[Geology2] United States Diamond Mines and Mining

United States Diamond Mines and Mining

There is only one active diamond mine in the United States but exploration in other locations will likely find more.

The Most Popular Gemstone with US Consumers In 2010 consumers in the United States spent about $19 billion on gemstones. Of that amount $18 billion was spent on diamonds and less than $1 billion was spent on colored stones. Diamonds are the most popular gemstones with U.S. consumers by a wide margin. [1] Crater of Diamonds - The Only Active U. S. Mine Although millions of carats of diamonds are consumed each year in the United States, only a few hundred carats are domestically produced. The only active diamond mine in the country is the Crater of Diamonds Mine near Murfreesboro, Pike County, Arkansas. There, recreational prospectors have been finding a few hundred carats of diamonds per year since the early 1970s. Most of the stones are white, yellow and brown in color but a wide range of diamond colors has been found at the mine. The mine is a dig-for-fee operation maintained by the Crater of Diamonds State Park. The diamonds are hosted in a lamproite breccia tuff and its overlying soil. Collectors pay a fee of a few dollars per day to prospect and can keep any diamonds that they find. This is the only diamond mine in the world that is open to the public. Crater of Diamonds has produced several significant finds. These include: The "Strawn-Wagner Diamond" This diamond was found at the Park as a 3.03 carat rough stone in 1990 by Shirley Strawn. In 1997 it was cut to yield a 1.09 carat, "round brilliant" stone that received a perfect grading of 0/0/0 from the American Gem Society. It stands as the most perfect diamond the American Gem Society has ever certified. [2] The "Uncle Sam" Diamond The "Uncle Sam" is a 40.23 carat white diamond that stands as the largest diamond ever found in North America. It was found at the Crater of Diamonds in 1924 before the property was opened as a State park. [2] The Kahn Canary Diamond This 4.25-carat, canary-color diamond with a perfect dodecahedral pillow shape was found in 1977 by George Stepp. Stan Kahn purchased the diamond from Stepp and did not have it cut because even in its rough shape it is an especially beautiful gem. Kahn has shared the stone with the public by loaning it to museums around the world for temporary display. Kelsey Lake Mine At present, there are no commercial diamond mines operating in the United States. The only mine that has ever operated commercially was the Kelsey Lake Diamond Mine, located near Fort Collins, Colorado on the state boundary between Colorado and Wyoming. Kelsey Lake was opened as a commercial diamond mine by Redaurum Limited in 1996. Great Western Diamond Company, a wholly-owned subsidiary of McKenzie Bay International Limited, purchased the property in 2000 and operated the mine until 2002. It was closed due to legal problems rather than a lack of diamonds. [4] Most of the diamonds produced at the Kelsey Lake Mine were clear, gem-quality stones and almost one-third of the stones were one carat or larger in size. When the mine closed there was an identified resource of 17 million tons of ore with an average grade of 4 carats per hundred tons. In 2003 the United States Geological Survey reported that the most valuable stones produced from the Kelsey Lake Mine were valued at $89,000 and $300,000. [3] Other Potential Diamond Areas The discovery of numerous commercial diamond deposits in Canada has generated some prospecting interest in the United States. Areas with similar geologic settings to the Canadian deposits exist in Alaska, Colorado, Minnesota, Montana, and Wyoming. Diamond indicators and confirmed diamond pipes have been found but none have attracted significant investments or commercial mining. Wyoming Diamond Deposits The Wyoming Geological Survey believes that a $1 billion diamond industry could develop in that state. Wyoming has comparable conditions to the Canadian deposits and hundreds of kimberlite pipes are believed to exist. Their website has maps showing the location of diamond-hosting intrusives, reported placer diamonds, kimberlite indicator mineral anomalies, lamproites and diamond stability indicator minerals. [4]

A small portion of a diamond exploration map published by the Wyoming Geological Survey. WSGS has identified several hundred concentrations of kimberlite indicator minerals, indicative of possible nearby hidden diamond deposits. Image by Wyoming Geological Survey. [4] SOURCE FULL SIZE WY DIAMOND MAP Simplified cross-section of a lamproite pipe and residual soil deposit similar to the one at the Crater of Diamonds Mine. Information Sources [1] Olson, Donald W., (2011). 2009 Minerals Yearbook: Gemstones. 2009 Minerals Yearbook, Volume I, Metals and Minerals, Gemstones. United States Geological Survey. [2] Crater of Diamonds State Park website. Arkansas Department of Parks and Tourism. [3] Olson, Donald W., (2003). 2003 Minerals Yearbook: Gemstones. 2003 Minerals Yearbook, Volume I, Metals and Minerals, Gemstones. United States Geological Survey. [4] Wyoming Geological Survey. Wyoming Diamonds. Wyoming Geological Survey Website.

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