A Summary of Progress in Petrography. in 1887-1896 |
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Page 13
... twinned individuals , which by their combination build up a form possessing a geometrical symmetry of higher grade than that be- longing to its individual constituents . Martin has examined several organic compounds , and is thereby led ...
... twinned individuals , which by their combination build up a form possessing a geometrical symmetry of higher grade than that be- longing to its individual constituents . Martin has examined several organic compounds , and is thereby led ...
Page 17
... Twinned crystals are quite common , the combination possessing an 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 ...
... Twinned crystals are quite common , the combination possessing an 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 ...
Page 18
... twinned that both individuals have their basal planes in common , and one appears to have been revolved about 88 ° 2 ' around an axis normal to the base . The limestone of Villefranque and of Biarritz , France , contains long needles of ...
... twinned that both individuals have their basal planes in common , and one appears to have been revolved about 88 ° 2 ' around an axis normal to the base . The limestone of Villefranque and of Biarritz , France , contains long needles of ...
Page 20
... twinned orthorhombic forms with a prismatic angle of 128 ° . They have a very perfect cleavage parallel to oP , so that they may easily be mistaken for mica . Often the prisms are twisted so that they resemble worm tubes to such ...
... twinned orthorhombic forms with a prismatic angle of 128 ° . They have a very perfect cleavage parallel to oP , so that they may easily be mistaken for mica . Often the prisms are twisted so that they resemble worm tubes to such ...
Page
... twinned octahedra of a darker color than those of polydimite . It is associated with quartz , tetrahedrite , and pyrite . Its density is 4.758 , and composition : Cu Fe Co Ni 40.645 18.984 .927 35-786 3.658 ( CoCuNiFe ) , S , S ...
... twinned octahedra of a darker color than those of polydimite . It is associated with quartz , tetrahedrite , and pyrite . Its density is 4.758 , and composition : Cu Fe Co Ni 40.645 18.984 .927 35-786 3.658 ( CoCuNiFe ) , S , S ...
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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...