Limestone outcrops along several low ridges just east of Robertson Creek, 32 kilometres northeast of Lillooet.

The deposit lies near the eastern margin of a 10 to 15 kilometre wide belt of carbonate of the middle to Upper Permian Marble Canyon Formation (Cache Creek Complex) that trends north-northwest for 65 kilometres. The strata are locally dissected by a north-trending fault. Bedding west of the fault strikes 108 to 152 degrees and dips 30 to 90 degrees southwest. On the east side, bedding strikes north to 147 degrees and dips 63 degrees southwest to 76 degrees northwest.

Detailed mapping and sampling over a 1 by 1.5 kilometre area along the ridge tops encountered mostly light grey to dark grey, rarely black or white, fine to medium grained, commonly massive, locally thin bedded or brecciated limestone with a few irregular zones of light grey, fine to medium-grained dolomite and magnesian limestone up to 7 metres thick. These zones commonly overlie fine grained, thin bedded limestone strata. The dolomite is siliceous in a few instances. Veins and blebs of white calcite occur sporadically throughout the carbonates. Ten 20-kilogram samples collected from various outcrops yielded the following range in values and average compositions in per cent (B.C. Hydro Report SE 822, Addendum, Samples 20 to 29):

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Range Average

CaO 44.08 - 55.55 52.02

MgO 1.68 - 9.97 4.09

SiO2 1.56 - 3.72 2.31

Al2O3 0.02 - 0.03 0.02

Fe2O3 0.09 - 0.14 0.115

TiO2 0.02 - 0.03 0.02

Na2O 0.02 - 0.11 0.035

K2O 0.02 - 0.03 0.02

P2O5 0.02 - 0.06 0.027

Ig.Loss 37.29 - 41.98 39.69

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Mapping and sampling was carried out by B.C. Hydro during 1981 and 1983. The company was exploring for dolomite in the Hat Creek area for use as sulphur sorbent to scrub gases from a proposed coal- fired electrical generating plant utilizing pressurized fluidized bed combustion.