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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 29 (2005), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The articles that comprise this critical review serve to draw attention to research papers published in specific fields of interest during 2003, provide critical comment on the relevance and importance of individual publications in these fields, and offer an overview of the comparative importance of advances in particular areas. In this way, these articles aim to assist experts in the field by keeping them informed of relevant recent publications, as well as providing an important resource for students or early career researchers who are embarking on studies in an area new to them. This year, five papers provide summaries of developments in bulk sample determinations employing (1) ICP-AES and ICP-MS (trace elements), (2) XRF and atomic absorption spectrometry and INAA, (3) isotope ratio measurements (TIMS, MC-ICP-MS, ICP-MS, ToF), as well as in situ measurements conducted using (4) secondary ion mass spectrometry and (5) laser ablation ICP-MS (trace element and isotope ratio determinations).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 20 (1996), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: In a previous study of the reference sample zircon 61.308B, it has been suggested that either the sample is heterogeneous or inter-method comparisons introduce analytical dispersions. New determinations by LA-ICP-MS show relative standard deviation in the order of 20% for Heavy Rare Earth Elements (HREE). This is four times the variation attributable to analytical method. A possible explanation is that HREE concentration varations in geochemical reference zircon were created by crystal fractionation or oscillatory variation in the host magma. This confirms that zircon 61.308B is heterogeneous for trace elements.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 14 (1990), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Instrumental neutron activation analysis of rocks and minerals is currently done on basis of collecting 2 or 3 energy spectra. We have found that, by collecting one spectrum one week after irradiation, satisfactory results for the USGS and CRPG geochemical reference samples can be obtained.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 18 (1994), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Comparison of analytical results obtained for geochemical reference samples with accepted results is tedious and error prone. Graphical representation facilitates comparison. Nevertheless, currently used diagrams lack representativeness when a wide range of concentrations are studied. A newly designed graph representing normalized results against concentrations is proposed. It allows comparison of a wide range of concentrations and helps detect analytical problems for particular ranges of concentrations.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 28 (2004), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Many chromite-rich rocks contain relatively high concentrations of the platinum-group elements (PGE). In many cases, the phases carrying PGE occur as either platinum-group minerals (PGM) or as base metal sulfides in solid solution in sulfides. In some cases, such as the UG-2 unit of the Bushveld Complex, the PGM are occluded inside chromite grains. Chromites are notably difficult to dissolve in most fluxes and if the chromite contains some PGM the possibility exists that not all the PGE will be recovered during fusion. In this work, shortcomings in published methods of analysis based on the nickel sulfide fire assay procedure were investigated and a new procedure developed based on the addition of sodium metaphosphate to the fusion mixture. Optimum composition of the fusion mixture was found to be 10 g sodium metaphosphate and 9 g silica to 10 g sample, 15 g sodium carbonate, 30 g lithium tetraborate, 7.5 g nickel and 4.5 g sulfur to achieve complete dissolution of chromite grains. The new flux mixture was evaluated by the analysis of reference material CHR-Pt+ (which is known to contain PGM inside chromite grains) and no undissolved chromite grains were found in the glassy slag. Analysis of the nickel sulfide beads from this fire assay using neutron activation analysis showed similar results for Rh and Ru when compared with published conventional true (or accepted) values, while Au, Ir, Os, Pd and Pt values determined here were 10 to 30% higher than the corresponding published conventional true values. It was concluded that the addition of sodium metaphosphate improved chromite dissolution in the flux and appears to improve PGE recovery.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 29 (2005), S. 0 
