Spectral Signatures of Particulate Minerals in the Visible and Near Infrared

Abstract

The utility of multispectral remote sensing techniques for discriminating among materials is based on the differences that exist among their spectral properties. As distinct from spectral variations that occur as a consequence of target condition and environmental factors, intrinsic spectral features that appear in the form of bands and slopes in the visible and near infrared (.325 to 2.5 μm) bidirectional reflection spectra of minerals (and, consequently, rocks) are caused by a variety of electronic and vibrational processes. These processes, such as crystal field effects, charge‐transfer, color centers, transitions to the conduction band, and overtone and combination tone vibrational transitions are discussed and illustrated with reference to specific minerals. Spectral data collected from a large selection of minerals are used to generate a “spectral signature” diagram that summarizes the optimum intrinsic information available from the spectra of particulate minerals. The diagram provides a ready reference for the interpretation of visible and near infrared features that typically appear in remotely sensed data. In the visible‐near infrared region, the most commonly observed features in naturally occurring materials are due to the presence of iron in some form or other, or to the presence of water or OH groups.

Advances in research on mineral resources, 1994

“…In the cases of diatomite and gypsum, diagnostic absorption features in the 2.1-2.45-nm wavelength range produced by structural water molecules would probably permit identification of these minerals in a remote-sensing context. The calcitic carbonate rock shows a strong absorption feature near 2.335 ^m, which is related to vibrational absorption processes involving the CC>3 anion group (Hunt, 1977). On the other hand, the calcitic kimberlite sample lacks obvious absorption features, probably because of strong masking absorption by opaque carbonaceous impurities.…”

“…In the case of pyrophyllite, the absorption features are caused by vibrational absorption processes involving aluminum and hydroxyl, whereas, in talc and vermiculite, the features are due to vibrational processes involving magnesium and hydroxyl (Hunt, 1977). The two borate minerals, ulexite and colemanite, exhibit bands due to hydrate water molecules and perhaps to vibration modes of the borate anion group (Hunt and others, 1972).…”

“…The two borate minerals, ulexite and colemanite, exhibit bands due to hydrate water molecules and perhaps to vibration modes of the borate anion group (Hunt and others, 1972). Hunt and Salisbury (1970), Hunt (1977), Clark and others (1990), and Crowley (1991) spectrum exhibits features attributable to the phosphate group (Farmer, 1974). The perlite spectra exhibit broad emission features due to silicon-oxygen stretching and bending modes, which evidently extend over a wide range of energies in these structureless silicate glasses.…”

“…data). Although a number of general reviews dealing with the spectral properties of minerals and rocks are available (e.g., Hunt, 1977;Clark and others, 1990;Salisbury and others, 1991), none deals explicitly with industrial minerals. Similarly, the potential use of remotesensing data as an aid to exploration for industrial minerals has received only limited attention.…”

A standard design for collecting vegetation reference spectra: Implementation and implications for data sharing

“…Numerous references discuss the relationship between physical/biophysical variables and EMR, including: the way in which minerals absorb photons and their associated wavelength dependency (for example, see Hunt and Salisbury, 1970;Hunt et al, 1971a and b;Rowan et al, 1977;Hunt and Ashley, 1979;Hunt, 1977 and1979;Goetz and Rowan, 1981); the spectral reflectance of vegetation (Collins, 1978;Horler et al, 1983;Milton and Mouat, 1989;Boochs et al, 1990;Elvidge, 1990;King et al, 1995;Campbell, 1996;Dawson and Curran, 1998;Datt, 1999 and2000); and, characteristics of soils (Baumgardner et al, 1985;Irons et al, 1989).…”