Fluorite with Quartz, Sphalerite

specimen number:
2013566

location:
Davis-Dearfoff Mine, Hardin Co., Illinois, USA

description:
An attractive miniature from this famous old locality. Rosy purple mostly gemmy cubic crystals of fluorite to 1.0 cm in size perched attractively up on a crystallized quartz matrix with lustrous black crystals of sphalerite. In good condition with slight micro-cleaving present.

The Davis-Deardorff Mine, situated in the Rosiclare District of Hardin County, Illinois, was a significant producer within the Illinois-Kentucky Fluorspar District. Geologically, the deposit consisted of high-grade hydrothermal vein and bedded replacement ores hosted in Mississippian-aged limestones, specifically the Ste. Genevieve and St. Louis formations. These deposits formed as fluorine-rich fluids ascended along the complex fault systems of the Reelfoot Rift, precipitating spectacular cubic crystals of fluorite often accompanied by sphalerite, galena, and barite. The mine is particularly noted for its distinctive yellow, purple, and blue fluorite specimens that frequently exhibit sharp zoning. Historically, the Davis-Deardorff was operated primarily by the Ozark-Mahoning Company, with its most productive years occurring from the early 1940s through the late 1950s. While it contributed heavily to the domestic supply of acid-grade fluorspar during and after World War II, mining eventually ceased as deeper reserves became less economical to reach. Today, the site is a classic locality represented in many collections by its vibrant, multi-colored fluorite cubes.

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