著者

新田 富也 深堀 康昌 山田 毅

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.23, no.118, pp.99-110, 1973-05-25 (Released:2009-06-12)

参考文献数

12

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Several copper orebodies are discovered in the deeper portion of the Mozumi mine during a recent development. Some results of the investigation on the geologic structure, mineralization and occurrence of ore minerals are summarized as follows:1) The Mozumi ore deposits have been developed more than 900 meters in depth. A remarkably vertical zonal arrangement of the ore minerals is observed as follows; in descending order, none mineralized limestone, lead-zinc ore with calcite-quartz (shiroji ore), lead-zinc ore with skarn (mokuji ore), copper-zinc ore with skarn (mokuji ore), copper ore bearing pyrrhotite with skarn (mokuji ore), barren skarn.2) Copper orebodies occur generally in the center of mineralized area.3) Copper ores can be classified into four types by the mineral assemblage. It is observed that the mineral assemblage is simpler in the center of mineralization.4) These copper orebodies are considered to be formed during two mineralization stages. The earlier mineralization stage was mainly lead-zinc, which was associated with small amount of copper. The mineralization of later stage which was overlapped to the earlier stage in some places, was mainly copper.5) The main copper mineral is chalcopyrite. Generally in these copper orebodies, it is observed that sphalerite includes fine grained chalcopyrite and pyrrhotite as exsolution paragenesis6) The iron content of sphalerite in copper orebodies are higher than that of sphalerite in lead-zinc orebodies.7) Two types of pyrrhotite are recognized; One is a monoclinic type and another is a hexagonal type. The hexagonal pyrrhotite occurs usually in the center of the mineralization. In an orebody, the hexagonal pyrrhotite occurs usually at the core. In some cases, it is observed that these arrangements are disturbed and, microscopically, they show exsolution lamellae texture.