Geology of the Kanagato Copper Mine, Yamaguchi Prefecture

Abstract

The Kanagato copper mine is situated at about 20 km. N. of Ogori Station, Sanyo Railway. Ore deposits of the mine are of hypothermal fissure-filling type.
Ore minerals are mainly chalcopyrite, arsenopyrite, pyrrhotite and pyrite, accompanied by small amounts of scheelite, bismuthinite and native bismuth. Ore deposits are characterized by the presence of tourmaline as well as by a minor content of cobalt in arsenopyrite. Fissures filled with ores are shear fractures, linked with each other and running in the directions of N 20 W and N 10-20 E. Elongation of the fissure zones attains to more than 1, 000 meters. There are several zones containing ores. Ore bodies, numbering one hunderd or more in developed areas, are variable in shape such as lenses bunches, etc., and are irregulanly scattered in the fissure zones.
Ore shoots are elongated vertically, being 2-20 meters in horizontal length and 10-200 cm. in width. The west-Hobenzan granodiorite, intruding the upper Palaeozoic formation of slate, sandstone and schalstein, is the ore bringer, whereas the Palaeozoic formation are the wall rock of ore deposits. Stock of the granodiorite has slightly metamorphised rhyolite which is believed of be a member of upper Cretaceous volcanics.