The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
Search
Advanced search
OR
Browse
Search
Volume 47, Issue 6
Displaying 1-4 of 4 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
  • Zircons in rhyolites and dacites
    Takashi Yamamoto, Kazuko Matsukuma
    1962 Volume 47 Issue 6 Pages 205-212
    Published: June 05, 1962
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.47.205
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Mineralogical properties (crystal faces, elongation-ratio and size) of zircons in rhyolites and dacites are examined with the following results.
    (1) Color of zircons ranges from plae pink, yellowish brown to colorless.
    (2) Size of zircons is mostly about 0.15×0.08mm.
    (3) Zircons occur mostly as beautiful, euhedral crystals, free from corrosion.
    (4) The elongation-ratio (longer axis/shorter axis) falls mostly in group II (1.6-2.0).
    (5) When the crystal habits of zircon are classified into a, b, c, d, and e, the c-type is the most common, amounting to 80%.
    View full abstract
    Download PDF (329K)
  • Alkali-pyroxene in doleritic basalt flow from the Higashi-Matsuura district, Saga Prefecture,
    Kiyoshi Ishibashi
    1962 Volume 47 Issue 6 Pages 213-222
    Published: June 05, 1962
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.47.213
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The clino-pyroxenes in basaltic folws from the Higashi-Matsuura district, range i the chemical composition from purple-augite through salite to aegirine-augite. In distinctly porous doleritic basalt flows, purple-augite grades in its margin into soda-augite or aegirine. Such an occurrence of zoned pyroxene is not uncommon in intrusive alkalic rocks, but rare in extrusive flows. Two kinds of purple-augite separated from parts of different of porosity a single lava flow were chemically analysed. Chemical formulas and optical porperties are as follows:
    No. 1.
    (Ca0.79 Na0.05 K0.05) 0.85 (Fe''0.32 Fe'''0.09 Mg0.74 Ti0.05) 1.21 (Si1.86 Al0.10) 1.96 O6.00 β=1.698-1.702 2Vz=50°-54° c∧Z=50°-52°
    No. 2.
    (Ca0.28 Na0.08 K0.01) 0.85 (Fe''0.29 Fe'''0.10 Mn0.01 Mn0.01 Mg0.72 Ti0.04 Al00.1) 1.16 (Si1.87 Al0.13) 2.00 O6.00
    β=1.701-1.704 2Vz=53°-58° c∧Z=50°-52°
    Genetic consideration on these pyroxenes is also given.
    View full abstract
    Download PDF (1594K)
  • Mineralogical studies on the chromites in the Tari District, Tottori Prefecture (II)
    Jun-ichi Kitahara
    1962 Volume 47 Issue 6 Pages 223-231
    Published: June 05, 1962
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.47.223
    JOURNAL FREE ACCESS
    Download PDF (560K)
  • TEXTURES AND STRUCTURES OF THE GOLD-COPPER ORES OF THE CHINKUASHIH MINE, TAIWAN
    C. K. HUANG
    1962 Volume 47 Issue 6 Pages 232-240
    Published: June 05, 1962
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.47.232
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Various textures and structures indicative of cavity-filling and replacement of the Chinkuashih gold-copper ores are described and interpreted.
    They are in general characterized by the formation under the conditions of low temperatures and shallow depths. However, there is no evidence for the hypogene minerals deposited as colloids even in the interesting botryoidal and reniform ores.
    It is worthy of note that inter-mineral movement has occurred after deposition of enargite and luzonite and before that of alunite.
    View full abstract
    Download PDF (2005K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top