The area around Swakum Mountain consists of folded Upper Triassic Nicola Group volcanic rocks with interbedded sedimentary units. These rocks are intruded by large north trending felsic to intermediate intrusions (batholiths) east and west of the mountain. Nicola Group rocks on the mountain strike north to northeast with generally steep dips. For a large part they consist of andesitic flows and tuffs, agglomerates, and occasional basalts and rhyolites. A break occurs in the volcanic stratigraphy and is comprised of a mixed volcanic-sedimentary unit consisting of a thick sequence of felsic volcanic flows, lithic and crystal tuffs, limy sediments and a prominent limestone. This unit has a northeast strike and crosses the mountain for a 2.5 kilometre strike length. The unit has been historically used as a marker horizon in interpreting a large, asymmetrical, south plunging anticline with its north trending axis near Swakum Mountain summit. Narrow quartz porphyry dykes locally intrude the Nicola Group sequence. To the east of this marker unit are a thick, unconformable wedge of immature sediments, predominantly coarse polymictic conglomerates (fan-type) and grits with minor cherty units. Most of the old workings on the mountain occur in close proximity to or within this volcanic-sedimentary unit. The Swakum Mountain deposits consist of polymetallic skarn-type mineralization, lead-zinc-silver bearing quartz veins and replacements, and polymetallic quartz veins.
On the Lucky Mike property, polymetallic skarn mineralization is associated with altered sections of the marker horizon unit of the Upper Triassic Nicola Group. Limy volcanics, tuffs and limestone of this marker unit have been in part, converted to garnet-epidote- calcite skarn with associated copper, tungsten, silver and minor gold and zinc mineralization. Recent drilling has indicated that tungsten mineralization is widespread in the garnet skarn while copper-zinc- gold-silver values tend to be restricted to late crosscutting structures.
The main skarn unit is 110 metres long with a northeast strike. It occurs at the contact between epidotized andesitic breccias and intermediate to felsic crystal-lithic tuffs within a lens of limy volcanic rocks, lithic tuffs and limestone (skarn protoliths). The skarn is bimodal in mineralogy, consisting of interfingering garnet skarn (andradite garnet, magnetite, epidote, hornblende, chlorite and calcite) and carbonate skarn (coarse calcite, epidote, hornblende, chlorite, minor magnetite or hematite) possibly reflecting original compositional variation (protolith-coarse, highly carbonated lithic tuffs(?)). Numerous late, fairly wide, east dipping (30-50 degrees) fracture zones cut the skarn with local displacements. A major fault zone is evident in the hangingwall lithic tuffs.
The skarn geometry is complex with the marble line (skarn edge) having a tooth-like cross section. Locally wide, near to surface (up to 25 metres true width), the skarn tapers to depth with narrow 1 to 2 metre wide "roots" 50 metres below surface. Tungsten mineralization is confined to the bimodal skarn with fine to coarse disseminated scheelite. A drill hole intersection across 14.1 metres of skarn mineralization assayed 0.152 per cent tungsten (Assessment Report 18583). Copper mineralization with silver and local zinc values appears to be structurally controlled and located along shallow east dipping fault zones within the skarn and in the footwall epidotized volcanics. The structures are late (post-skarn). They are wider in the skarn than in the volcanics but yield lower copper and silver values than in the volcanics below. Sulphides consist of chalcopyrite, pyrrhotite and pyrite. Galena and sphalerite are also reported. A diamond-drill hole intersection across 3.6 metres of skarn mineralization assayed 0.18 per cent copper and 38.39 grams per tonne silver (Assessment Report 18583). Tungsten values occur with the copper and silver where the structures cut through the skarn. Tungsten mineralization in the skarn body appears to be early (prograde(?)) while copper, silver, zinc and gold mineralization is late (retrograde(?)) associated with fracturing.
Diamond drilling has tested the skarn for 110 metres strike length and at a variety of elevations 40 to 80 metres below the old surface workings. Based on present and past drilling, indicated reserves of skarn available for tungsten mineralization is less than 90,710 tonnes (Assessment Report 18583).
Geologic reserves at the Lucky Mike skarn copper-tungsten deposit are estimated at 317,485 tonnes grading 0.56 per cent copper, 0.30 per cent WO3 (0.23 per cent W) and 20.5 grams per tonne silver (Assessment Report 24600, page iii).