Bournonite (“cogwheels”) black which is typically what you

which is typically what you would expect out of a metamorphic contact like this

Specimen # CUAUS72011

Good Bolivian Coppers are not common on the market

this was one of only a handful of crystals recovered according to my source who acquired them directly at the locality

and eye-catching “closed” twin of Ferberite with great form

Bournonite (“cogwheels”) black which is typically what youA hard to find "cogwheel" group of sharp, thick, blocky modified twinned crystals of Bournonite with excellent metallic luster. The piece displays well from a few angles. The stacked appearance of the crystals, combined with the bright luster, makes this one of the more eye catching smaller Bournonites available. Specimen # BOL711B23