The Iota occurrence is on the north slope of Stemwinder Mountain, 300 metres north-northwest of its summit, 4.5 kilometres northwest of Hedley.

Stemwinder Mountain is underlain by argillite and siltstone with thin interbedded limestone of the Upper Triassic Stemwinder Mountain Formation (Nicola Group). The unit is intruded to the northwest by granodiorite to quartz monzonite of the Early Jurassic Bromley batholith. Dykes and sills of hornblende porphyritic diorite of the Early Jurassic Hedley Intrusions occasionally cut these sediments. Bedding strikes north to northeast and dips steeply east over the top of Stemwinder Mountain along the west limb of a northeast plunging syncline.

A 0.8 to 1.0-metre wide zone of brecciation and veining, in thinly-bedded calcareous argillite and limestone, strikes 070 degrees for at least 146 metres and dips 76 to 80 degrees south. Diamond drilling has traced the zone to a depth of 24 metres. The zone appears to be controlled by a well-developed axial plane cleavage.

Black, drusy chalcedonic quartz, in stringers or as a breccia matrix, is mineralized with fine-grained disseminated pyrite, argentite, galena and sphalerite. Galena is also observed to occur as coarse stringers in brecciated limestone. The quartz and wallrocks are locally limonitic. The texture and composition of this mineralization suggests it may be of epithermal origin.

Samples comprised of limestone, containing black quartz stringers and massive quartz, assayed 233 to 854 grams per tonne silver (Minister of Mines Annual report 1947, page 147). A 0.91- metre chip sample across black quartz assayed trace gold, 854 grams per tonne silver and 0.6 per cent lead, and a 0.79-metre chip sample across black quartz and limestone breccia assayed 0.69 gram per tonne gold, 542 grams per tonne silver and 1.2 per cent lead (Minister of Mines Annual Report 1947, page 147). A sample of "agate breccia" analysed 0.91 gram per tonne gold, 435.9 grams per tonne silver, 1.2 per cent zinc and 0.54 per cent copper (Assessment Reports 14287, 14753, sample 51271).

Between 1946 and 1952, the deposit was explored by 14 opencuts, 190 metres of diamond drilling in 8 holes, a 12-metre shaft, and a 130-metre long adit about 23 metres below surface workings. Sixty-eight tonnes of ore were extracted from the shaft in 1950 and 1951, and shipped to the Trail smelter, producing a total of 137 grams of gold, 36,200 grams of silver, 3.8 tonnes of lead and 0.73 tonnes of zinc (Minister of Mines Annual Reports 1950, page 115 and 1951, page 132).