A Summary of Progress in Petrography. in 1887-1896 |
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Page 10
... parallel to oP and P. Hardness = 5 , and density 2.845 . Compo- sition : ∞ ∞ Sio , Fe , O , 53.03 .10 CaO MnO 30.28 4.25 Na2O H2O CO2 8.99 2.43 .82 3 Bull . Soc . Franç . d . Min . , XIII . , 1890 , p . 100 . Neues Jahrb . f . Min ...
... parallel to oP and P. Hardness = 5 , and density 2.845 . Compo- sition : ∞ ∞ Sio , Fe , O , 53.03 .10 CaO MnO 30.28 4.25 Na2O H2O CO2 8.99 2.43 .82 3 Bull . Soc . Franç . d . Min . , XIII . , 1890 , p . 100 . Neues Jahrb . f . Min ...
Page 11
... parallel to Po The optical axial plane is oP , with 6 the negative acute bisec- trix . The absorption is B > A > C , with Bc = opaque ; A = b = reddish - brown , and C a reddish - yellow . Trimerite ( ptusprjs = three - fold ) was found ...
... parallel to Po The optical axial plane is oP , with 6 the negative acute bisec- trix . The absorption is B > A > C , with Bc = opaque ; A = b = reddish - brown , and C a reddish - yellow . Trimerite ( ptusprjs = three - fold ) was found ...
Page 12
... parallel to P2 extin- guish at about 4 ° from c . 2V 83 ° 29 ' , with a very slight dispersion . The angles a , ẞ and y are all nearly 90 ° , so that the combination is somewhat similar to the combination of orthorhombic aragonites to ...
... parallel to P2 extin- guish at about 4 ° from c . 2V 83 ° 29 ' , with a very slight dispersion . The angles a , ẞ and y are all nearly 90 ° , so that the combination is somewhat similar to the combination of orthorhombic aragonites to ...
Page 15
... parallel to each . The optical angle 2 En2 = 63 ° 3 ′ , and the extinction in the macropinacoid is 16o - 17 ° , in acute B. Fibres of sideronatrite show a slight pleochroism , with a pale straw - yellow color parallel to the longer axis ...
... parallel to each . The optical angle 2 En2 = 63 ° 3 ′ , and the extinction in the macropinacoid is 16o - 17 ° , in acute B. Fibres of sideronatrite show a slight pleochroism , with a pale straw - yellow color parallel to the longer axis ...
Page 16
... parallel aggregates . Their axial ratio is a : b : c = 1.9192 : 1 : .5245 with ẞ = 84 ° 1 ′ , on the assumption of the plane P , determined by Descloizeaux in the Limoges crystals as the ground form . The habit of the Branchville ...
... parallel aggregates . Their axial ratio is a : b : c = 1.9192 : 1 : .5245 with ẞ = 84 ° 1 ′ , on the assumption of the plane P , determined by Descloizeaux in the Limoges crystals as the ground form . The habit of the Branchville ...
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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...