The Hi Yogi area is underlain by Upper Paleozoic Stikine Assemblage rocks consisting of metamorphics which include Permian limestones, dolomitic limestones with chert, and fine-grained clastic sediments and intercalated volcanics. These rocks are crosscut by a northeast trending, Tertiary felsite dike swarm of the Sloko-Hyder plutonic suite.
The metamorphic rocks are dominated by thin-bedded siltstones and mudstones, which are locally comprised of pyritic-graphitic mudstone. They have been strongly folded and show a northwest plunging lineation. Coarse, milky quartz veins are abundant and show deformation with the host rocks. Commonly, they are present as elongated lenses and pods parallel with the lineation and host pyrite and/or pyrrhotite.
Numerous stratiform gossans are present within the metasediments. The limonite and iron-staining are a result of weathering of lenses and pods containing disseminated pyrite and pyrrhotite. Locally, a few concentrations of massive pyrrhotite up to 2 centimetres across are present.
In 1980, a sample from metasediments just south of a contact with a major felsite dyke assayed 0.2 grams per tonne silver, 0.011 per cent zinc, 0.002 per cent lead, and 0.007 per cent copper. Another sample taken 500 metres north of the dike assayed 0.8 gram per tonne silver, 0.015 per cent zinc, 0.004 per cent lead, and 0.015 per cent copper. (Assessment Report 8433).
The Hi-Moly and Hi-Yogi claims were staked in the fall of 1978 by Valiant Resources Inc. to follow up on molybdenite-bearing alaskite float. In 1980, Valiant collected nine stream sediments and talus fines samples along the edge of Wright Glacier above the moraine. Parts of the former Hi-Moly and Hi-Yogi property were staked by DeCoors Mining Corp. in October of 2006 and sold to Optima Minerals Inc. in November 2006 and are now part of the Taku Gold block of the Taku Property. In the early to mid 2000s, the Hi Yogi area was staked as part of the Taku property owned by Optima Minerals Inc. The showing was not visited by Optima Minerals.
