The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
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Volume 82, Issue 3
Displaying 1-4 of 4 articles from this issue
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  • Polarization color indices of ore minerals, calculation method and application to mineral identification
    Xu GUOFENG, Mei JIANMING
    1987 Volume 82 Issue 3 Pages 91-99
    Published: March 05, 1987
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.82.91
    JOURNAL FREE ACCESS
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    The possibility of determination of ore mineral polarization color indices by using the principle and method of colorimetry are discussed in this paper. More than one hundred values of polarization color indices of ore minerals (Rvis, X, Y, λd, Pe) are calculated, in the first place, by using the principal reflectances (R1 and R2) of anisotropic ore minerals, determined under different wavelengths.
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  • Contrast behaviour of octahedral Cr3+ in clinopyroxenes at elevated pressure
    HARUO OHASHI, TOSHIKAZU OSAWA
    1987 Volume 82 Issue 3 Pages 100-105
    Published: March 05, 1987
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.82.100
    JOURNAL FREE ACCESS
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    There exists two pyroxenes of low and high pressure types in the system NaCrSi2O6- NaScSi2O6. The observed optical transition of octahedral Cr3+ 4A2g→4T1g denoted by ν2 clearly show two separate trends in the wave number-chemical composition diagram, reflecting the conditions under which the pyroxenes formed. The two separate trends are related to the variation of the O1A1-M1-O1B2 angle in the pyroxene structures.
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  • Serpentine minerals from Sasaguri area, Fukuoka Prefecture, Japan
    Seiichiro Uehara
    1987 Volume 82 Issue 3 Pages 106-118
    Published: March 05, 1987
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.82.106
    JOURNAL FREE ACCESS
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    Serpentinized ultramafic rocks and Sangun metamorphic rocks occur in the Sasaguri area, Fukuoka Prefecture. Lizardite and antigorite are the most abundant rock-forming minerals in the Sasaguri ultramafic rocks and are accompanied by lesser amounts of chrysotile (2Mcl and 2Orcl), magnetite, chromite, pyrite, pentlandite, millerite, forsterite, chlorite, talc, tremolite, anthophyllite, calcite, dolomite, magnesite, aragonite, hydromagnesite, artinite, brucite, pyroaurite, coalingite, szaiberyite, sepiolite, and deweylite, Serpentinites can be divided into following four types by the assemblage and grain size of serpentine minerals:
    (1) lizardite serpentinite,
    (2) lizardite-antigorite serpentinite,
    (3) fine-grained antigorite serpentinite,
    (4) coarse-grained antigorite serpentinite.
    The representative rock-forming serpentine minerals (five antigorites and one lizardite) and the two vein-forming fibrous chrysotiles in lizardite serpentinite were examined by X-ray, chemical, electron optical, thermal, and infrared absorption analyses.
    The significant differences in chemical composition and structural properties of antigorties are found. Fine-grained antigorites have low Fe contents (total FeO=1.6-2.5 wt%) and long supercell parameters (A=41.8-42.5 Å), and coarse-grained antigorites have high Fe contents (toal FeO=4.9-6.0 wt%) and short supercell parameters (A=35.4-40.5 Å).
    Lizardite and chrysotile show low Fe contents (total FeO=1-3 wt%). Many lizardite serpentinites in this area contain chrysotile 2Mcl. Its proportion is approximately 20 to 30 wt%.
    Povlen-type chrysotile is found in the vein-forming chrysotile specimen by electron microscope examinations.
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  • Incompatible trace element abundances of basanite from Nanzaki volcano, Izu peninsula
    Ken-ichiro Aoki, Takeyoshi Yoshida, Ken-ichi Ishikawa
    1987 Volume 82 Issue 3 Pages 119-122
    Published: March 05, 1987
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.82.119
    JOURNAL FREE ACCESS
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    Major and trace element abundances of basanite from Izu peninsula have been determined. Although primordial mantle-normalized incompatible element patterns of tholeiite and highalumina basalt in Izu peninsula district show a typical island arc type, those of basanite only exhibit the similarity to oceanic island alkali basalt type, except low ratios of Zr and Hf.
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