山形県磯部小山鉱山の金銅鉱床

• 磯部 清

  合同資源産業株式会社

• 保科 恒二

  合同資源産業株式会社

• 苣木 浅彦

  山口大学工学部資源工学科

書誌事項

タイトル別名

• The Gold and Copper Ore Deposits of the Isobe Koyma Mine, Yamagata Prefecture

抄録

The Isobe Koyama mine is situated at about 30 kilometers northwest of Yamagata City and is producing copper and gold ores. The district is composed mainly of Miocene pyroclastic rocks and their lava flows of intermediate to acid type with some mudstone. The ore deposits of this mine consist of twelve bodies which occur in mudstone, muddy tuff, and green tuff. They are of an epithermal type and occuring veins, stockwork or as disseminating bodies. Native gold, chalcopyrite, sphalerite, pyrite, and galena, are the principal ore minerals, associated with such gangus minerals as quartz, kaolin, chlorite, barine and carbonate minerals.<BR>Native gold occurs in intimate association with quartz, kaolin, sphalerite and chlcopyrite. The ore comprising chalcopyrite, sphalerite chlorite and quartz is often so rich in gold that its gold tenor is more than one kilogram per ton. However, the grade of silver in the ore is always less than that of gold. The gold-silver ratio is a characteristic of the ore from the mine in comparison with that of the ores from the so-called epithermal gold-silver deposits in which the tenor of silver is usually ten or several ten times of that of gold.<BR>The vertical zoning of ore deposit is obvious, often divided into the following five zones from upper to lower : 1) quartz-kaolin zone, 2) quartz-kaolin-sphalerite zone, 3) sphalerite zone, 4) sphalerite-chalcopyrite zone and 5) chalcopyrite zone. The native gold occurs in the zones 1), 2), 3) and 4), especially richest in zone 4). In zone 5 ), the tenor of gold rapidly decreases to less than 2 grams, per ton. This zoning is also found in lateral derection. The central zone is the chalcopyrite zone, which may indicate a center of mineralizaton in this mine. Also, the fissures filled with ores seem to be mostly tension fractures, judging from their pattern.

収録刊行物

• 鉱山地質

  鉱山地質 17 (81), 22-37, 1967

  資源地質学会

詳細情報

• CRID: 1390282681501820288
• NII論文ID: 130003639126
• DOI: 10.11456/shigenchishitsu1951.17.22
• ISSN: 00265209
• データソース種別:
  • JaLC
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可