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: This review for the year 2003 deals with three relatively well-established, mature, analytical techniques (neutron activation analysis, atomic absorption spectrometry and X-ray fluorescence spectrometry) that nevertheless remain very important for the characterisation of geological and environmental samples. Developments in neutron activation analysis included modification to the technique in relation to the determination of platinum-group elements, as well as consideration of sample size in ore grade estimation. A considerable body of literature was published on the application of atomic absorption spectrometry in the analysis of environmental samples. Many of these proposed technical and methodological improvements, notably in extraction procedures. X-ray fluorescence spectrometry saw developments in in situ analysis, synchrotron micro-XRF (μ-SRXRF) and a confocal X-ray set-up for 3D elemental imaging. XRF technologies were used in the analysis of geological samples, reference materials, glasses, solutes and environmental materials.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Mineralogy and petrology 46 (1992), S. 109-121 
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die archaischen Karbonatitgänge von Dolodau liegen in der Nähe eines spättektonischen Syenit-Stockes in der nördlichen vulkanischen Zone des Abitibi Greenstone Belts. Die Biotit-Sovit- and Amphibol-Biotit Silicokarbonatit-Gänge führten zu Fenitisierung der umgebenden Gesteine. Die Dolodau-Karbonatite lassen sich gut mit phanerozoischen Karbonatiten vergleichen, was Petrographie, Mineralogie and Geochemie betrifft. Ein archaisches Alter wird durch Geländebeziehungen and Isotopendaten belegt. Diese Ähnlichkeiten weisen darauf hin, daß archaische Karbonatit-bildende Vorgänge ihren modernen äquivalenten ähnlich sind.
    Notes: Summary The Archean Dolodau carbonatite dykes occur near a late tectonic syenite stock located in the Northern Volcanic Zone of the Abitibi greenstone belt. The biotite sovite and amphibole-biotite silicocarbonatite dykes produced fenitization of the host rocks. The Dolodau carbonatites compare favourably with Phanerozoic carbonatites in petrography, mineralogy and geochemistry. An Archean age is suggested by field geology and the isotope data available. The similarities suggest that Archean carbonatite petrogenetic processes were similar to modern day processes.
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  • 8
    Publication Date: 1996-11-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
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  • 9
    Publication Date: 1993-01-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
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  • 10
    Publication Date: 2020-09-01
    Description: Mineralogical and chemical zonations observed in massive sulfide ores from Ni-Cu-platinum group element (PGE) deposits are commonly ascribed to the fractional crystallization of monosulfide solid solution (MSS) and intermediate solid solution (ISS) from sulfide liquid. Recent studies of classic examples of zoned orebodies at Sudbury and Voisey’s Bay (Canada) demonstrated that the chemistry of magnetite crystallized from sulfide liquid was varying in response to sulfide fractional crystallization. Other classic examples of zoned Ni-Cu-PGE sulfide deposits occur in the Norilsk-Talnakh mining district (Russia), yet magnetite in these orebodies has received little attention. In this contribution, we document the chemistry of magnetite in samples from Norilsk-Talnakh, spanning the classic range of sulfide composition, from Cu poor (MSS) to Cu rich (ISS). Based on textural features and mineral associations, four types of magnetite with distinct chemical composition are identified: (1) MSS magnetite, (2) ISS magnetite, (3) reactional magnetite (at the sulfide-silicate interface), and (4) hydrothermal magnetite (resulting from sulfide-fluid interaction). Compositional variability in lithophile and chalcophile elements records sulfide fractional crystallization across MSS and ISS magnetites and sulfide interaction with silicate minerals (reactional magnetite) and fluids (hydrothermal magnetite). Estimated partition coefficients for magnetite in sulfide systems are unlike those in silicate systems. In sulfide systems, all lithophile elements are compatible and chalcophile elements tend to be incompatible with magnetite, but in silicate systems some lithophile elements are incompatible and chalcophile elements are compatible with magnetite. Finally, comparison with magnetite data from other Ni-Cu-PGE sulfide deposits pinpoints that the nature of parental silicate magma, degree of sulfide evolution, cocrystallizing phases, and alteration conditions influence magnetite composition.
    Print ISSN: 0361-0128
    Electronic ISSN: 1554-0774
    Topics: Geosciences
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