The North Bullion deposit occurs in similar host rocks as the Pinion deposit and is also considered to be a Carlin-type, sedimentary-rock-hosted deposit. It has similarities to Nevada Gold Mines’ Rain Deposit approximately 7km to the north. Mineralization is submicroscopic, disseminated, and hosted principally in sedimentary rocks, with some mineralization in felsic dikes and sills as well.
Mineralization is focused in the footwall of the Bullion fault zone. Faults appear to be important controls on mineralization. In general, gold-silver mineralization is localized in gently to moderately dipping, strongly sheared rocks of the Webb and Tripon Pass formations, in dissolution-collapse breccia developed above and within silty micrite of the Tripon Pass Formation, and calcarenite of the Devils Gate Limestone. The top of gold mineralization varies from 105m to 400m below the surface and varies in dip from 10° to 45° to the east. Gold is associated with “sooty” sulfide minerals, silica, carbon, clay, barite, realgar, and orpiment.
The North Bullion deposit sulphide Inferred Mineral Resource uses a cut-off grade of 1.25 g/t Au, which is constrained within an optimized pit shell, and is comprised of 2.05 million tonnes at 2.60 g/t Au for 171,400 contained ounces of gold. The North Bullion deposit underground Inferred Mineral Resource, which is reported at a lower 2.25 g/t Au cut-off grade, comprises 5.55 million tonnes at 3.29 g/t Au for 587,700 contained ounces of gold.