Effects of Weathering and Lichen Cover on the Middle Infrared Spectra of Rocks

A program to study the spectral characteristics of geologic materials in a near natural condition has been initiated at the Engineer Topographic Laboratories. Much of the present infrared spectral data on rocks and minerals has been determined with samples carefully prepared to maximize certain spectral features and does not reflect the effects of natural processes such as weathering, contamination or lichen growth. Use of such data in the interpretation of remotely sensed imagery could be misleading. This paper reports the results of some initial studies to determine if the spectral effects of rock weathering or lichen cover in the infrared region are important in remote sensing.