Bournonite (fine ''cogwheel'' twins) on Pyrite

Item Description

Here we have a beautiful display specimen of Bournonite from one of the premier localities for the species in the last 25 years or so. This well-known and desirable lead copper antimony sulfosalt is found in many world localities, but most of these localities do not produce fine specimens. The Machacamarca District in Bolivia has for many years been a source of some of the finest examples 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, with sparkling metallic golden Pyrite on matrix. The largest twin measures 2.1 cm across. The piece actually sits on its own without the aid of a base or clay. No major damage I can find. It's incredibly rare to find such a complete / undamaged Bournonite specimen from this area, especially a multi-crystal group like this with great aesthetics. Very rare and significant for what it is. 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.