A Summary of Progress in Petrography. in 1887-1896 |
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Page 9
... orthoclase have been changed . Quartz fragments in the altered forms have been surrounded by aureoles of augite . The new minerals developed in the surrounding rock by the solution of the inclusion are spinel , hypersthene , and ...
... orthoclase have been changed . Quartz fragments in the altered forms have been surrounded by aureoles of augite . The new minerals developed in the surrounding rock by the solution of the inclusion are spinel , hypersthene , and ...
Page 14
... orthoclase , until it finally resembles a granite . Among the effusives of this age are mentioned quartz - porphyries and porphyrites.Weinschenck communicates additional information with respect to the rocks of these islands , as a ...
... orthoclase , until it finally resembles a granite . Among the effusives of this age are mentioned quartz - porphyries and porphyrites.Weinschenck communicates additional information with respect to the rocks of these islands , as a ...
Page 14
... orthoclase , apatite , sphene , zircon , and an unknown , probably positive , uniaxial mineral . — The interesting Chilian minerals continue to be subjects of investigation to those who are fortunate enough to come into possession of ...
... orthoclase , apatite , sphene , zircon , and an unknown , probably positive , uniaxial mineral . — The interesting Chilian minerals continue to be subjects of investigation to those who are fortunate enough to come into possession of ...
Page 23
... orthoclase . In the inner zone all resemblance to gneiss and mica - schists has dis- appeared , and the rocks have become aggregates of cordierite , anda- lusite , plagioclase , sillimanite , tourmaline , garnet , spinel , corundum ...
... orthoclase . In the inner zone all resemblance to gneiss and mica - schists has dis- appeared , and the rocks have become aggregates of cordierite , anda- lusite , plagioclase , sillimanite , tourmaline , garnet , spinel , corundum ...
Page
... orthoclase , but with a large proportion of sodium in its composi- tion ( SiO , 66.83 ; Al , O , 19.20 ; CaO = .06 ; K , 0 = 6.29 ; Na , O = 6.8 ) . " ————— Zirkel ' has determined the small hexagonal crystals in the altered sandstone ...
... orthoclase , but with a large proportion of sodium in its composi- tion ( SiO , 66.83 ; Al , O , 19.20 ; CaO = .06 ; K , 0 = 6.29 ; Na , O = 6.8 ) . " ————— Zirkel ' has determined the small hexagonal crystals in the altered sandstone ...
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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...