No known historical data exists for the Tobaru mine workings, however there are reports that describe the larger Fuke mine situated immediately west of the property.

The Fuke Au mine was discovered in 1891 by local people and subsequently developed into a small scale mine.  Over the life of the mine (1891-1971) 3,300 kg of gold (106,100 ounces) was produced at reported grades of 8.2-11.4 g/t Au and 4.8-9.4 g/t Ag (¹MITI, 1989).    

1978-1980:  The greater Tobaru area (Kuwanoki-cho, Ohkuchi, Shimo-ushio, Fuke) was explored by MMAJ.  Geophysical surveys revealed zones of low resistivity.  Five holes were drilled targeting the resistivity anomalies revealing extensive hydrothermal alteration of the Hokusatsu andesite at depth.

Late 1980’s to early 1990’s: A partnership between Mitsui Mining & Smelting Company and BHP-Utah Japan Inc. explored the Tobaru area. As part of this exploration program a Masters study focusing on the Tobaru alteration was undertaken (²Hamilton, 1993). The study describes a northeast oriented 1,500 by 700 metre zone of silicification and quartz veining that includes pockets of advanced argillic alteration. The central silicified zone is enveloped by argillic and propylitic alteration outwards, which are bound by steeply dipping fractures. X-ray diffraction indicated the presence of pyrophyllite, tourmaline and quartz in silicified rocks, illite and smectite in argillized rocks and chlorite in propylitized rocks. 

A single drillhole (DDHT1) was drilled to the south of the main alteration zone is referenced by ²Hamilton (1993), but no other public data on drilling has been sourced to date.