Fluorspar
For many years Illinois has led the nation in the production of fluorspar, accounting annually for about half the total United States output. The industry is centered in Hardin and Pope Counties where the deposits occur in veins and beds in rocks of the Mississippian System. Reserves of fluorspar are adequate to supply the industry for many years.
Figure 12—Sand and gravel is produced at many places in the state. Silica sand is produced only from a sandstone in northern Illinois. Tripoli is found only in southern Illinois.
KEY Sand and Gravel Silica Sand Molding Sand Tripoli
Fluorspar is used in the manufacture of hydrofluoric acid, as a flux in the manufacture of steel, in the refining of aluminum, for the manufacture of fluorine compounds used in a variety of products, in ceramic glazes, and for other special purposes.