Following two years of field and laboratory work, the Wyoming State Geological Survey (WSGS) has published the results of their research on the Iron Mountain kimberlite district. The district is located west of Chugwater in the central Laramie Mountains of southeastern Wyoming. The research included detailed geological mapping, sampling, geochemical studies, and geophysical transects. The results indicate that these kimberlites (one of only two known rock types currently mined for diamonds in the world) originated from great depth in the earth and may have originally contained diamonds. In fact, one macro-diamond and a few micro-diamonds were recovered from one of the kimberlites in the northern part of the district about two decades ago.

WSGS Report of Investigations 54, entitled Geology of the Iron Mountain kimberlite district and nearby kimberlitic indicator mineral anomalies in southeastern Wyoming, is by W. Dan Hausel, Robert W. Gregory, and Wayne M. Sutherland of the WSGS in Laramie, and Roger H. Motten, a consulting geologist from Casper. The 42-page report also contains three oversized plates and can be purchased for $10.00 over-the-counter from the WSGS publications sales office in Laramie. Orders for the publication can be placed by phone, fax, or Email and should include $2.55 for shipping and handling and 6% sales tax from Wyoming residents.

Kimberlite is one of the rarest rock types found on earth. It was originally described in the Kimberly region of South Africa in the 1800s. Kimberly later became an important diamond-mining center and still is a source for diamonds.

Field work by the WSGS expanded the known extent of kimberlite in the Iron Mountain area and identified several geophysical and some geomorphic anomalies thought to represent hidden kimberlite. The Iron Mountain district is now recognized as one of the two largest kimberlite districts in the U.S. The other district, the State Line district located south of Iron Mountain on the Colorado-Wyoming border, has yielded more than 130,000 gem-quality and industrial diamonds from both Wyoming and Colorado since 1975. During this study, several other anomalies outside the Iron Mountain district were also identified in southeastern and central Wyoming by the WSGS, suggesting the presence of several more undiscovered diamond deposits.

The Metals and Precious Stones Section at the WSGS, using its diamond research laboratory, hopes to test and evaluate some of the Iron Mountain kimberlites for diamonds in the future. According to W. Dan Hausel, senior author and project chief, the geology of Wyoming is very favorable for the discovery of gem-quality diamonds. Several high-quality gemstone diamonds were recovered from a mining operation in the State Line district in the 1990s including gem diamonds weighing more than 28 carats. One company even predicts that diamonds weighing as much as 80 to 100 carats will be found in the district.

For more information on this topic please contact:
W. Dan Hausel, dhausel@uwyo.edu
Phone: 307 766-2286 x229

Sales: (307)766-2286 x224
Fax: (307)766-2605
Email: sales-wsgs@uwyo.edu

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