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abundant accessory apatite amount apatite aplite Baltimore biotite granite gneiss bowlders Cecil County chemical analysis chlorite coal dust Coastal Plain Colliery color and medium County crystalline dark blue-gray granite decayed developed dikes Ellicott City epidote experiments explosion exposures feet feldspar and quartz fire damp flame foliated gallery Geol Georgia grain granite area Granite Company's quarry granite mass granite quarries Guilford hornblende igneous ignition inches inclusions Intergrowths irregular kaolin light-gray granite Lithonia magnetite Maryland granites mica microcline mineral composition minerals are potash mines moisture muscovite North Carolina northeast northwest numerous occur oligoclase opened orthoclase orthoclase and microcline outcrops pegmatite pegmatite dikes phenocrysts places plagioclase porphyritic porphyritic granite Port Deposit potash feldspar orthoclase pounds pressure principal quartz and feldspar Richmond River rock schistose secondary chlorite soda-lime feldspar oligoclase southwest Stone Mountain structure surface Survey tests texture thickness thin sections titanite usually vertical joints strike Virginia Woodstock zircon
Seite 34 - ... more or less rounded, the spaces between the different boulders being filled with incoherent granitic sand, derived from the decomposed edges and the sides of the blocks. It is quite evident that the granitic mass was originally everywhere jointed, and that atmospheric decay took place much faster on the edges and corners than on the flat sides of the great fragments, thus quickly rounding and forming them into boulders like those found throughout drift areas. The sandy matrix is DKTAII.K1) VIKW,...
Seite 272 - Gi'llmore, QA Report on the compressive strength, specific gravity, and ratio of absorption of various kinds of building stones from different sections of the United States tested at Fort Tompkins, Staten Island, NY Engineer Department, US Army.
Seite 131 - The mantle of red soil with ore partides ranging in thickness from a fraction of an inch to several inches, is only a few feet thick.
Seite 17 - If the place where a shot is to be fired is dry and dusty, then the shot shall not be fired unless one of the following conditions is observed, that is to say...
Seite 155 - consists of granite of varying texture and color, and of schists and granitoid gneisses derived from the granite. Included in the formation are small or local beds of schistose basalt, diorite, hornblende schist and pegmatite . . . "Keith, Arthur, US Geol.
Seite 17 - ... (2) The occurrence of a blown-out shot in localities where only small proportions of fire damp exist in the air, in the presence of even comparatively slightly inflammable, or actually noninflammable, but very fine, dry, and porous dusts, may give rise to explosions, the flame from which may reach to distant localities where either gas accumulations ordepositsof inflammable coal dust maybe inflamed, and may extend the disastrous results to other regions.
Seite 21 - The witnesses, who included those best qualified from scientific or practical experience to speak on the question, expressed opinions which were often widely divergent, as to the best means of meeting the danger of explosions, but they were generally agreed on two points — that coal dust is liable to explosion with or without the presence of fire damp, under conditions which are at present to be found in most coal mines in this country and abroad, and that there is pressing need for the elucidation...
Seite 17 - ... the propagation of flame through very considerable areas, and even by the communication of flame to distant parts of the workings where explosive gasmixtures, or dust-deposits in association with non-explosive gas mixtures exist.
Seite 25 - ... or W., to N. 80° E. or W. Out of the total number of joint-planes measured fifty-six lie in the northeast quadrant and forty-five in the northwest quadrant; while nineteen strike in a north-south direction, as against sixteen having an east-west strike. Slickensides. — As a rule, the joint-planes show smooth, more or less polished and striated surfaces, indicating considerable movement in the rocks since the formation of the joints. Striae are developed in a thin coating of yellow to yellowish-green...