Limestone was once mined underground by Cominco Ltd. as a source of flux beside the C.P. Railway, 2.4 kilometres east of Proctor on the west shore of Kootenay Lake.

A 9 to 15 metre thick bed of limestone in schist of the Mississippian Milford Group outcrops along the railway track and continues up the steep mountain side west of the lake. The bed strikes 0.25 degrees and dips 30 degrees northwest.

The limestone is coarse to fine grained and white to bluish white in colour. The rock is comprised largely of calcium limestone with some thin beds of dolomite. The limestone is cut by some veins of white quartz. A sample comprised of chips taken at various places in underground workings contained 44.18 per cent CaO, 7.34 per cent MgO, 5.61 per cent SiO2, 0.20 per cent Al2O3, 0.26 per cent Fe2O3 and 0.02 per cent sulphur (Canada Bureau of Mines Report 811, p. 202, Sample 68)

The deposit was explored underground by 490 metres of drifting by Cominco between 1935 and 1938. 6896 tonnes of limestone were mined during this development work. In 1960 the property was leased to B & P Lime Development, which mined 318 tonnes.