The Lemac occurrence is located north of Retallack on the north side of the Kaslo River at 1037 metres elevation above sea level, in the Slocan Mining Division. The property includes the Paupers Dream, Sloper Fraction and Vancouver Crown grants and the Kaslo Reverted Crown grant (Lots 1163, 5990, 2024 and 822 respectively).

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. Volcanic rocks of the Permian to Carboniferous Kaslo Group are exposed west of the occurrence (Paper 1989-5).

The property is underlain by thinly bedded calcareous argillite, shale and slate of the Slocan Group. Minor limestone and quartzite beds are also present. The sedimentary rocks strike northwest and dip southwest.

No geological description could be located for this occurrence but over 4400 cubic metres of trenching was carried out in 1978 to expose some silver-lead-zinc mineralization (Exploration in British Columbia 1978).