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  • 1965-1969  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 11 (1965), S. 614-620 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Some of the upper cretaceous sedimentary rocks near Regensburg, Germany, are rich in glauconite pellets of 63–200µ diameter. The clay fractions 〈 2µ ϕ of the same rocks are rich in glauconite-mica too. X-ray analysis, chemical analysis and petrographical tests show that, the glauconite pellets must be excrements of marine animals which took up glauconite-mica from sea-bottom. The glauconite materials from these rocks are 1M-micapolymorphs. A comparison of this glauconite with 1M-glauconites cited in literature by other authors shows close aggreement in K2O/MgO- and K2O/Fe2O3 ratios. Within the range of analytical errors the structure formulae of all these 1M-glauconites differ from one another only by the oxidation ratio of iron and — corresponding to this ratio — by the aluminum contents of the octahedral lattice layer. The differences of the 1M-glauconites in octahedral layer populations may due to different redox potentials during glauconite formation or to oxidation during rock diagenesis or rock weathering later on. In a similar manner 1Md-polymorphs of glauconite-mica may have developed from 1M-glauconite by oxidation of iron and corresponding removement of K+ and (H3O)+ ions from interlayer lattice positions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 12 (1966), S. 168-172 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract An x-ray fluorescence spectrographic method is described for the determination of rubidium, strontium, barium and lead in kaolins and clays. The method is most usefull within a concentration range of 50–2000 p.p.m. Rb, Sr, Ba or Pb in the sample. Dried powder samples of kaolins resp. clays are compressed in a suitably shaped die and its x-ray radiations are compared with those of the same kaolins or clays to which small amounts of Rb, Sr, Ba or Pb had been added. A homogenous distribution of small amounts of these elements in kaolins and clays is obtained by precipitation of Pb, Ba and Sr as sulfate and Rb as Rb[B(C5H6)4] in a concentrated clay resp. kaolin suspension. The prepared suspensions are filtered (by membran-filters) and dried before compressing and x-ray measuring. The instrumental conditions were: Siemens x-ray spectrograph “Kristalloflex IV” fitted with a lithium fluoride analysing crystall, molybdenum-target x-ray tube (type AG Mo 61), 50 kV 30 m.amp. for measuring of the Sr Kα-, Rb Kα-, Pb L/gB-lines and 60 kV 36 m.amp. for measuring of the Ba Kα-line. The standard deviations were: ± 3 p.p.m. Rb for samples containing 25– 150 p.p.m. of Rb ± 6 p.p.m. Sr for samples containing 200– 400 p.p.m. of Sr ± 60 p.p.m. Ba for samples containing 1000–2000 p.p.m. of Ba ± 9 p.p.m. Pb for samples containing 250– 800 p.p.m. of Pb
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