A Summary of Progress in Petrography. in 1887-1896 |
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Page 11
... hexagonal habit , due to twinning of triclinic individuals , whose triclinic nature is discoverable only by optical methods . In order to show their relations to the Willemite 8 Zeits . f . Kryst . , XVIII . , 1890 , p . 361 . USE ce al ...
... hexagonal habit , due to twinning of triclinic individuals , whose triclinic nature is discoverable only by optical methods . In order to show their relations to the Willemite 8 Zeits . f . Kryst . , XVIII . , 1890 , p . 361 . USE ce al ...
Page 12
... hexagonal sys- tem with a c = 1 : .7233 . They are thick , tabular forms , bounded by oP , ∞P2 , ∞P , § P2 , P2 and 15 P , and other pyramids with com- plicated symbols . Brögger finds that sections parallel to P2 extin- guish at ...
... hexagonal sys- tem with a c = 1 : .7233 . They are thick , tabular forms , bounded by oP , ∞P2 , ∞P , § P2 , P2 and 15 P , and other pyramids with com- plicated symbols . Brögger finds that sections parallel to P2 extin- guish at ...
Page 15
... 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 notes of observations on a ...
... 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 notes of observations on a ...
Page 17
... hexagonal habit.- -The rare zeolite mordenite has been discovered by Pirsson 19 in the cavity of an amygdaloidal basalt , forming fragments in a breccia near Hoodoo Mt. in Western Wyoming . The mineral is in very small crystals , with a ...
... hexagonal habit.- -The rare zeolite mordenite has been discovered by Pirsson 19 in the cavity of an amygdaloidal basalt , forming fragments in a breccia near Hoodoo Mt. in Western Wyoming . The mineral is in very small crystals , with a ...
Page
... hexagonal crystals in the altered sandstone of Steinberg , in the Habichtswald , Germany , to be cordierite , produced probably by the solution of the interstitial sub- stance of the sandstone by basalt . — Termier 8 notes the ...
... hexagonal crystals in the altered sandstone of Steinberg , in the Habichtswald , Germany , to be cordierite , produced probably by the solution of the interstitial sub- stance of the sandstone by basalt . — Termier 8 notes the ...
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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...