Illinois State Museum

Southern Illinois Fluorite Region

mines map
A 65 square kilometer (40 mi2) area in southeastern Illinois (primarily Hardin County) was the country's leading producer of fluorite.

Fluorite, also called fluorspar, was first mined in Illinois in 1842. By the 1960s, an average of 118,820 metric tons (130,700 tons) of fluorite were removed each year from underground mines up to 305 meters (1,000 ft.) deep. Vein deposits are up to 12 meters (40 ft.) wide and 515 meters (1,690 ft.) long. The veins mostly contain fluorite and calcite, but also barite, quartz, sphalerite, and galena. Masses of pure fluorite 3 meters (10 ft.) across have been discovered in mines near Rosiclare in Hardin County.

The Illinois General Assembly made fluorite the State mineral in 1965. Competition from foreign sources, along with the high cost of underground mining, eventually made fluorspar mining unprofitable in Illinois. The last Illinois mine closed in December 1995.
Fluorspar is no longer mined in the United States.

Use of Fluorite

Fluorite is used as a flux in smelting iron, aluminum, and other metal alloys and in welding. It is also used in the manufacture of glass, enamel glazes, ceramics, cement, and other chemical compounds. Fluoride, derived from fluorite, is used in toothpaste, optical lenses, concrete hardeners, organic chemicals, plastics, refrigerants, nonstick coatings, lubricants, stain repellants, dyes, herbicides, anesthetics, cleaning solvents, and degreasing and foaming agents.