An interesting report from the Chile Mining council, who explain that average grades of copper mineral mined in Chile have dropped from 1.61% Cu in 1992 to 0.87% Cu today. What's more, the forecast is for an average of 0.67% in 20 years' time. Chart please!
Or put in a manner that applies to you and not just Chile, the days of $2/lb Cu are over. Forever. Get used to the idea.