The Big Ben occurrence is located at 1478 metres elevation above sea level, on the north side of Twelve Mile Creek, in the Slocan Mining Division. The occurrence includes the Marble Arch and California showings which are believed to be the extension of the Big Ben occurrence. This occurrence is likely the Silver King, a producer in 1916, operated by J. Koski.

Regionally, the area lies on the western margin of the Kootenay Arc, in allochthonous rocks of the Quesnel Terrane. In the vicinity of the occurrence, the Quesnel Terrane is dominated by the Upper Triassic Slocan Group, a thick sequence of deformed and metamorphosed shale, argillite, siltstone, quartzite and minor limestone. Rocks of the Slocan Group are tightly and disharmonically folded. Early minor folds are tight to isoclinal with moderate east plunging, southeast inclined axial planes and younger folds are open, southwest plunging with subhorizontal axial planes. The sedimentary sequence has been regionally metamorphosed to lower greenschist facies.

South of the occurrence, the Slocan Group has been intruded by the Middle Jurassic Nelson intrusions which comprise at least six texturally and compositionally distinct phases ranging from diorite to lamprophyre. The most dominant phase is a medium to coarse grained potassium feldspar porphyritic granite. Several feldspar porphyritic granodiorite dikes, apparently related to the Nelson intrusions, also cut the sedimentary sequence near the occurrence (Paper 1989-5).

The occurrence consists of a brecciated vein cutting carbonaceous limestone, calcareous argillite and schist of the Slocan Group and a granitic stock of the Nelson intrusions. The vein strikes 070 degrees, dips 67 degrees northwest and is composed essentially of broken wallrock and gouge. The shear has been explored with 3 shafts and 5 adits along 400 metres of strike length.

On the California claim, disseminated galena, sphalerite and pyrite occur along a band of fractured limestone and calcareous argillite. The shear has a maximum width of 6 metres. The shear extends up the slope on the Marble Arch showing where a shallow shaft and two short adits are developed on a quartz-filled shear containing stringers of galena and tetrahedrite. A grab sample of a mineralized stringer assayed 4.8 grams per tonne gold, 13,495 grams per tonne silver and 70 per cent lead (Minister of Mines Annual Report 1926). The wallrock is calcareous schist.

Further up the slope, at the Big Ben occurrence, the vein is 45 to 50 centimetres wide and mineralized with stringers and masses of galena and pyrite in quartz. Here, the vein is hosted within porphyritic granite of the Nelson intrusions.