Chalcopyrite with Dolomite

specimen number:
2072298

location:
Treece, Tri-State District, Kansas, USA

description:
Sharp crystals of chalcopyrite to 0.4 cm in size across the top of a chert matrix with very light pink to almost colorless crystals of dolomite. Classic material for the locality, in good condition.

The Treece area, located in Cherokee County, Kansas, represents the northern extension of the Picher Field within the massive Tri-State Mining District. Geologically, the region is characterized by Mississippi Valley-type (MVT) deposits where lead and zinc sulfides, primarily galena and sphalerite, precipitated within the Mississippian-age Boone Formation limestones and cherts. These ores were deposited in brecciated zones and solution cavities created by ancient groundwater movement. Historically, mining and quarrying operations in the Treece area began in the early 20th century, with production peaking during the 1920s to satisfy global industrial demand for lead and zinc. Extraction activities continued through the mid-20th century, but large-scale commercial mining largely ceased by the 1970s as ore grades depleted and environmental concerns mounted. By 2026, the town of Treece has become a significant site for environmental reclamation following its designation as part of a federal Superfund site due to historical mining subsidence and heavy metal contamination. Despite the cessation of active mining, the area remains a key historical reference for the vast mineral wealth that once fueled the industrial growth of the American Midwest.

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