People have been digging, processing, and transporting fluorite in Rosiclare and Hardin County since 1842. In the 1940s, the area led the U.S. in fluorite production and was known as the "Fluorite Capital of the World." Fluorite, the Illinois State Mineral, is a blue, purple, yellow, green, or colorless mineral that often forms cube-shaped crystals and is used in producing steel, glassware, ceramics, cookware, enamels, lubricants, aluminum, jewelry, fluoride, and microscope and telescope lenses. At times more than 1,100 miners worked underground in the Rosiclare area, and by 1900 local fluorite was being shipped around the world. During World War II, fluorite was considered so important that mines were guarded and the U.S. government built housing for 150 families involved in mining. Companies operating in Rosiclare included Rosiclare Lead & Fluorspar Co., Fairview Mining Co., Hillside Mining Co., Blue Diggings Mining Co., Knight, Knight & Clark Mining Co., and Ozark-Mahoning Mining Co. In the mills, ore was crushed or ground into smaller pieces, and a tram carried ore from the mine down Main Street to the river and brought back coal. The Ohio River was central to transporting fluorite, galena, and other local minerals by wagons, trains, trucks, and ships around the nation and the world. Mining also carried a heavy toll: at least 25 miners have died in local mines since 1915. On April 12, 1971, Bill Long entered the Barnett mine south of Rosiclare and did not return; his brother Wayne went in after him and also died from hydrogen sulfide gas. Five more miners died trying to rescue them: Jerry Jenkins, Orval Holbrook, James R. Lane, Randel "Jock" Belford, and Gale Bates. The seven deaths devastated the community and led to mining safety reforms nationwide. Rosiclare's annual Fluorspar Festival and the American Fluorite Museum reflect fluorite's historic and continuing importance to the community.