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November 06, 2004
A very big hole!
The Kimberley Mine Museum is worth a visit for several reasons, not least the recreated "Old Kimberley" and the Big Hole itself. This hole was created by hand - miners shifting the dirt and rock with picks and shovels. All the more remarkable because it is the site of what was once a sizable hill!
The crater created by miners digging out the diamonds for which Kimberley is famous. The grey-blue rock is the famous "Kimberlite" - volcanic rock from the throat of an extinct volcano!
The hole was eventually 244 metres deep, that's 805 feet to the non-metricated, and it was all shifted by hand. Some 22.5 million tons of rock which produced 2,722 kg of diamonds (14,504,566 carats). The workings continued in shafts underground after it became impractical to continue the open cast operation, but all working ceased here in 1914, although other mines in the area continue in production. The shaft workings reached a depth of 1,047 metres (3,455 feet) which, as Kimberley is just over 3,200 feet above sea level, means that these mines go around 200 feet below that!
Only around 2% of all the diamonds produced are of the finest gem quality. The rest are either in one of the lower gem grades or sold as "industrial" diamonds for use on abrasive cutter blades, oil drill bits, or similar uses.
Posted by The Gray Monk at November 6, 2004 08:11 PM