Coloumn: Threat of strikes looms large for copper supply ...
(Image to left: Early day miners stand in front of a mine portal near Morenci, AZ) ... By the 1870's a plethora of hardrock mines were yielding prodigious volumes of copper, lead, zinc, silver and gold ore. In 1912, the newly christened state of Arizona supported 445 active mines, 72 concentrating facilities, and 11 smelters with a gross value of …