Duftite on Calcite

specimen number:
1052735

location:
Tsumeb Mine, Otjikoto, Namibia

description:

Classic specimen for this locality, green crystallized duftite coating most of the top of a matrix that is covered with rhombohedral crystals of calcite measuring to 2.5 cm in size. In good condition.

The Tsumeb mine, located in the Oshikoto Region of northern Namibia, was a legendary underground mining operation internationally famous for its exceptionally complex polymetallic ore body and a vast array of secondary minerals. Geologically, the deposit was a steeply dipping, pipe-like structure that penetrated deep into the Neoproterozoic-age Otavi Group dolostones, formed as a massive paleokarst solution collapse breccia tube that acted as a major conduit for ascending hydrothermal fluids. These metalliferous fluids deposited rich primary sulfide ores containing copper, lead, zinc, silver, arsenic, and germanium, which later underwent extensive, deep-reaching groundwater oxidation across multiple distinct oxidation zones to produce unparalleled concentrations of rare arsenate and carbonate minerals like dioptase, azurite, mimetite, and cerussite. Historically, indigenous San and Damara people surface-mined and smelted the copper outcrops for centuries before European exploration led to the formation of the Otavi Minen- und Eisenbahn-Gesellschaft, which initiated formal industrial underground mining at the site in 1900. The mine operated almost continuously through the twentieth century under various corporate entities, including Newmont and Amax under the Tsumeb Corporation Limited banner, sinking deep shafts down to nearly fifteen hundred meters to extract millions of tons of high-grade base metal ore. Heavy commercial extraction sustained the local economy for nearly a century until structural financial difficulties, labor strikes, and the eventual depletion of economic deep-level ore reserves led to the permanent cessation of all mining operations at Tsumeb in 1996.

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