Now considered to have produced some of the finest crystals of Bournonite crystals ever seen, the Viboras mine in Potosí Department, Bolivia has not produced many other mineral species of note, except perhaps for 'Freibergite'. In recent years the reclassification of Tetrahedrite Supergroup species has lead to a complicated list of new species and reclassifications. What was formerly known as Freibergite, a silver-dominant analogue of Tetrahedrite, has now become two species but the exact composition of the Viboras material has not yet been established and so for now it is now simply Freibergite Subgroup. This excellent miniature specimen is a really classy display of the stunning glossy metallic gun-metal grey 'cog-wheel' twinned Bournonite crystals with fine-grained darker and duller grey Freibergite Subgroup surrounding the base of the Bournonite. There are three main freestanding Bournonite crystals, the largest reaching nearly 2 cm across, and all are in excellent condition with just very light surface chipping. An extremely fine crystallized miniature Bournonite.
