20 Gemstone and Semiprecious Minerals and Host Rocks in the Western United States

Thursday, 9 May 2002
8:00 AM - 11:00 PM

GEOLOGY OF THE IRON MOUNTAIN KIMBERLITE DISTRICT, WESTERN WYOMING

Paper number: 20-1
Program: THEME SESSIONS
Time: 10:40 AM – 11:00 AM

Authors

Abstract

Recent mapping and geophysical studies by the Wyoming State Geological Survey, in the Iron Mountain kimberlite district in the central Laramie Range of southeastern Wyoming, resulted in the discovery of several previously unknown kimberlites and geophysical anomalies. The kimberlites are part of an extensive, 5 mile long, northeast-trending, dike-blow complex root zone.

Geochemical analyses of samples suggest that a large portion of the kimberlites originated within the diamond stability field in the upper mantle.

Based on mapping, the Iron Mountain district is one of the two largest kimberlite districts in the United States. The other district of similar size is the Colorado-Wyoming State Line district located to the south of Iron Mountain, where more than 130,000 gem- and industrial diamonds have been recovered.