The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
Volume 53, Issue 1
Displaying 1-3 of 3 articles from this issue
  • ASAHIKO SUGAKI
    1965 Volume 53 Issue 1 Pages 1-18
    Published: January 05, 1965
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    To use unmixing chalcopyrite and bornite intergrowth as geothermometer, it is necessary to take into account the relation between composition of solid solution and its unmixing temperature. The relation is to be acquired from the solvus in the phase diagram of the join Cu5FeS4-CuFeS2-x From this veiwpoint, thermal study on the solvus was carried out by the author by using bornite-chalcopyrite solid solutions synthesized by reaction between copper and iron sulfides, which were made by heating metallic copper, iron and crystal sulfur in glass tube sealed under vacuum. The results obtained are as follows:
    1) The solvus on the bornite side in this a join is given in Fig. 4. From this solvus, it is found that unmixing temper a ture of the solid solution with 93.4%, 81.8%, 67.5%, 63.3% and 59.4% bornite in molecule are 375°C, 425°C, 500°C, 525°C and 540°C respectively. Thus the solvus between 375°C and 525°C is shown by a straight line having gentle slope, while it shows a steep inclination above 525°C. It is also presumed that the curve shows a steep gradient below 375°C.
    2) The relation between lattice constant and composition of solid solution from 100% to 59.4% in bornite molecule is represented by a straight line between 10.946 ?? and 10.847 ?? as shown in Fig. 3.
    3) As seen in Figs. 4 and 5, the area of solid solution on the bornite side is distinctly wider than that on the chalcopyrite side. It agrees with the fact that, in nature, chalcopyrite lamellae unmixed from bornite solid solution are very common, when examined under microscope, whereas exsolution bornite lamellae in chalcopyrite are very rare.
    Using the relation between lattice constant and composition of the solid solution together with solvus in this join, unmixing or forming temperature of the bornite-chalcopyrite solid solution can be inferred.
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  • Yu Hariya, Shoichi Terada
    1965 Volume 53 Issue 1 Pages 19-25
    Published: January 05, 1965
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    Pyrolusites from two localities in southwestern Hokkaido, Japan, were studied by means of DTA, thermo-balance and high temperature X-ray analysis. From the thermal behavior of the first endothermic reaction generally pyrolusite seems to deoxidize abruptly at about 680°C transforming into α-Mn2O3. A specimen from Hanaishi, however, shows double peaks by endothermic reaction at about 710°C and 773°C. The first endothermic peak at 710°C of this specimen shows transformation into α-Mn2O3 and γ-Mn2O3. γ-Mn2O3 phase is an unstable from at high temperature. The second peak at about 773°C of this pyrolusite is due to the following endothermic reaction: α-Mn2O3+γ-Mn2O3→α-Mn2O3+Mn3O4. Two types of pyrolusite, one with a single peak and the other with double peaks can be distinguished from DTA and thermo-balance curves.
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  • Hitoshi Onuki
    1965 Volume 53 Issue 1 Pages 26-38
    Published: January 05, 1965
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    Nine clinopyroxenes, separated from serpentinized peridotite, olivine clinopyroxenites, clinopyroxenite, hornblened clinopyroxenite and clinopyroxene hornblendites of the Miyamori ultrabasic intrusive, Kitakami mountainland, have been chemically analysed and optically determined. These clinoproxenes have a range from Ca47.1 Mg49.1 Fe3.8 to Ca48.6 Mg35.2 Fe16.2. The trend line of the clinopyroxene crystallization takes a course from diopside field to salite field. The Al proportions in the clinopyroxenes are thought to be mainly controlled by chemical composition of the magma from which they are crystallized in the case of the Miyamori ultrabasic body as well as the Hayachine ultrabasic complex. Some considerations on the chemical nature of clinopyroxenes are shortly discussed.
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