Fluorite

The Minerva No. 1 Mine in southern Illinois was one of the most important mines in the Cave-in-Rock Fluorspar District. Operating from the 1940s until 1996, it produced some of the district’s finest fluorite specimens, along with sphalerite and several less common barium-bearing minerals. Some of its most sought-after fluorite came from the Cross-Cut orebody, where crystals formed alongside hydrocarbon-rich material that influenced their growth and appearance. The mine remains a classic locality for American fluorite collectors.