The Buho Project lies within the Sapporo-Iwanai Mineral district, which contains at least 65 known gold-silver and polymetallic mineral deposits formed during the Neogene. Historic epithermal gold mines within this district include Chitose (736 Koz at 14.5 g/t Au, 2.7 Moz Ag), Tiene (352 Koz at 7.5 g/t Au, 4.2 Moz Ag) and Todoroki5 (188.3 Koz Au and 7 Moz Ag – 1METI, 1990). Kuroko-type deposits occur in the region, such as Toyoha (1.8 Mt Zn, 0.5 Mt Pb, 3 Kt Ag and 8 Kt Cu). There is no known gold and silver production reported from the historic Buho workings that lie within the tenement. These are believed to be near-surface workings developed in silicified rhyolite and associated with preserved hot-spring depositional features such as hydrothermal eruptive breccia and silica sinter.
The Buho workings and the immediate area were most recently explored by a joint venture between the Nisho Iwai trading company and the Australian company Austpac Gold NL (‘NICA JV’) in the early 1990’s. The NICA JV completed geological mapping, geochemical rock sampling, a CSAMT survey, two diamond and three percussion drillholes that tested beneath, and surrounding, the Buho workings. Soils above the Buho workings are enriched in mercury and the CSAMT survey defined strong resistivity contrasts suggesting hydrothermal alteration at depth. Six mine dump samples collected by the NICA JV averaged 1.9 g/t gold with a high of 9.1 g/t gold and 370 g/t silver. A 40 cm wide vein exposed in an upper adit assayed 5.0 g/t gold and 27 g/t silver. One diamond drill hole DDH-B1 intersected a zone of epithermal quartz-adularia breccia veins at about 100 to 140 m below surface, which returned a high-grade gold-silver intercept of 3.5 m at 21.8 g/t Au and 42 g/t Ag from 130.1 m (including 0.9 m @ 72.8 g/t Au and 65 g/t Ag – 2Austpac 1992). True widths were not reported or are unavailable. The best percussion hole (B4) interval was 0.4 m @ 10.0 g/t Au and 10 g/t Ag from 184.7 m. Exploration ceased after Austpac withdrew from the joint-venture and ceased its operations in Japan.
After the NICA JV exploration program, the Metal Mining Agency of Japan (‘MMAJ”) completed a regional exploration program over the mineral district including Buho, which entailed an airborne magnetics survey , but no detailed work was completed over the target area.