Fluorite with Galena, Sphalerite, Quartz

specimen number:
2092163

location:
Hill-Ledford Mine, Hardin Co., Illinois, USA

description:
Classic old specimen from southern Illinois with rosy purple mostly transparent crystals of fluorite to 4.0 cm on edge across the top of a large breccia matrix with small crystals of sphalerite and galena. The matrix is coated with microscopic quartz. A fine old timer. Very little cleaving present. Overall in good condition.

The Hill-Ledford Mine, located near Cave-in-Rock in Hardin County, Illinois, was a significant operation within the historic Illinois-Kentucky Fluorspar District. Geologically, the mine targeted bedded replacement deposits, or mantos, situated along the Sparks Hill Fault system where hydrothermal fluids replaced specific Mississippian-aged limestone layers, primarily within the Ste. Genevieve Formation. These fluorine-rich fluids originated from deep-seated magmatic sources associated with the Hicks Dome structure, precipitating massive fluorite along with secondary sulfides and carbonates. Historically, the mine began operations in the late 1940s to early 1950s and served as a vital source of metallurgical and acid-grade fluorspar for decades. It remained active through the mid-20th century but, like many mines in the region, faced increasing economic pressure from foreign imports, eventually leading to its closure in the late 1970s. Despite its industrial focus, the mine is remembered by the mineralogical community for producing exceptional crystal-lined pockets that provided a window into the complex geochemical history of the Ohio River Valley.

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