Calcite with Fluorite

specimen number:
2013512

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

description:
Aesthetic gemmy and glassy complex crystals of calcite across the top of a purple fluorite crystal matrix. This is in really good condition. Collected in the mid 1980s.

The Denton Mine, located in the Cave-in-Rock District of Hardin County, Illinois, is a premier locality within the Illinois-Kentucky Fluorspar District. Geologically, it is a Mississippi Valley-Type (MVT) deposit hosted within Mississippian-aged limestones, specifically the Ste. Genevieve and St. Louis formations. The mineralization occurred when fluorine-rich hydrothermal fluids moved through the regional fault systems, creating extensive bedding-replacement deposits known as mantos and filling large solution cavities. Historically, the mine was operated by the Ozark-Mahoning Company and began production in the late 1970s, quickly becoming one of the most significant producers of acid-grade fluorspar in the United States. It remained a vital industrial site until the mid-1990s, when the decline of the domestic fluorspar industry led to the permanent cessation of mining operations in the district.

For mineral collectors, the Denton Mine is legendary for producing some of the finest calcite crystals ever found in North America. These specimens are famous for their sharp, scalenohedral habit and a distinctive "honey-yellow" to "amber" color, often exhibiting a high degree of transparency and a brilliant vitreous luster. The calcite crystals frequently occur in aesthetic association with vibrant, multi-colored fluorite cubes, brassy chalcopyrite, and sparkling sphalerite. Many of the most iconic Denton calcites are found as large, double-terminated crystals perched dramatically on a matrix of cubic fluorite, creating a world-class contrast in both color and form. Because the mine is now closed and flooded, these superb calcites have become highly prized classics of American mineralogy, representing the pinnacle of crystallized carbonate minerals from the Midwestern United States.

Questions about this specimen?
Send an email or call us: 314-341-1811.