The Pebble deposit has been the focus of intensive geological investigations for more than 24 years.
In addition to extensive geological mapping, geochemical surveys and induced polarization (IP) surveys, previous owner Cominco (now Teck) undertook 75,000 feet of drilling in 164 holes from 1988 to 1997. Since 2001, Northern Dynasty and the Pebble Partnership have expanded surface investigations and completed another 992,500 feet of drilling in 1,036 holes.
In total, the Pebble deposit and surrounding exploration lands have been the subject of more than 1,000,000 feet of drilling in 1,200 holes. That's more than 200 miles of drilling, making Pebble one of the most intensively studied, undeveloped mineral systems in the world.
Drilling at Pebble is undertaken for a number of purposes, including:
- exploration and delineation holes to define subsurface mineral resources;
- geotechnical holes to support engineering design of mine facilities;
- to provide metallurgical samples to support design of ore processing;
- groundwater monitoring wells.
The 2014 Pebble mineral resource estimate is based on results from 699 core holes. At a 0.30% copper equivalent (CuEQ)(1)
cut-off, total known mineral resources are:
(1) 2014 Pebble mineral resource estimate
- 6.44 billion tonnes of Measured and Indicated Mineral Resources grading 0.76% CuEQ containing 57 billion pounds of copper, 70 million ounces of gold, 3.4 billion pounds of molybdenum and 344 million oz of silver; plus
- 4.46 billion tonnes of Inferred Mineral Resources grading 0.54% CuEQ, containing 24.5 billion pounds of copper, 37 million ounces of gold, 2.2 billion pounds of molybdenum and 170 million oz of silver.