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CHROMITE , a member of the See also:spinel See also:group of minerals; an See also:oxide of See also:chromium and ferrous See also:iron, FeCr2O4. It is also known as chromic iron or as chrome-iron-ore, and is the See also:chief commercial source of chromium and its compounds. It crystallizes in See also:regular octahedra, but is usually found as grains or as granular to compact masses. In its iron-See also:black See also:colour with submetallic lustre and See also:absence of cleavage it resembles See also:magnetite (magnetic iron-ore) in See also:appearance, but differs from this in being only slightly if at all magnetic and in the See also:- BROWN
- BROWN, CHARLES BROCKDEN (1771-181o)
- BROWN, FORD MADOX (1821-1893)
- BROWN, FRANCIS (1849- )
- BROWN, GEORGE (1818-188o)
- BROWN, HENRY KIRKE (1814-1886)
- BROWN, JACOB (1775–1828)
- BROWN, JOHN (1715–1766)
- BROWN, JOHN (1722-1787)
- BROWN, JOHN (1735–1788)
- BROWN, JOHN (1784–1858)
- BROWN, JOHN (1800-1859)
- BROWN, JOHN (1810—1882)
- BROWN, JOHN GEORGE (1831— )
- BROWN, ROBERT (1773-1858)
- BROWN, SAMUEL MORISON (1817—1856)
- BROWN, SIR GEORGE (1790-1865)
- BROWN, SIR JOHN (1816-1896)
- BROWN, SIR WILLIAM, BART
- BROWN, THOMAS (1663-1704)
- BROWN, THOMAS (1778-1820)
- BROWN, THOMAS EDWARD (1830-1897)
- BROWN, WILLIAM LAURENCE (1755–1830)
brown colour of its See also:powder. The hardness is 51; specific gravity 4.5. The theoretical See also:formula FeCr2O4 corresponds with chromic oxide (Cr203) 68%, and ferrous oxide 32%; the ferrous oxide is, however, usually partly replaced by See also:magnesia, and the chromic oxide by alumina and ferric oxide, so that there may be a See also:gradual passage to picotite or chromespinel. Much of the material See also:mined as ore does not contain more than 40 to 50% of chromic oxide. In the See also:form of isolated grains the See also:mineral is a characteristic constituent of ultrabasic igneous rocks, namely the peridotites and the serpentines which have resulted from their alteration. It is also found under similar conditions in meteoric stones and irons. Often these rocks enclose large segregated masses of granular chromite. The earliest worked deposits were those in the See also:serpentine of the See also:Bare Hills near See also:Baltimore, See also:Maryland, U.S.A.; it was also formerly extensively mined in See also:Lancaster See also:county, See also:Pennsylvania, and is now mined in See also:California, as well as in See also:Turkey, the Urals, Dun See also:Mountain near See also:Nelson in New See also:Zealand, and Unst in the Shetlands.
Chrome-iron-ore is largely used in the preparation of chromium compounds for use as See also:pigments (chrome-yellow, &c.) and in See also:calico-See also:printing; it is also used in the manufacture of chrome-See also:steel. (L. J.
End of Article: CHROMITE
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