New Pebble mineral resource estimate increases rhenium sources by 84 per cent

Photo: Wikimedia Commons

The controversial Pebble project in southwest Alaska may turn out to be not just a prominent producer of base and precious metals, but also of the strategic mineral rhenium required by the US to secure military dominance.

Northern Dynasty Minerals announces the results of an updated mineral resource estimate for southwest Alaska’s Pebble Project. Already considered among the most significant accumulations of copper, gold, molybdenum and silver ever discovered in the United States, the current study confirms the Pebble deposit also contains substantial quantities of Rhenium – a metal used in jet engines and other military applications, and to produce high-octane fuels.

The US Geological Survey (“USGS”) considers Rhenium a strategic metal and confirms the United States currently relies on foreign producers for 82% of its Rhenium needs.

“Certainly the US military has identified Rhenium as a critical mineral, and one the United States must develop additional domestic production of in order to enhance its military security,” said Ron Thiessen, Northern Dynasty President & CEO. “The development of Alaska’s Pebble Project would clearly go a long way toward filling that gap, while also addressing substantial US domestic supply deficits for other critical minerals – notably copper and silver.”

The inclusion of Rhenium into the Pebble resource estimate is based on more than 58,000 analyses from 699 core holes, totaling more than 840,000 feet of drilling.

For the estimate, the Pebble deposit was domained based on geology, alteration and grade distribution.

Estimation parameters including top cuts, search strategy, and variography were developed for each modelled domain. Rhenium values were interpolated into the Pebble block model using Ordinary Kriging and classified according to existing criteria.

At a 0.30% copper equivalent cut-off, the Pebble Deposit contains:

• 2.6 million kg of rhenium, 57 billion pounds of copper, 71 million ounces of gold, 3.4 billion pounds of molybdenum and 345 million ounces of silver within the 6.5 billion tonnes in the combined Measured and Indicated categories at a grade of 0.40% copper, 0.34 g/t gold, 240 ppm molybdenum, 1.7 g/t silver and 0.41 ppm rhenium; and

• 1.6 million kg of rhenium, 25 billion pounds of copper, 36 million ounces of gold, 2.2 billion pounds of molybdenum and 170 million ounces of silver within the 4.5 billion tonnes in the Inferred category at a grade of 0.25% copper, 0.25 g/t gold, 226 ppm molybdenum, 1.2 g/t silver and 0.36 ppm rhenium.

Current total Rhenium resources in the United States are approximately 5 million kg. Pebble’s total Rhenium endowment represents an 84% increase to the nation’s known Rhenium resource base.

According to the USGS, some 8,400 kg of Rhenium was produced at six US operations in 2019. However, the United States also imported 39,000 kg – more than 82% of its current needs. Rhenium is used mainly in superalloys for turbine engines and for petroleum reforming catalysts, and demand is expected to grow.


Globally, the primary source of Rhenium is mines developed on porphyry copper deposits like Pebble, recovered as a by-product through treatment of molybdenum concentrates.

As a significant deposit of Rhenium on US soil, development of the Pebble resource will materially advance America’s goal of achieving self-sufficiency in the critical minerals needed to support and sustain its economic growth, military security, manufacturing industries and transition to a lower carbon future.