The Pend Oreille mine is a carbonate-hosted zinc-lead orebody situated within the Metaline Formation in the southern portion of the Kootenay arc, an arcuate, narrow belt of sedimentary, volcanic and metamorphic rocks separating Precambrian metasediments to the east and Mesozoic volcanic and sedimentary units to the west. Metaline carbonates host the known zinclead deposits within the district.

Mineralization at the Pend Oreille mine is located within the Yellowhead horizon of the Metaline Formation, an intensely altered stratabound dolomitic solution breccia, which has been invaded and replaced by fine-grained pyrite with lesser zinc and lead sulphides. The sulphide zone has relatively simple mineralogy. Sphalerite and galena are the two ore minerals of interest. Gangue minerals include pyrite, dolomite and calcite.

The mine uses the “room and pillar” mining technique, which involves removing ore in a honey-combed network of underground rooms up to 30 feet in width and 70 feet in height.

The mineral processing facilities employ conventional grinding and sulphide flotation methods to produce high quality zinc and lead concentrates.