Opened in 1921 near Clarksville as the Edward Mine under the Chartiers Southern Coal Company, the operation gained a company town called Chartiers after 70 houses were built in 1923, then was taken over by Emerald Coal and Coke Company and renamed Emerald Mine. From 1930 to 1962, Emerald Mine produced 19.5 million tons of coal, with a peak year in 1957 when 865 miners produced 1.73 million tons. In June 1944, the Chartiers community suffered two disasters: on June 7, a mine fire caused by a broken trolley wire that ignited hay killed six men and 30 horses, though 151 other night-shift miners escaped through the air shaft near Lippencott, and on June 23, a tornado destroyed two rows of company houses and the company store, demolishing more than 40 houses and killing at least 11 Chartiers residents among the 23 deaths in Greene County. In 1963, Gateway Coal Company, formed by Jones and Laughlin Steel Company, Pittsburgh Steel Company and Pittsburgh Coke and Chemical Company, took control of Emerald Mine and renamed it Gateway Mine. It continued for many years as one of Greene County's largest mines, working about 8,000 acres of the Pittsburgh coal seam across Morgan, Jefferson, Franklin and Washington townships. By 1980, six shafts ranging from 133 to 586 feet reached the seam, with portals at Chartiers, Browns Run, Grimes and Ruff Creek, and coal moved underground by belts to a tipple on the Monongahela River between Rices Landing and Millsboro for barge shipment to the cleaning plant at LaBelle. Gateway operated continuously from 1963 through 1989, introduced Greene County's first longwall mining in November 1970, reached peak employment of 685 miners in 1979, and in its final year 241 miners produced 1.7 million tons of coal.