Myrni MineThe Myrni mine (also called the Mir mine) is an inactive diamond mine that began productio

Myrni MineThe Myrni mine (also called the Mir mine) is an inactive diamond mine that began production in 1957 and closed in 2004. As with most diamond mines, the rocks being dug up were kimberlites – the result of violent volcanic eruptions that start deep beneath Earth’s crust and carry intact pieces of the mantle, including diamonds, rapidly up to the surface.Kimberlite eruptions produce vertical pipes that break through the Earth’s crust, so the best way to mine them is to dig straight down. The more excess rock moved out of the way, the more expensive the mine is to operate, so to get at the ore, the miners dug as close to straight down as possible, leaving only tiny ledges to prevent rockfalls.Mining on the site didn’t even stop when the surface mine closed; an underground mine continued sampling the kimberlite pipe for years after the surface mine became to expensive to continue operating. Near the end of its operation, it took nearly 2 hours for a vehicle to drive from the surface to the bottom.The mine is over 500 meters deep, making it one of the 5 deepest man-made holes in the ground and 2nd largest by volume. Its size gives it another distinction; there is a declared no-fly zone for planes and helicopters over the pit because the changing air currents over the hole can actually disturb the path of an aircraft enough to cause it to crash.-JBBImage credit: https://www.flickr.com/photos/jeande/2730864493Read morehttp://www.usmra.com/photos/bigpit/http://www.mining.com/mir-diamond-mine-38690/http://gizmodo.com/the-nearly-mile-wide-diamond-mine-that-helped-build-the-1593234924 -- source link

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