Although various resources attribute the discovery of lead to several different individuals—a slave boy owned by John C. Cox, William Tingle, or David Campbell—E.R. Moffet and John B. Sergeant's 1870 strike was the first major lead strike within Joplin and the one that put the city on the map. In August 1870, the two miners leased a tract near Joplin Creek and sank a discovery shaft that reportedly produced $60,000 worth of lead. This major strike became a defining moment in Joplin history, sparking the mining boom that continued for 75 years.