A Summary of Progress in Petrography. in 1887-1896 |
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Page 8
... zone of secondary calcite and an outer rim of brucite . The rutile merits special atten- tion , because what appears to be the ordinary black variety is found in thin section to be sometimes this , and sometimes like the violet rutile ...
... zone of secondary calcite and an outer rim of brucite . The rutile merits special atten- tion , because what appears to be the ordinary black variety is found in thin section to be sometimes this , and sometimes like the violet rutile ...
Page 14
... zones , he defines as those containing the planes with the greatest capacity for resisting solution . Many more results of interest are contained in the paper , the character of which is sufficiently indicated by the conclusions above ...
... zones , he defines as those containing the planes with the greatest capacity for resisting solution . Many more results of interest are contained in the paper , the character of which is sufficiently indicated by the conclusions above ...
Page 22
... zones : an outer one , the zone of the ilmenite - frucht - schiefer , in which the phyllites have suffered merely the change of their chlorite into biotite , and an inner zone , in which andalusite is an important constituent . The ...
... zones : an outer one , the zone of the ilmenite - frucht - schiefer , in which the phyllites have suffered merely the change of their chlorite into biotite , and an inner zone , in which andalusite is an important constituent . The ...
Page 23
... zones . In the outer one the normal gneiss and mica - schists have been changed into cordierite and andalusite varieties , containing a fibrous orthoclase . In the inner zone all resemblance to gneiss and mica - schists has dis ...
... zones . In the outer one the normal gneiss and mica - schists have been changed into cordierite and andalusite varieties , containing a fibrous orthoclase . In the inner zone all resemblance to gneiss and mica - schists has dis ...
Page
... zone - circles and face - points in a stereographic projection . 16 Handbuch der Mineralogie . 4te Lief . , pp . 481-640 . Leipzig , 1891 . 17 Bull . Soc . Franc . d . Min . , 1890 , p . 341 . 18 Bull . Geol . Soc . Amer . , Vol . II ...
... zone - circles and face - points in a stereographic projection . 16 Handbuch der Mineralogie . 4te Lief . , pp . 481-640 . Leipzig , 1891 . 17 Bull . Soc . Franc . d . Min . , 1890 , p . 341 . 18 Bull . Geol . Soc . Amer . , Vol . II ...
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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...