Chalcocite

Name:
Chalcocite
Detailed information:

Chemistry name:	copper glance
M Formula:	Cu2S
Properties:
Lead-gray color, tarnishing dull black, metallic luster. D 5.5–5.8, Mohs hardness 2.5–3.
Occurrence:
Montana, Arizona, Utah, Nevada, Alaska, Chile, Mexico, Europe.
Use:
Important ore of copper.