MAIN (river of Germany) MALLET, DAVID MAIN (power or strength) MALLET, PAUL HENRI MAINA and MAINOTES MALLET, ROBERT MAINE, ANNE LOUISE DE BOURBON MALLET DU PAN, JACQUES MAINE, SIR HENRY JAMES SUMNER MALLING, EAST and WEST MAINE (French province) MALLOCK, WILLIAM HURRELL MAINE (U.S. state) MALLOW (town of Ireland) MAINE DE BIRAN, FRANÇOIS-GONTHIER MALLOW (botanical genus) MAINE-ET-LOIRE MALMEDY MAINPURI MALMESBURY, JAMES HARRIS MAINTENANCE MALMESBURY, JAMES HOWARD HARRIS MAINTENON, FRANÇOISE D'AUBIGNÉ MALMESBURY MAINZ MALMÖ MAIRET, JEAN DE MALMSEY MAISTRE, JOSEPH DE MALOCELLO, LANCILOTO MAISTRE, XAVIER DE MALOLOS MAITLAND, EDWARD MALONE, EDMOND MAITLAND, FREDERIC WILLIAM MALONE MAITLAND, SIR RICHARD MALONIC ACID MAITLAND, WILLIAM MALORY, SIR THOMAS MAITLAND, EAST and WEST MALOT, HECTOR HENRI MAITREYA MALOU, JULES ÉDOUARD XAVIER MAIWAND MALOUET, PIERRE VICTOR MAIZE MALPIGHI, MARCELLO MAJESTY MALPLAQUET MAJLÁTH, JÁNOS MALSTATT-BURBACH MAJOLICA MALT MAGNETITE, a mineral forming the natural magnet (see MAGNETISM), and important also as an iron-ore. It is an iron-black, opaque mineral, with metallic lustre; hardness about 6, sp. gr. 4.9 to 5.2. When scratched, it yields a black streak. It is an oxide of iron having the formula Fe3O4, corresponding with 72.4% of metal, whence its great value as an ore. It may be regarded as a ferroso-ferric oxide, FeO·Fe2O3, or as iron ferrate, Fe´´Fe2´´´O4. Titanium is often present, and occasionally the mineral contains magnesium, nickel, &c. It is always strongly magnetic. Magnetite crystallizes in the cubic system, usually in octahedra, less commonly in rhombic dodecahedra, and not infrequently in twins of the "spinel type" (fig. 1). The rhombic faces of the dodecahedron are often striated parallel to the longer diagonal. There is no distinct cleavage, but imperfect parting may be obtained along octahedral planes. [Illustration: FIG. 1.]