Smithsonite

specimen number:
2262280

location:
Tsumeb Mine, Otjikoto, Namibia

description:
Sharply formed lustrous rhombohedral crystals of smithsonite to 0.5 cm in size across the top of matrix. In great condition.

The Tsumeb mine, located in the Otjikoto Region of northern Namibia, was a legendary underground mining operation internationally famous for its unprecedented wealth of base metal ores and secondary minerals. Geologically, the deposit consists of a steeply dipping, pipelike polymetallic replacement structure that cuts through a thick sequence of Neoproterozoic marine carbonates belonging to the Otavi Group dolomite. High-temperature hydrothermal fluids channeled through regional fault systems dissolved the host dolostones, precipitating massive primary sulfide ores rich in lead, copper, zinc, silver, arsenic, and germanium. Over millions of years, extensive groundwater circulation and deep weathering of these primary sulfides created a highly advanced, multi-stage oxidation zone that penetrated to great depths, resulting in the formation of hundreds of rare, brightly colored secondary minerals including world-class specimens of azurite, malachite, dioptase, mimetite, and cerussite. Historically, indigenous peoples surface-mined the rich green copper outcrops for centuries before formal European exploration led to the founding of the Otavi Minen- und Eisenbahn-Gesellschaft (OMEG), which initiated large-scale industrial shaft-sinking and commercial production in 1907. The mine operated nearly continuously through the twentieth century, transitioning to ownership under Tsumeb Corporation Limited (TCL) in 1947, which modernized the infrastructure and pushed the deep underground workings to a final depth of over 5000 feet. Severe economic challenges, labor strikes, and the eventual depletion of the deepest accessible high-grade ore bodies forced the permanent cessation of all underground extraction and the flooding of the lower levels in 1996.

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