Pebble mine is a copper mine by volume, but also holds large amounts of gold silver and molybdenum. They use Cyanide to leach out gold. This will be stored in a reserve pit for eternity next to the mine site. It's containment walls will be over 700 feet tall... they just broke one of these a couple years ago in Canada ( Mount Poly Mine ).. look it up. The same engineering firm that designed that mine was to be the same one that Northern Dynasty was using.......