The Silver Coin occurrence is located at an elevation of approximately 1150 metres on a south-facing slope, north of Woodbury Creek and approximately 5.2 kilometres northwest of the creeks mouth on Kootenay Lake.
Regionally, the area is underlain by hornblende schists, limestone and banded quartzite of the Upper Mississippian to Permian Milford Formation, basaltic volcanic rocks of the Carboniferous to Permian Kaslo Group and limestone, slate, siltstone and argillite of the Triassic Slocan Group. To the west granodioritic intrusive rocks of the Middle Jurassic Nelson Batholith are exposed.
The occurrence area is underlain by argillaceous and limey units of the Triassic Slocan Group where they are in contact with the basinal volcanics of the Carboniferous to Permian Kaslo Group. The sediments are cut by ultramafic (lamprophyre?) dikes probably related to the nearby hornblendite intrusive rocks. The Silver Coin shear zone is hosted by mauve-grey calcareous argillites on the hangingwall and a silicious chert breccia unit on the footwall. Between the chert breccia and the Kaslo volcanics, which form the hinge for a major anticlinal structure, is an enclosed bed of altered limestone. The shear zone traverses across the western limb of the anticline progressing towards the hinge as it travels upslope. East of the hinge, altered black Slocan argillites are in contact with an intrusive sill.
Small quartz stringers, 1 to 15 centimetres wide, occur in a steep-dipping fracture zone in calcareous black argillite. These stringers carry small amounts of galena, sphalerite, tetrahedrite, argentite and native silver. Later work, in the 2010s, described the observed mineralization as consisting of galena, sphalerite, pyrite, azurite, malachite and hydrozincite hosted by a limey carbonaceous shear cut by veins and swarms of quartz. A high-grade zone is present in the workings at level No. 4 adjacent to the slickensided hangingwall where fault gouge contains high silver values over narrow widths.
The shear zone has been explored by five levels over a vertical elevation of 155 metres.
The No. 1 level is located at 1045 metres elevation and has been developed over a length of 53 metres along an argillaceous shear zone, approximately 2 metres wide, cemented with gouge and calcite veining up to 0.40 metre wide. In 1980, samples (U-80-227 to -230) yielded from 4.1 to 10.9 grams per tonne silver, with an average of 5.1 grams per tonne silver (Assessment Report 8807). In 1984, 14 trench samples from the dump for this level yielded values from 3.2 to 9.7 grams per tonne silver (Assessment Report 12896).
The No. 2 level is located at 1110 metres elevation, has been developed over a length of 80 metres and follows the same structure as the No. 1 level. A raise follows the zone for approximately 15 metres towards the surface. In 1980, samples (U-80-200 to -212) yielded from trace to 173.7 grams per tonne silver, with an average of 85.8 grams per tonne silver (Assessment Report 8807). In 1984, 16 trench samples from the dump for this level yielded values from 26.0 to greater than 100.0 grams per tonne silver (Assessment Report 12896).
The No. 3 level is located at 1150 metres elevation and is caved in after 3 metres. This zone was mined in the 1950s. In 1980, samples (U-80-176 to -189) yielded from 79.2 to 1766.5 grams per tonne silver, with an average of 668.9 grams per tonne (Assessment Report 8807). The waste dump from this level is estimated to contain approximately 292 tonnes averaging 250 grams per tonne silver (Assessment Report 11654).
The No. 4 level is located at an 1190 metres elevation and is caved in after 23 metres. The level follows a zone of sheared argillite mineralized with veinlets of quartz and calcite. Sampling of the roof and backs, in 1979 and 1980, averaged approximately 137 grams per tonne silver across 1.0 to 1.5 metres over the length of the adit. Narrow quartz veins and gouge zones are reported to carry much higher values, commonly averaging between 686 and 1030 grams per tonne silver, with the highest value being 5900 grams per tonne silver. Previous records of mining indicate a zone of massive sulphide was removed from this level and averaged 4800 grams per tonne silver, 10 per cent lead and 3 per cent zinc (Assessment Report 8807, 36055). In 1983, a sample (S-83-8) of vein breccia from the main zone on level 4 yielded 92.2 grams per tonne silver (Assessment Report 11250). The waste dump from this level is estimated to contain approximately 762 tonnes averaging 107 grams per tonne silver (Assessment Report 11654).
The No. 5 level is located at 1200 metres elevation and is caved at the portal. In 1980, samples (U-80-213 to -220) yielded an average of 188.7 grams per tonne silver (Assessment Report 8807). In 1983, two samples (S-83-3 and S-83-4) from the main zone on the 5th level yielded 97.9 and 130.0 grams per tonne silver, respectively (Assessment Report 11250). The waste dump from this level is estimated to contain approximately 230 tonnes averaging 226 grams per tonne silver (Assessment Report 11654).
In four years, from 1938 to 1946, 29 tonnes of ore were mined. From this ore 142 980 grams of silver, 3225 kilograms of lead and 889 kilograms of zinc were produced. In the 1950s, a company is reported to have mined a further 13.6 tonnes of ore yielding approximately 9330 grams of silver (Assessment Report 12896).
Work History
In the 1890s, mineralized float in Woodbury Creek was traced to the occurrence. Development work has apparently been confined to three periods, during 1938 to 1940, 1946 and in the mid-1950s. This work was carried out by a number of different owners and leasers. The shear zone has been explored by five levels over a vertical elevation of 155 metres. The two upper adits are approximately 15.2 metres vertically apart and mineralized stringers occur in both. In the two lower adits the fracture zone is barren.
In 1980, Lacana Mining Corp. conducted a program of geological mapping, geochemical (silt, soil and rock) sampling and a ground magnetic survey on the area. In 1983, Western Horizons Resources Ltd. completed a program of geological mapping, rock sampling and trenching on the area. In 1984, Victoria Resource Corp. conducted a program of rock and soil sampling.
During 2007 through 2011, Goldcliff Resource Corp. completed programs of prospecting, geological mapping, geochemical (rock, silt and soil) sampling and an airborne geophysical survey on the regionally extensive Ainsworth Silver property. In 2015, Goldcliff Resource Corp. conducted a program of prospecting, geological mapping, geochemical (rock, silt and soil) sampling and a 4.1 line-kilometre ground electromagnetic survey on the area as part of the Ainsworth Silver property.
In 2020 and 2021, Goldcliff Resource Corp. conducted a further program of geochemical (rock, silt and soil) sampling and a 508.0 line-kilometre airborne magnetic, electromagnetic and radiometric survey on the Ainsworth Silver property.
