A Summary of Progress in Petrography. in 1887-1896 |
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Page 9
... tourmaline , sphene , muscovite , and garnet dissemi- nated in a ground - mass of feldspar and quartz . Other granulites are very rich in cordierite , and these are in general less rich in quartz than are those bearing andalusite ...
... tourmaline , sphene , muscovite , and garnet dissemi- nated in a ground - mass of feldspar and quartz . Other granulites are very rich in cordierite , and these are in general less rich in quartz than are those bearing andalusite ...
Page 10
... 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 , thought by Herrimann and Weber to be ...
... 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 , thought by Herrimann and Weber to be ...
Page 14
... tourmaline and hematite , and a chloritic amphibolite whose principal feldspar is albite . Gabbros and peridotites cut the Paleozoic strata . In some specimens of the former piedmontite was noticed as an alteration product of hornblende ...
... tourmaline and hematite , and a chloritic amphibolite whose principal feldspar is albite . Gabbros and peridotites cut the Paleozoic strata . In some specimens of the former piedmontite was noticed as an alteration product of hornblende ...
Page 15
... tourmaline , from an unknown locality . The twinning plane is R , and the forms observed in the individuals are ∞P2 and - 2R . A pseudomorph of aragonite after calcite , from Müsen in Siegen , is one of the few instanesc described in ...
... tourmaline , from an unknown locality . The twinning plane is R , and the forms observed in the individuals are ∞P2 and - 2R . A pseudomorph of aragonite after calcite , from Müsen in Siegen , is one of the few instanesc described in ...
Page 23
... tourmaline , garnet , spinel , corundum , and zircon . The replacement of the orthoclase of the outer zone by plagioclase in the inner one indicates a difference in the composition of the two belts , but this is thought not to be a ...
... tourmaline , garnet , spinel , corundum , and zircon . The replacement of the orthoclase of the outer zone by plagioclase in the inner one indicates a difference in the composition of the two belts , but this is thought not to be a ...
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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...