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 and consist of polymetallic skarn-type mineralization, lead-zinc-silver bearing quartz veins and replacements, and polymetallic quartz veins.
On the Old Alameada claim (L.4507), a north trending structure with shallow west dips (30-40 degrees) hosts narrow quartz veins with significant sulphides. The volcanic stratigraphy in the vicinity strikes north and appears to dip east and is comprised of felsic to intermediate porphyritic volcanics. Minor historic underground workings have exploited a main vein 0.6 metres wide, striking north and dipping west. The vein is mineralized with pyrite, sphalerite, galena and chalcopyrite. Vein material in the dump showed quartz with well-developed comb structure.
Recent diamond drilling intersected the main quartz vein within a clayey fracture zone. Drill intersections across 0.68 metres (true width) assayed 167.97 grams per tonne silver, 1.09 per cent copper, 5.25 per cent lead, 20.9 per cent zinc and 0.34 grams per tonne gold (Assessment Report 18583).