Mineral Assemblages and Textures of the Ores from Uchinotai Ore Deposits, Kosaka Mine (Part 1)

The ores are devided into three types. Keikô(siliceous ore) and Ôkô(yellow ore) show simple textures and mineral assemblages. The former consists of pyrite, chalcopyrite and quartz and the latter of pyrite and chalcopyrite. In both ores, pyrite is euhedral or subhedral. On the contrary, mineral assemblages and textures of Kurokô(black ore) are very complicated. Main constituents are barite, pyrite, chalcopyrite, sphalerite, galena and tetrahedrite. Under the microscope, diaspore, native gold and unknown Ni-bearing mineral are found. These minerals are intimately associated with each other making colloform and mottled textures. A cupola of keikô, located near the center of the deposits, differs from the keikô above-mentioned in showing colloform textures and bearing minor barite, sphalerite and galena.