A Summary of Progress in Petrography. in 1887-1896 |
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Page 8
... pyroxene gneisses of Norway . The pyroxene and amphibole gneisses of this region and the wernerite gneisses present few peculiarities . The marbles , pyroxene gneisses , and granu- lites of St. Barthélemy are all marked by interesting ...
... pyroxene gneisses of Norway . The pyroxene and amphibole gneisses of this region and the wernerite gneisses present few peculiarities . The marbles , pyroxene gneisses , and granu- lites of St. Barthélemy are all marked by interesting ...
Page 11
... pyroxene , garnet , etc. The density 3.474 , and hardness = 6-7 . The pulverized mineral dissolves in hot hydrochloric acid , with the separation of gelatinous silica . Its composition : Sio , 39.77 BeO 17.08 MnO 26.86 : FeO CaO 3.87 ...
... pyroxene , garnet , etc. The density 3.474 , and hardness = 6-7 . The pulverized mineral dissolves in hot hydrochloric acid , with the separation of gelatinous silica . Its composition : Sio , 39.77 BeO 17.08 MnO 26.86 : FeO CaO 3.87 ...
Page 13
... pyroxene , or feldspar - like silicate , combined with meta- or orthosilicic acid , and also an amount of water varying with the temperature . The crystal water may be driven off at high temperature , and taken up again at a lower one ...
... pyroxene , or feldspar - like silicate , combined with meta- or orthosilicic acid , and also an amount of water varying with the temperature . The crystal water may be driven off at high temperature , and taken up again at a lower one ...
Page 14
... pyroxene which sometimes forms intergrowths with hypersthene . Among the rocks from the extinct volcanoes is a bronzite trachyte containing biotite , garnet , and tridymite in a ground - mass of the same minerals and zircon , in a ...
... pyroxene which sometimes forms intergrowths with hypersthene . Among the rocks from the extinct volcanoes is a bronzite trachyte containing biotite , garnet , and tridymite in a ground - mass of the same minerals and zircon , in a ...
Page 24
... pyroxene , mica , and olivine . Carefully examined , the ground - mass is found to be a colorless glass containing microlites of the same minerals as occur in the phenocrysts , and occasionally a few laths of plagioclase . The glassy ...
... pyroxene , mica , and olivine . Carefully examined , the ground - mass is found to be a colorless glass containing microlites of the same minerals as occur in the phenocrysts , and occasionally a few laths of plagioclase . The glassy ...
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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...