Bournonite has long been famous from this venerable old South American location but new finds in 2012 have made significant impact on the quality this rare species. This is a very large specimen from the location both in terms of actual size and for the size and abundance of the bournonite crystals. Cogswheels to 3 cm across in groups 4.5 x 5 cm are perched on a drusy, sparkly matrix of brassy pyrite and transparent quartz. The surface of the matrix is completely covered with mineralization to all sides. The specimen is virtually undamaged. In addition, there are numerous associated black crystals scattered over the matrix that appear to be pseudomorphs of an unknown sulfide or perhaps oxide: with analysis these may also prove to be significant. The best of the lot I acquired.