A Summary of Progress in Petrography. in 1887-1896 |
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Page 8
... varieties of humite , brucite , amphibole , phlogopite , scapolite , spinel , corundum , sphene , rutile , zircon , and many other less common minerals . One variety of the humite occurs in rounded crystals of a clear yellow color ...
... varieties of humite , brucite , amphibole , phlogopite , scapolite , spinel , corundum , sphene , rutile , zircon , and many other less common minerals . One variety of the humite occurs in rounded crystals of a clear yellow color ...
Page 14
... 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 new product , and in limestone ...
... 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 new product , and in limestone ...
Page 18
... varieties contain quite large amounts , ( 1–8 % ) . The axial ratio of the purest scheelite is 1 : 1.5315 . that of calcium molybdenate is 1 : 1.5458 , and that of most scheelites between these limits.In the pegmatite veins cutting ...
... varieties contain quite large amounts , ( 1–8 % ) . The axial ratio of the purest scheelite is 1 : 1.5315 . that of calcium molybdenate is 1 : 1.5458 , and that of most scheelites between these limits.In the pegmatite veins cutting ...
Page 23
... varieties , containing a fibrous 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 ...
... varieties , containing a fibrous 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 ...
Page
... varieties of these minerals.- -Dufet 17 describes a new method for the determina- tion of the optical orientation and of the dispersion of the axes in triclinic minerals , and applies his method to the study of potassium bichromate . Mr ...
... varieties of these minerals.- -Dufet 17 describes a new method for the determina- tion of the optical orientation and of the dispersion of the axes in triclinic minerals , and applies his method to the study of potassium bichromate . Mr ...
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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...