It is actually a abandon diamond mine.
Wikipedia
The Mir mine is in the town. It is an open hole, 525-meter (1,722 ft) deep and has a diameter of 1.25 kilometers (0.78 mi) (reckoned to be the 4th largest in the world). The mine was closed in 2011, due to the difficulties of working in that location.
Transportation[edit]
The town is served by the Mirny Airport. Safety concerns have been raised about aircraft operations near to the open diamond mine; helicopters are forbidden to pass over the abandoned workings.
Takes balls of steel to drive those truck in the hole.