From a viewpoint at about 6,190 feet above sea level, a giant hole in the Oquirrh Mountains stretches two and a half miles wide and ¾ of a mile deep. Trucks with tires bigger than a sedan look like ...

In the walls, floor and ceilings of squelching tunnels deep beneath a hill in County Tyrone lie minerals that may be worth more than $20bn (£15bn). The hoard is mostly gold and silver but also ...