A Text-book of Mineralogy: With an Extended Treatise on Crystallography and Physical Mineralogy

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Page 61 - The sine of any middle part is equal to the product of the tangents of the Adjacent parts. RULE II. The sine of any middle part is equal to the product of the cosines of the opposite parts.
Page 88 - Twin crystals. Crystals In which one or more parts, regularly arranged, are In reverse position with reference to the other part or parts. They often appear externally to consist of two or more crystals symmetrically united, and sometimes have the form of a cross or star.
Page 391 - ... softening or any appearance of incipient fusion. 1376. 5. Cannel Coal (Parrot Coal). — A variety of bituminous coal, and often caking; but differing from the preceding in texture and to some extent in composition, as shown by its products on distillation. It is compact, with little or no luster, and without any appearance of a banded structure; and it breaks with a conchoidal fracture and smooth surfaces; color, dull black or grayish-black. On distillation it affords, after drying, 40 to 66...
Page 392 - Sulphur is present in nearly all coals. It is supposed to be usually combined with iron, and when the coal affords a red ash on burning, there is reason for believing this true. But Percy mentions a coal from New Zealand which gave a peculiarly white ash, although containing 2 to 3 per cent.
Page 119 - THE specific gravity of a mineral, is its weight compared with that of another substance of equal volume, whose gravity is taken at unity.
Page 255 - Lustre silky, often submetallic; sometime? dull and earthy. Color of surface of fracture various shades of brown. commonly dark, and none bright ; sometimes with a nearly black varnishlike exterior ; when earthy, brownish-yellow, ochre-yellow. Streak yellowish-brown.
Page 117 - ... galena. Sectile, when pieces may be cut off with a knife without falling to powder, but the substance still goes to pieces under the hammer. This is really a condition intermediate between brittle and malleable. Malleable, when the substance can be beaten out under the hammer without flying to pieces, like gold. Ductile, when the substance can be extended or drawn out by tension, as in...
Page 391 - ... Pennsylvania; 1.81, Rhode Island; 1.26 to 1.36, South Wales. Luster bright, often sub-metallic, iron-black, and frequently iridescent. Fracture conchoidal. Volatile matter after drying, 3 to 6 per cent. Burns with a feeble flame of a pale color. The anthracites of Pennsylvania contain ordinarily 85 to 93 per cent, of carbon; those of South Wales, 88 to 95 ; of France, 80 to 83 ; of Saxony, 81 ; of Southern Russia, sometimes 94 per cent. Anthracite graduates into bituminous coal, becoming less...
Page 224 - ... silver 59.8$. BB on charcoal, fuses with spurting to a globule, gives off antimonous fumes, and coats the coal white; with soda on charcoal, in the OF, or by prolonged heating without fluxes in the RF, gives a globule of silver. In the closed tube, gives a reddish sublimate of antimonous sulphide; in the open tube, gives sulphurous fumes and a white sublimate of antimonous oxide. In some varieties arsenic is present, in which case it can be recognized by its garlic odor when the pulverized mineral...

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