Barite with Fluorite

specimen number:
2102381

location:
Annabel Lee Mine, Hardin Co., Illinois, USA

description:
Good old combination piece for this locality, colorless and lustrous partly transparent bladed crystals of barite across the top of a crystallized fluorite matrix. This is in good condition. From the very early 1990s.

The Annabel Lee mine, located near the town of Harris Creek within the famous Cave-in-Rock fluorspar district of Hardin County, Illinois, was a premier underground mining operation renowned among mineralogists for producing exceptional, world-class crystal specimens of zoned fluorite, barite, and chalcopyrite. Geologically, the mine exploited a classic Mississippi Valley-Type (MVT) epigenetic deposit, where low-temperature, metal-rich hydrothermal fluids migrated through regional faults and selectively replaced Mississippian-age sedimentary limestones, specifically within the St. Louis Limestone formation. This process formed extensive horizontal bedded replacement deposits (mantos) and filled major dissolution cavities with mineral-lined pockets containing magnificent cubes of transparent purple, yellow, and clear fluorite, often associated with pristine crystals of sphalerite, galena, and calcite. Historically, the mine was one of the last major shafts developed in the district, with construction commencing in 1982 by the Ozark-Mahoning Company, a subsidiary of Pennwalt Corporation, which sank a 1000-foot vertical production shaft and brought the facility into full continuous commercial operation by 1984. Miners working the deep, highly mechanized underground headings regularly encountered spectacular, fluid-filled pockets that yielded thousands of museum-quality specimens for the global collector market. However, due to severe global economic competition from low-cost Chinese imports and the ultimate exhaustion of high-grade, easily accessible ore reserves, all corporate underground mining operations at the Annabel Lee site were permanently shut down and the pumps stopped in early 1995, marking the end of a golden era for Illinois fluorspar mining.

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