Detailed information
Dimensions
57 x 75 x 91
mm
Locality
Viboras Mine, Machacamarca Cornelio Saavedra Province Potosí Department, Bolivia
Condition
No recorded repairs
The remote Viboras mine, at Machacamarca in Potosí Department, Bolivia first came to prominence in 2001 with the discovery of some very well crystallized twinned 'cogwheel'-type Bournonite crystals, but many were damaged, or smaller in size. Since then, there have been several new pockets discovered and now this is regarded as having produced the finest individual twinned Bournonite crystals from anywhere on Earth (although the Chinese specimens from Yaogangxian mine run it close). It is not only their size, but their sharpness and definition, their bright glossy resinous metallic lustre and how they present so perfectly on matrix that sets them apart. Some collectors still obsess over historical pedigree of 19th century British specimens but, for sheer quality, there can be no comparison. If you want to know how good the very best crystals get, then you need look no further. This cabinet-sized matrix-hosted specimen features a stunning, double-layered 6.3 cm long 'cogwheel' crystal (2.8 cm wide by 1 cm thick) parallel and on top of another slightly thicker (1.2 cm) 'cogwheel' crystal. Not only are these crystals exceptionally large for the species, but they display magnificently, rising partially up from their siliceous rock matrix, and are in incredible condition. Their stepped, cogwheel-like edges display bevelled edges and stepped parallel growth lines around the 'cogs'. This is not only a world-class crystallized Bournonite, but a reference for how great this species can be.
