The U. S. Geological Survey, Digital Spectral Library: Version 1 (0.2 to 3.05 microns)

[Adapted from The U. S. Geological Survey, Digital Spectral Library:
Version 1 (0.2 to 3.05 microns) Abstract,
'http://speclab.cr.usgs.gov/spectral.lib04/clark1993/spectral_lib.html#Abs']

ABSTRACT

The U.S. Geological Survey Spectroscopy Lab has developed a digital
reflectance spectral library, with management and spectral analysis
software. The library includes 498 spectra of 444 samples (some
samples include a series of grain sizes) measured from approximately
0.2 to 3.0 microns. The spectral resolution (Full Width Half Maximum) of
the reflectance data is <= 4 nm in the visible (0.2-0.8 microns) and
<= 10 nm in the NIR (0.8-2.35 microns). All spectra were corrected to
absolute reflectance using an NIST Halon standard. Library management
software lets users search on parameters (e.g. chemical formulae,
chemical analyses, purity of samples, mineral groups, etc.) as well as
spectral features.

Minerals from borate, carbonate, chloride, element, halide, hydroxide,
nitrate, oxide, phosphate, sulfate, sulfide, sulfosalt, and the
silicate (cyclosilicate, inosilicate, nesosilicate, phyllosilicate,
sorosilicate, and tectosilicate) classes are represented. X-Ray and
chemical analyses are tabulated for many of the entries, and all
samples have been evaluated for spectral purity. The library also
contains end and intermediate members for the olivine, garnet,
scapolite, montmorillonite, muscovite, jarosite, and alunite
solid-solution series. The U.S. Geological Survey Spectroscopy Lab has
included representative spectra of H2O ice, kerogen, ammonium-bearing
minerals, rare-earth oxides, desert varnish coatings, kaolinite
crystallinity series, kaolinite-smectite series, zeolite series, and
an extensive evaporite series. Because of the importance of vegetation
to climate-change studies The Spectroscopy Lab has included
17 spectra of tree leaves, bushes, and grasses.

The library and software are available as a series of U.S.G.S. Open
File reports. PC user software is available to convert the binary data
to ascii files (a separate U.S.G.S. open file report). Additionally, a
binary data files are on line at the U.S.G.S. in Denver for anonymous
ftp to users on the Internet. The library search software enables a
user to search on documentation parameters as well as spectral
features. The analysis system includes general spectral analysis
routines, plotting packages, radiative transfer software for computing
intimate mixtures, routines to derive optical constants from
reflectance spectra, tools to analyze spectral features, and the
capability to access imaging spectrometer data cubes for spectral
analysis. Users may build customized libraries (at specific
wavelengths and spectral resolution) for their own instruments using
the library software.

The lab is currently extending spectral coverage to 150 microns. The libraries
(original and convolved) will be made available in the future on a
CD-ROM.