6.8" Purple, Cubic Fluorite Cluster - Cave-In-Rock, Illinois

The Cave-In-Rock mining district of Hardin County, Illinois is world renown for it's fluorite which is widely considered to be some of the highest quality fluorite in the world. The area has a long history of producing spectacular fluorite specimens from several different mines. All of the major mines have been closed for years and the cut off in supply has sent prices of this material, soaring. A recently bored mine is now producing small amounts of material, but it hasn't made a dent in demand or prices.

Fluorite is a halide mineral comprised of calcium and fluorine, CaF2. The word fluorite is from the Latin fluo, which means to flow. In 1852 fluorite gave its name to the phenomenon known as fluorescence, or the property of fluorite to glow a different color depending upon the bandwidth of the ultraviolet light it is exposed to. Fluorite occurs commonly in cubic, octahedral and dodecahedral crystals in many different colors. These colors range from colorless and completely transparent to yellow, green, blue, purple, pink or black. Purples and greens tend to be the most common colors seen.

Archaeological discoveries near the Cave-In-Rock mining district of beads and other ornaments made of fluorite have placed the use of the stone to about 900 years ago when the land was inhabited by the Native Mississippian Americans. Early European settlers mining for galena in the 1830's discarded the fluorite as the lead they sought was more valuable at the time. In the 1880's it was discovered that fluorite was very useful in a new steel-furnace technology and demand increased considerably, leading to the emergence of several commercial fluorite mining companies in the Illinois/Kentucky region.

Barite, commonly spelled baryte, is well-known for its great range of colors and varied crystal forms and habits. It is a heavy mineral consisting of barium sulfate, and typically has the chemical formula of BaSO4. The barite group consists of baryte, celestine, anglesite and anhydrite. It's generally white to colorless and is the main source of barium.