Illinois-Kentucky Fluorspar District, USAi

Regional Level Types
Illinois-Kentucky Fluorspar District	Mining District
USA	Country

The large mineralized area in southern Illinois and western Kentucky is loosely referred to as the Illinois-Kentucky fluorspar district because fluorspar has been the most important product of the region. The known mineralized area covers about 540 square miles (1 ,400 km 2) and contains many districts. The geology of the area has been studied for many years; general references include reports by Ulrich and Smith (1905), Bastin (1931), and Weller, Grogan, and Tippie (1952).

The known mineral deposits occur as four major structural types: veins, bedded deposits, breccias of solution-slump origin, and diatremes. Deposits of all types contain fluorite, sphalerite, galena, chalcopyrite, and barite, and at least one diatreme also contains uranium-, thorium-, niobium-, and rare-earth-element-bearing minerals. Mining activity has concentrated on the vein and bedded types, and the solution-slump breccias and diatremes are not well known.

Nearly all the deposits of the region contain large amounts of fluorspar and differ significantly from other major deposits in the Mississippi valley, which are mined mainly for lead and zinc minerals. The lead and zinc now produced here are byproducts of fluorspar mining. Lead, however, was the first commodity mined (Ulrich and Smith, 1905, p. 16- 21; Weller and others, 1952, p. 11), starting about 1835. In early mining, fluorite was considered to be a gangue mineral, but in the late 1800's fluorite became valuable for its use as flux in the open-hearth furnaces of the steel plants in the upper part of the Ohio River valley. Sulfide minerals were detrimental to this use of the fluorspar ore, and ore free of sulfides was desired. Milling by selective flotation and by the sink-float process came into general use in the area in the late 1930's and early 1940's; lead and zinc have been recovered since then, and multicomponent ores are now mined.

The use of fluorspar has steadily increased for many years, and, because the Illinois-Kentucky mineralized area is the largest source of domestic fluorspar, production can be expected to increase correspondingly. Hence, the production of other commodities associated with fluorite -- chiefly lead, zinc, cadmium, and possibly barite -- will also increase. Many deposits contain fairly large amounts of barite, some of which is now being recovered in conjunction with other products; until recently, problems of separating the barite from the other components of the ore discouraged significant production of barite.

As stated in Mines and Minerals of the Western Kentucky Fluorspar District:

"The earliest mining in the district was for lead at the Columbia Mine, Crittenden County, in 1835 (Ulrich and Smith, 1905, p. 115). From 1835 to the early 1870's, little fluorspar was mined. Only small amounts were produced from the early 1870's to about 1890, when an expanded market was created by the development of the basic open-hearth steel furnace, in which fluorspar was used for flux. Production since 1890 has been erratic, but in general has risen. During World Wars I and II and the Korean conflict, production rose sharply, but because of rising imports from 1955 to 1958, production in the district decreased. It rose in 1970, but declined rapidly, and all production ceased in Kentucky by 1985. Sporadic milling of recycled government stockpiles continued into the 1990's. Exploration is intermittent in the district, and currently there is one operating mine, near the Klondike Mine complex.

Since mining began in 1873, the Western Kentucky Fluorspar District has produced about 3.5 million tons of fluorspar, 70,000 tons of zinc, 12,500 tons of lead, and 45,000 tons of barite concentrate (Anderson and others, 1982). Some trace elements, such as silver, copper, cadmium, and gallium, have also been recovered. Thirty percent of the fluorspar came from the Tabb Fault System, a major curvilinear fault in southern Crittenden and western Caldwell Counties (Trace and Amos, 1984). Zinc has also been produced since 1940, some as a byproduct of mining fluorite. The Hutson Mine was a primary zinc producer in the district. Substantial quantities of barite have also been produced. Lead has been a minor byproduct in recent years, as have silver, cadmium, and germanium."