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Engineering feat of the month: Mirny Diamond Mine

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The Mirny Diamond Mine is the second largest excavated hole in the world (after Bingham Canyon mine), with a depth of 525 metres and a colossal diameter of 1,200 meters.

This open pit mine in Russia is now inactive but was operational for over 45 years between 1957 and 2004. It was originally constructed under Stalin’s orders to satisfy the Soviet Union’s need for industrial-grade diamonds following the Second World War.

Challenging conditions

Being located in the Sakha Republic of Eastern Siberia meant that the mine was exposed to the extremely harsh Siberian climate conditions and this initially made the area very difficult to mine. The long Siberian winter meant the ground was consistently frozen and temperatures could drop to as low as -70℉ (-56℃). In the summer months the permafrost would become sludge, increasing the risk of surrounding buildings sinking. To combat this the buildings had to be raised on piles and the main processing plant relocated 20km away from the mine.

During winter months, steel tools would break like matchsticks, rubber tires would shatter and oil would freeze. The whole mine had to be covered during the evening to prevent the machinery from freezing solid. In order to break through the thick layers of permafrost, workers would use jet engines or even dynamite to burn through and access the kimberlite underneath.

Minerals were brought up to the surface of the mine via 20ft tall rock-hauling trucks. These trucks used the spiral road that curved around the inside of the mine from top to base.


During the Mirny Diamond Mine’s peak years of operation, over 10 million carats of diamonds per year were mined, with over 20% of these being of gem-quality. The upper layers of the mine contained high diamond content and the bottom of the pit contained 1.5-2 carat of diamonds per ton.

Production rates slowed to two million carats per year as operations reached the bottom of the pit but this was still on par with South Africa’s diamond trade. Between 1957 and 2000 the mine produced $17bn worth of diamonds in total.

Today Mirny is closed but mining still continues beneath its void through dozens of tunnels. It still nets an impressive haul of 4,000+ diamonds per year.

The engineers involved in the inception of the Mirny Diamond Mine were forced to go to extreme lengths in order to dig the pit and put together a successful mining operation. It was an incredible feat considering the conditions they faced.

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