Bournonite (''cogwheel'' twins) on Pyrite

Item Description

This is a wonderful display quality specimen of these superb Bournonites from one of the premier localities for the species in the last 25 years or so. Bournonite is widely considered one of the more metallic minerals among collectors, and although this lead copper antimony sulfosalt is found in many world localities, most of them do not produce fine specimens. The Machacamarca District in Bolivia has for many years been a source of some of the best crystallized pieces of this beloved, yet uncommon mineral. These specimens are some of the largest, finest and most crystalographically impressive examples to come from any contemporary locale. This piece is a showy and aesthetic example featuring a few groups of highly lustrous (splendent), sharp, well-formed, metallic, bright gun-metal colored, tabular crystals forming wonderful "cogwheel" twins, which are sitting atop sparkling metallic golden Pyrite matrix with minor accenting dark grey-black Sphalerite. The largest Bournonite twin measures 2.7 cm across. The piece actually sits on its own, but it's a little precarious, so I would suggest if you want to display it safely, a custom base would be a good idea. No major damage I can find to the central portion of the specimen, but the outer edges are contacted where the piece was removed from the pocket wall. It's fairly rare to find a multi-crystal group on matrix like this with great aesthetics from Viboras. 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.
Bournonite was named after the French mineralogist Jacques Louis, Comte de Bournon. Interestingly, Bournon elected to name the species Endellionite in honor of St Endellion, Cornwall, England, the type locality for the species, but it instead was named Bournonite by Scottish mineralogist Robert Jameson (Jamesonite).
Valued at $1,500.