Ann: High-Grade Depth Extensions at Jericho, page-31

When I started investing in gold 30 years ago, on the candid advice of a Swiss friend, he said invest in the highest cost producers who are just breaking even or making just a small margin. His advice now relates to copper.
With high cost producers like AIC your returns are asymmetrical if/when the CU price rises. This is inverted for lower cost producers. For simplicity a $1 increase in the CU price will double AIC profits. This is simply not the same for a lower cost producer.
So whilst the risks with a high cost producer are higher if the CU price falls the rewards are exponentially higher if CU rises.
Its pretty simple, risk v reward. If you believe the CU price is going to rise AIC sp returns will be large.