Fluorite

specimen number:
2212153

location:
Southern Illinois Fluorspar District, Illinois, USA

description:
Attractive cluster of light purple to blue color zoned mostly gemmy lustrous fluorite crystals. Some hydrocarbon present. Damage is present as seen.

The Southern Illinois Fluorspar District, spanning Hardin and Pope counties, was the largest producer of fluorite in the United States and is celebrated for its world-class, multicolored fluorite crystals. Geologically, the district is located within the Illinois-Kentucky Fluorspar District, where fault-controlled, hydrothermal vein deposits and bedding-replacement ore bodies formed during the Permian period as mineral-rich fluids moved through Mississippian limestone formations. This unique mineralization produced massive aggregates and sharp, cubic crystals of fluorite in vibrant shades of purple, yellow, and blue, frequently accompanied by calcite, sphalerite, and galena. Historically, commercial mining and quarrying operations began in 1842 near Rosiclare, initially targeting lead but quickly shifting to fluorite to meet the demands of the steel industry for use as a flux. Production peaked during the mid-20th century, with dozens of active mines operating continuously until cheap foreign imports forced the closure of the Hastie Quarry and the final underground operation, the Minerva Number One mine, in 1995.

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