Sphalerite with Chalcopyrite

specimen number:
8311494

location:
Swalley Mine, Baxter Springs, Kansas, USA

description:
A grouping of large iridescent sphalerite crystals, these hosting crystals of chalcopyrite. The sphalerite crystals exhibit twinning, overall in good condition with just slight micro-damage present. This is classic material for this old locality. The iridescence makes this quite attractive.

The Swalley mine, situated near Baxter Springs in Cherokee County within the extreme southeastern corner of Kansas, United States, represents a historical underground lead and zinc operation located in the western portion of the famous Picher Field of the Tri-State District. Geologically, this Mississippi Valley-type (MVT) deposit is hosted within Mississippian-age cherty limestones of the Boone Formation, where low-temperature hydrothermal fluids circulated through complex tectonic breccias, shear zones, and solution cavities beneath a regional unconformity. The mineralization consists primarily of massive, dense beds of coarse-grained sphalerite and galena intimately associated with abundant gray and brown chert, jasperoid, and minor late-stage dolomite or calcite crystals. Historically, while early exploration and shallow shafts expanded into this part of Cherokee County during the early 1900s, modern mechanized development at the Swalley property intensified mid-century, culminating in its operation as a major incline mine by Eagle-Picher Industries. The facility remained highly productive throughout the 1960s, serving as a vital regional producer until its final closure in October 1970, which officially marked the end of all lead-zinc mining within the state of Kansas.

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