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LEFT MINERALOGY 241 MINERVA MINERALOGY (-al'-), in natural his- tory, a science treating of those natural inorganic products of the earth which possess definite physical and chemical characters. In 1669 Nicolas Steno, a Dane, made the discovery that in crys- tals of quartz the angles of inclination of adjoining faces were constant, and that the number of faces and their grouping, notwithstanding variations in size, were always the same. In this year also the doubly-refracting property of Iceland spar was observed. In 1772 Rome de risle announced that the various shapes of crystals of the same product were in- timately related. The Abbe Haiiy in 1784 discovered that 10 forms, including six of de risle, could be produced from various minerals by cleavage,^ and that these must be the true primitive forms. Professor Weiss, of Berlin (1809-1815), established fundamental lines, which he called axes, and to which he showed how all the primitive forms and second- ary planes were related. Subsequently, though independently. Mohs (1820-1825) arrived at a division of crystals into four systems of crystallization which coin- cided with the four axial groups of Weiss. He also announced two other systems of crystallization, in conse- quence of more precise measurements being obtainable by the use of the re- flective goniometer. The discovery by Malus in 1808 that a ray of ordinary light reflected at a certain angle from a glass plate possessed the same prop- erties as that which emerged from Ice- land spar, enabled Brewster in 1819 to point out the intimate relation which ex- isted between the cleavage form of a mineral and its action on light. The early attempts at classification were very vague, and were founded on supposed external differences, being di- vided into Earths, Stones, and Metals. Cronstedt's "Essay" (1758) was the first foreshadowing of a principle in a system of classification. The earths he classed as Calcareous, Siliceous, Argillaceous, and so on. Werner's last system divided fossils (as minerals were then called) into four classes: viz.. Earthy, Saline, Combustible, and Metallic. The system of Haiiy (1801), like that of Werner, was a mixed one, but it was the first to di- rect attention to the importance of crys- tallographic form to a system of classi- fication. MINERAL PRODXJCTION, UNITED STATES. The table which appears on pages 242-243 gives the production of metals and minerals in the United States for 1918, with estimates of production for 1919. MINERAL WATERS, waters so far impregnated with mineral matter as to give them a peculiar taste or smell, and specific medicinal properties, which may exert effects on the human body dif- ferent than on ordinary water. They are usually divided into four classes — car- bonetted, or those containing free car- bonic acid gas; chalybeate, or those im- pregnated with iron; saline, containing considerable quantities of neutral salts, as sulphate of magnesia, chloride of sodium, etc.; and sulphurous, or waters containing sulphuretted hydrogen. The term mineral waters is also applied to artificial aerated waters. Natural min- eral waters are generally connected with recent or extinct volcanoes, and they are most common in volcanic regions. Some are thermal. MINERAL WAX. See Ozokerite. MINERS, WESTERN FEDERATION OF, a labor organization of employees of mines, smelters, etc., founded in 1893, on the industrial union principle, and now covering over two dozen States, mostly in the Rocky Mountain region. The Federation indorses socialism, its slogan being "labor produces all wealth; therefore all wealth belong;? to those who produce it." It played a very prominent part in the Cripple Creek strikes, in 1894, when the militia was called into the field. It also backed the strike in the Coeur d'Alene Mines in Colorado, in 1899, when martial law was declared on account of the revolutionary violence of the strikers. The official organ of the organization is "The Miners' Maga- zine." MINERSVILLE, a town in Schuylkill CO., Pa., in the midst of the anthracite coal-mining district. Three railroads en- ter the borough, the Pennsylvania, Le- high Valley, and the Reading. An elec- tric road connects it with Pottsville. Pop. (1910) 7,240; (1920) 7,845. MINERVA (mi-nur'va), in Roman mythology, the goddess of wisdom and war, the liberal arts, scie>nce, and learn- ing. She is reputed to have been the off- spring of Jupiter's brain, without a mother. She is also called Athena, Pallas, Parthenos, Tritonia, Glaucopsis (Blue- Eyes), Agoraea, Hippia, Stratea, Area, Sais, etc., according to the arts she taught or the functions over which she presided. The serpent, the owl, and the cock were sacred to her; and among the plants, the olive. She was worshiped over all parts of Greece; but her great temple was the Parthenon at Athens, where she was the presiding goddess,