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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of intersite distribution of Mg and Fe in olivine and the associated change of lattice parameters (1985)
    Springer
    Physics and chemistry of minerals 12 (1985), S. 1-8 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The cation distribution of natural and heated ferromagnesian olivine with chemical composition, Fo67Fa33, from metagabbro was examined by X-ray diffraction. Heating and quenching experiments were made by a newly devised apparatus which enables us to obtain very fast quenching speed in comparison with the usual technique. The distribution constants, K D=(Fe+2/Mg) M1/(Fe+2/Mg) M2, of the natural samples were less than 1.07, and those of heat-treated samples were more than 1.15, indicating that cation ordering takes place with temperature. The distribution of Fe+2 and Mg is nearly random at low temperatures, whereas Fe+2 shows a slight but significant preference for a smaller M1 site at high temperatures. The change of the distribution constant was observed on specimens which were heated for a short period of time (6–1,060 s) and quenched within 10 ms. Thus the rate of the cation reordering reaction is a very fast process. The lattice parameters b and c decrease whereas a increases with the increase of distribution constant. The overall effect on unit cell volume is a decrease with the increasing distribution constant, suggesting the presence of significant pressure dependence of the cation distribution towards the ordering of Fe at M1 site in ferromagnesian olivine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348738
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  • 2
    Electronic Resource
    Electronic Resource
    Diffusion of rare-earth elements in fish teeth from deep-sea sediments (1990)
    [s.l.] : Nature Publishing Group
    Nature 345 (1990), S. 607-609 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/345607a0
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  • 3
    Electronic Resource
    Electronic Resource
    Coexisting sodic augite and omphacite in a Sanbagawa metamorphic rock, Japan (1984)
    Springer
    Contributions to mineralogy and petrology 86 (1984), S. 241-247 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Coexisting sodic augite and omphacite were found in a zoisite amphibolite from the Iratsu epidote amphibolite mass in the Sanbagawa metamorphic terrain of central Shikoku, Japan. The occurrences of the sodic augite-omphacite pairs are classified into four types by texture: independent, composite, intergrowth and exsolution types. Sodic augite and omphacite of the independent and composite types (pair A) have X Na (=Na/(Na + Ca)) = 0.15 and 0.35, respectively, and were stable in the epidote amphibolite facies during the Sanbagawa progressive metamorphism. On the other hand, X Na values of sodic augite and omphacite of the intergrowth and exsolution types (pair B) are 0.10 and 0.44, respectively. The Na-poor augite and Na-rich omphacite of the pair B were formed by re-equilibration of the pair A at lower temperature. The pair A of the Iratsu sample suggests that a compositional gap lies between sodic augite and C2/c omphacite under epidote amphibolite facies conditions, and is in marked contrast to the coexistence of sodic augite and P2/n omphacite reported from some low-grade, high-pressure metamorphic terrains. A possible phase diagram to explain the chemistry and mode of occurrence of the coexisting sodic pyroxenes is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373669
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  • 4
    Electronic Resource
    Electronic Resource
    A study of subsolidus relations of the Skaergaard pyroxenes by analytical electron microscopy (1978)
    Springer
    Contributions to mineralogy and petrology 67 (1978), S. 111-117 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Within augite and pigeonite grains of the Skaergaard ferrogabbro 4430, the Ca-poor phases contain only three mole percent of CaSiO3, and the Mg-Fe partition coefficients between the Ca-poor and Ca-rich phases are extremely small with 0.46 for augite and 0.51 for pigeonite grains. These values indicate existence of diffusion within each grain (intragranular diffusion) at considerably low temperatures. The compositions are slightly but definitely different between the Ca-rich phases in augite and pigeonite grains as well as between the Ca-poor phases in augite and pigeonite grains. This indicates that the diffusion among the grains (inter-granular diffusion) has not taken place under the subsolidus condition of the Skaergaard intrusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046569
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of titanium atoms in oxy-kaersutite (1975)
    Springer
    Contributions to mineralogy and petrology 51 (1975), S. 167-172 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The distribution of Ti atoms in oxy-kaersutite has been studied by the neutron diffraction method. The cation distribution over the three octahedral sites determined by the x-ray method (Kitamura and Tokonami, 1971) is as follows; M1∶0.40MG+0.60 FE, M2∶0.75 MG+0.25 FE, M3∶0.50 MG+0.50 FE, where MG and FE represent (Mg+Al) and (Fe+Ti), respectively. The neutron diffraction study indicates that Ti atoms are enriched in the M1 site more than M2 and M3 sites as follows; M1∶0.40 MG+0.33 Fe+0.27 Ti, M2∶ 0.75 MG+0.23 Fe+0.02 Ti, M3∶0.50 MG+0.46 Fe+0.04 Ti. This distribution agrees with the result based on the Madelung energy of oxy-kaersutite by Whittaker (1972).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372077
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  • 6
    Electronic Resource
    Electronic Resource
    Laser-induced changes in the electron density distribution of crystals: Ca3Cr2Si3O12 (1992)
    Springer
    The European physical journal 87 (1992), S. 163-164 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Difference of electron density distribution between a crystal being He−Ne laser-irradiated and non-irradiated has been investigated by in situ X-ray diffraction methods. Difference Fourier analysis between these data revealed electron density decrease of 2.1 eÅ−3 at the trivalent site occupied 64% by Cr3+, the absorbant; while the calcium, silicon, and oxygen sites remained practically unchanged. Crystal data: [Natural uvarovite from Outokumpu, Finland; Ca3(Cr1.284Al0.692Fe0.024)Si3O12 (EPMA analysis); Cubic garnet structure; $$Ia\bar 3d$$ ;Z=8;a 0=11.936(1) Å;V=1700.5 Å3 D x =3.775 Mgm−3; λ(MoKα)=0.71069 Å; μ=4025 m−1;F(000)=1900;T=293 K].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01315643
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