Bulletin of the United States Geological SurveyThe Survey., 1906 - Geology |
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analyses andalusite bedding and cleavage biotite black slate brilliant aggregate polarization calcareous calcite Cambrian Cambrian slate carbonaceous carbonaceous matter carbonate cent chemical chlorite chlorite scales clay cleavage dip cleavage surface cold dilute hydrochloric constituents County crystals deposits dikes false cleavage feet feldspar ferrous ferrous oxide folds fractures graphitic green slates hematite hogback hydrochloric acid inch lenses lime limestone limonite magnesia magnetite matrix of muscovite mica microscope miles mineral muscovite muscovite sericite Ordovician oxide parallel particles Pawlet Peach Bottom Pennsylvania plagioclase planes plicated purple slate pyrite quartz quartz grains quartzite quartzite beds red slate Rept rhombs ribbons rock roofing slate rutile rutile needles sawn edge schist secondary sediments sericite shale silica SiO2 slate belt Slate Company slate quarries Slatington slaty cleavage slip cleavage sonorous specimen square millimeter structure syncline texture thickness thin section tourmaline U. S. Geol unfading green veins Vermont vertical western Vermont
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Page 105 - ... The slate from this quarry is very dark gray with a greenish hue, and to the unaided eye has a granular sparkling crystalline texture and a roughish, but very lustrous, cleavage surface. It is slightly graphitic (or carbonaceous). The sawn edge shows pyrite. It contains rare particles of magnetite, does not effervesce in cold dilute hydrochloric acid, and is very sonorous. Under the microscope the Fontaine quarry slate shows alternating bedlets of fine, more muscovitic, and coarser, more quartzose,...
Page 7 - ... derived from the waste of granitic land masses, with sandy sediments consisting of coarser material from the same source. The repeated alternation of such fine and coarse sediments is attributed to the alternation of calm water, favorable to the deposition of fine material, with strong currents that bring coarse sediments more rapidly from the shore. These materials consisted largely of quartz, feldspar, and mica, but included also zircon and other silicates, various compounds of iron, lime,...
Page 7 - ... at least the lower portion of the strata into wave-like folds, and thus to shorten its horizontal area in one direction and increase its vertical thickness. The character of this folding is well shown in the Pennsylvania and western Vermont slate regions (see Pis. Ill, XIII, XIV, XVII, XVIII, XXII, XXV). But another effect of this compression was to metamorphose the shale into slate. This metamorphism probably did not take place until the folding was well initiated. The transformation included...
Page 45 - T\ to ^ of an inch in thickness. The pieces were supported in a horizontal position, upon wooden knife edges 22 inches apart and the loads were applied upon another knife edge placed half way between the supports. This load being applied by means of sand running out of an orifice in a box, at the rate of 70 pounds per minute, the flow being checked by means of an electric attachment the moment rupture took place. The deflection or bending of the slate in the pieces tested was sufficiently great to...
Page 58 - Chickamauga limestone," which here contains beds of pure nonmagnesian limestone, which have been quarried at several points in the vicinity and burned into lime. The cement company purchased the property of the old Georgia Slate Company, about half a mile southwest of Rockmart, and carried on extensive operations with the diamond drill. The intention was to quarry the slate, sell as slate the portions best suited for that use, and utilize the scrap and waste in the manufacture of cement. The quarries...
Page 52 - ... acid, is very sonorous and very fissile. Under the microscope this slate shows a matrix of muscovite (sericite), with a very brilliant aggregate polarization and an unusually fine texture and great homogeneity. Quartz grains are few and not over 0.01 millimeter in diameter. Rutile needles unusually minute. Many opaque particles of irregular shape, some of which are pyrite, others magnetite, and some coaly or graphitic matter. No carbonate. The constituents, arranged in descending order of abundance,...
Page 52 - ... very little magnetite; does not effervesce with cold dilute hydrochloric acid, and is somewhat sonorous. Under the microscope it shows a matrix of muscovite (sericite), with a brilliant aggregate polarization and is of very fine texture and homogeneity, but the cleavage is crossed at an angle of ]3° by a very close bedding foliation and also by an obscure slip or "false
Page 138 - BACK JOINT. Joint plane more or less parallel to the strike of the cleavage and frequently vertical. BED. A continuous mass of material deposited under water at about one time. BLIND JOINT. Obscure bedding plane. BOTTOM JOINT. Joint or bedding plane horizontal or nearly so. BRECCIA. Rock made up of angular fragments produced by crushing and then recemented by iuliltrating mineral matter.
Page 56 - green slate" is in reality grayish green in color. It splits readily, though with not so smooth a surface as the black slate. It stands punching and trimming well, and is sufficiently strong for roofing use. Considering its origin and composition it is probable that it will be a highly durable slate, holding its color well. At present it is sold entirely for trimming and lettering on black slate roofs, for which purpose it is particularly well adapted, giving a strong but pleasant color contrast....
Page 110 - Dale the chief constituents of this slate arranged in descending order of abundance appear to be muscovite (sericite), quartz, pyrite, graphite, magnetite, chlorite, calcium carbonate, and accessory rutile and tourmaline.