A Treatise on Mineralogy

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C.U. Shepard, 1857 - Mineralogy - 451 pages
 

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Page 273 - U]x>n the nature of these admixtures. The specular iron is infusible before the blow-pipe, but melts with borax, and forms a green or yellow glass, like pure oxide of iron. It is likewise soluble in heated muriatic acid. The specular iron (in the crystalline, lamelliform and compact varieties, with...
Page 368 - The Pitch Lake is one and a half miles in circumference ; the bitumen is solid and cold near the shores, but gradually increases in temperature and softness towards the centre, where it is boiling. The solidified bitumen appears as if it had cooled, as the surface boiled, in large bubbles. The ascent to the lake from the sea, a distance of threequarters of a -mile, is covered with a hardened pitch, on which trees and vegetables flourish ; and about Point la Braye, the masses of pitch look like black...
Page 45 - First, we try, with a corner of the given mineral, to scratch the members of the scale, beginning from above, in order that we may not waste unnecessarily the specimens representing lower members. After having thus arrived at the first, which is distinctly scratched by the given mineral, we have recourse to the file, and compare upon it the hardness of this degree, that of the next higher degree, and of the given mineral. Care must be taken to employ specimens of each of them nearly agreeing in form...
Page 363 - ... strontian. It also occurs with copper pyrites, galena, and orpiment. It is deposited from several springs, and in large quantities from volcanoes. In Sicily, and several provinces of Italy, sulphur is found in splendid crystals, as well as in globular concretions. It occurs in imbedded spheroidal masses of a brown color, which is owing to bitumen, at Radoboy, near Crapina, in Croatia. The finest crystals, after those of Sicily, are brought from Conil, near Cadiz, in Spain. It occurs in veins...
Page 45 - ... hardness will be easily perceived. A short practice is sufficient for rendering these perceptions more delicate and perfect, so that in a short time it is possible to determine differences in the hardness very much less than those between two subsequent members of the scale. " Upon these observations is founded the application of the scale, the general principle of which consists in this, that the degree of hardness of the given mineral is compared with the degrees of hardness of the members...
Page 214 - Quartz frequently fills up the space of petrified bodies, as, for instance, echinites in chalk, and petrified wood in sandstone and in alluvial deposits. 5. The numerous varieties of the present species are spread all over the globe, but some of the most distinguished varieties are found only in a few localities. The finest and largest Rock-crystals of high degrees of transparency are found in the alps of Salzburg, the Tyrol, Switzerland, Dauphiny, Piedmont, and Savoy, also in the isle of Madagascar,...
Page 298 - But native gold is more often found in the sand of rivers in valleys and plains, into which it has been carried from its original repositories, in the shape of larger or smaller, generally flat pebbles, mingled with quartz.
Page 306 - H. ROSE. Upon charcoal it becomes black before the blowpipe, and red on cooling. It melts into a globule, which becomes magnetic if kept in the blast for some time. With borax it yields a globule of copper. It is partly soluble in dilute nitric acid ; the solution is green, and the undissolved part consists of sulphur.
Page 311 - Its chemical composition is, iron 33.5, arsenic 46.5, and sulphifr 20. Before the blow-pipe, upon charcoal, it emits copious arsenical fumes, and melts into a globule, which is nearly pure sulphuret of iron. It is soluble in nitric acid, with the exception of a whitish residue. It sometimes contains a small proportion of silver ; when it is denominated argentiferous arsenical pyrites.
Page 201 - It also occurs in pseudomorphoses of carbonate of lime ; fracture conchoidal, of various degrees of perfection, sometimes highly perfect; lustre vitreous, in some varieties inclining to resinous ; color white, yellow, red, brown, green and gray : none of them lively, except some red...

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