The Ptarmigan mine is situated at 2683 metres elevation above sea level near the headwaters of Red Line Creek, a tributary of MacDonald Creek, in the Golden Mining Division. The property consists of a single Crown grant (Lot 5345) which is incorrectly located on the 1:50,000 scale topographic map (Toby Creek 82K/8) (Assessment Report 11739).
Regionally, the area is underlain by Proterozoic clastic sedimentary rocks of the Purcell and Windermere supergroups and by lower Paleozoic strata of the Beaverfoot and Mount Forster formations (Geoscience Map 1995-1).
The Purcell Supergroup strata include the Aldridge, Creston, Kitchener, Dutch Creek and Mount Nelson formations. The Windermere Supergroup unconformably overlies the Purcell Supergroup rocks and includes the Toby Formation and Horsethief Creek Group (Paper 1990-1).
In the vicinity of the occurrence, rocks of the Kitchener and Dutch Creek formations have been further subdivided and assigned to the Van Creek and Gateway formations. The Van Creek Formation correlates with the Lower Kitchener Formation while the Gateway Formation is equivalent to the lower portion of the Dutch Creek Formation. The Mount Nelson Formation has been subdivided into seven discrete members, a lower quartzite, a lower dolomite, a middle dolomite, a purple dolomite, an upper middle dolomite, an upper quartzite, and an upper dolomite (Open File 1990-26).
Rocks of the Horsethief Creek Group, Beaverfoot and Mount Forster formations are folded and overthrusted by rocks of the upper portion of the Dutch Creek Formation and the lower members of the Mount Nelson Formation. The sedimentary rocks have undergone regional metamorphism to at least greenschist facies.
The Ptarmigan mine consists of a series of adits driven along a fault that downthrows the Windermere Supergroup rocks to the east against rocks of the lower dolomite member of the Mount Nelson Formation (Open File 1990-26, Figure 19b). Mineralization consisting of galena and tetrahedrite occurs as narrow, interconnecting quartz veins and as large pods of stratabound manto replacement zones of massive crystalline pyrite. All mineralization is situated below the Windermere unconformity and usually occurs below a less permeable strata such as quartzite (Open File 1990-26).
A total of 657 tonnes of high-grade ore were selectively mined from the Ptarmigan deposit between 1900 and 1959. This production yielded about 2.7 million grams of silver, 3546 grams of gold, 3812 kilograms of copper, 3519 kilograms of lead and 848 kilograms of zinc.
In 2008, Rupestris Mines Inc. began refurbishing the historical access trails and cleaning up and securing the former mine workings. In 2009, a program of surface and underground geological mapping, prospecting, ground IP magnetic susceptibility survey, trenching, and 1388.2 metres of diamond drilling was completed. In 2010-2011, the property was acquired by Silver Mountain Mines Inc. and program of geochemical sampling and diamond drilling, totalling 3712 metres, was performed.
In 2009, grab and chip sampling of the massive pyrite returned 10 to 2410 grams per tonne silver and 0.26 to 1.06 gram per tonne gold. The best diamond drillhole (PT09-13) intercepted 6.92 metres grading 53 grams per tonne silver and 0.26 grams per tonne gold (Assessment Report 31512).
In 2011, diamond drilling on the East Ptarmigan zone returned 6.41 metres at 95.5 grams per tonne silver and 3.70 per cent lead in drillhole PT11-37. Drillhole PT11-55 returned 9.05 metres at 72.3 grams per tonne silver and 1.94 per cent lead, including 1.14 metres at 263.0 grams per tonne silver and 3.69 per cent lead (Press Release, Silver Mountain Mines Inc., February 21, 2012).
In 2012, Silver Mountain Mines Inc. completed an exploration program of soil, silt and rock sampling and diamond drilling. Highlights include drillhole PT12-75, which returned 0.3 metres grading 8.48 grams per tonne gold, 9680 grams per tonne silver and 4.22 per cent copper, and sample E5525022, which returned 6.91 grams per tonne gold, 12346 grams per tonne silver, 0.26 per cent zinc and 6.23 per cent copper (Press Release, Silver Mountain Mines Inc., November 15; December 4, 2012)