The area is underlain by rock of the Lower Jurassic Unuk River Formation, Hazelton Group. These rocks consist of sandstone, wackes, and shale overlain by lapilli-tuff of andesitic composition. The Brucejack fault and associated splay faults cut the country rock in a north-south to northwest direction. North of Brucejack Lake, the fault system is bounded on the east by rocks of the Lower Jurassic Betty Creek Formation, Hazelton Group. A variety of Jurassic horn- blende syenite and alkali feldspar syenites occur in the area.

Several lead-zinc showings were discovered on the Red River claim in 1976 by Granduc Mines Ltd. (Assessment Report 6255). These sphalerite and galena showings were reported to occur in hornfelsed arenaceous rock (Exploration in British Columbia, 1976).

This particular showing occurs about 1.0 kilometre west of Brucejack Lake on Brucejack Flats. Massive galena and sphalerite are reported to occur in limy material. Samples contained 102.86 grams per tonne gold and 1028.58 grams per tonne silver (Personal Communication: J.M. Britton, 1988).

Refer to Brucejack (104B 193) for details of related mineralization and work history.