A Summary of Progress in Petrography. in 1887-1896 |
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Page 9
... granites and gneisses rich in quartz , and frequently containing cordierite , sillimanite , garnet , corundum , diaspore , and zircon . The changes effected in them by the basic lavas varies in intensity , but not materially in kind ...
... granites and gneisses rich in quartz , and frequently containing cordierite , sillimanite , garnet , corundum , diaspore , and zircon . The changes effected in them by the basic lavas varies in intensity , but not materially in kind ...
Page 10
... granite in the Lausitz , Saxony , is changed to knotty ( Knoten ) graywackes , in which muscovite , biotite , quartz , feld- spar , and tourmaline occur as new products , and finally into a quartz- mica rock with cordierite , tourmaline ...
... granite in the Lausitz , Saxony , is changed to knotty ( Knoten ) graywackes , in which muscovite , biotite , quartz , feld- spar , and tourmaline occur as new products , and finally into a quartz- mica rock with cordierite , tourmaline ...
Page 14
... granite con- sists of corroded crystals of the first generation cemented by a granitic ground - mass . This fact is thought to be an indication of the correct- ness of the view that the constituents of granite are mainly of the second ...
... granite con- sists of corroded crystals of the first generation cemented by a granitic ground - mass . This fact is thought to be an indication of the correct- ness of the view that the constituents of granite are mainly of the second ...
Page 14
... Granite and diorite in many varieties cut through the sedimentary rocks , and change them near the contact into hornstones holding cordierite and ottrelite . In sericite - gneiss garnets are produced , in amphibolites andalusite is a ...
... Granite and diorite in many varieties cut through the sedimentary rocks , and change them near the contact into hornstones holding cordierite and ottrelite . In sericite - gneiss garnets are produced , in amphibolites andalusite is a ...
Page 18
... granite near Meissen , Saxony , Sauer and Ussing have found Baveno twins of microcline in which the gridiron structure is lacking . Lamellæ of albite are intergrown with the microcline , but sufficiently large areas of the latter ...
... granite near Meissen , Saxony , Sauer and Ussing have found Baveno twins of microcline in which the gridiron structure is lacking . Lamellæ of albite are intergrown with the microcline , but sufficiently large areas of the latter ...
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Common terms and phrases
acid Al,O alteration Amer AMERICAN NATURALIST analysis andalusite angle aragonite augite axial ratio basalts beryl biotite brucite Bull calcite calcium chlorite cleavage Colby University color colorless composition constituents containing cordierite corresponding crystalline crystals density described diabase double refraction dyke eruptive rocks Fe,O Fe₂O feldspar FeO MgO CaO FeO MnO forms formula Franc gabbro-diorites gabbros garnet Genth gneisses granite granulites ground-mass H₂O habit hexagonal hornblende humite hypersthene imbedded inclusions Jour Kryst leucite masses melanophlogite metacinnabarite mica mineral MINERALOGY AND PETROGRAPHY.¹ Mitth molecules muscovite Neues Jahrb nosean occur olivine optical original orthoclase ottrelite parallel Penfield Petrog PETROGRAPHY.¹ Petrographical phenacite plagioclase plane plates polymorphism prismatic produced pseudomorphs pyroxene quartz regarded rock individual Rosenbusch schistose schists serpentine silica sodium soluble specific gravity specimens spinel structure substance sulphur symmetry tabular temperature tonalite tourmaline twinned varieties W. S. Bayley Waterville yielded Zeits zircon zone
Popular passages
Page 19 - The plane of the optical axes is perpendicular to the plane of symmetry, and makes with c an angle of °7 in acute /9. A = b. 2H na = 104° 27'.
Page 14 - The larger part of the dust is thought to be a sediment from the air, and to have been obtained by it from a region of crystalline schists. The chondri, on the other hand, are thought to be of cosmic origin, since they are similar to the chondri obtained in deep-sea soundings. If the amount of the dust collected from the snow in Greenland represents the fall of one year, the total amount falling upon the entire surface of the earth in this time is 125 million kilograms, equivalent to a cube of thirty-one...
Page 14 - Wiilfing 21 for investigation, by whom it has been found to consist in greater part of feldspar, quartz, mica, and hornblende. There are present in it also garnet, zircon, magnetite, augite, and sillimanite, and with them is mixed a nitrogenous organic substance. The most interesting constituents of the dust...