Barite with Fluorite

specimen number:
2013587

location:
Crystal Mine, Hardin Co., Illinois, USA

description:

Pale blue lustrous tabular crystals of barite and attractive clusters to 5.0 cm in size across the top of a crystallized fluorite matrix. This is in super condition. Wonderful large cabinet example from this important locality.

The Crystal Mine, located near Spar Mountain in the Cave-in-Rock District of Hardin County, Illinois, is a legendary locality celebrated for producing some of the finest fluorite specimens in the world. Geologically, the mine exploited bedded replacement deposits within Mississippian-aged limestones, where fluorine-rich hydrothermal fluids interacted with the Ste. Genevieve and Renault formations to create expansive mineralized zones. These pockets yielded spectacular cubic fluorite crystals, often featuring a vibrant yellow core with distinct purple zoning and exceptional clarity, frequently found in association with sphalerite, galena, and barite. Historically, the mine was a primary asset of the Minerva Oil Company and saw its most significant period of industrial activity from the early 1940s through the 1970s. As a vital contributor to the Illinois-Kentucky Fluorspar District, it provided critical raw materials for the steel and chemical industries while simultaneously providing collectors with museum-quality specimens. Although commercial operations ended in the late 20th century as the district faced economic challenges from global competition, the Crystal Mine remains a benchmark locality for the study of Mississippi Valley-Type (MVT) deposits and aesthetic mineral crystallization.

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