The South Wellington No. 10 mine of Canadian Collieries (Dunsmuir) Ltd., was in operation for about 13 years and produced about 2.5 million tonnes of highly volatile, bituminous rank coal. This mine is the largest coal producer in the South Wellington District, opening in 1938 and closing permanently in 1952. The extraction of the pillars was very high, due to the efficient organization of the work.

The coal that was worked is part of the Douglas Seam in the Early Campanian Newcastle Member which occurs within the Upper Cretaceous Pender Formation, Nanaimo Group. The seam strikes northwest and dips shallowly northeast, varying in thickness from 0.1 to 9.1 metres. Variations in thickness are commonly caused by undulations in the floor which is predominantly shale. The coal is overlain by sandy shale and rock partings within the seam are common.