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High spectral resolution reflectance spectroscopy of minerals

January 1, 1990

The reflectance spectra of minerals are studied as a function of spectral resolution in the range from 0.2 to 3.0 μm. Selected absorption bands were studied at resolving powers (λ/Δλ) as high as 2240. At resolving powers of approximately 1000, many OH‐bearing minerals show diagnostic sharp absorptions at the resolution limit. At low resolution, some minerals may not be distinguishable, but as the resolution is increased, most can be easily identified. As the resolution is increased, many minerals show fine structure, particularly in the OH‐stretching overtone region near 1.4 μm. The fine structure can enhance the ability to discriminate between minerals, and in some cases the fine structure can be used to determine elemental composition. For example, in amphiboles and talcs, four absorption bands are observed in the samples analyzed in this study that are due to hydroxyl linked to Mg3, Mg2Fe, MgFe2, and Fe3 sites. The band intensities have been shown by other investigators to give the Fe:Fe+Mg ratio from transmission spectra. This study shows that the same equations can be used to obtain the ratio from reflectance spectra of unprepared samples. High‐resolution reflectance Spectroscopy of minerals may prove to be a very important tool in the laboratory, in the field using field‐portable spectrometers, from aircraft, and from satellites looking at Earth or other planetary surfaces.

Publication Year 1990
Title High spectral resolution reflectance spectroscopy of minerals
DOI 10.1029/JB095iB08p12653
Authors R. N. Clark, T. V. V. King, M. Klejwa, Gregg A. Swayze, N. Vergo
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research Solid Earth
Index ID 70016091
Record Source USGS Publications Warehouse
USGS Organization Crustal Geophysics and Geochemistry Science Center