The area of the Tan 3 showing is underlain by Upper Triassic Stuhini Group rocks consisting of volcaniclastics, tuffs, tuffaceous breccias, argillites and minor limestone. These are intruded by several small structurally controlled stocks of hornblende diorite to augite porphyry of Triassic age, or possibly Jurassic. The rocks are regionally metamorphosed to lower greenschist facies. Faults, with shear directions of 018 to 027 degrees, occur in the area.

Gossans, containing ankerite, hematite, pyrite and sometimes chalcopyrite and malachite, occur within the stratified rocks and sometimes adjacent to faults and diorite stocks. A sample of altered rock near argillaceous sediments and greenstone assayed 1.0 per cent arsenic (Assessment Report 13840). A nearby 3 metre chip sample from silicified limestones assayed 10 per cent copper (Assessment Report 15894).

In 1992, a BC Geological Survey geological mapping project in the Tatsamenie and Bearskin lakes area resulted in an updated regional geological framework and the discovery of several new showing including Muse (104K 119), located just south of the Tan and Oro showings.

In 2019, Brixton Metals Corporation expanded their Thorn property through staking and acquisition of claims including those covering all the Tan showings as well as the Oro and Muse showings. See Thorn (104K 031), Chivas (104K 180) and East Outlaw (104K 083) for further information on the Thorn property.

In 2020, Brixton Metals Corporation completed a program of geochemical (rock and soil) sampling, a 12.5 line-kilometre ground induced polarization survey, a 715 line-kilometre airborne magnetic and electromagnetic survey and 19 diamond drill holes, totalling 5292 metres, on the area of as part of the Thorn property. Drilling was performed on the Outlaw (MINFILE 104K 176) occurrence area.

For work history and related geological details pertaining to Tan 3, see Tan showings (104K 102 and 103), ORO (104K 039), Muse (104K 119) and Golden Bear mine (104K 079).