Could Wyoming Become The Next Diamond Hotspot?

When we think about diamonds we don't usually think of Wyoming.

Russia comes to mind; maybe Canada, and -- thanks to a well-known Leonardo DiCaprio movie -- Africa.

The state of Arkansas is probably the most well-known diamond site in the U.S. and the only place where the public are invited to search for diamonds in their original volcanic source.

But diamonds have been found in other states. Namely Colorado, Wyoming, Montana, and New Mexico.

This is due to the location of kimberlites -- volcanic rocks that can carry diamonds from the Earth's mantle to the surface.

Because kimberlites tend to get beaten up and buried they are usually found deep in the ground and often beneath rocks, making them difficult to find.

Wyoming diamonds from the State Line kimberlite district. [Credit: Wayne M. Sutherland, WSGS][/caption]"Soils derived from weathered kimberlite contain abundant montmorillonite clay, often support more vigorous growth of grasses than do surrounding areas, and may show a marked absence of woody plants. These vegetative anomalies and topographic depressions are clues that may point to the existence of hidden kimberlitic intrusions" hints the Wyoming State Geological Survey.

Wyoming, I was surprised to find out, has a high potential for the occurrence of diamonds.

"The ancient core of the North American continent, the Archean craton, extends southward from Canada and lies beneath most of Wyoming where it is known as the Wyoming craton or Wyoming Province" (WSGS).

And although most of the state has not been explored for diamonds, several diamondiferous (probably my new favorite word) kimberlite and host rocks have been discovered in Wyoming, mostly on the Wyoming-Colorado line.

"Diamonds were discovered in southeastern Wyoming in 1975 about 25 miles south of Laramie. Since then, more than 130,000 diamonds have been found in the Colorado-Wyoming State Line kimberlite district. These vary from microdiamonds to high-quality gems, with one as large as a 28.3-carat diamond found in Colorado. The largest diamond found in Wyoming to date weighed 6.2 carats" (WSGS).

The potential for new diamond discoveries in Wyoming is great, as is the possibility for one or more diamond mines in Wyoming’s future.

Diamonds are, obviously, a valuable gemstone. In 2018, at least one prospector was actively exploring areas of the Cowboy State for kimberlites and diamonds.

"Development of a diamond mine begins with extensive exploration followed by claim staking where the minerals are federally owned or by leasing of state- or privately-owned minerals. However, finding economic diamond deposits is much more difficult than locating deposits of other minerals."

"Even in a world-class diamond mine, diamonds account for less than one part per million in the host rock. Once a diamond-bearing rock has been located, sampling to evaluate the diamond content of the deposit begins. Sampling progresses in stages beginning with a few tons. With favorable results, sampling increases to a few hundred tons and then to a few thousand tons. Continued favorable diamond showings at each step will eventually lead to full-scale mining."

"A small Colorado diamond mine operated along the Wyoming-Colorado border from 1996 to 2003. The ore grade varied from 5 to 15 carats per 100 tons, and the mine produced many high-quality gems larger than one carat in size. The largest diamond extracted there weighed 28.3 carats. However, the mine closed due to legal problems rather than a lack of diamonds. The State Line kimberlite district has never been fully evaluated" (WSGS).