MOLYBDENITE, mollbide-nite, a native sulphid of molybdenum crystallizing in tabular or hexagonal forms. It commonly occurs in granite, gneiss and other crystalline rocks. In the United States it is found in the New Eng land States, and in New York, Pennsylvania, Colorado and California. It also occurs in Canada, in Pontiac County, Quebec, in Renfrew County, Ontario, and in other parts of the world. It is the chief of the commercial ores yielding the important metal molybdenum (q.v.), among which also are wulfenite, molyb dite and other minerals, described as follows: Molybdenite or molybdenum disulphide, MoSI, contains about 60 per cent molybdenum and 40 per cent sulphur. It is a soft, opaque mineral, with a lead-gray color, sometimes bluish or brownish, and with metallic lustre. When crystallized it is found in tabular or short prismatic, hexagonal crystals. It has a perfect cleavage, andyields flakes which are flexible but not elastic. It is sectile and feels slightly greasy. Its hardness is 1 to 1.5, and its specific gravity is 4.7 to 4.8. Its streak is lead-gray metallic, bluish-gray on paper, and greenish on glazed porcelain. It occurs in fine granular or foliated masses or scales scattered through or imbedded in many crystalline rocks, including granite, gneiss, zircon syenite and granular limestone. Its appearance is similar to that of graphite, for which it is frequently mistaken by the prospector. Wulfenite is a molybdate of lead, PbMo0., and contains about 262 per cent molybdenum and 56.4 per cent lead. Its color is bright red to orange or wax yellow; sometimes brown, grayish-white, or nearly colorless; occasionally yellowish-gray to pale green. Its lustre is resinous to adamantine. When crystalline it is translucent and occurs commonly in thin, square, tabular, tetragonal crystals. Sometimes octahedral and prismatic forms are found. It occurs also as crystal crusts and in massive granular forms. It is always found with other lead minerals, espe cially pyromorphite and vanadinite. It has one good pyramidal cleavage, and two less distinct. It is brittle and its fracture is subconchoidal, Its hardness is 2.75 to 3, and its specific gravity is 6.7 to 7. Its streak is white. Molybdite, or molybdic ochre, is a hydrous ferric molybdate, Fe,011.3Mo0..7TAH20, and contains 39.6 per cent
molybdenum. It occurs as an earthy, yellow powder, or in hair-like crystals of pale yellow color, usually associated with molybdenite, of which it is an alteration product. Alone it is I not an important ore of molybdenum. It has a dull lustre, a straw yellow streak, a hardness of 1 to 2, and a specific gravity of 4.5. Powel lite is calcium molybdate, and contains 48 per cent molybdenum. Sometimes tungsten replaces part of the molybdenum. green ish-yellow to dull gray in color, subtransparent, resinous, without cleavage, has an uneven frac ture, a hardness of 3.5, and a specific gravity of 4.52. Ilsemannite is an oxide of molybdenum, Mo02.4MoO,, and contains about 68 per cent molybdenum. It is a blue-black to black cryptocrystalline mineral, associated with barite and wulfenite. It •is soluble in water, giv;ng a deep blue solution which on evaporation yields dark blue crystals. Rare. Belonesite is mag nesium molybdate, MgMoO., and contains 52 per cent molybdenum. It is a white transparent mineral, occurring in minute tetragon ll crystals. It. occurs in rock fragments enveloped in Vesu wan lava. Rare. Pateraite is cobalt molyb date, CoMoO., and contains 43.8 per Cent molybdenum, or it is molybdate of cobalt and iron, FeCoMC20., and contains 44.1 per cent molybdenum. It is an impure massive black mineral associated with uranium minerals., Rare. Achrematite is lead arsenate, chloride and molybdate, 3 (3PbsAs208.PbC1.) 4 (Pbs Mo0f), and contains 3.4 per cent molybdenum. It is a massive, cryptocrystalline mineral with an uneven to subconchoidal fracture, is brittle, has a hardness of 3 to 4, and a specific gravity of about 6. Its color is sulphur-yellow to orange and red, but in mass is liver-brown, ow ing to admixture of limonite. Its streak is pale cinnamon brown. Its lustre is resinous to adamantine, and fragments are translucent on thin edges. Eosite is a vanado-molybdate of lead, and contains 8.9 per cent molybdenum. Its color is deep. Aurora-red. It has a brownish, orange-yellow streak. Its hardness is 3 to 4. It occurs in minute octahe dral crystals of the tetragonal system which are found on pyromorphite and cerrusite. Molybdurane is molybdate of uranium, UO2U0s.2Mo04. Molybdofersite is molybdate of iron, FeMoa.