Chat (mining) - Wikipedia
Chat is fragments of siliceous rock, limestone, and dolomite waste rejected in the lead-zinc milling operations that accompanied lead-zinc mining in the first half of the 20th century. Historic lead and zinc mining in the Midwestern United States was centered in two major areas: the tri-state area covering more than 2,500 square miles (6,500 km 2) in southwestern Missouri, southeastern Kansas ...