HISTORY OF THE PICHER MINING FIELD
Mining practiced in the Picher Mining Field is commonly referred to as random room-and-pillar mining where rooms were excavated and pillars were left to support the mine roof. Approximately 1,200 vertical mine shafts between 90 and 350 feet were sunk to intercept the main ore horizons. Milling depended primarily on specific gravity methods, including jigs and tables. In the 1920s the flotation process became the primary means for extracting concentrates from the finely ground ore remaining from the initial milling process and remilling tailings. By the late 1920s, 227 mills were operating in the mining field. By the late1930s most of the higher grade ore had been mined and most tailings piles remilled. Several central mills were built to replace the smaller, less efficient mills in order to extend the life of the field.
The amount of ore mined annually continued to decrease in the 1950s and 60s until 1970 when all mining ceased and all pumps were removed from the mines. The abandoned mine workings continued to fill with water until 1979 when the entire underground workings in the field were flooded.