This is the Lavender Pit, part of the Copper Queen Mine in Bisbee, Arizona. The Phelps Dodge Corporation began work on this huge hole in 1951, but they had to move 46 million tons of material before they reached the copper.

However, by 1975 over one billion tons of copper had been successfully extracted, at which point the price of copper plummeted, and the whole mine was closed.

Given that the demand for copper is currently rising again (and therefore the price), I wonder which bright spark will try to reopen one of these ecological disasters first?

Read more about the Lavender Pit at Wikipedia.

Thanks to Jeff and John B.