Title :
Longwave Thermal Infrared Spectral Variability in Individual Rocks
Author :
Balick, Lee ; Gillespie, Alan ; French, Andrew ; Danilina, Iryna ; Allard, Jean-Pierre ; Mushkin, Amit
Author_Institution :
Space & Remote Sensing Sci. Group, Los Alamos Nat. Lab., Los Alamos, NM
Abstract :
An hyperspectral imaging spectrometer measuring in the longwave thermal infrared (7.6-11.6 mum), with a spatial resolution less than 5 mm at a range of 10 m, was used in the field to observe the variability of emissivity spectra of individual rock surfaces. The rocks were obtained commercially, were on the order of 20 cm in size, and were selected to have distinct spectral features: they include alabaster (gypsum), soapstone (steatite with talc), obsidian (volcanic glass), norite (plagioclase and orthopyroxene), and ldquojasperrdquo (silica with iron oxides). The advantages of using an imaging spectrometer to characterize these rocks spectrally are apparent. Large spectral variations were observed within individual rocks that may be attributed to roughness, surface geometry, and compositional variation. Nonimaging spectrometers would normally miss these variations as would small samples used in laboratory measurements, spatially averaged spectra can miss the optimum spectra for identification of materials, and spatially localized components of the rock can be obscured.
Keywords :
geochemistry; infrared imaging; infrared spectrometers; luminescence; minerals; remote sensing; rocks; alabaster; compositional variation; emissition spectra; gypsum; hyperspectral imaging spectrometer; imaging spectrometer; iron oxide; jasper; laboratory measurement; longwave thermal infrared wavelength; material identification; mineral surface geometry; norite; obsidian; optimum spectra; orthopyroxene; plagioclase; rock; rock roughness; silica; soapstone; spatial resolution; steatite; talc; volcanic glass; wavelength 11.6 mum; wavelength 7.6 mum; Hyperspectral; infrared; remote sensing; rock; spectra; thermal;
Journal_Title :
Geoscience and Remote Sensing Letters, IEEE
DOI :
10.1109/LGRS.2008.2006005