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 81, Issue 10
Displaying 1-5 of 5 articles from this issue
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  • Teallite from the Toyoha mine, Hokkaido
    Asahiko Sugaki, Kenichiro Hayashi
    1986 Volume 81 Issue 10 Pages 393-398
    Published: October 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.393
    JOURNAL FREE ACCESS
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    Teallite was firstly found in Japan from a new vein (Sorachi uwaban-hi) of the Toyoha mine, Hokkaido. It occurs in association with galena and sometimes sphalerite in central drusy portion of zinc and lead veinlet, 0.5 to 1.0cm in width, which cuts principal pyrite ore containing sphalerite, arsenopyrite, quartz and small amounts of cassiterite and stannite in the vein.
    Teallite appears as aggregate of curved thin-platy or flaky crystals, 0.5 to 5.0mm in length and 1 to 20μm in thickness, and shows metallic ruster of silver white in color. Under ore microscope, it has distinct pleochroism from yellowish white to pale brownish white, and strong anisotropism from brownish gray to bluish brown. It changes to black immediately by HNO3 (1:1), and reacts slightly with FeCl3 (20%) to stain pale brown. No etching reaction with HCl(1:1), HgCl2 (sat.), KCN (20%) and KOH (sat.) was observed. The reflectances measured at 406, 436, 497, 546, 586 and 648nm in wave length are: 34.3-50.0, 31.5-50.7, 32.1-50.2, 34.7-49.7, 35.2-48.6, 34.5-49.5%, respectively. Vickers hardness (10g load) on {010} is 10.8-19.3kg/mm2. Its cell dimension is orthorhombic, a=4.258 (1), b=11.447 (3), c=4.103 (1)Å. Chemical compositions of teallite obtained by EPMA are Pb1.07-1.10Cu0.02-0.04Fe0.01-0.02Zn0.02-0.08Sn0.84-0.87S1.95-2.02 on the basis of 4 atoms per molecule. They are plotted in PbS side of PbSnS2 in the PbS-SnS join, although all the compositions of teallite reported by authors up to now are in the SnS side of the join.
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  • Chemical composition of Cr-bearing garnets in Japan
    Teruko Kobayashi
    1986 Volume 81 Issue 10 Pages 399-405
    Published: October 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.399
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    Existence of uvarovite has not been reported so far in Japan. Specimens labeled uvarovite crystals from 19 localities in Sakurai Collection were analysed by an electronprobe microanalyser, confirming some uvarovite crystals. Uvarovite and Cr-bearing andradite occur in a fine vein in aggregate of chromite or magnesiochromite. In serpentine with diopside or talc occur uvarovite, Cr-bearing andradite and Cr-bearing grossular.
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  • Photon-activation analysis of standard rocks using an automatic γ-ray counting system with a micro-robot
    TAKEYOSHI YOSHIDA, KAZUYOSHI MASUMOTO, KEN-ICHIRO AOKI
    1986 Volume 81 Issue 10 Pages 406-422
    Published: October 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.406
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    Nondestructive multi-element photon-activation analysis has been used to determine the abundance of thirteen trace elements: Ba, Ce, Co, Cr, Cs, Nb, Ni, Rb, Sc, Sr, Y, Zn and Zr in nine GSJ standard rocks (JR-1, JR-2, JG-1, JA-1, JB-1, JB-2, JB-3, JGb-1 and JP-1) and four USGS standard rocks (G-2, GSP-1, AGV-1 and BCR-1). Rock samples and multi-element standards were irradiated simultaneously with 30 MeV bremsstrahlung. The (γ, n) and (γ, p) reaction products were measured with an automatic γ-ray counting system with a micro-robot.
    In a typical measurement, the counting statistics error is lower than 5% for concentrations>2ppm for Nb, 5ppm for Ce, 10ppm for Co, Rb, Sr, and Y, and for Zr at concentrations>20ppm. The abundance of elements in the rock standards obtained with the present facility are in good agreement with the reported data in most cases. Precision is better than ±5% (lσ) for concentrations>10ppm for Nb and Y, >50ppm for Sr, and for Co, Rb, and Zr at concentra-tions>25 to 40ppm, depending on the element. It is important for volcanic geochemistry in island arcs to determine Nb, Y, and Zr together with Rb and Sr accurately.
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  • Cenozoic minette from Kawamoto district, Shimane Prefecture, Southwest Japan
    Takashi Nagao, Yukio Matsumoto, Takaaki Matsuda, Shigeru Iizumi, Motoa ...
    1986 Volume 81 Issue 10 Pages 423-426
    Published: October 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.423
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    In Southwest Japan arc, Cenozoic alkali basalts are widely distributed. Recently, we found highly potassic mafic lavas (minette) erupted in the Kawamoto district, Shimane Prefecture. The rock is high in K2O content (7.12wt%) and its K2O/Na2O ratio (2.6) is also high. The rock is characterized by phenocryst of phlogopite in a groundmass consisting of sanidine, apatite, Capyroxene, titanian aegirine, phlogopite and titanomagnetite. The phlogopite phenocryst has high mg value (100×Mg/Mg+Fe) ranging from 85.8 (core) to 79.3 (rim) and high Cr2O3, content (0.5wt% in core).
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  • Report on the 14th IMA General Meeting
    Ichiro Sunagawa
    1986 Volume 81 Issue 10 Pages 427-431
    Published: October 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.427
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