Mir mine

The Mir mine (Russian: Кимберлитовая алмазная трубка «Мир» Kimberlitovaya Almaznaya Trubka "Mir"; English: kimberlite diamond pipe "World" or "Peace"), also called the Mirny mine, is a former open pit diamond mine, now inactive, located in Mirny, Eastern Siberia, Russia. The mine is 525 meters (1,722 ft) deep (4th in the world) and has a diameter of 1,200 m (3,900 ft), and is the second largest excavated hole in the world, after Bingham Canyon Mine. The airspace above the mine is closed for helicopters because of alleged incidents in which they fell in due to air temperature differences and unexpected currents.^{[2][3][4][5][6]}

• http://en.wikipedia.org/wiki/Mir mine