Calcite

specimen number:
2212102

location:
Big John Mine, Treece, Cherokee Co., Kansas, USA

description:
Sharp mostly transparent colorless to slightly purplish crystal of calcite. This has inclusions of marcasite throughout. In good condition.

The Big John Mine, located near Treece in Cherokee County, Kansas, was a significant producer within the Picher Field of the Tri-State Mining District. Geologically, it exploited Mississippi Valley-Type (MVT) mineralization, where lead and zinc sulfides were deposited within the Mississippian Boone Formation, specifically replacing brecciated chert and limestone. The mine is mineralogically famous for producing large, sharp scalenohedral calcite crystals that are typically colorless but frequently exhibit distinctive purple phantom interiors or cores. These aesthetic calcites often occur alongside classic specimens of galena, sphalerite, and pink dolomite, representing the complex hydrothermal history of the region. Historically, mining and quarrying at the Big John site flourished during the first half of the 20th century, with peak production occurring between the 1920s and 1940s to support industrial demand during the World Wars. As part of the interconnected network of mines near the Oklahoma-Kansas border, it contributed to the districts status as a global leader in zinc production before large-scale operations in the Treece area largely ceased by the late 1960s.

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