Several masses of limestone outcrop on the east side of and near the top of Rattlesnake Hill on the north side of the Thompson River, 5.3 kilometres northeast of Ashcroft. The limestone is contained within a sequence of argillite and quartzite of the Upper Triassic Nicola Group.

The limestone is sugary textured, light grey to white with small masses and grains of white quartz and blue chert. Several dikes intrude the limestone. A sample of chips taken at irregular intervals over the main outcrop analysed 48.00 per cent CaO, 0.33 per cent MgO, 11.56 per cent SiO2, 1.38 per cent Al2O3, 0.66 per cent Fe2O3 and a trace of sulphur (Canada Bureau of Mines Report 811, page 184, Sample 48).