Pebble Resource Estimate
| Classification | Tonnes | CuEQ % |
Cu % |
Au g/t |
Ag g/t |
Mo ppm |
Re ppm |
Cu Recovered B lbs |
Au Recovered M oz |
Ag Recovered M oz |
Mo Recovered B lbs |
Re Recovered Kg |
Cu Contained B lbs | Au Contained M oz | Ag Contained M oz | Mo Contained B lbs | Re Contained Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Measured | 527,000,000 | 0.65 | 0.33 | 0.35 | 1.7 | 178 | 0.32 | 3.35 | 4.58 | 20.4 | 0.15 | 118,000 | 3.87 | 5.94 | 28.2 | 0.21 | 166,000 |
| Indicated | 5,929,000,000 | 0.77 | 0.41 | 0.34 | 1.7 | 246 | 0.41 | 49.64 | 49.24 | 228.9 | 2.62 | 1,731,000 | 53.38 | 63.90 | 315.2 | 3.21 | 2,445,000 |
| M+I | 6,456,000,000 | 0.76 | 0.40 | 0.34 | 1.7 | 240 | 0.40 | 52.99 | 53.82 | 249.3 | 2.78 | 1,849,000 | 57.24 | 69.84 | 343.4 | 3.42 | 2,611,000 |
| Inferred | 4,454,000,000 | 0.55 | 0.25 | 0.25 | 1.2 | 226 | 0.36 | 22.66 | 28.11 | 121.7 | 1.81 | 1,025,000 | 24.47 | 36.40 | 166.8 | 2.22 | 1,448,000 |
Notes:
David Gaunt, P.Geo., a qualified person as defined under 43-101 who is not independent of Northern Dynasty, is responsible for the estimate. The effective date is August 2020.
Copper equivalent (CuEQ) calculations use metal prices: US$1.85/lb for Cu, US$902/oz for Au and US$12.50/lb for Mo, and recoveries: 85% Cu, 69.6% Au, and 77.8% Mo (Pebble West zone) and 89.3% Cu, 76.8% Au, 83.7% Mo (Pebble East zone).
Recovered metal based on projected metallurgical recoveries in the Company’s 2023 technical report. Contained metal calculations are based on 100% recoveries.
A 0.30% CuEQ cut-off is considered to be appropriate for porphyry deposit open pit mining operations in the Americas. The mineral resource estimate is constrained by a conceptual pit shell that was developed using a Lerchs-Grossman algorithm and is based in the following parameters: 42 degree pit slope; metal prices and recoveries of US$1,540.00/oz and 61% Au, US$3.63/lb and 91% Cu, US$20.00/oz and 67% Ag and US$12.36/lb and 81% Mo, respectively; a mining cost of US$1.01/ton with a US$0.03/ton/bench increment and other costs (including processing, G&A and transport) of US$6.74/ton.
All mineral resource estimates, cut-offs and metallurgical recoveries are subject to change as a consequence of more detailed analyses that would be required in pre-feasibility and feasibility studies.
The mineral resource estimates contained herein have not been adjusted for any risk that the required environmental permits may not be obtained for the Pebble Project. The risk associated with the ability of the Pebble Project to obtain required environmental permits is a risk to the reasonable prospects for eventual economic extraction of the mineralisation and their definition as a mineral resource.
