Economic Geology of the Iron Mountain Kimberlite District, Wyoming

Abstract Recent mapping and geophysical studies by the Wyoming State Geological Survey has resulted in a considerable expansion of the Iron Mountain kimberlite district in the central Laramie Range of southeastern Wyoming. This district is now known as 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. Geochemical analyses of samples from the Iron Mountain kimberlites suggest that several of the kimberlites originated within the diamond-stability field in the upper mantle. However, diamond testing in the district remains minimal.