Further occurrence of brown ores in Kuroko-type deposits in Japan

The occurrence of so-called brown ore from the Kuroko-type deposits in Japa n 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 sub sidiary companies. In addition, occurrences from the Fukazawa, Matsumine, E zuri, Shakanai, and Ginzan deposits were previously reported. The brown ore is characterized by its color and by its higher Ag concentration (up to ar ound 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 br own ore is a type of Au-rich massive sulfide ore formed in submarine hydrot hermal system.