Sphalerite with Dolomite, Chalcopyrite - image 1

Sphalerite with Dolomite, Chalcopyrite

Unknown Owner

A superb large sharp grouping of twinned semi lustrous black sphalerite crystals perched aesthetically up on a dolomite and chalcopyrite crystal matrix. This is in really good condition. The quality is way better than most for this famous old locality.The Picher Field was the most productive part of the Tri-State Mining District, spanning the border of northeastern Oklahoma and southeastern Kansas. Geologically, it is a world-class Mississippi Valley-Type (MVT) lead-zinc deposit hosted within the Mississippian-aged Boone Formation, which consists primarily of cherty limestones. During the Pennsylvanian Period, metal-rich hydrothermal fluids migrated through regional tectonic structures, depositing minerals in large solution-collapse breccias and along bedding planes where the limestone had been dissolved. Historically, mining began in the Picher area around 1913, and the field quickly became the leading producer of zinc and lead in the United States, playing a critical role during World War I and World War II. Large-scale operations continued until the 1960s, leaving behind a complex legacy of massive underground workings and environmental challenges that eventually led to the town of Picher becoming part of a federal Superfund site.For mineral collectors, the Picher Field is legendary for producing some of the finest sphalerite specimens in North America. The sphalerite from this locality is famously known as "ruby jack" when it exhibits a deep reddish-brown transparency, or simply "blackjack" for the more common, lustrous black crystals. These crystals often form as sharp, complex tetrahedrons or dodecahedrons, frequently reaching several centimeters in size with a brilliant, sub-metallic luster. They are commonly found in aesthetic association with "chalcocite-coated" galena cubes, brassy chalcopyrite, and large, cream-colored "saddle-shaped" dolomite crystals. The specimens are often anchored to a dark, fractured chert matrix, providing a rugged and classic appearance. Although the mines are now closed and largely inaccessible, Picher sphalerite remains a cornerstone of American mineralogy, representing the immense scale and mineral diversity of the historic Tri-State District.