Epithermal Gold Exploration in the Iriki District, Kagoshima, Japan

Abstract The Iriki district was chosen by the Metal Mining Agency of Japan (MMAJ) as a target for epithermal gold exploration on the basis of the following criteria: the presence of steam-heated acid alteration, a gravity anomaly high, geochemical characteristics of hot spring water similar to those of water from the Hishikari gold deposit, and old mining activity. In 1994 and 1995 the MMAJ carried out exploration that included alteration mapping, geochemical and geophysical surveys, and diamond drilling. of note, several drill holes intersected gold mineralization returning approximately 6 g/t Au at more than 4 m beneath the steam-heated acid alteration. On the basis of the sulfide assemblage, mineralization in the Iriki district is not typically high sulfida- tion, as alteration assemblages and the presence of arsenopyrite may suggest, but is more akin to the intermediate-sulfidation style described by Hedenquist et al. (2000 and 2001). The characteristics of the mineralization in the Iriki district are concordant with the magmatic characteristics of hot springs from the Iriki and with the presence of young host volcanic rocks in the Iriki district.