Diamond Exploration and Mining Heating Up 

In North America

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Diamond exploration in Canada has led to a major new industry that did not exist prior to six years ago. Yet today, Canada ranks as one of the world’s leading producers of gem-quality diamonds. Fifteen percent of the world’s diamonds are now being mined in Canada, which surpassed production from South Africa last Spring.

The diamonds are recovered from just two mines in the Northwestern Territories, and significant discoveries at several other localities has led to the discovery of 500 kimberlites (one of the principal host rocks for diamond) and proposals to add four additional diamond mines before the end of the decade.

Canadian diamond production in 2003 amounted to 11.2 million carats resulting in a $1.7 billion per year industry where none existed prior to 1998. The value of raw diamond production is dramatically increased as the rough stones are faceted by Canadian gem cutters and mounted in jewelry to be sold for more than 10 times the raw value.

In other words, the Canadian economy has taken a major, multi-billion dollar boost due to mining and added hundreds of new jobs.

Can this happen in Wyoming? According to W. Dan Hausel, senior economic geologist at the Wyoming State Geological Survey (WSGS), the possibilities are good.

Wyoming is underlain by the same kind of rocks found in Canada (see map 1), and essentially the entire state has high potential for the discovery of commercial diamond deposits. Some companies are starting to recognize these similarities, and over the past month, several companies and consultants have contacted the WSGS for information on the potential diamond deposits.

Wyoming already has several known gem and industrial diamond deposits and has an incredible number of “kimberlitic indicator mineral anomalies,” indicating that there could easily be hundreds of hidden deposits waiting to be found. Kimberlitic indicator mineral anomalies, according to Hausel, are rare minerals that are eroded from nearby diamond pipes or dikes that are usually recovered in gold pans. After they are found, a prospector will continue panning up stream until the mineral anomaly disappears. At that point, the diamond deposit typically lies somewhere (usually buried) nearby.
Only two rock types are mined for diamond—kimberlite and lamproite. The WSGS has already mapped the two largest kimberlite districts in the US, the largest lamproite field in North America, and has found indications of hundreds of other pipes in Wyoming.

Wyoming has 22 known diamond pipes. Twenty are found in the State Line district south of Laramie (see map 2), with another 20 found in Colorado. One diamond pipe occurs at Iron Mountain north of Cheyenne, and another diamond-bearing rock is found at Cedar Mountain southeast of Ft. Bridger. Diamonds have also been found or reported in the Powder River Basin near Gillette, at three different localities in the Medicine Bow Mountains, in the Sierra Madre, Wind River, Gros Ventre and Granite Mountains, as well as in the Butcherknife Draw area south of Green River. 
Over the past 20 years, the WSGS identified more than 300 kimberlitic indicator mineral anomalies in the Laramie, Medicine Bow, Seminoe, and Sierra Madre Mountains. An enormous mineral anomaly was also found in the Green River Basin and other indicator mineral anomalies have been identified in the Owl Creek Mountains, the Hartville uplift, and the Bighorn Basin. So the possibilities are tremendous.

  
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Additional information on locating diamonds in Wyoming can be found in the December 2003 issue of ICMJ’s Prospecting and Mining Journal, “Searching For Placer Diamonds,” by W. Dan Hausel, Senior Economic Geologist, Wyoming State Geological Survey.

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