Bulletin of the United States Geological SurveyThe Survey., 1898 |
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abundant acid aggregate albite alteration analysis andesite angles apatite appears augite basalt beds biotite brown calcite carbonate of lime cement chemical chlorite clay cleavage color colorless composed composition constituents contains COUNTY crossed nicols crystalline crystals dark deposited DESCRIBED BY J. S. diabase double refraction epidote eruptive extinction feldspar fragments gabbro Geological Survey glass gneiss granite green groundmass H₂O hornblende hypersthene igneous rocks inclusions iron irregular grains J. S. DILLER K₂O lava limestone magma magnetite mass material metamorphic mica microcline microscope mineral minute muscovite Na₂O nephelite nodules occurs olivine oolite optical original orthoclase oxide parallel particles pebbles phenocrysts plagioclase plane plates pleochroism portion Price 15 cents prismatic prisms pyroxene quartz rhyolite sand sandstone sanidine schistose schists seen serpentine shale siliceous SiO2 sometimes Specific gravity spherulites structure substance surface thin section tion twinning U. S. Geol United States Geological usually volcanic zircon
Δημοφιλή αποσπάσματα
Σελίδα 223 - Rocks, by Whitman Cross, with, a Geological Sketch of Buffalo Peaks, Colorado, by SF Emmons. 1883. 8°. 42pp. 2 pi. Price 10 cents. 2. Gold and Silver Conversion Tables, giving the coining value of troy ounces of fine metal, etc..
Σελίδα iii - Survey in relation to the ganging of streams and to the methods of utilizing the water resources may be printed in octavo form, not to exceed one hundred pages in length and five thousand copies in number; one thousand copies of which shall be for the official use of the Geological Survey, one thousand five hundred copies shall be delivered to the Senate, and two thousand five hundred copies shall be delivered to the House of Representatives, for distribution.
Σελίδα 277 - The most striking feature in the texture of the unaltered gabbro is the repeated and abrupt change in the coarseness of the grain which is seen at some localities. It was undoubtedly caused by some irregularity in the cooling of the original magma from a molten state, for which it is now difficult to find a satisfactory explanation.
Σελίδα 398 - Price $8.40. XIII. Geology of the Quicksilver Deposits of the Pacific Slope, with atlas, by George F. Becker, 1888.
Σελίδα 399 - Price 5 cents. 7. Mapoteca Geológica Americana. A Catalogue of Geological Maps of America (North and South), 1752-1881, in geographic and chronologic order, by Jules Marcou and John Belknap Marcou.
Σελίδα 398 - IV. Comstock Mining and Miners, by Eliot Lord. 1883. 4°. xiv, 451 pp. 3 pi. Price $1.50.
Σελίδα 374 - ... sand, are of a compound nature, being aggregates of quartz and feldspar, with small amounts of mica and other minerals. In the finer material, on the other hand, each particle represents but a single mineral, the process of disaggregation having quite freed it from its associates, excepting, of course, in the case of microscopic inclusions, which could be liberated only by a complete disintegration of the host itself.
Σελίδα 126 - First, by diminution of the tension of the carbonic acid in the atmosphere ; second, by agitation of the solution." "Theoretically either one of three things may occur to the neutral carbonate of lime, if it be thrown out of solution by either one of these processes. The carbonate may be redissolved, deposited as a calcareous mud, or built into organic structures.
Σελίδα 373 - ... to the weathering, the first mentioned being judged as largely post-Cretaceous and the last post-Glacial. Materials of the nature here described are subject to considerable variation, and the descriptions given must be accepted as descriptive of the general results produced rather than as definitely applicable to any particular sample. The fresh rock, illustrated by the small fragment in the box with the residual sand, No. 147, is a strongly foliated micaceous granite, the foliation being secondary...
Σελίδα 76 - Its economic value above ground is great, but it is greater below. In its outcrops it is a source of the finest building stone and the best grindstone grit of the country; and when it dips beneath the surface it becomes the repository of invaluable supplies of petroleum, gas and salt water.