Mixite

specimen number:
2262095

location:
Neubulach, Calw, Karlsruhe, Baden-Wurttemberg, Germany

description:
Light green acicular crystals of mixite in clusters to 0.4 cm in size throughout this quartz matrix. Good example for the species.

The Neubulach mining district, located near Calw within the Northern Black Forest of Baden-Wuerttemberg, Germany, is a historic hydrothermal vein system situated in the Buntsandstein (Lower Triassic sandstone) and underlying basement rocks. Geologically, the deposit consists of barite-fluorite veins enriched with copper, bismuth, and secondary minerals formed through the oxidation of primary sulfides. The locality is well-known for producing mixite, a rare bismuth copper arsenate hydrate that typically occurs as delicate, needle-like or acicular crystals in radiant tufts or felt-like coatings with a characteristic emerald-green to pale-green color. Historically, mining and quarrying at Neubulach date back to the Middle Ages, specifically the 13th century, with peak periods of silver and copper extraction occurring during the 14th and 16th centuries. Most commercial operations ceased by the mid-19th century, though the Hella-Glueck adventure mine was later reopened for tourism and mineralogical study, remaining an active site for educational and specimen interest through 2026. This district stands as a significant cultural and geological landmark, reflecting the long-standing mineral heritage of the Black Forest region.

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