Chalcocite

specimen number:
8311238

location:
Flambeau Mine, Rusk Co., Wisconsin, USA

description:
A large matrix less cluster of bluish purple iridescent chalcocite crystals. In good condition all around. Very choice for this classic locality.

The Flambeau Mine, located near Ladysmith in Rusk County, Wisconsin, was a remarkable high-grade copper-gold deposit known for its exceptional mineral specimens and rapid operational lifespan. Geologically, it was a volcanogenic massive sulfide (VMS) deposit hosted within the Precambrian Penokean Volcanic Belt, where tectonic activity created a steeply dipping ore body enriched by supergene processes. This enrichment zone produced world-class chalcocite specimens, characterized by sharp, lustrous, metallic-black crystals that often exhibited complex twinning and iridescent surface coatings. Historically, the deposit was discovered in 1968 by Kennecott Exploration, but environmental and legal reviews delayed production for decades. The Flambeau Mining Company finally conducted open-pit operations between 1993 and 1997, extracting over 180,000 tons of copper. Following the cessation of mining in 1997, the site was immediately reclaimed and backfilled, making the recovery of further specimens impossible. Today, Flambeau chalcocite is regarded by collectors as some of the finest ever found in North America, representing a unique chapter in Midwestern mining history.

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