FLUORITE, or fluorspar, is made up of the elements calcium and fluorine.
The mineral is easily identified by its perfect cleavage, color, and
hardness.
It occurs in cubic crystals that may be twinned but is more often found
as irregular masses. It can be split into diamond-shaped, eight-sided
forms (octahedrons). Fluorite is commonly gray, white, or colorless, but
it may be green, blue, purple, pink, or yellow. The streak is colorless
and the luster glassy. It can be scratched by a knife or a piece of
window glass, is fairly light weight, and is transparent to translucent.
Extensive deposits of fluorite, one of Illinois’ important commercial
minerals, occur in Hardin and Pope Counties in extreme southern
Illinois, where it is associated with galena, sphalerite, calcite,
barite, and other less abundant minerals.
Fluorite is used to make hydrofluoric acid, to form a fluid slag in the
production of iron and steel, in the manufacture of aluminum, to make
many chemical products, and in the ceramic industry, in which it is used
to make colored glass, enamels, and glazes.