Fluorite

specimen number:
2072324

location:
Denton Mine, Hardin Co., Illinois, USA

description:
Attractive mostly gemmy in color zoned bluish purple crystals of fluorite to 6.0 cm on edge across the top of matrix. Typical of these large pieces from this area, slight damage present, this one still in good condition.

The Denton Mine, located in the Cave-in-Rock District of Hardin County, Illinois, is a premier example of a Mississippi Valley-Type (MVT) deposit hosted within the Mississippian-aged St. Genevieve and St. Louis Limestones. Geologically, the site is characterized by bedded-replacement mineralization where fluorine-rich hydrothermal fluids flowed through fault systems and replaced carbonate layers with high-grade fluorspar. The mine is famous for producing world-class fluorite specimens, often featuring large, transparent cubes in shades of purple, blue, and yellow, frequently found with petroleum inclusions and associated with calcite, sphalerite, and galena. Historically, the Denton Mine was developed by the Ozark-Mahoning Company, with construction of the main shaft beginning in 1978 and full-scale mining and quarrying operations commencing in 1980. The mine was a major producer of industrial fluorspar until the decline of the domestic industry led to its closure in 1994. As of 2026, the Denton Mine is remembered as one of the last great producers of the Illinois-Kentucky Fluorspar District, and its specimens remain highly sought after for their geometric perfection and vivid color zoning.

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