Reports of the North Carolina Geological and Economic Survey, Volume 1The Survey, 1905 - Forests and forestry |
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Common terms and phrases
alteration alumina amphibole amphibole-peridotite amphibolite anorthite asbestos associated Balsam Gap basic magnesian rocks belt biotite border Buck Creek chemical chlorite chromite Clay County cleavage color colorless corun corundum corundum crystals Corundum Hill corundum occurs corundum-bearing crystalline deposits described developed diameter dikes diorite dunite emery enstatite feet wide feldspar fibrous Fork GEOLOGICAL gneiss granular green harzburgite hornblende igneous inches irregular Jackson County Jour lamination localities Macon County magma magnesia magnetite masses massive mica Microscopic mile north miles east miles northeast mineral mining Mountain nodules North Carolina observed olivine olivine grains one-half mile origin outcrop oxide parallel peridotite peridotite area picotite planes plates pleochroism portions pyroxene pyroxenite region Ridge River Sapphire schistose schists serpentine Shooting Creek silicates similar SiO2 slopes soapstone specimen spinel surface Survey talc tale thick Thin section troctolite U. S. Geol usually vein Webster websterite yellowish
Popular passages
Page 323 - ... 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.
Page 356 - 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...
Page 117 - It is believed that the above concise statements cover the ground held by the hitherto prevailing neptunean and plutonist schools, neither of which, it is maintained, expresses correctly the present state of our knowledge. In opposition to both of these are the views taught for the last twenty years by the writer, and now accepted by many geologists, which may be thus defined : — 1st. All gneisses, petrosilexes, hornblendic and micaceous schists, olivines, serpentines, and in short, all silicated...
Page 324 - 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.
Page 366 - ... inches thick, respectively, extended. Fifteen tons of ore were taken out of the main pocket. About 200 yards farther south, on the opposite side of the creek, a shallow pit was sunk which encountered considerable chromite. Both these openings were near the contact of the peridotite and gneiss. Between these and in their near vicinity there is a large quantity of float ore. These facts point to this locality as one worthy of further development, with an expectation of finding a large quantity...
Page 372 - ... 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...
Page 80 - 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...
Page 187 - ... 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...
Page 366 - The property is owned by the Highland Forest Company of Waynesville, NC No large deposits of chromite have yet been found in North Carolina, but the work done shows that extensive deposits may exist in the State, those described above being the most promising ones known. The standard chrome ore contains 50 per cent of Cr2 OSI and the value of the ore increases with each unit over this.
Page 376 - NW-SE direction for nearly 6OO 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 found.