this substance was in some way related to the oxid of manganese, the latter began to be called magnesia nigra. From the middle of the eighteenth century the combinations of manganese were studied by various chemists, and finally, in 1774, the metal manganese was isolated by Gahn, but for years there was much confusion in regard to its specific name, and it was not until after the beginning of the present century that the name manganese (mangan in German) began to be generally adopted. The Latin termination in -um (manganesium) is rarely used in modern technical works. This metal has never been found native. As eliminated from its ores by chemical processes, it is grayish-white in color, resembling cast-iron, but varying considerably in hardness and luster according to the nature of the methods by which it was obtained. It is very hard and brittle, and has a specific gravity of about 8. It oxidizes rapidly on exposure to the air. Manganese resembles iron in that its ores are widely diffused, and differs from that metal remarkably in the fact that, on the whole, its ores are only rarely found in considerable quantity in any one locality, while those of iron exist in abundance in many regions. The important ores of manganese are all oxids, and of these the peroxid (pyrolusite), called in commerce the black oxid of manganese, or simply manganese, is the most valuable and important. Other manganiferous minerals (all oxids) are braunite, hausmannite, psilomelane, and various earthy mixtures called bog-manganese, wad, cupreous manganese, etc. Practically, the ore called manganese in commerce is a mixture of various oxids, different samples differing greatly in value, which value has to be determined by chemical analysis. The ores and salts of manganese are of very considerable importance in chemical manufactures, both as bleaching and oxidizing reagents. The nature and importance of this metal in the manufacture of iron and steel will be found indicated under steel and spiegel.

Wiktionary

1. n. A metallic chemical element (symbol Mn) with an atomic number of 25.

GNU Webster's 1913

1. n. (Chem.) An element obtained by reduction of its oxide, as a hard, grayish white metal, fusible with difficulty (melting point 1244° C), but easily oxidized. Its ores occur abundantly in nature as the minerals pyrolusite, manganite, etc. Symbol Mn. Atomic number 25; Atomic weight 54.938 [C=12.011].

WordNet 3.0

1. n. a hard brittle grey polyvalent metallic element that resembles iron but is not magnetic; used in making steel; occurs in many minerals