A Summary of Progress in Petrography. in 1887-1896 |
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Page 23
... Dykes of porphy- rite cut the schists , and a single one occurs in the tonalite , but none of them merit ... dyke Brazil plutor lite , a to give tugal among dense mica , be a co in the glassy elæolit Mine yllite ment As ecog ...
... Dykes of porphy- rite cut the schists , and a single one occurs in the tonalite , but none of them merit ... dyke Brazil plutor lite , a to give tugal among dense mica , be a co in the glassy elæolit Mine yllite ment As ecog ...
Page 24
... dyke rocks and their corresponding plutonic facies , has lately appeared under the names of Hunter and Rosenbusch , who have discovered that one of the rocks occurring in dyke form in the elæolite - syenite region of the Serra de Tinguá ...
... dyke rocks and their corresponding plutonic facies , has lately appeared under the names of Hunter and Rosenbusch , who have discovered that one of the rocks occurring in dyke form in the elæolite - syenite region of the Serra de Tinguá ...
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... dykes and flows in Menez - Hom , Finistère , France . The diabases he divides according to structure into granular and ... dyke of basic rock on Stop Island , in Rainy Lake , Canada , consists of diabase - porphyrite with an almost ...
... dykes and flows in Menez - Hom , Finistère , France . The diabases he divides according to structure into granular and ... dyke of basic rock on Stop Island , in Rainy Lake , Canada , consists of diabase - porphyrite with an almost ...
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... dyke the texture is gabbroitic , while hornblende replaces the augite . Quartz is also a prominent constitu- ent of the center of the dyke , whereas it is only sparingly present at fifteen feet from the contact , and is entirely absent ...
... dyke the texture is gabbroitic , while hornblende replaces the augite . Quartz is also a prominent constitu- ent of the center of the dyke , whereas it is only sparingly present at fifteen feet from the contact , and is entirely absent ...
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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...