The Minto polymetallic veins are on the north side of Carpenter Lake, 1.7 kilometres northeast of the mouth of Gun Creek.
The property is underlain by northwest trending argillites, cherty quartzites, ribbon cherts and volcanics of the Mississippian to Jurassic Bridge River complex. Upper Cretaceous dykes of feld- spar porphyry, andesite porphyry, felsite and microdiorite cut north to northwest across the sediments, dipping steeply. Mineralization occurs in shear zones following the intrusive contact of porphyry dykes or the stratigraphic contact between sediments and volcanics. The strata, dykes and veins are offset by late strike-slip faults. The principal ore shoot occurs in cherty quartzites in a strong shear which follows, in part, along the footwall of a 6-metre wide, altered, fine-grained feldspar porphyry dyke (the "Minto dyke"). Veins up to 1.2 metres wide contain lenses and narrow bands of quartz, calcite and ankerite with coarsely crystalline arsenopyrite, pyrite, sphalerite, stibnite, pyrrhotite, galena, chalcopyrite and rare tetrahedrite, jamesonite, bismuth and gold.
Vein material generally has a banded structure defined by alternating metallic mineral concentrations and quartz-carbonate gangue. The vein also contains fragments of altered wallrock. Wallrock alteration is characterized by rare to abundant ankerite and calcite with lesser chlorite, sericite and mariposite.
The fissure, or zone of shearing, continues away from the dyke, but mineralization becomes irregular and weaker. Immediately west of the sediments, the fissure enters greenstone which is leached, carbonatized and slightly mineralized. Northeast and east of the main Minto orebody, within 500 metres, are other zones of mineralization: the Ponderosa zone is a wide area of mineralized cherts carrying small arsenopyrite-pyrite veins and lenses; the Rainbow zone is a 200 metre long narrow shear with stibnite, arsenopyrite and pyrite veins; and the Winter zone where an old (1934) adit explored galena-sphalerite-stibnite-arsenopyrite-pyrite veins in a narrow 200 metres long shear. The best recent assay, obtained from the Rainbow zone, graded 7.78 grams gold per tonne over 1.0 metre and 3.5 grams silver per tonne over 1.5 metres (Assessment Report 14740). The Minto mine was in operation from 1934 to 1940 during which time over 2130 metres of underground work was done, and a total of 80,650 tonnes of ore grading 6.8 grams gold and 19.9 grams silver per tonne was produced. The mine yielded 546 kilograms gold, 1,573 kilograms silver, 9,673 kilograms copper and 56,435 kilograms lead.