The area of the Stemwinder occurrence is underlain by rocks of the Elise Formation, Rossland Group consisting of lapilli tuff with plagioclase and augite-bearing volcanic clasts. Contact with granite to granodiorite of the Middle to Late Jurassic Nelson Intrusions occurs in the vicinity of the showing and may itself be the host rock.

A shaft was sunk on the Stemwinder to a depth of about 7 metres revealing a 0.46 metres vein of chalcopyrite grading 26.76 grams per tonne gold (Hodges, 1897). Further tunneling to 12 metres from surface is reported.