The Mir mine (also called Mirny) was an open-pit diamond mine, now inactive, located in Mirny, Eastern Siberia, in Russia. It is the second-largest excavated hole in the world, surpassed only by the Bingham Copper Mine in Utah.
Discovery of Mir Diamond Mine
The diamond-bearing deposits were discovered on June 13, 1955, by Soviet geologists Yuri Khabardin, Ekaterina Elagina, and Viktor Avdeenko during the large Amakinsky Expedition in Yakut ASSR. They found traces of the volcanic rock kimberlite, which is usually associated with diamonds. This finding was the second success in the search for kimberlite in Russia, after numerous failed expeditions of the 1940s and 1950s. For this discovery, in 1957 Khabardin was given the Lenin Prize, one of the highest awards in the Soviet Union.
Development of Mir Diamond Mine
Excavation of the pit began in 1957, and today it is 1,722 feet (525 meters) deep, and 3,900 feet (1.25 kilometers) across. Stalin ordered the construction of the mine to satisfy the Soviet Union’s need for industrial-grade diamonds following the war.
The Siberian winter lasted seven months which froze the ground, making it hard to mine. During the brief summer months, permafrost would become mud turning the entire mining operation into a land of sludge. Buildings had to be raised on piles so that they would not sink. The main processing plant had to be built on better ground, found 20 km away from the mine. The winter temperatures were so low that car tires and steel would shatter and oil would freeze. During the winter, workers used jet engines to burn through the layer of permafrost or blasted it with dynamite to get access to the underlying kimberlite. The entire mine had to be covered at night to prevent the machinery from freezing.
During its peak years of operation, the mine produced 10 million carats of diamond per year, of which a relatively high fraction (20%) were of gem quality. This worried De Beers company, which at that time was distributing most of the world’s diamonds. The company was forced to buy larger and larger shipments of high-quality Russian diamonds in order to control the market price. For De Beers, Mir was a puzzling mystery. The mine’s enormous output was not consistent with the relatively small size of the mine.
By the 1970s, when the Mir should have been producing smaller and smaller quantities of diamonds, the Soviets were producing an increasing quantity of gem diamonds. Finally, in 1976, De Beers requested a tour of the Mir mine to satisfy their curiosity. Permission was granted, but the Russians kept delaying the visit and by the time the team of delegates reached the Mir mine, their visas were about to expire, so that they could only have 20 minutes at the Mir mine. The visit did little to shed light on the mystery of the Mir’s diamond production.
After the collapse of the USSR, in the 1990s, the mine was operated by the Sakha diamond company. Later, the mine was operated by Alrosa, the largest diamond producing company in Russia, and employed 3,600 workers. It had long been anticipated that the recovery of diamonds by conventional surface mining would end. Therefore, in the 1970s construction of a network of tunnels for underground diamond recovery began. By 1999, the project operated exclusively as an underground mine. In order to stabilize the abandoned surface main pit, its bottom was covered by a rubble layer 45 m (148 ft) thick. After underground operations began, the project had a mine life estimate of 27 years, based on a drilling exploration program to a depth of 1,220 m (4,000 ft). Production ceased in 2001, and the Mir mine closed in 2004. The mine was recommissioned in 2009 and is expected to remain operational for 50 more years.