2014 Resource Estimate has Different Metal PricingThere are two values given for gold and copper pricing. There is the one on page 132, section 14.8 of the Dec 31, 2014 report, entitled "Reasonable Prospects Of Economic Extraction". Under the heading Pebble Deposit Conceptual Pit Parameters, gold is assigned a value of $1,540 an ounce, and copper $3.63 lb. Recovery is estimated at 89% and 72% respectively.
Then there are the values of $902 oz gold and $1.85 lb copper assigned on page 118, section 14.1, entitled Pebble Deposit Mineral Resource Estimate 2014. This assumes 100% metal recovery, which isn't possible.
Pricing valuation for the "Resource" is treated differently from "Economic Extraction". I'm not completely sure of the reason for the discrepancy. Perhaps the later recognizes the need to make profit, and may be related to differential metal recoveries, being 100% in the resource estimate, and substantially less in economic extraction. Then there is waste material to consider. That costs money as well. So, we have a theoretical resource estimate price, which everyone quotes, and an economic extraction price for gold and copper which is substantially higher.