An Introduction to Mineralogy: Adapted to the Use of Schools, and Private Students : Illustrated by Nearly Two Hundred Wood Cuts

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B.B. Barber, 1832 - Mineralogy - 343 pages
 

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Page 278 - On being exposed to the air, it is gradually decomposed : first the colour of the surface becomes brown or black ; afterwards, also, the streak is changed into red or brown; hardness and specific gravity are diminished; and even the chemical constitution is altered, the whole being converted into hydrate of iron.
Page 253 - Before the blowpipe On charcoal it usually decrepitates, then melts, and on cooling forms a polyhedral globule, the faces of which present concentric polygons ; if this globule be pulverized and mixed with borax and again heated, a...
Page 324 - Susquehannah; in various places west of that branch; also on the Juniata, and on the waters of the Alleghany, and Monongahela. In Connecticut, a coal formation, commencing at Newhaven, crosses Connecticut river at...
Page 335 - ... mineral through which an object cannot be seen, but which transmits some light, is termed translucent. Rock salt, sometimes quartz, flint, and fluor, &c. are translucent : many minerals are translucent on the edges, as common marble, &c. Transparent. Those minerals are transparent through which an objeet may • be clearly seen.
Page 135 - It abounds with very distinct and perfect impressions of fish, sometimes a foot or two in length ; the head, fins and scales, being perfectly distinguishable. A single specimen sometimes presents parts of three or four fish, lying in different directions, and between different layers. The fish are sometimes contorted, and almost doubled. Their colour, sometimes grey, is usually black ; and the fins and scales appear to be converted into coal. The same shale contains impressions of vegetables, sometimes...
Page 330 - Chromate ; a mineral in which the chromic acid is united with a base, as of lead, in the chromate of lead. Cleavage. This term is most commonly used in relation to the fracture of those minerals which, having natural joints, possess a regular structure, and may be cleaved into more or less geometrical fragments; as, into varieties of the parallelepiped, the rhomboid, &c. Coherent. In minerals that are brittle, the particles are strongly coherent; in such as are friable, they are slightly coherent....
Page 46 - The reason of this is obvious, for if the substance was not, bulk for bulk, heavier than water, it would not sink in it, but if it sinks, its weight must be diminished by exactly that of the quantity of water it displaces. To find the specific gravity of a substance, therefore, it must first be weighed in air, or in the ordinary manner, and then weighed in water, when its specific gravity may be found " by dividing its weight in air by its loss in water.
Page 333 - Pass into. One mineral is said to pass into another, when both are found so blended in the same specimen, that it is impossible to decide where the one terminates, and the other begins. Flint is found passing into chalcedony. Pectinated. If a mineral exhibit short filaments, crystals, or branches which are nearly parallel and equidistant, it is pectinated ; pecten, in Latin, signifies a comb. Peroxide, when a metal has the largest quantity of oxygen.
Page 315 - Species 3. DIAMOND. External characters. Colourless, or of a yellowish, bluish, yellowish green, clove brown, brownish black, Prussian blue, or rose red colour ; occurs crystallized, and in roundish grains, which often present indications of crystalline faces ; form, the octohedron, with its varieties ; faces often convex ; structure perfectly lamellar, with cleavage parallel to all the planes of an octohedron ; transparent, translucent, or opake : sp. gr. 3.5. It is the hardest of all known substances....
Page 261 - Before the blowpipe, it gives out a copious arsenical vapour, on the first impression of the heat ; it melts only partially, and that with great difficulty, and is not attractable by the magnet ; on the addition of borax, it immediately melts into a grey metallic globule, colouring the borax of a deep blue.

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