A Summary of Progress in Petrography. in 1887-1896 |
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Page 10
... biotite , quartz , feld- spar , and tourmaline occur as new products , and finally into a quartz- mica rock with cordierite , tourmaline , and some other new products . On the granitic side the rock has assumed a gneissic aspect ...
... biotite , quartz , feld- spar , and tourmaline occur as new products , and finally into a quartz- mica rock with cordierite , tourmaline , and some other new products . On the granitic side the rock has assumed a gneissic aspect ...
Page 14
... biotite , garnet , and tridymite in a ground - mass of the same minerals and zircon , in a trichitic glass . The most interest- ing rock of the series bears the same relation to the andesites as the augitites do to the basalts . It ...
... biotite , garnet , and tridymite in a ground - mass of the same minerals and zircon , in a trichitic glass . The most interest- ing rock of the series bears the same relation to the andesites as the augitites do to the basalts . It ...
Page 20
... biotite by its weak pleochroism , and its weak double refraction . Leverrierite is found as a metamorphic constituent in carbonaceous clay slates , and in interstratified carbonif- erous eruptives . 31 Ref . Neues Jahrb . f . Min ...
... biotite by its weak pleochroism , and its weak double refraction . Leverrierite is found as a metamorphic constituent in carbonaceous clay slates , and in interstratified carbonif- erous eruptives . 31 Ref . Neues Jahrb . f . Min ...
Page 22
... biotite , chlorite , and andalusite , of which the biotite and andalusite are new products . Corundum , tour- maline , sillimanite , and zircon are also new products , but are present only in small quantity . A cordierite - biotite rock ...
... biotite , chlorite , and andalusite , of which the biotite and andalusite are new products . Corundum , tour- maline , sillimanite , and zircon are also new products , but are present only in small quantity . A cordierite - biotite rock ...
Page 24
... biotite , muscovite , sericite , rutile , anatase , and sphene . Each of these is carefully described , and the conditions under which it was formed are carefully examined . The genesis of the schistose structure is finely worked out ...
... biotite , muscovite , sericite , rutile , anatase , and sphene . Each of these is carefully described , and the conditions under which it was formed are carefully examined . The genesis of the schistose structure is finely worked out ...
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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...