Further Occurrence of Brown Ores in Kuroko-type Deposits in Japan |
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| Authors: | Akira IMAI Osamu ISHIZUKA † Ryoichi YAMADA Hiroshi MIYAMOTO |
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| Institution: | Department of Earth and Planetary Science, University of Tokyo, 7–3–1 Hongo, Bunkyo–ku, Tokyo 113–0033, Japan [e-mail: ];Department of Geochemistry, Geological Survey of Japan, 1–1–3 Higashi, Tsukuba, Ibaraki 305–8567, Japan;Dowa Engineering Co. Ltd., 5–10–5 Shimbashi, Minatoku, Tokyo 105–0001, Japan;Akita Engineering Co. Ltd., 145 Doyashiki, Hanaoka, Ohdate–city, Akita 017–0005, Japan |
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| Abstract: | Abstract: The occurrence of so-called brown ore from the Kuroko-type deposits in Japan was examined. Brown ore specimens from the Kannondo, Inarizawa, Matsumine, Fukazawa, Uchinotai, Kosaka (orebody unknown) and Nurukawa deposits have been found in the ore collection stored by Dowa Mining Co. Ltd. and the subsidiary companies. In addition, occurrences from the Fukazawa, Matsumine, Ezuri, Shakanai, and Ginzan deposits were previously reported. The brown ore is characterized by its color and by its higher Ag concentration (up to around 2,400 g/t) than ordinary black ores. This type of ore occurs commonly in the Kuroko-type deposits in Japan, whereas its extent is limited. The brown ore is a type of Au-rich massive sulfide ore formed in submarine hydrothermal system. |
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| Keywords: | brown ore Kuroko–type deposits massive sulfide Au–Ag mineralization |
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