A Summary of Progress in Petrography. in 1887-1896 |
From inside the book
Results 1-5 of 13
Page 10
... Cleavage is perfect , 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 ...
... Cleavage is perfect , 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 ...
Page 11
... Cleavage is 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 ) ...
... Cleavage is 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 ) ...
Page 14
... cleavage is octahedral . This includes the first four minerals mentioned above , and is known as the helvite group . All its members can be represented by formulas of the garnet type . Die Japanischen Inseln . , 1st Lief . , Berlin ...
... cleavage is octahedral . This includes the first four minerals mentioned above , and is known as the helvite group . All its members can be represented by formulas of the garnet type . Die Japanischen Inseln . , 1st Lief . , Berlin ...
Page 14
... cleavage . Embraced in this is the garnet series proper , with a composition R , " R , " ( SiO , ) ,, and the series of the alkaline garnets . The etched figures on the latter indicate that they are all tetrahedrally hemihedral , and a ...
... cleavage . Embraced in this is the garnet series proper , with a composition R , " R , " ( SiO , ) ,, and the series of the alkaline garnets . The etched figures on the latter indicate that they are all tetrahedrally hemihedral , and a ...
Page 15
... cleavage is 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 ...
... cleavage is 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 ...
Other editions - View all
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...