Treatise on Mineralogy: Second Part, Consisting of Descriptions of the Species, and Tables Illustrative of Their Natural and Chemical Affinities ...

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H. Howe & Company and Herrick & Noyes, 1835
 

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Side 239 - In a strong heat, the faces of crystallization, but not those of cleavage, are covered with small blisters, which, however, immediately crack. With borax it melts slowly into a transparent glass. Its powder colon the tincture of violets green.
Side 263 - It decrepitales before the blowpipe, but melts, if first reduced to powder, into a dark brown or black scoria, which moves the magnetic needle. It is soluble in dilute sulphuric and nitric acids. The friable varieties are found white in their original repositories, but like the white powder of the crystals, they soon assume a blue tinge, on being exposed to the air. 3. The varieties of the present species occur in different kinds of natural repositories. Some of them are found crystallised, particularly...
Side 269 - ... into lavender-blue, and some shade of green ; the color becomes brown on being exposed to light; streak shining; translucent ; sectile ; hardness about that of talc ; specific gravity 5.5. It occurs also in crusts and granular masses. It consists of silver 76.0, oxygen 7.6, and muriatic acid 16.4. It is fusible in the flame of a candle, and emits fumes of muriatic acid. Horn silver is most frequently found in the upper parts of veins in clayslate, but occurs also in beds, generally along with...
Side 63 - The varieties called slate coed, foliated coal, coarse coal, cannel coal, and piteh coal, occur chiefly in the coal formation ; some varieties of pitch coal, also the moor coal, bituminous wood, and common brown coal, are met with in the formations above the chalk ; the earthy coal, and some varieties of bituminous wood and common brown coal, are often included in diluvial and alluvial detritus. The coal seams alternate with beds of slaty clay and common clay, sandstone, limestone, sand, &c.
Side 109 - Pcarlstone is formed, the distinguishing mark of which consists of those roundish masses into which it may be separated, and that generally allow themselves to be resolved into thin films, not unf'requently including a grain of Obsidian. The Obsidian itself is often vesicular, the cavities being small, and keeping a constant direction. If there are a great many of them of larger sizes, the whole mass becomes apparently very light, the original colour disappears, and there is pearly or silky lustre...
Side 234 - Lustre adamantine. Colour various shades of white, grey, yellow, red, brown, black. Streak pale grey, in some varieties it is pale brown. Semitransparent, sometimes almost transparent ... nearly opake. Brittle. Hardness = 6-0 ... 7-0. Sp. Gr. = 6-960, a crystallised variety; = 6-519, thin columnar composition. Compound Varieties. Twin-crystals : Axis of revolution perpendicular, face of composition parallel to one, or sometimes to several faces of P. Small reniform, rarely botryoidal shapes : original...
Side 90 - ... formation. Lately, however, some very fine specimens of this substance have bee"n discovered in the Faroe islands; and most beautiful ones, sometimes quite transparent, are obtained near Gracias a Dios, in the province of Honduras, in America.
Side 204 - A third variety of this species, employed in jewelry, is the avanturine feldspar, which comes from the island of Cedlovatoi, near Archangel, and which is of a honey-yellow color, and every where penetrated by little golden spangles. 4. The pure varieties of feldspar are used in the composition of the paste of porcelain ; also for the enamel with which it is covered ; and the decomposed variety, or porcelain earth itself, is the most important material in that department of manufactures. (See...
Side 217 - ... Lime-haloide, and often also with prismatoidal Hal-baryte. In veins it occurs with pyramidal Copperpyrites, hexahedral Lead-glance, hemi-prismatic Sulphur, &c. It is deposited from several springs, and in large quantities from volcanoes. Sometimes it occurs in beds of bituminous Mineral-coal. „ 4. Prismatic Sulphur is found in splendid crystals, and pure massive varieties, also in globular concretions, which, however, are seldom without earthy or bituminous admixtures, in Sicily, and several...
Side 68 - ... places that it has been found in sufficient abundance to make the search for it profitable. Native gold exists in veins in primitive mountains, but not in the greatest quantity in those which are esteemed to be of the oldest formation. It is more often found in the sand of rivers, in plains and valleys, into which it has been carried from its original repositories, in the shape of larger or smaller, generally flat, pebbles, mingled with quartz. In ancient times, gold was obtained from the valleys...

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