A limestone bed of the Devonian-Permian Chilliwack Group, at least 76 metres thick, is exposed for 1600 metres along the steep southwest face of Bear Mountain on the south end of Harrison Lake, just east of Harrison Hot Springs. The limestone and the enclosing siliceous argillite strike northwest and dip steeply to vertically. The bed pinches out to the northwest and is truncated by a mass of granodiorite to the southeast.

The deposit is composed of medium to coarse grained, white to grey to brown limestone with scattered argillaceous interbeds. A chip sample across 79 metres on the south end of the deposit analysed 51.6 per cent CaO, 0.16 per cent MgO, 10.1 per cent insolubles, 0.42 per cent R2O3, 0.19 per cent Fe2O3, 0.007 per cent MnO, 0.025 per cent P2O5, 0.003 per cent sulphur and 37.1 per cent ignition loss (Bulletin 40, page 44).