The sulphide veins in the Silver Valley district are famous for their long strike length (>0.5 km) and great vertical depth (>1 km) and at some mines the grades increase with depth. The veins carry galena and sphalerite with variable quantities of argentiferous tetrahedrite, chalcopyrite, boulangerite and minor gold. Steeply dipping mesothermal, sulphide rich veins, often occur as sub-vertical slabs that are highly suitable for underground stope mining.