Dioptase with Duftite

specimen number:
2072307

location:
Mindouli, Pool, Republic of Congo

description:
Sparkling deep emerald green crystals of dioptase, these forming hollow casts after a now gone spherical shaped species. Small greenish crystals of duftite are scattered throughout. This neat and attractive specimen is in good condition with just slight micro-damage present.

The Mindouli mining district, located in the Pool Department of the Republic of the Congo, is situated within the Neoproterozoic West Congo Belt. Geologically, the area is characterized by a series of copper-lead-zinc deposits hosted in carbonate rocks and sandstones, where tectonic activity created fractures that were later mineralized by hydrothermal fluids. The locality is historically famous for producing exceptional dioptase, but it gained specific notoriety around 2020 for the discovery of unusual dioptase casts. These specimens formed when vibrant, emerald-green dioptase grew over a previous mineral of unknown identity, which subsequently dissolved or was removed, leaving behind a hollow shell that preserves the original crystal habit. Historically, mining and quarrying in Mindouli began in the early 1900s during the French colonial era, with the Mindouli Mine operating as a significant copper producer until the mid-20th century. While large-scale industrial operations have largely ceased, small-scale and artisanal specimen mining has remained active, leading to the recovery of these distinctive and scientifically interesting structures. As of 2026, the district continues to be a primary global source for high-quality copper silicates and unique mineral formations.

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