 It is a classic Mississippi Valley type lead/zinc deposit in Cambrian carbonate rocks though it contains an unusually high proportion of lead.The principal minerals are galena (lead, PbS) and sphalerite (zinc, ZnS) with lesser amounts of chalcopyrite (copper, CuFeS2).Lead concentrates from the area contain more than 75 percent lead, versus an industry average of 45 to 50 percent lead.