Duftite on Calcite

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A cluster of rhombohedral calcite crystals, these complete all around with no points of attachment. One side is completely coated with light green crystallized duftite. In good condition all around. From the 1970s. The Tsumeb mine, located in the Otavi Mountains of northern Namibia, is a globally famous polymetallic deposit that operated commercially from 1897 until its closure in 1996. Long before European colonization, indigenous peoples, including the San, Herero, and Ovambo, mined and smelted the surface copper ores. Geologically, the orebody is a steeply dipping, pipe-like breccia structure that cuts through Neoproterozoic dolomites of the Otavi Group. This pipe was filled with sand and carbonate fragments that underwent intense alteration from deep-seated, rising hydrothermal fluids. The site is mineralogically unique due to its deep groundwater circulation, which created multiple distinct oxidation zones. This process allowed primary lead, copper, and zinc sulfides to react over millions of years, yielding over 300 distinct mineral species, including abundant secondary carbonates, arsenates, and sulfates.