A Summary of Progress in Petrography. in 1887-1896 |
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Page 8
... plates , often several millimeters in length , or in fibres forming aureoles around unaltered cores of humite . Another alteration is into chryso- tile . This is rare , and the change is usually incomplete . A third method of ...
... plates , often several millimeters in length , or in fibres forming aureoles around unaltered cores of humite . Another alteration is into chryso- tile . This is rare , and the change is usually incomplete . A third method of ...
Page 14
... plates . In this way a high grade of symmetry is imitated , while the plates are really of a low grade . He also adds a nineteenth substance to the list of rotatory polarizing bodies , viz . , ( NH ) LiSO , which is apparently biaxial ...
... plates . In this way a high grade of symmetry is imitated , while the plates are really of a low grade . He also adds a nineteenth substance to the list of rotatory polarizing bodies , viz . , ( NH ) LiSO , which is apparently biaxial ...
Page 14
... plates and crystals , often arranged in radial aggregates . Their hardness is 3 , and specific gravity 2.17 . Miner . u . Petrog . Mitth . , XI . , 1890 , p . 214 . 8 • Zeits . f . Kryst . , 1882 , VI . , ) p . 627 . H 9 = They remain ...
... plates and crystals , often arranged in radial aggregates . Their hardness is 3 , and specific gravity 2.17 . Miner . u . Petrog . Mitth . , XI . , 1890 , p . 214 . 8 • Zeits . f . Kryst . , 1882 , VI . , ) p . 627 . H 9 = They remain ...
Page 23
... plate that tals , not upon pluto Roser dyke Brazil plutor lite , a to give tugal among dense mica , be a co in the glassy elæolit Mine yllite ment As ecog- ones . nged clase . = 572 [ June , The American Naturalist .
... plate that tals , not upon pluto Roser dyke Brazil plutor lite , a to give tugal among dense mica , be a co in the glassy elæolit Mine yllite ment As ecog- ones . nged clase . = 572 [ June , The American Naturalist .
Page 24
... plates of rock structures render great aid to the reader . It is evident that the schists of Michigan cannot grade into the overlying fragmen- tals , and since they are much more squeezed than these , that they can- not be of the same ...
... plates of rock structures render great aid to the reader . It is evident that the schists of Michigan cannot grade into the overlying fragmen- tals , and since they are much more squeezed than these , that they can- not be of the same ...
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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...