愛媛県ひ之奥鉱床の鉱石鉱物

抄録

The Hi-no-oku ore-deposits are of the bedded cupriferous iron sulfide deposits type and occur generally along the schistosity plane of green schist of the Kawaguchi formation in the Sanbagawa metamorphic zone, Shikoku.
The ore minerals consist chiefly of pyrite, chalcopyrite and pyrrhotite. The ore is rich in pyrrhotite, wich is somewhat different from other ordinary bedded cupriferous iron sulfide deposits in the Sanbagawa metamorphic zone. This kind of deposits is, however, commonly found also in the same zone as the Hi-no-oku ore-deposits.
The colloform texture of pyrite, the intergrowth of pyrite and magnetite, and pyrite and marcasite pseudomorph after pyrrhotite are observed. These textures are found only in pyrrhotite-bearing ores and seem to be secondary texture due to alteration of pyrrhotite.
The writer thinks that there are two types of occurrence of colloform pyrite in the bedded cupriferous iron sulfide deposits ; one is primary type occurring in weakly metamorphosed area, and the other is secondary type occurring in association with pyrrhotite. In the latter case, the country rocks vary in grade of metamorphism.
'Colloform' pyrite and marcasite in the Hi-no-oku ore-deposits may have been. formed by the retrogressive metamorphism in the later stage of the Sanbagawa metamorphism.