Fluorite

specimen number:
2013009

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

description:

An absolutely gorgeous cluster of glassy gemmy zoned cubic fluorite crystals. This is complete all around with very minimal micro-damage present. The luster and color zoning, especially when backlit, makes the specimen spectacular.

The Hill-Ledford mine, situated just north of Cave-in-Rock in Hardin County, Illinois, is a classic American mineral locality celebrated for producing magnificent specimens of fluorite, also known as fluorspar, alongside major byproduct galena and sphalerite. Geologically, this deposit is situated within the famous Illinois-Kentucky Fluorspar District, a world-class Mississippian Valley-Type (MVT) mineralized zone where low-temperature, metal-bearing hydrothermal fluids migrated through deep sedimentary sequences. Mineralization at the Hill-Ledford property occurred predominantly as bedded replacement deposits and vein fillings within the Mississippian-age St. Louis and Ste. Genevieve Limestones, with fluorite precipitating into open cavities at the Rosiclare and Sub-Rosiclare stratigraphic levels to form highly distinctive, blocky cubic crystal clusters that typically display deep violet, dark purple, near-black, or yellow color zoning and lustrous, naturally etched growth features. Historically, while early lead extraction occurred in the broader district during the mid-19th century, intensive underground mining and exploratory quarrying at the Hill-Ledford site accelerated during the early to mid-20th century to supply high-grade fluorite flux for the booming Ohio River Valley steel industries. The mine reached its primary era of modern productivity under corporate operators like the Ozark-Mahoning Company during the 1950s and 1960s, a period when the underground workings yielded tons of industrial ore and many of the finest large cabinet specimens known for the locality before shifting economic conditions and localized resource depletion led to the eventual abandonment of the site in the 1970s.

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