Corundum and Its Occurrence and Distribution in the United States: (a Rev. and Enl. Ed. of Bulletin No. 180)U.S. Government Printing Office, 1906 - 175 Seiten |
Andere Ausgaben - Alle anzeigen
Häufige Begriffe und Wortgruppen
abrasive Alteration product alumina amphibole amphibolite basal plane basic magnesian rocks belt biotite blue border vein Buck Creek Bull Chester chlorite chromite Clay County color corun corundum corundum crystals corundum deposits corundum gems Corundum Hill corundum is found corundum occurs corundum-bearing Cowee crystals of corundum cyanite decomposed described developed dikes dunite emery feet feldspar found associated garnet gneiss grains granite gravels hornblende inclosed interior veins Jour Laurel Creek limestone localities Macon County magma magnesia magnetite masses of corundum metamorphism mica mica-schist miles mining molten Mountain muscovite nearly nodules norite North Carolina observed obtained occurrence of corundum origin of corundum outcrops oxide peridotite peridotite formation peridotite rocks plagioclase portions prism pyroxenite quantity quartz rhombohedron River Rock constituent ruby sapphires saprolitic schists seams separated serpentine silicates similar specimens spinel surface Survey syenite U. S. Geol vary vermiculite wheel width zone
Beliebte Passagen
Seite 77 - 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 11 - In the spring of the same year Dr. CL Hunter * discovered corundum and emery in place in Gaston County, NC The first record of the occurrence of corundum in Canada was made in 1863.
Seite 77 - appear to have formed after a great portion of the original corundum had changed into chlorite, as if there had been an excess of alumina ready for combination, which, not finding a supply of the requisite amount of silicic acid and bases, had again crystallized as corundum.
Seite 90 - From what has been observed in nature and from the experiments that have been made in the laboratory, it seems that the separation of alumina as corundum from molten magmas is dependent upon the composition of the chemical compounds that are the basis of the magma, upon the oxides that are dissolved with the alumina in the magma and upon the amount of alumina itself.
Seite 35 - Transylvania counties, a pyroxenite composed of interlocking, coarse-bladed, gray enstatite constitutes an important part of the outcrop; and at a number of places the pyroxenite alone forms oval and lenticular masses in every way similar to those composed of peridotite. In both cases corundum-bearing zones of secondary minerals are frequently formed along the borders of the pyroxenite and intersect the mass of the rock in exactly the same manner as described above for peridolite.
Seite 106 - ... stones have been cut, have been found here in the gravels of the stream, together with blue and yellow corundum of gem quality. By following up the gravels the corundum was located in a small vein in the decomposed peridotite. At the Sapphire and Whitewater mines, near Sapphire, fragments of corundum of a fine blue color have been found, from which small but good gems have been cut. Quite large amounts of commercial corundum have been taken out at the Bad Creek and Socrates mines, and also at...
Seite 103 - Figs. 9 and 10, which represent the more common development of these repeated growths, there is but one secondary rhombohedron and base, which sometimes has one of its rhombohedron faces a continuation of one of the rhombohedron faces of the crystal. Figs. 11 and 12...
Seite 129 - Appalachain crystalline belt passes under the Cretaceous and later sedimentary formations in the central part of the State near Montgomery. Representatives of the peridotite belt have been found in the vicinity of Dudleyville, in Tallapoosa county, and corundum has been found in fragments on the surface both in this and Coosa, the adjoining county on the west. A little search would doubtless reveal the presence of peridotite, and perhaps also, corundum, to the very borders of the crystalline rocks.
Seite 21 - K2CO•) in a platinum crucible over an ordinary Bunsen burner. The fused mass is extracted with hot water and the solution decanted through a filter. The residue is treated with a large excess of dilute hydrochloric acid, and this solution is decanted through the same filter. The filter paper is dried and ignited in a platinum dish, the residue from treatment with hydrochloric acid is added to the dish, and the whole is treated with an excess of concentrated hydrofluoric acid.
Seite 77 - That, at the great period when the chromiferous chrysolite beds (in part subsequently altered into serpentine, etc.) were deposited, a large quantity of alumina was separated which formed beds of corundum...