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Reflectance Spectroscopy as a Rapid Assessment Tool for the Detection of Amphiboles from the Libby, Montana Region

By Roger N. Clark1, Todd M. Hoefen1, Gregg A. Swayze1, K. Eric Livo1, Greg P. Meeker1, Steve J. Sutley1, Steve Wilson1, Isabelle K. Brownfield1, and J. Sam Vance2

U.S. Geological Survey Open-File Report 03-128

Version 1.0

1 U. S. Geological Survey, Denver, Colorado
2 Environmental Protection Agency, Denver, Colorado

The vermiculite mineral deposit near Libby, Montana was mined from the 1920's to 1990. During this period, the Libby mine was a major source of the nation's vermiculite, which was used in a variety of applications such as loose-fill insulation, additives to potting soil, packing materials for hazardous chemicals, and many others. Asbestiform amphiboles occur in veins throughout the deposit and it is difficult to separate all asbestos from the vermiculite. This paper illustrates the unusual electrostatic properties of the fibrous amphibole shows that the fibrous amphibole also occurs intergrown in the vermiculite, between the layers of the vermiculite sheet silicate. The reflectance spectral properties of geologic materials from the Libby region are also presented and it is shown how reflectance spectroscopy can be used as a rapid assessment tool to detect the amphiboles. This report also discusses some limitations of this tool. logo