A Summary of Progress in Petrography. in 1887-1896 |
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Results 6-10 of 16
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... possesses an electrical axis which does not correspond to any crystallographic axis.3 - E . Cohen has de- scribed pseudomorphs after the concretionary markasite occur- ring in the chalk at Rügen , Pomerania . The pseudomorphs are ...
... possesses an electrical axis which does not correspond to any crystallographic axis.3 - E . Cohen has de- scribed pseudomorphs after the concretionary markasite occur- ring in the chalk at Rügen , Pomerania . The pseudomorphs are ...
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... possess a " shagreen " surface , due to numer- ous oval indentations . All the feldspar of the norites is filled with little inclusions of plates , rods , and dots . These seem not to be arranged in any definite position with regard to ...
... possess a " shagreen " surface , due to numer- ous oval indentations . All the feldspar of the norites is filled with little inclusions of plates , rods , and dots . These seem not to be arranged in any definite position with regard to ...
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... possess a well - marked schistose structure , a fact which led Professor Dana ' to ascribe to them a metamorphic origin from sedimentary deposits . A study of their thin sections , however , shows this schistosity to be but another ...
... possess a well - marked schistose structure , a fact which led Professor Dana ' to ascribe to them a metamorphic origin from sedimentary deposits . A study of their thin sections , however , shows this schistosity to be but another ...
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... possesses many of the characteristics of the Coahuila irons , described by the late J. L. Smith , and from the similarity of the two concludes that the former must be classed as one of the latter , and should not be regarded as an ...
... possesses many of the characteristics of the Coahuila irons , described by the late J. L. Smith , and from the similarity of the two concludes that the former must be classed as one of the latter , and should not be regarded as an ...
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... possesses very weak pleochroism . It extinguishes 44 ° 25 ' in the clinopinacoidal section , is positive and 2Va = 65 ° 3 ' for yellow light . Rhodonite usually occurs massive . But few fine crystals have heretofore been described . In ...
... possesses very weak pleochroism . It extinguishes 44 ° 25 ' in the clinopinacoidal section , is positive and 2Va = 65 ° 3 ' for yellow light . Rhodonite usually occurs massive . But few fine crystals have heretofore been described . In ...
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Common terms and phrases
acid alteration Amer American Naturalist analysis yielded andesites apatite augite axial ratio basalts calcite calcium carbonate cent chemical cleavage clinopinacoid composition compounds Comptes Rendus constituents contains corresponding County crystallographic described diabase diallage diopside Edited by Dr eral examined Fe,O feldspar forms formula garnet Geol Geological glass glaucophane gneisses grains granite ground-mass H₂O hemimorphic heulandite hexagonal hornblende inclusions intergrown isomorphous Jour K₂O Kryst Madison magma magnesium magnetite manganese meteoric iron meteorites Mexico mica microscope MINERALOGY AND PETROGRAPHY Mitth mixture monoclinic Na,O Na₂O Neues Jahrb norites olivine origin orthoclase orthorhombic parallel Penfield Petrog PETROGRAPHY plagioclase pleochroic porphyritic porphyritic crystals possess potassium prismatic Professor Genth pseudomorphs pyroxene quartz recently refractive regard result rocks rutile Schefferite schists serpentine silicates SiO2 sodium specific gravity specimens structure substance supposed tion topaz tourmaline twinning plane variety W. S. BAYLEY xxxii Zeits