American Fluorite Museum, Illinois

A museum devoted to the mineral fluorite (also known as fluorspar, especially within those industries which regularly use various processed forms of it), that boasts specimens, photographs, and displays pertaining to its mining and refining. The museum is located on the site of the former Rosiclare Lead and Fluorspar Mining Co. Fluorite is used in the manufacture of glass, ceramics, enamels, refrigerants, and hydrofluoric acid. It is also used as a flux during the production of steel and aluminum.  Illinois once produced over half of the U.S.'s fluorite supply, beginning in the 1940's. By the 1990's, however, domestic suppliers could no longer compete with foreign producers, culminating in the closure of Illinois' last fluorite mine in 1995. Nevertheless, fluorite remains the official state mineral of Illinois.