THE Chilean copper mining industry, which accounts for a third...

THE Chilean copper mining industry, which accounts for a third of the world's output, is at a turning point as ore grades are retreating and bigger capital expenditures are needed to maintain production levels, according to the head of BHP Billiton's base metals division, Peter Beaven.
As mines in Chile age, ore grades decrease and the minerals mined become harder and are located farther away from the surface, increasing mining costs and reducing copper production.

http://www.theaustralian.com.au/business/mining-energy/copper-grades-on-the-retreat/story-e6frg9df-1226519130969