The Mir mine, also called the Mirny mine, is an open pit diamond mine located in Mirny, Sakha Republic, in the Siberian region of eastern Russia. The mine is more than 525 meters (1,722 ft) deep (4th in the world), has a diameter of 1,200 m (3,900 ft), and is one of the largest excavated holes in the world.
Open-pit mining began in 1957 and was discontinued in 2001. Since 2009, it has been active as an underground diamond mine.
The Mir mine was the first developed and the largest diamond mine in the Soviet Union. Its surface operation lasted 44 years, finally closing in June 2001. After the collapse of the USSR, in the 1990s, the mine was operated by the Sakha diamond company, which reported annual profits in excess of $600 million from diamond sales.
According to en.wikipedia