in Zaruma press elease dated April 1, 2008 - 9:25 AM EDT
They had these numbers:
At a selling price of $2.235 and an operating cost of $0.92 per pound.
compared to
1.55 cost of production/lb and assuming copper is 3.35/lb. (now)
The good thing I like about Zaruma is that they always base the estimates on the worst case senario.
other companies has the production cost at .75 to 1.05
and copper is currently trading around 3.83.
All the best