The Mission prospect is located on a south-facing slope at the headwaters of Jamieson Creek, 4 kilometres southwest of Hedley.
An elongate mass of medium-grained biotite granodiorite of the Middle Jurassic Cahill Creek pluton extends northwest from the main intrusive body into argillite, siltstone and limestone of the Upper Triassic Hedley and Stemwinder Mountain formations (Nicola Group). The granodiorite is cut by a number of shear zones commonly striking at 030 and 060 degrees. Significant mineralization is contained along three principle shear zones, the Barnes, Walker and Winkler zones. The Barnes zone strikes 030 degrees and dips 70 degrees southeast. The zone has been traced for 240 metres and is between 3 and 5 metres wide. The Walker and Winkler zones extend southwest from the Barnes zone, both striking 060 degrees for 90 and 140 metres respectively, and dipping 80 degrees northwest and 85 degrees southeast respectively.
The granodiorite is altered in the shear zones to a white granular material comprised of quartz, sericite and orthoclase, with minor chlorite (altered biotite) and traces of epidote and calcite. The zones contain disseminations, bands and lenses of sulphides forming between trace and 40 per cent of the altered granodiorite. The sulphides include pyrite, fine-grained arsenopyrite, dark brown sphalerite and minor tetrahedrite and chalcopyrite. A chip sample taken from the Mission pit (Barnes zone?) assayed 0.17 gram per tonne gold and 32.6 grams per tonne silver across 3.0 metres (Assessment Report 9222, drill hole plan, sample 2). A selected grab sample from the Barnes zone contained 6.9 grams per tonne gold, 686 grams per tonne silver and 10.8 per cent zinc (Minster of Mines Annual Report 1936, page D12, sample 4).
Diamond drilling in the vicinity encountered thin stringers and disseminations of pyrite, arsenopyrite and sphalerite in silicified and propylitized granodiorite, in addition to a number of silver-zinc-bearing quartz veins. One drill core sample analysed 0.31 gram per tonne gold, 40.8 grams per tonne silver and 1.75 per cent zinc over 0.61 metres (Assessment Report 9222, Hole 80-2, 214.5-216.5 feet).
