At the Sylvia showing, turbidites of the Helikian Middle Aldridge Formation (Purcell Supergroup) host a diorite sill of the Proterozoic Moyie Intrusions. Traces of galena and sphalerite are disseminated within the sediments and are associated with very localized chlorite alteration. Chalcopyrite and pyrite are hosted by quartz-calcite veining associated with the intrusive sill. The vein is up to 2 metres wide, strikes 063 degrees and dips 85 degrees southeast.