The Iron Cap occurrence is situated at 2745 metres elevation above sea level near the headwaters of Red Line Creek which is a tributary of MacDonald Creek, in the Golden Mining Division. The property consists of a single Crown grant (Lot 5347) which is incorrectly located on the 1:50,000 scale topographic map (Toby Creek 82K/8) (Assessment Report 11739). The occurrence has been explored in conjuntion with the Ptarmigan (MINFILE 082KSE030) mine, approximately 900 metres to the north.
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 Iron Cap occurrence consists of three small adits driven along a fault that downthrows the Windermere Supergroup rocks to the east against rocks of the middle dolomite member of the Mount Nelson Formation (Open File 1990-26, Figure 19b). Mineralization consisting of galena, sphalerite and tetrahedrite occurs as narrow interconnecting quartz veins in dolomite. The veins are replacement structures within a north trending fault zone. A 1 metre chip sample across a mineralized section of the quartz vein assayed 800 grams per tonne silver, 17.3 per cent lead, 0.6 per cent zinc and only trace gold (Minister of Mines Annual Report 1920).
In 1920, 32 tonnes of ore were mined from the Hell Diver claim by J. L. MacKay and G. Larrabee. This production yielded 27,184 grams of silver and 8774 kilograms of lead. The ore was probably extracted from the upper adit on the Iron Cap property (Minister of Mines Annual Report 1920).
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 a program of geochemical sampling and diamond drilling was performed.
In 2011, diamond drill hole PT11-42 intersected an oxidized and brecciated sulphide vein that returned 3,610 grams per tonne silver and 1.33 per cent copper over 0.36 metres (Press Release - Silver Mountain Mines Inc., February 21, 2012).
