Mineralogical Journal
Online ISSN : 1881-4174
Print ISSN : 0544-2540
ISSN-L : 0544-2540
Volume 7, Issue 6
Displaying 1-6 of 6 articles from this issue
  • SATOSHI MATSUBARA, KOZO NAGASHIMA
    1975 Volume 7 Issue 6 Pages 513-525
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    Orthoericssonite, BaMn2+2Fe3+ [O|OH|Si2 O7], hitherto reported only from the Långban mine, Sweden, was found in a jacobsite-bearing rhodonite-aegirine-tephroite ore from the Hijikuzu mine, Iwate Prefecture, as a product of strong thermal metamorphism due to granitic intrusion. It is orthorhombic, space group Pmmn, a0=20.30Å, b0=6.986Å, c0=5.387Å, Z =4. Wet chemical analysis by K. N. gives the empirical formula (Ba0.688Sr0.256K0.024Na0.013Li0.003)0.984(Mn1.4352+Fe0.5462+Mg0.086)2.067(Fe0.9313+Ti0.093Al0.034)1.058Si2.062 O7.000(O1.389(OH)0.611)2.000 as O=9, specifying it as a strontian and ferroan variety. It is optically biaxial positive, 2V about 50°, r ?? v strong, ns α=1.802, β=1.840, γ=1.888; strongly pleochroic, X=yellowish brown, Y=reddish brown, and Z=dark brown.
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  • YASUNORI MIÚRA, TAKESHI TOMISAKA, TOSHIO KATO
    1975 Volume 7 Issue 6 Pages 526-541
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    The well-known optical behavior of iridescent labradorite is discussed. The observation of labradorescence, in which the color changes from violet to red as the lamellar thickness and An content increase, is supported by the results of calculation. Theoretical treatment of the optical phenomenon of labradorescence corresponds to a kinematic theory of diffraction. Based on the observations with an electron probe microanalyzer and an electron microscope, the ideal behavior of alternate lamellae in the Bφggild intergrowth is estimated. The thickness of An-rich lamella increases up to An65±, while that of An-poor lamella increases up to An50 and then decreases describing a parabola.
    The regression equation for the lamellar thickness d(Å) and the wavelength λ(Å), where the maximum of reflected intensity appears, is obtained as follows : λ=3.105•(d)-21.178. The result of calculation from the equation obtained suggests, together with this regression equation itself, that the maximum of reflected intensity takes higher value when (na, nb)=(1.55, 1.57) in violet- to blue-iridescent labradorite, (1.55, 1.56) in green one, (1.54, 1.57) and (1.55, 1.56) in yellow-to red-one, where na=(αa+βaa)/3 and nb=(αb+βbb)/3, than the case of other combinations. This calculated result may sufficiently explain the experimental results and data obtained from analytical electron microscope.
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  • Y. FUJIKI, Y. HASEGAWA
    1975 Volume 7 Issue 6 Pages 542-551
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    Conditions and process of hydrothermal growth of As2S3 crystals were examined. Although it has been known that As2S3 is quite soluble only in alkaline solutions, it was found in this study that it is also soluble in weakly acid solution, as well as in neutral solution. As2S3 crystals usually grew in the form of spherulitic aggregation regardless of the growth conditions and the chemical species in the solvents. The process of spherulite formation is discussed. The crystals grown from an H20 solvent gave a=11.394±0.009Å, b=9.581±0.008Å, c=4.267±0.004Å, β=90°03′±6′, V=465.8±0.5Å3.
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  • TATSUO TATSUMI, FUMIMARO NAKAYAMA, TETSURO URABE, HIDEHIKO SHIMAZAKI
    1975 Volume 7 Issue 6 Pages 552-561
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    Mode of occurrence and mineralogical properties of carrollite from the Sazare mine are described. The deposits of the mine are of the stratabound massive sulphide type in the Sanbagawa metamorphic terrain in Shikoku, Southwest Japan. The carrollite is found exclusively in a copper rich ore which occurs close to hanging- or footwall side of the main orebody or to apophyses, while common massive or banded ore does not contain the mineral. The mineral is usually associated with chalcopyrite and bornite, and also with pyrite, sphalerite or tetrahedrite in some cases. Under the reflection microscope, the mineral shows rather similar appearance to pyrite, but is more faint in reflection colour giving always traces of cubic cleavage. Its chemical composition analysed by EPMA was as follows: Cu=20.2, Co=38.0, Fe=0.2, Ni=0.9, S=42.0, Total=101.3 in wt. %. Atomic ratio of metals in the mineral calculated on the basis of S=4.00 is (Cu0.97Co1.97Fe0.01Ni0.05)3.00S4.00. a0 by powder camera method (Ø=114.59mm) is 9.478±0.002 Å. The mineral is thought to be of metamorphic origin which was formed through recrystallization of chalcopyrite-pyrite ore during the Sanbagawa metamorphism from its mode of occurrence. Cobalt in the carrollite seems to be originally contained as a minor element mainly in primary pyrite. Chemical composition and a0 value of carrollite from the Nkana mine, Zambia were also determined for comparison.
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  • A moonstone having sodium phase twinned according to pericline law
    MASAHISA TATEKAWA
    1975 Volume 7 Issue 6 Pages 562-574
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    The moonstone examined is anorthoclase cryptoperthite (Or40, Ab50, An10) having a bluish purple iridescence which may be caused by fine lamellae in parallel to rhombic section (near (-601)). The moonstone is composed of one monoclinic potassium phase, one monoclinic sodium phase and three triclinic sodium phases, all these four sodium phases having same chemical composition. The iridescence disappeared on heating the moonstone at temperatures above 618°C at which the moonstone lost the lamellar structure.
    In the light of the mutual orientation of those constituent five phases, the perthitic structure of the moonstone is a new type, a model of which is proposed in Fig. 7.
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  • MASAHISA TATEKAWA
    1975 Volume 7 Issue 6 Pages 575-581
    Published: 1975
    Released on J-STAGE: March 18, 2008
    JOURNAL FREE ACCESS
    A zonally grown mica from a granitic pegmatite was examined with the following results.
    (1) The mica may be a chemically discontinuous overgrowth of iron-muscovite (marginal part) on biotite (core).
    (2) They are crystallographically continuous and both are of 3-layer monoclinic polytype.
    (3) X-ray precession photographs of the mica show that the mica is a twin crystal, the twinning plane of which is (07-1).
    (4) The diffuseness of the X-ray reflection spots of the mica indicates that the crystal lattice is regular in the direction approximately parallel with the a-axis while it is less regular in the direction approximately parallel with the b- and c-axes.
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