The Hishikari gold deposit, discovered by the Metal
Mining Agency of Japan, has become a giant class epithermal gold deposit with
the highest grade of gold yet recorded in the world through detailed exploration
and development by the Sumitomo Metal Mining Co Ltd. The exploration strategy
involved a regional approach combining geological and gravity surveys over a 900
km2 area which had historically produced over 120 t of
gold. These surveys were carried out to grasp the common geologic features of
epithermal gold deposits in the survey area. A genetic model for epithermal gold
deposits in the area under regional survey was also considered based on detailed
research of the Kushikino epithermal gold deposit which was in operation at that
time. This model was applied to the targeted areas, and important relationships
between mineralisation, host lithology, intensive propylitic alteration and
gravity highs became apparent. The Hishikari block was selected in this way and
bonanza gold was discovered during drilling. Since the development of the
Hishikari mine, information useful for further exploration for the same type of
deposit has been accumulated.