Here's another Bournonite that is a good reference quality specimen. There is a somewhat flatted "cog-wheel" crystal group in the center of piece that measures 4.3 cm across. The Bournonite crystals are sharp and lustrous but that lie flat against a micro crystallized Quartz and Pyrite matrix. I am told that this mine has not produced a crumb of Bournonite for almost six months now, and keeping in mind the ever uncertain and unstable political status in Bolivia combined with the long periods of mining inactivity, there is a good chance that there may not be any more of these specimens for a long time. 6.5 x 5.3 x 4.3 cm