Machacamarca District (Colavi District), Saavedra Province, Potosi Department, Boliviah
Simply put, this is a spectacular example of bournonite. This piece has sizable, blocky crystals displaying excellent "cogwheel" form, with a luster that probably cannot get any better for the species. The main crystal is well exposed, and unusual thick.
It is an amazing piece for the species-- I do try to keep the extra salesman-y BS to a minimum in my descriptions, but this really is a great specimen, and compared to what the price would be in Tucson or on other websites, I would say this is very much on the reasonable side.
The last time this mine produced particularly good lustrous crystals was 2012-- there was another find of large blocky crystals around 2015, but they didn't have much going for them as far as luster was concerned, nor did I see any on matrix.
Eat your heart out Cornwall.