The Silver Tunnel deposit is situated along Brandywine Creek in the Pacific Ranges of the Coast Crystalline tectonic belt.

Andesitic volcanic rocks of the Lower Cretaceous Gambier Group, preserved within the Callaghan roof pendant, are in contact with diorite, granodiorite and quartz monzonite of the Jurassic to Tertiary Coast Plutonic Complex. A series of felsite (quartz latite, latite) dykes intrude the volcanic and plutonic rocks. Mafic volcanic rocks of the Pliocene Garibaldi Group covers part of the property.

Pyrite-sphalerite-galena-silver-gold mineralization occurs as bands, narrow veins and fracture fillings in felsite which is locally sheared and crushed. Ruby silver has been noted. A 2.1 by 33.5- metre sample of this material contained 2.4 grams per tonne gold and 306 grams per tonne silver (Assessment Report 9265). Pyrite- sphalerite-galena-chalcopyrite-silver-gold mineralization also occurs as disseminations and narrow bands in andesite and diorite. Both modes of mineralization are erratic and discontinuous. Disseminated pyrite-chalcopyrite and/or tetrahedrite mineralization in latite porphyry was found to contain no significant precious metal content. Quartz-carbonate vein-like structures indicate that some hydrothermal activity occurred.

Indicated (probable) reserves of Block A are 101,413 grading 414.7 grams per tonne silver, 0.27 gram per tonne gold, 0.19 per cent lead and 0.43 per cent zinc. Inferred (possible) reserves of Block B are 146,224 tonnes at similar grades to the Block A reserves. Inferred reserves of Block C are 55,060 tonnes grading 0.68 gram per tonne gold, 397.6 grams per tonne silver, 0.27 per cent lead and 0.45 per cent zinc (Northern Miner - July 8, 1976).

The Silver Tunnel deposit experienced brief underground production in conjunction with the Tedi pit (092JW 001), located 1.8 kilometres north-north west, during 1977. In November 2002, Auramex Resource Corp. acquired the property. A complete exploration histrory can be found at the Ted Pit.

In 2010, Auramex Resource Corp. completed three vertical diamond drill holes, totaling 175.57 metres. Five samples, each 1.5 meters in length, from Hole BRW10-5 returned gold values ranging from 1.017 to 6.231 grams per tonne gold (Assessment Report 32240).