A very rare example of copper from the Katanga Copper Crescent region of the Southern D.R. Congo.  It might sound ridiculous for copper to be rare in a region bearing its name, and that also happens to contain one of the world's richest deposits of the metal, but native copper is almost never seen as specimens from here. These are rather crude crystals, but you can definitely see the form of the copper, and they seem have a surface alteration of cuprite.  Unusual stuff.