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172 SULPHIDES. In crystals, globular, botryoidal, reniform, having a radiating columnar or fibrous structure ; massive; pseudomorphous after calcite, fluor, pyrite, stephanite, proustite, disseminated; earthy. Is not so abundant as pyrites, and is not found in the older rocks. It frequently accompanies pit coal and brown coal; occurs in sandstone, marl, chalk, beds of clay, and in peat. Is found in Saxony near Freiberg, Memmendorf in Bohemia; at Johann-Georgenstadt, Joachimsthal, Littmitz and Altsattel near Toplitz, Przibram ; Almerode in Hessia; in the Harz at Clausthal, Zellerfeld, Iberg ; Conde in France; Cornwall; Derbyshire. 61. MOLYBDENITE.—Sulphuret of molybdena; Phillips. Molybdene ; Hauy. Dirhomboedrischer Eutom-Glanz; Mohs. Molybdiinglanz ; Hausmann. Molybdanit; llai dinger. Ehombohedral. o ill, a Oil, b 2ll, x 120. 00 90° o' FIG. 169. ad 60 0 bd 30 0 Combinations, oa, ax. The faces o smooth; x, a striated parallel to their intersections with o. Cleavage, o, very perfect. Opaque. Lustre metallic. Lead- grey. Streak the same on paper ; on por celain greenish-grev. In thin leaves very flexible. Very sectile. II = 1-0...1-5. G = 4-5...4-6. Before the blowpipe in the forceps imparts a green colour to the flame; on charcoal sulphurous acid is disengaged, and a white sublimate is deposited upon the charcoal. In the inner flame imparts a brown colour to a mixture of borax and nitre. In powder is decomposed by nitric acid, leaving a residue of molybdic acid. "With hot nitromuriatic acid forms a greenish solution ; with boiling sulphuric acid a blue solution. MoS ! , molybdenum 68 - 92, sulphur 41'08. Analyses of molybdenite a from Altenberg by Brandes, b from Chester in Pennsylvania by Seybert, c, d, e from Lindas in Smaland, /from Bohusliin by Svanberg and Struve :— a b c d e f Molybdenum . 69'6 69'42 69'07 69 10 69-13 69 01 Sulphur . . . 404 39-68 40-93 4090 40'87 40'99