The Mountain Con occurrence consists of two Reverted Crown grants (Lots 9840 and 9841). The workings are located on Lot 9841 (Mountain Con), near the headwaters of Long Creek, in the Slocan Mining Division at 2410 metres elevation above sea level.
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.
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 (Paper 1989-5).
The Mountain Con occurrence consists of a 10 to 80 centimetre wide quartz vein associated with a narrow lamprophyre dike that is emplaced parallel to a northeast trending joint set within the porphyritic granite phase of the Nelson intrusions. The dike occurs in places on the hangingwall, and in places on the footwall side of the vein. The vein is regular and persistent and has well defined walls. It consists of galena, sphalerite, pyrite and cerussite in a matrix of white quartz, siderite and crushed wallrock.
The vein has been explored with at least four adits covering a vertical range of 150 metres. Surface outcrops of the vein are strongly oxidized.
Sporadic production from the Mountain Con between 1899 and 1927 yielded 6,417,608 grams of silver, 130,826 kilograms of lead, 485 kilograms of zinc and 373 grams of gold from 448 tonnes mined.
