Fluorite with Chalcopyrite

specimen number:
2292233

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

description:
An attractive gemmy cluster of semi lustrous color zoned blue and purple fluorite crystals. This is in really good condition. Beautiful when backlit as shown in the picture and at the end of the video. Collected in 1984.

The Denton mine, located near Cave-in-Rock in Hardin County, Illinois, was a major underground fluorspar operation within the famous Illinois-Kentucky Fluorspar District, celebrated by collectors for producing iconic, sharply zoned purple, blue, and yellow fluorite crystals. Geologically, the deposit is classified as a Mississippi Valley-Type (MVT) bedded replacement deposit, where fluorine-rich hydrothermal fluids ascended along structural faults and reacted with Mississippian-age limestones, substituting carbonate minerals with calcium fluoride, sphalerite, galena, and barite. Developed and operated by the Ozark-Mahoning Company, the underground mine reached a depth of approximately 640 feet and was placed into active commercial operation in 1981. The facility produced hundreds of thousands of tons of high-grade industrial fluorspar alongside legendary mineral specimens until economic pressures and foreign competition forced the cessation of production and subsequent flooding of the mine shafts in 1993.

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