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Please use this identifier to cite or link to this item: http://hdl.handle.net/10087/6833

Title: 群馬県片品村赤澤鉱山からトパーズ含有鉱石の発見
Other Titles: The occurrence of topaz-bearing ore from Akazawa mine, Katashina, Gunma, Japan
Authors: 吉川, 和男
真崎, 将太
小林, まさ代
Yoshikawa, Kazuo
Mazaki, Shota
Kobayashi, Masayo
Issue Date: 14-Feb-2012
Publisher: 群馬大学教育学部
Citation: 群馬大学教育学部紀要 自然科学編 60, 15-25, 2012
Abstract: The topaz-bearing ores were found from the Akazawa mine,Katashina,Gunma Prefecture,Japan. This is the first finding of topaz from the mines in Gunma Prefecture. The Akazawa mine is an abandoned copper mine and the ore deposit lies in the Okunikkou rhyolites (late Cretaceous~Paleozoic). Seventeen minerals were found in the wastes from the Akazawa mine:chalcopyrite,sphalerite,arsenopyrite, pyrite, pyrrhotite, galena, native sulfur, quartz, topaz, calcite, chlorite, sericite, kaolinite, feldspar, anglesite, goethite and jarosite. The unit-cell dimensions of chalcopyrites, sphalerites, arsenopyrites, pyrites, pyrrhotites, galena, quartzes and topazes were calculated. Galena occurs only in the wastes carrying topaz. Anglesites are formed at the margin or along the cleavage planes of galena. A small amount of sericite and kaolinite occur only in topaz-bearing wastes. Most of gangue minerals are quartz. Two kinds of quartz are found in the topaz-bearing wastes. One is coarse-grained euhedral to subhedral crystals or their fragments. The other occurrence is fine-grained quartz mosaic,surrounding coarse-grained quartz. Some coarse-grained quartzes are partly corroded and are recognized the successively growing after the corrosion. Topaz occurs in a few wastes as the radial aggregates of colorless columnar crystals (usually less than 0.1mm in long) around chalcopyrites, sphalerites and galenas. In the quartz mosaic, topazes crystallize between quartz grains and seem to be going to replace quartzes. The OH/(OH+F) value of topaz was estimated from the unit-cell dimensions and volume (Wunder et al. 1993). The average value was 0.21 atom.% and this is corresponding to 16.39wt% in F contents of the topaz.The temperature of the formation of the arsenopyrite from the Akazawa mine is 490~560℃,on the basis of the arsenopyrite geothermometer by Sharp et al. (1985).
URI: http://hdl.handle.net/10087/6833
ISSN: 0017-5668
Appears in Collections:第60巻 (2012)

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