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Chat (mining)
Chat is a term for 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 in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma and the Old Lead Belt covering about in southeastern Missouri. The first recorded mining occurred in the Old Lead Belt in about 1742. The production increased significantly in both the Tri-state area and the Old Lead Belt during the mid-19th century and lasted up to 1970.
==Cleanup==
Currently production still occurs in a third area, the Viburnum Trend, in southeastern Missouri. Mining and milling of ore produced more than 500 million tons of wastes in the Tri-State area and about 250 million tons of wastes in the Old Lead Belt. More than 75 percent of this waste has been removed, with some portion of it used over the years. Today, approximately 100 million tons of chat remain in the Tri-State area. The EPA, the states of Oklahoma, Kansas and Missouri, local communities, and private companies continue to work together in implementing and monitoring
response actions that reduce or remove potential adverse impacts posed by remaining mine wastes contaminated with lead, zinc, cadmium, and other metals.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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