A particularly well-developed crystal specimen of Bournonite adorns the specimen from the Trepca Ore Complex, Kosovo. Crystals of bright metallic grey Bournonite measuring to 1.5cm and as an intergrown cluster, display the classic cogwheel twinning to advantage on a crystallised metallic yellow pyrite matrix, with a later development of a Siderite druse. The specimen has been stablilsed.