A Summary of Progress in Petrography. in 1887-1896 |
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Page 9
... 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 . Micaceous and quartzitic schists from the neighborhood of Ax embrace zircon ...
... 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 . Micaceous and quartzitic schists from the neighborhood of Ax embrace zircon ...
Page 14
... mass of granite con- sists of corroded crystals of the first generation cemented by a granitic ground - mass . This fact is thought to be an indication of the correct- ness of the view that the constituents of granite are mainly of ...
... mass of granite con- sists of corroded crystals of the first generation cemented by a granitic ground - mass . This fact is thought to be an indication of the correct- ness of the view that the constituents of granite are mainly of ...
Page 14
... 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 consists principally of acicular crystals of ...
... 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 consists principally of acicular crystals of ...
Page 14
... mass of nterest- s as the crystals gnetite alls the num- helvite , These n they ed into minant inerals embers may be . 111 written ( MnFeCa ) , ( Mn , S ) Be , ( SiO ) ,, danalite as ( FeZnMn ) , [ ( Zn Fe ) , S ] Be ̧ ( SiO ) ...
... mass of nterest- s as the crystals gnetite alls the num- helvite , These n they ed into minant inerals embers may be . 111 written ( MnFeCa ) , ( Mn , S ) Be , ( SiO ) ,, danalite as ( FeZnMn ) , [ ( Zn Fe ) , S ] Be ̧ ( SiO ) ...
Page 15
... masses , is thought to be hexagonal . Its indices of refraction are = 1.558 , € = 1.613 , and its composition is SO , 51.30 ; Fe , O , 17.30 ; Na , O 19.95 ; H , O = 11.89 ; specific gravity = 2.547-2.578 . Darapsky 12 also gives a few ...
... masses , is thought to be hexagonal . Its indices of refraction are = 1.558 , € = 1.613 , and its composition is SO , 51.30 ; Fe , O , 17.30 ; Na , O 19.95 ; H , O = 11.89 ; specific gravity = 2.547-2.578 . Darapsky 12 also gives a few ...
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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...