Mirny Diamond Mine: The World’s Second Largest Man-made Hole

On the outskirts of a small town Mirny in eastern Siberia, there’s a Mirny mine which is also referred to as Mir mine. Next to Bingham Copper Mine in Utah, this former diamond mine is the second largest excavated hole in the world. Now inactive, the mine is nearly 1722 feet deep and 3900 ft wide. 

Discovery of the Mir Mine

In June 1955, the Soviet geologists, Yuri Khabardin, Ekaterina Elagina & Viktor Avdeenko, found diamond-bearing deposits during the large Amakinsky Expedition in Yakut ASSR. The three geologists unearthed pipes of igneous rock kimberlite which sometimes contains diamonds. 

After many failed excavations in the 1940s and 1950s, this was the second successful exploration after the Zarnitsa mine in 1954. In 1957, the geologist Yuri Khabardin was also honored with the Lenin Prize, one of the prestigious awards in the Soviet Union.

Mirny Mine Development & Discovery of Mine’s Largest Diamond

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In 1957, the development of mine began in extremely harsh climatic conditions. The mining was hard because the ground stayed frozen in the seven winter months of the year. And at the time of summers, it turned into slush. 

The buildings had to be built on piles to prevent them from sinking which could be caused due to the building’s warmth that melting the permafrost. The primary processing plant was constructed, 20 km away from mine, on better ground.

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In winters, the jet engines were used by workers to defrost and dig out the permafrost. They sometimes blasted it with dynamite to get to the kimberlite. The whole mine was covered during the night for preventing machinery from freezing.

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During the 1960s, the mine was producing 10,000,000 carats of diamond every year, of which nearly 20% was of gem quality. The yield dwindled to 2 carats per tonne & the production rate reached 2,000,000 carats per year near its bottom.

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On 23 December 1980, the "26th Congress of the Communist Party of the Soviet Union" was the largest diamond ever discovered in the mine. This fancy lemon yellow raw diamond weighed 342.5 carats. In the 1990s, mine operation was put on halt at a depth of 340 m after the pit bottom became flooded but resumed later.

Mirny Mine’s Surface Operations Lasted 44 Years

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The former Mir mine was the first and largest diamond mine developed in Soviet Russia. Closed in June 2001, the mine stood operational for 44 years. Post the USSR collapse in the 1990s, the Sakha diamond company operated the mines reporting annual profits of over $600 million from diamond sales. 

Later, the largest diamond mining company of Russia ‘Alrosa’ operated the mine employing 3,600 workers. In the 1970s, the construction work of a network of tunnels for underground diamond recovery started. Until 1999, the project operated only as an underground mine.

For stabilization of the abandoned surface mine pit, the bottom was covered by a 45m thick rubble layer. And soon after underground operations started, the project lasted for nearly 27 years. The mining stopped in 2004 with a permanent shut down in 2011.