Viboras Mine, Machacamarca, Machacamarca District (Colavi District), Cornelio Saavedra Province, Potosí Department, Bolivia
The sheer AMOUNT of Bournonite on this specimen is more than virtually any other piece of comparable size from this mine. It has some of the largest "cogwheel"-twinned crystals of Bournonite that I have seen on or off matrix from Machacamarca as well. The crystals themselves are broad and impactful with a matte-grey luster and are sitting atop a mound of massive Quartz with associated Pyrite and minor Tetrahedrite. This is a full cabinet size display specimen, which is next to impossible to obtain from this locality, as the majority of pieces are either too damaged or too ugly to be considered by most collectors. Relatively speaking, this piece is very good condition, especially for the size. The few pieces I have seen that are in this size range are typically broken on all sides and terribly unaesthetic. With a custom base, this piece would display very well, and would certainly attract some attention as it resembles the famous "Bancroft Bournonite" from Cornwall (but for a tiny fraction of the price).