The Study of Rocks: An Elementary Text-book of PetrologyAppleton, 1881 - 321 Seiten |
Häufige Begriffe und Wortgruppen
acid aggregates albite alteration andesine apatite appear augite axis basal plane basalts beds biotite blowpipe calcareous calcspar carbonate cent character chemical composition chlorite cleavage colour colourless consist contain crossed Nicols crystalline crystallographic crystals dark decomposition deposits developed diabase diallage dichroism diorite direction eruptive rocks exhibit eye-piece felsitic felspar felstones fibrous foliated fragments frequently garnet Geology glass gneiss grains granite granular granules hauyne hexagonal hornblende inclosures iron labradorite lacunæ Lasaulx lava less leucite lime limestones magnesia magnetite matrix matter metamorphic mica microliths microscope mineral constitution minute nepheline nosean numerous obsidian occasionally occur oligoclase olivine optical orthoclase parallel perlite phonolites pitchstones plagioclase plate polarised light porphyritic prisms pyroxene quartz refraction regarded represent rhombic right angles Rosenbusch sandstones sanidine schistose sedimentary rocks serpentine silica slates sometimes sphene spherulites stone structure surface syenite tachylyte termed thin sections tion trachytes triclinic triclinic felspar twinning usually varieties vitreous rocks volcanic Zirkel
Beliebte Passagen
Seite 313 - Die Steiger Schiefer und ihre Contactzone an den Granititen von Barr-Andlau und Hohwald.
Seite 312 - LOMMEL (Dr. E.). The Nature of Light : With a General Account of Physical Optics.
Seite 2 - On the Microscopical Structure of Crystals, indicating the Origin of Minerals and Rocks,' and a short article by the late David Forbes, in the ' Popular Science Review,' Oct. 1867, entitled 'The Microscope in Geology.' The observations recorded in these papers were based upon the microscopic examination of thin sections of minerals and rocks ; and although Mr. Sorby appears to have been the first to apply this kind of examination to purely mineralogical and petrological questions, still the method...
Seite 267 - ... is thus formed and carried down into the lower regions. Mud derived from this source descended, in 1797, from the sides of Tunguragua in...
Seite 74 - ... for further information on the subject the reader is referred to the following works : — 'Manuel de Mine'ralogie,' A. Descloizeaux (Introduction), p. xxvi. ti 1862. ' Mdmoire sur 1'emploi du Microscope polarisant.' A. Descloizeaux. ' Text-Book of Mineralogy/ ES Dana. Wiley & Sons, New York 1878. 'Elemente d. Petrographie,
Seite 254 - Steam pares and fluid lacuna; are also of common occurrence in them. The olivine sometimes appears in tolerably well-defined crystals ; but it is more usually in roundish grains, or in granular aggregates. The latter are sometimes of considerable size, and occasionally show, in external configuration, that they are large, rudely-developed crystals. The plagioclase basalts are of more frequent occurrence than any of the other rocks belonging to the basalt group."* The most interesting of the basalts,...
Seite 208 - ... geologists who believe that water played a much more important part in the formation of granites and traps than it has done in the production of trachytes, basalts, and lavas, and that they owe their relatively high specific gravity to its agency.
Seite 313 - Notes of a Course of Nine Lectures on Light, delivered at the Royal Institution. , By John Tyndall, FRS Crown 8vo. is. sewed, or is. 6d. cloth. Notes of a Course of Seven Lectures on Electrical Phenomena and Theories, delivered at the Royal Institution.
Seite 208 - ... originally fused, and when in liquid fusion, poured into veins and dykes in pre-existing rocks, are subsequently altered in specific gravity and arrangement of minerals, by the action of water acting at temperatures which, though still high, would be quite inadequate to fuse the rock ; and...
Seite 291 - ... the altered area, the slate first becomes faintly spotty, the spots being of a somewhat oblong or oval form, and a few crystals of chiastolite appear. Then these crystals become more numerous, so as to entitle the rock to the name of Chiastolite Slate. This passes into a harder, more thickly bedded, foliated and massive rock, Spotted (or Andalusite) Schist ; and this again into Mica Schist of a generally grey or brown colour, and occurring immediately around the granite.