Origin of chalcocite
Examples from the Web for chalcocite
In the United Verde Mine, oxidizing conditions at present prevail to the bottom of the chalcocite zone.
The streak will serve to identify any specimen, however, it being a lead-gray of much lighter shade than that of chalcocite.
Chalcocite occurs in vein deposits as one of the important copper ores, especially at Butte, Montana.Geology|William J. Miller
No traces of other primary minerals are present and the chalcocite here is regarded as probably primary.
Copper pyrites (or yellow ore), erubescite (or purple ore), and chalcocite (or grey ore) are the most important.A Textbook of Assaying: For the Use of Those Connected with Mines.|Cornelius Beringer and John Jacob Beringer