Bournonite (fine ''cogwheel'' twins)

Item Description

Bournonite is a well-known sulfosalt mineral, and one of the more popular metallic minerals for collectors. The species has been reported from many world localities, but most crystals you'll see are typically single blades. With that said, there are few world localities which have produced excellent "cogwheel"-shaped twins, arguably the most desirable style for the species. The Machacamarca District in Bolivia has produced some of the finest examples of this beloved, yet uncommon lead copper antimony sulfosalt mineral in the last 25 years or so. These specimens are some of the largest, finest and most crystalographically impressive examples to come out of any mind in the modern era of mineral collecting. This piece is a showy and aesthetic example featuring several lustrous, well-formed, metallic, bright gun-metal colored, tabular crystals forming wonderful "cogwheel" twins measuring up to 2.3 cm across, sitting on grey Quartz matrix with minor associated Sphalerite. Very good condition, with little damage I can find. It's incredibly rare to find such complete Bournonite crystals on matrix from this area. Don't miss out, it's one of the better Bournonites from Machacamarca that we've had to offer in the auctions in recent months.
An interesting historical note: Bournonite was named in honor of the French mineralogist Jacques Louis, Comte de Bournon. Originally, Bournon elected to name the species Endellionite in honor of St Endellion, Cornwall, England, the type locality for the species, but it instead was later Bournonite by Scottish mineralogist Robert Jameson (the namesake for Jamesonite).