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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Stonewall Playa Dry Mud Field DESCRIPT

DOCUMENTATION_FORMAT: MIXTURE

SAMPLE_ID: CU01-000

MIXTURE_TYPE: Intimate

MIXTURE: all components of dry playa mud

FORMULA: Not Available

FORMULA_HTML: Not Available

COLLECTION_LOCALITY: Stonewall Playa, Cuprite, Nevada USA

ORIGINAL_DONOR: Gregg Swayze

COLLECTION_LATITUDE: Square Corners: N37 32.05', N37 32.067', N37 32.0167', N37 32.0167' # degrees and decimal minutes

COLLECTION_LONGITUDE: Square Corners: W117 09.367', W117 09.333', W117 09.35', W117 09.383' #degrees and decimal minutes

DATUM: NAD27 # coordinate datum

CURRENT_SAMPLE_LOCATION: Not a sample

ULTIMATE_SAMPLE_LOCATION: Not a sample

SAMPLE_DESCRIPTION:

This is not a spectrum of a collected sample but it is an average of 174 spectra collected of the Stonewall Playa surface when it was dry on Aug. 28th, 2001. The field spectra where collected in a polygonal area denoted by the GPS coordinates corners given above. Spectra were collected while holding the spectrometer fiber optic about 1 meter above the surface and walking while collecting. This proceedure smears the spectrum collection over an oval area a couple of meters long. About 6 offset traverses were made in each of two orthogonal direction within the sample polygon. This polygon is located a couple of hundred meters northeast of the big engraved "peace" sign. All 174 spectra were averaged, then corrected to absolute reflectance using a National Institue of Standards spectralon correction. Atmospheric absorptions were minimal during spectral collection and were removed from the averaged spectrum by physically moving the spectrum data points one at a time into positions corresponding to the ground reflectance given by laboratory spectra of a series of field samples. Only data points near 1.2, 1.4, 1.9, and 2.05 microns were modified in this way to remove all traces of atmospheric residues in the field spectra. The sample polygon is approximately a few hundred meters on a side.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Quartz (major), anorthite (minor), albite (minor), calcite (minor), orthoclase (minor), muscovite (minor), montmorillonite (minor), kaolinite (trace), magnesiohornblende (trace). XRD information from field sample Na-Montmorillonite CU93-52A collected 300 meters to the south of the field spectrum polygon.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: XRF # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

None

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

The spectrum is relatively bright with an over all reflectance of about 54%. Spectral absorptions are weak with the strongest 1.908 microns due to adsorbed or structural water in hydrated phases. The 1st OH overtone is located at 1.4110 microns. There is a weak Fe-absorption at 0.9127 microns. The 6% band at 2.2074 microns is mostly due to montmorillonite with contributions from muscovite. A very weak calcite band may be indicated by a .3% absorption at 2.344 microns.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib05a r 8996 0.2-3.0µm 200 g.s.=


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