Fluorite with Chalcopyrite

specimen number:
2013573

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

description:

Beautifully aesthetic large rectangular gemmy blue semi lustrous grouping the fluorite crystals with no matrix or points of attachment. Minor chalcopyrite is present. This is in really good condition all around. From the early 1980s. Very attractive when backlit as shown in the photo and at the end of the video.

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 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.

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