A large and interesting sulfide specimen from Machacamarca.  It has a couple very lustrous bournonite crystals to just over an inch, but I would say that the real star of this piece is the tetrahedrite-- you don't often see such good crystals of that species from Bolivia.  There is also some wacky pseudomorphing or alteration going on-- I'm not sure exactly to what, but it looks like some of the tetrahedrite was int he process of slowly being etched and recrystallized into something else.  Possible freibergite present, I but can't say for sure.