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Volume 21 (1999)
- Issue 4 Pages 145-
- Issue 3 Pages 103-
- Issue 2 Pages 53-
- Issue 1 Pages 1-
Volume 21, Issue 4
Displaying 1-3 of 3 articles from this issue
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Satoshi MATSUBARA, Akira KATO, Masayuki TAKADA, Ritsuro MIYAWAKI1999 Volume 21 Issue 4 Pages 145-150
Published: 1999
Released on J-STAGE: March 31, 2007
JOURNAL FREE ACCESSMorphological and chemical studies on high quartz-like trigonal dipyramids from voids in a medium-grained massive augelite-trolleite-andalusite-quartz rock from pyrophyllite deposit of the Hinomaru-Nako mine, Abu-cho, Yamaguchi Prefecture, western Japan, suggest they are trolleite-augelite pseudomorphs after berlinite. The occurrence indicates that the formation of berlinite was of hydrothermal origin and took place after the precipitation of pyrite, or under lower temperature and pressure conditions. Also, the existence of trolleite as a pseudomorph in voids is interpreted as proof that its formation does not always require high-pressure metamorphic conditions.View full abstractDownload PDF (663K) -
Makio OHKAWA, Setsuo TAKENO, Akira YOSHIASA, Kazumasa OHSUMI1999 Volume 21 Issue 4 Pages 151-156
Published: 1999
Released on J-STAGE: March 31, 2007
JOURNAL FREE ACCESSThe crystal structure of Fe-pumpellyite from Iwakake, Shimobe-cho, Nishiyatsushiro-gun, Yamanashi Prefecture, Central Japan was investigated by a Weissenberg camera combined with a monochromated synchrotron radiation of wavelength 1.000 Å and an imaging plate. Crystallo-graphic parameters are a = 8.884(3), b = 5.899(4), c = 19.292(6) Å, β = 97.49(3)°, A2⁄m. The octahedral X-site is larger than the octahedral Y-site. The obtained constrained occupancy ratios of Fe for the X- and Y-sites are 24% and 18%, respectively, i.e., 40% and 60% of total Fe distribute in the X- and Y-sites, respectively.View full abstractDownload PDF (840K) -
Kiyotaka ISHIDA1999 Volume 21 Issue 4 Pages 157-166
Published: 1999
Released on J-STAGE: March 31, 2007
JOURNAL FREE ACCESSCrystal-structural changes accompanied by oxidation and dehydrogenation processes have been examined for holmquistite, sodic-calcic and sodic amphiboles in which all Fe2+ ions occur at the M1 and M3 sites, using infrared and Mössbauer spectroscopy. When almost all Fe2+ are oxidized to Fe3+, a new OH-stretching band E appears at lower frequency (∼ a few cm−1) than the principal C band. This band is assigned to (MgMgFe3+)–OH stretching and its configuration to O2−–(MgMgFe3+)–(OH)−. The occupancy of Fe3+ at M1 increases greatly by oxidation and dehydrogenation.View full abstractDownload PDF (800K)
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