Corundum and the Peridotites of Western North Carolina

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State printer, 1905 - 464 Seiten
 

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Seite 331 - ... which exhibit the following order of formations : " (1) Chrysolitic rock somewhat mixed with anthophyllite ; (2) a layer of micaceous rock; (3) a seam of chalcedony; (4) a stratum of chloritic rock (ripidolite) ; (5) the same through which the corundum is regularly diffused sometimes in narrow veins or widening out to several feet.
Seite 366 - The constant occurrence of the chromite in rounded masses of varying proportions near the contact of the peridotite with the gneiss, and its occurrence in the fresh as well as the altered peridotite, indicate that the chromite has been held in solution in the molten mass of the peridotite when it was intruded into the country rock, and that it separated out among the first minerals as this mass began to cool. As has been said...
Seite 332 - He calls attention to the occurrence of corundum chiefly in chlorite veins and says: "The chlorite seems to have been first crystallized; and then the alumina, of which the corundum is composed, was evidently in a state of solution and must have permeated the chlorite either in thermal waters or steam.
Seite 386 - ... hydrous magnesium silicate known as chrysotile. It was the former of these minerals that was originally used commercially, but as the chrysotile began to be used for the same purposes it was placed on the market under the same name. While these minerals are equal in their heat-resisting properties, the chrysotile is superior in strength and elasticity of fiber to any variety of amphibole asbestos. The former mineral is usually greenish-white, green, yellowish to brownish in color, and has a decidedly...
Seite 88 - Total 0.23 0.11 0.03 0.30 Trace 100.36 crops. . . . Transparent colorless, allotriomorphic olivine grains constitute the mass of the rock. Chromite in scattering crystals or irregular grains is a constant accessory .... In the great majority of cases, even when the hand specimens look perfectly fresh, the olivine is found to have altered somewhat to serpentine, with sometimes more or less talc, chlorite, etc. Hence the olivine grains are usually completely separated from one another by these secondary...
Seite 195 - ... in syenites and other igneous rocks, as well as in various gneisses and schists. It has been found in many crystalline rocks, and in some of them as an original mineral, but...
Seite 391 - ... have a maximum length, as thus far observed, of three-fourths of an inch, varying from this down to not more than one-sixteenth of an inch. It is similar in all respects to the Canadian product, and is just as good in quality. The other variety occurs upon the slickensided surfaces that are common to serpentine, and the fibers form layers of varying thickness against these surfaces, and have been found varying in length from a fraction of an inch up to 3 or 4 inches.
Seite 390 - Wilkesboro is within three-quarters of a mile of the railroad and occurs in a serpentine formation that is from 75 to about 200 feet in thickness and can be traced in a general NW.-SE. direction for nearly 600 yards. The deposit has been worked by means of an open cut 100 feet long which was made on the land of Mr. JB Church. The cut varies in depth from 1 to 35 feet, and near the surface the serpentine encountered was much decomposed and altered, but at lower depths a compact, dark-green rock was...
Seite 193 - In this process, which is also called the silicate process, silicate of soda is used as the binding material. The silicate is thoroughly mixed with the emery or corundum and some drying material and tamped into molds. It is then subjected to an '
Seite 379 - ... yards from the main street of the town, on the land of Daniel Schneider. A pocket of chromite was uncovered here which yielded a number of tons of chromite, most of which was shipped. At a depth of nearly 9 feet the pocket pinched out, leaving but a small seam of chromite in sight. Many small seams and pockets of chromite are to be seen, but no other work has been undertaken for chromite on this side of the river. On the south side of the river, following...

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