A new resource estimate for Northern Dynasty's Pebble project in southwest Alaska makes it one of the world's most important copper-gold-molybdenum deposits, the company said Feb. 20. Inferred resources in the Pebble East deposit have increased nearly 90 percent, to 3.4 billion metric tons.

Pebble East is contiguous to and deeper than the 4.1 billion-ton near-surface Pebble West deposit, and is higher grade. Pebble West was the first area explored and is the potential location for an open pit mine. Geotechnical assessment has shown that Pebble East is amenable to low-cost, bulk underground mining, according to Northern Dynasty.

At a 0.60 percent copper equivalent cutoff, the estimated inferred mineral resources in the Pebble East deposit are now 3.4 billion tons grading 1.0 percent copper equivalent, containing 42.6 billion pounds of copper, 39.6 million ounces of gold and 2.7 billion pounds of molybdenum. At a 1.0 percent copper equivalent cutoff, the estimated inferred resources are 1.4 billion tons grading 1.29 percent copper equivalent, containing 24.6 billion pounds of copper, 20.9 million ounces of gold, and 1.2 billion pounds of molybdenum.

Pebble East: 132 core holes drilled

The new estimate is based on assay results from 132 core holes drilled in the Pebble East area. The estimate was audited by geological and mining consultants at Scott Wilson Roscoe Postle Associates, under the direction of David W. Rennie, P.Eng., an independent qualified person as defined by Canada's National Instrument 43-101, the regulations for assessing mineral resources.

"I think it's really exciting - the opponents out there can no longer claim that this is a stock play," Steve Borell, executive director of the Alaska Miners Association, told Mining News. "It's an indication of just how much opportunity exists in Alaska ... Opportunities for mineral development are just beginning to be realized." The chorus of opposition to Pebble is no different from what happens to projects everywhere else in the world, Borell said. "It's almost as if there's a death wish for the economy," he added.

A few weeks before the latest resource estimate was published, mining major Rio Tinto increased its indirect ownership in Northern Dynasty from 9.9 percent to 19.79 percent. On Feb. 1 Northern Dynasty was selected to receive the Thayer Lindsley International Discovery Award from the Prospector's and Developer's Association of Canada. The Thayer Lindsley Award is presented annually to recognize an individual or a team of explorers credited with a recent significant mineral discovery anywhere in the world.