Tsumcorite with Conichalcite

specimen number:
2063582

location:
Tsumeb Mine, Otjikoto, Namibia

description:
Brilliant yellow crystals measuring to 0.1 cm and less of tsumcorite scattered richly across the top of a calcite rich matrix with green balls of conichalcite. In good condition. Good example for the species. The specimen comes with a previous label from the collection of Ray DeMark. He acquired the piece from Clive King who was a geologist at the mine at the time.

The Tsumeb Mine, located in the Otavi Mountainland of northern Namibia, is a world-renowned poly-metallic deposit famous for its extraordinary mineral diversity and deep oxidised zone. Operating commercially from 1897 until its closure in 1996, the mine exploited a deep pipes-like breccia structure cutting through Precambrian dolomite strata. Hydrothermal ore fluids originally deposited rich primary lead, copper, and zinc sulfides, which later underwent intense deep weathering and secondary oxidisation by percolating groundwater over millions of years. This unusual geochemical environment gave rise to over 300 mineral species, including many rare secondary arsenates. Tsumeb is the type locality for tsumcorite, a rare hydrated lead iron zinc arsenate mineral discovered there in 1971, which forms yellow-brown to reddish-brown micro-crystalline crusts and prismatic crystals inside matrix cavities. Although physical collecting in the underground workings has ceased due to flooded levels, Tsumeb remains legendary among mineralogists and collectors worldwide for producing exceptional type-specimens.

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