Mineralization at the Blackfly showing occurs within acicular hornblende porphyry of the Paleocene to Eocene Sloko-Hyder Plutonic Suite, on the west ridge of Niagara Mountain. The porphyry is host to an irregularly spaced (5 to 10 metre) network of veins and linear breccia zones up to 50 centimetres wide (more commonly 5 to 10 centimetres). Galena, sphalerite, quartz, epidote and chalcopyrite dominate the vein assemblage. In one case, a lens of nearly pure galena occupies a vein segment 2 metres by 30 centimetres in cross-section. Analysis of grab and chip samples yielded values up to 1.9 per cent copper, 1.7 per cent lead. 2.7 per cent zinc and 209 grams per silver (Fieldwork 1994, page 338, Table 3).

The showing was discovered in 1994 by members of the BC Geological Survey Branch during a regional mapping program.