North America Diamond Mining
Near Murfreesboro, Arkansas, from what is now known to be a lamproite pipe, more than 100,000 stones averaging 0.25 carat each were formed between 1907 and 1933. The "State Line Kimberlite District" beside the Colorado-Wyoming border is home to the only operating diamond mine in the U.S., started at Kelsey Lake, Colorado, in June 1996. The leading diamond found so far is 28.3 carats, and about 25% of the 20,000-carat annual production is of gem quality.
CANADA: With much of Canada underlain by ancient bedrock, the existence of diamond-bearing kimberlite has been considered very likely, mainly with tantalizing diamonds found in Wisconsin in deposits swept down by glaciers from up north. Now the country is home to the most recent major diamond discovery.
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