A Summary of Progress in Petrography. in 1887-1896 |
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Page 14
... Gabbros and peridotites cut the Paleozoic strata . In some specimens of the former piedmontite was noticed as an alteration product of hornblende . the Mesozoic occurs the largest quantity of eruptives . Granite and diorite in many ...
... Gabbros and peridotites cut the Paleozoic strata . In some specimens of the former piedmontite was noticed as an alteration product of hornblende . the Mesozoic occurs the largest quantity of eruptives . Granite and diorite in many ...
Page 23
... gabbros among the basic types , and granites and quartz - porphyries among the acid types . The resulting Bull . No. 62 , U. S. Geol . Survey . phy of upo stru dur garn ara Con gend Scop pani of g from bros the space migh sugg The plate ...
... gabbros among the basic types , and granites and quartz - porphyries among the acid types . The resulting Bull . No. 62 , U. S. Geol . Survey . phy of upo stru dur garn ara Con gend Scop pani of g from bros the space migh sugg The plate ...
Page 24
... gabbro - diorites were formed from gab- bros in the Baltimore region . There are many interesting features of the Michigan schists that might be dwelt upon at some length did space permit , and many important mineralogical metamorphoses ...
... gabbro - diorites were formed from gab- bros in the Baltimore region . There are many interesting features of the Michigan schists that might be dwelt upon at some length did space permit , and many important mineralogical metamorphoses ...
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... gabbros is A Gabbro - dio hornblende regarded as calling the Published September 30th , 1891 . schistose pl ary . By th both classe derived fro are eviden and felds quartz and -Mess traps of V localities 1 Edited b Bull . U. Bull . Ge ...
... gabbros is A Gabbro - dio hornblende regarded as calling the Published September 30th , 1891 . schistose pl ary . By th both classe derived fro are eviden and felds quartz and -Mess traps of V localities 1 Edited b Bull . U. Bull . Ge ...
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... gabbro in which the hornblende is largely second- ary . By the loss of nearly all of their pyroxene the gabbro - diorites of both classes pass into hornblende - gneisses . In the gabbro - granites , derived from the gabbros by an ...
... gabbro in which the hornblende is largely second- ary . By the loss of nearly all of their pyroxene the gabbro - diorites of both classes pass into hornblende - gneisses . In the gabbro - granites , derived from the gabbros by an ...
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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...