Journal of The Gemmological Society of Japan
Online ISSN : 2189-8413
Print ISSN : 0385-5090
ISSN-L : 0385-5090
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Articles
  • Masayuki KAWASAKI
    2020 Volume 34 Issue 1-4 Pages 3-12
    Published: March 30, 2020
    Released: March 29, 2020
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    Our recent observation on the morphology of natural and synthetic quartz crystals is reviewed. The basal face in natural quartz crystal from Four Peaks(Arizona), Sichuan (China) and Nose (Osaka), the Japanese twin from Narushima (Nagasaki) and the abacus ball-type crystals from Dal’negorsk (Russia) are mentioned. On the synthetic quartz crystals, it is stressed that mixed dislocations play a different role in the growth mechanism between the smooth interfaces (r, z, m) and the rough interface (Z). Mixed dislocations form spiral growth hillocks (r, z, m), and show two-dimensional morphological instability to form cobble II (Z). Adsorption of Al impurity along steps on the vicinal face of growth hillocks on the m face controls the macro-morphology (enlargement of the S face).

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  • Mikio Hara
    2020 Volume 34 Issue 1-4 Pages 13-20
    Published: March 30, 2020
    Released: March 29, 2020
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    The author summarizes technical development of mass production of high quality quartz crystals in Toyo Communication Equipment Co. Ltd where he worked since 60 years ago. In the project, reactors have been increased to volume of 650 mmφ x 14 m long with overcome of many problems such as sealing structure and temperature control system. Episodes on seed crystals, high quality crystals for optical applications, colored crystals, accidents and awards are also presented.

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Articles
  • Shigenori OGIHARA
    2020 Volume 34 Issue 1-4 Pages 21-26
    Published: March 30, 2020
    Released: March 29, 2020
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    Yooperlite is a fluorescent stone distributed on the shores of Lake Superior. Microscopic observation, chemical analysis and X-ray analysis were performed on the origin of Yooperlite fluorescence. Yooperlite is syenite in the rock name, and the fluorescent mineral is sodalite. The short wave fluorescence of Yooperlite is 30 times stronger than the long wave fluorescence. The origin of long wave fluorescence has been reported to be Sulfur (S). In contrast, the origin of short wave fluorescence is probably Iron (Fe) and/or Tin (Sn). Yooperlite analyzed in this study, has a low S concentration. Therefore, short wave fluorescence is a relatively stronger compared to long wave fluoresence. Yooperlite lacks nepheline, and margin of albite in Yooperlite altered to sodalite. The origin of sodalite is probably due to the alkaline alteration of nepheline and albite.

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