Mineralogical Journal
Online ISSN : 1881-4174
Print ISSN : 0544-2540
ISSN-L : 0544-2540
Volume 15, Issue 4
Displaying 1-2 of 2 articles from this issue
 
  • Kazumasa SUGIYAMA, Masayasu TOKONAMI
    1990 Volume 15 Issue 4 Pages 141-146
    Published: 1990
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    The crystal structure refinements of Sr3(PO4)2 [a=5.3901(8), c=19.785(5)Å; space group R-3m] and Ba3(PO4)2 [a=5.6038(7), c=21.000(5)Å; space group R-3m] have been carried out by means of the single-crystal diffraction data and the final R(Rw) factors have been converged to 0.0299 (0.0309) and 0.0296 (0.0335), respectively. The rod sequence of coordination polyhedra, PO4–M(2)O10–M(1)O12–M(2)O10–PO4, where M = Sr or Ba, is characteristic in these structures. The M(1)O12 and M(2)O10 polyhedra show smaller distortion with increase in the ionic radius of the constituent elements.
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  • Kiyotaka ISHIDA
    1990 Volume 15 Issue 4 Pages 147-161
    Published: 1990
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    Infrared absorption spectra in the 4000–330 cm−1 range of the glaucophane-riebeckite series alkali amphiboles are presented with some discussions on their relationship to chemical composition.
    The compositions of the (M(1)·M(1)·M(3)) sites cations were calculated according to the areal intensity relations of their OH stretching bands at 3700–3600 cm−1, and these values roughly coincide with those obtained through chemical analyses. The ionic substitutions, (Fe2+ + Mn)-for–Mg in the M(1) and M(3) sites, and Fe3+-for–Al in the M(2) sites, cause a frequency decrease for most bands in the 1300–330 cm−1 range. The ratios of Fe3+ and Al in M(2) sites can be estimated approximately by the peak intensity relationships of three kinds of bands: near 990 and 970 cm−1 (Si–O stretchings); near 690 and 670 cm−1 (mainly OH librations); near 640 cm−1 (probably chain deformation). The nature of the bands near 465, 550, and 365 cm−1 is also useful to estimate the degree of Fe2+-for-Al substitutions in the M(2) sites.
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