Chalcocite has a very distinct color when fresh. This is a split and thus the fresh color can be seen as a dull grey. When scratched with a knife, Chalcocite will show some sectility and is a little softer than Bornite. It is, also, not as brittle as Bornite. This is best seen under the microscope. When massive, like this specimen, a conchoidal fracture can be seen. The vein here is nearly 2cm thick. Chalcocite contains more copper than Bornite coming in at almost 80% and thus a major ore of copper.