High-grade Clays of the Eastern United States: With Notes on Some Western Clays, Volume 8, Issue 708

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U.S. Government Printing Office, 1922 - Clay - 314 pages
 

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Page 27 - Their thickness ranges from a fraction of an inch up to 6 or more feet. Many of them are lenticular in shape, the length varying from four or five to twenty or more times the thickness. ' In numerous places these quartz streaks or veins are persistent through the whole length of the pegmatite exposed. Some inclose feldspar or mica bodies; others do not. The quartz of these segregations is massive and generally granular, though locally crystallized. If crystallized it may be translucent or clear and...
Page 27 - The mica occupies various positions in the pegmatite. Where the rock has a typical granitic texture, the mica may be found evenly distributed through it. More commonly the larger crystals will be found either in clusters at intervals through the "vein," in places connected by streaks of small crystals, or collected along one or both walls of the pegmatite, with some of the crystals partly embedded in the wall rock. Where there is a quartz streak within the pegmatite, the mica occurs on either or...
Page 63 - ... at one point a considerable quantity of fine white kaolin is encountered. There are, however, occasional streaks of fresh feldspar and on all sides of the lens there is semi-kaolinized material; these facts justify the assumption that the kaolin is merely an isolated lens and would not justify the equipment of an extensive outfit for handling it, although the presence in the neighborhood of other isolated kaolin deposits would justify the sinking of shafts and the removal of this kaolin to a...
Page 27 - Generally, however, they occur in bands or sheets lying parallel to the walls. There may be one or more of these quartz bands constituting varying proportions of the pegmatite. Their thickness ranges from a fraction of an inch up to 6 or more feet. Many of them are lenticular in shape, the length varying from four or five to twenty or more times the thickness. In numerous places these quartz streaks or veins are persistent through the whole length of the pegmatite exposed. Some inclose feldspar or...
Page 50 - ... referred to above as having been explored by borings that cover about four and two-thirds acres. The borings are in lines running northeast and northwest and at intervals of about 50 feet. The overburden averages in thickness not more than seven or eight feet and the depth of the clay penetrated varies from 20 to 45 feet. On the assumption that the average thickness of the clay is 30 feet and that the average yield of commercial kaolin is about 20 per cent of the crude tonnage the productive...
Page 71 - The property is undeveloped, but cuts on the railway and on the highway one-fourth mile west of the railroad expose a white kaolin. On the east side of the railroad right-of-way a section of about 160 feet is exposed and between this and the track are a couple of shallow pits. The section is in alternating schists and kaolin. At its north end a width of 20 feet of kaolin is shown, followed to the south by 20 feet of quartz, 110 feet of kaolin and finally schists. (See Fig.
Page 19 - ... belts of kaolin that result from the decomposition of pegmatite dikes. Where feldspathic granites or other feldspathic rocks occur over large areas these may give rise to deposits of kaolin (the "blanket deposits" of Ries) that are so large, that by their very massiveness they may reveal themselves on the surface. Because of its striking appearance, the kaolin, even when much mixed with other materials, may be recognized, and, because it may migrate down slopes, in many cases it may appear to...
Page 151 - ... small white granules of clay, producing an amygdaloidal structure. These small granules have about the same degree of hardness as the surrounding kaolin. Under the microscope the porcelain-like kaolin exhibits a granular appearance, the grains being apparently spherical in form and in some sections arranged in a dendritic structure. The dendritic structure may be due to the loss of water and consequent shrinkage when the section is heated during its preparation. In some places the white kaolin...
Page 159 - ... chemistry of the clay and hematite deposit, for, though similar in its chemical composition to kaolin, this clay differs physically and owes its origin to an entirely distinct set of causes and effects. While the former is derived from the decomposition of the feldspar of feldspathic rocks, such as granite, porphyry, etc., the porcelain clay of Lawrence county has resulted from the decomposition, by chemical waters, of a bed of limestone and the mutual interchange of molecules in the solution,...
Page 32 - The walls of the deposit are not clearly defined, because excessive weathering has broken down the rock so that its character is not now recognizable. Keith,2 in the Pisgah Folio, maps the country rock as Carolina gneiss, which is in accord with the heavily micaceous weathering products in the overburden. The clay deposit is evidently a dike striking about northeast and dipping about 85 southeast. In general it was pretty uniform in composition, but in one place, at least, it was crossed by a mass...

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