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  • 1
    Electronic Resource
    Electronic Resource
    Relict grains in chondrules (1981)
    [s.l.] : Nature Publishing Group
    Nature 293 (1981), S. 558-561 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The spherical shapes and internal igneous textures of chondrules indicate that they were once molten. Although it is widely believed that chondrules were formed by melting of pre-existing solids4"8, it has also been suggested that they are nebular condensates9"11. The various textures observed in ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/293558a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Occurrence of oxidized components in Qingzhen enstatite chondrite (1984)
    [s.l.] : Nature Publishing Group
    Nature 311 (1984), S. 138-140 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The enstatite chondrites are characterized by an assemblage of highly reduced mineral phases5"7. Elements which are predominantly lithophile in other chondrite groups, display in enstatite chondrites, chalcophilic or siderophilic properties. Part of the Si is present in solid solution in the metal ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/311138a0
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  • 3
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    Occurrence of oxidized components in Qingzhen enstatite chondrite (1984)
    Springer Nature
    Details
    Publication Date: 1984-09-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 4
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    Relict grains in chondrules (1981)
    Springer Nature
    Details
    Publication Date: 1981-10-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 5
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    Gallium-bearing sphalerite in a metal-sulfide nodule of the Qingzhen (EH3) chondrite (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The composition and possible history of the Qingshen (EH3) chondrite is presented. The chondrite contains a population of spheroidal metal-sulfide nodules, which display textural evidence of reheating and melting. Evidence of metal sulfuration is also present, suggesting replacement of metal by sulfide during melting. This process has led to the nucleation of perryite along metal-sulfide interfaces. The Ga-bearing sphalerite that was found may have formed by injection of molten sulfide droplets into the metal followed by subsolidus diffusion of Ga from the metal into the sulfide. The latter may occur because of Ga supersaturation in the metal during progressive sulfuration and its decreased affinity for the metal phase during cooling below the taenite-kamacite transition point.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 21; 23-31
    Format: text
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  • 6
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    Occurrence of oxidized components in Qingzhen enstatite chondrite (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: It is shown that the most unequilibrated enstatite chondrite, Qingzhen, contains a population of enstatite grains which appear to have formed under more oxidizing nebular conditions than the bulk of the meteorite, which is highly reduced. These grains are black in transmitted light because of the presence of micron-sized inclusions of Ni-poor, Cr-rich metal, and occur either isolated within the matrix or in chondrule interiors. The textural occurrence of these grains argues against their having been introduced during collision of Qingzhen with an oxidized meteorite. Most likely, they originated in the same general nebular neighborhood of the reduced bulk Qingzhen material and were subsequently transported into the reducing environment either before or during the process of chondrule formation. The discovery of this once-oxidized material in Qingzhen posed significant constraints on existing models of formation of reduced matter in the solar system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 311; 138-140
    Format: text
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  • 7
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    Roedderite in the Qingzhen (EH3) chondrite (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The rare mineral roedderite, (Na1.09 K0.89 Ca0.02)2.00 (Mg4.71 Fe0.27)4.98 (Si11.80 Al0.09)11.89 O30 has been found in accessory amounts in the highly unequilibrated enstatite chondrite, Qingzhen. It occurs in association with minor amounts of albite and SiO2 as inclusions within the metal or sulfide phases of metal-sulfide assemblages. The roedderite crystals are connected through oxide and silicate veins to the surrounding matrix. The presence of glass coated vesicles on the surface of the assemblages strongly suggests that roedderite originated in the presence of a fluid phase, presumably during post-accretional planetary processes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 21; 141-149
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  • 8
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    Solar wind helium, neon and argon released by oxidation of metal grains from the Weston chondrite (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A set of experiments were carried out to test the feasibility of determining unfractionated elemental and isotopic ratios for the noble gases in the presumably ancient solar wind present in the gas rich meteorites. The problems of diffusive loss was avoided by analyzing metal rather than the usual silicates. In order to avoid chemical, and even harsh physical, treatment of the sample, which might have affected the surfaces of metal grains, a means of analyzing the metal in the presence of residual silicate not removed by gentle crushing and magnetic separation was devised. Preliminary results given were obtained by taking advantage of the differing properties of metal and silicates with regard to diffusion. The results suggests that, with some modifications in the choice of pyrolysis and combustion temperatures and in the amount of O2 used, it should be possible, by oxidizing the surfaces of metal grains from gas rich meteorites, to obtain data on solar wind that has not been fractionated by diffusive loss.
    Keywords: SOLAR PHYSICS
    Type: Lunar and Planetary Inst. Workshop on Past and Present Solar Radiation: The Record in Meteoritic and Lunar Regolith Material; p 12-13
    Format: application/pdf
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  • 9
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    Metal and associated phases in Bishunpur, a highly unequilibrated ordinary chondrite (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Bishunpur is one of the most unequilibrated ordinary chondrites, and preserves a relatively unaltered record of solar nebular processes. A survey of three polished thin sections of Bishunpur revealed that metal occurs in three textural domains: (1) in the matrix, (2) within chondrules and (3) in coatings on chondrules. A table provides a textural classification of the various metal types found in Bishunpur and their composition. Electron-microprobe analyses are discussed, and similarities between Bishunpur metal and opaques and those in carbonaceous chondrites are considered. Attention is given to low-Ni kamacite grains in chondrule olivine, Si-bearing chondrule metal, spheroidal metal in chondrules, metal and sulfide-bearing rims, coarse matrix metal, and fine matrix metal formation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 45; July 198
    Format: text
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  • 10
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    Si-rich Fe-Ni grains in highly unequilibrated chondrites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Consideration is given to the Si contents of Fe-Ni grains in highly unequilibrated chondrites, which have undergone little metamorphosis and thus best preserve the record of processes in the solar nebula. Electron microprobe determinations of silicon content in grains of the Bishunpur chondrite are presented for the six Si-bearing Fe-Ni grains for which data could be obtained, five of which were found to be embedded in olivine chondrules. In addition, all grains are found to be Cr-rich, with Cr increased in concentration towards the grain edge, and to be encased in FeS shells which evidently preserved the Si that entered the FeNi at higher temperatures. A mechanism for the production of Si-bearing metal during the condensation of the cooling solar nebula is proposed which considers the metal to have condensed heterogeneously while the mafic silicates condensed homogeneously with amounts of required undercooling in the low-pressure regions where ordinary and carbonaceous chondrites formed, resulting in Si mole fractions of 0.003 at nebular pressures less than 0.000001 atm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 287; Oct. 30
    Format: text
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