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MOLYBDENITE

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Originally appearing in Volume V18, Page 681 of the 1911 Encyclopedia Britannica.
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MOLYBDENITE , a See also:

mineral consisting of See also:molybdenum disulphide, MoS2. It closely resembles See also:graphite in See also:appearance, but may readily be distinguished from this by its greater See also:density (4.7) and by its behaviour before the See also:blowpipe. Crystals have the See also:form of six-sided plates or scales, but they are never sharply defined, and their reference to the hexagonal See also:system is doubtful. They have a perfect cleavage parallel to the large See also:surface of the plates, and the flakes are readily See also:bent, but are not elastic. The mineral is very soft (H = 1 to I z) and unctuous, and makes a bluish-See also:grey See also:mark on See also:paper: it is opaque and has a See also:bright metallic lustre. The See also:colour is See also:lead-grey differing slightly from that of graphite in having a bluish tinge. The name molybdenite is from the See also:Greek /2c Xu(3Sos, meaning lead or lead ore, with which graphite (See also:black-lead) and molybdenite were confused; the latter was distinguished by P. J. Hjelm, who in 1782 discovered the See also:element molybdenum in this mineral. Molybdenite occurs as disseminated scales in crystalline rocks—such as See also:granite, See also:gneiss, schist and See also:marble—and also in See also:quartz-See also:veins. It has been found in small amounts at many localities, but only those which have yielded large crystals need be specially mentioned here, viz. in a See also:pyroxene-See also:rock at Aldfield in See also:Pontiac See also:county, See also:Quebec; with native See also:bismuth at Kingsgate in See also:Gough county, New , See also:South See also:Wales; with See also:wolframite and See also:scheelite in quartz-veins at Caldbeck Fells in See also:Cumberland; and recently, as crystals 6 in. across, at Slangsvold near Raade in See also:Norway. Molybdenite has been used mainly for the preparation of molybdates for use as chemical reagents.

Recently, however, it has been used in the manufacture of molybdenum See also:

steel (ferro-molybdenum), which by See also:reason of its hardness and toughness is specially suitable for tools. (L. J.

End of Article: MOLYBDENITE

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MOLYBDENUM [symbol, Mo; atomic weight, 96 (0=16)]

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