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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: Montmorillonite-Na + others CU93-52A DESCRIPT

DOCUMENTATION_FORMAT: MIXTURE

SAMPLE_ID: CU93-52A

MIXTURE_TYPE: Intimate

MIXTURE: Na-montmorillonite + others

FORMULA: (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2*nH20

FORMULA_HTML: (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2•nH20

COLLECTION_LOCALITY: Stonewall Playa, Cuprite, Nevada, USA

ORIGINAL_DONOR: Gregg Swayze

COLLECTION_LATITUDE: N37 31.85' # degrees and decimal minutes (N or S)

COLLECTION_LONGITUDE: W117 09.42' # degrees and decimal minutes (W or E) P> DATUM: NAD27 # coordinate datum

CURRENT_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This sample was collected from the surface of the dry Stonewall Mud playa 1 km east of the eastern alteration center at Cuprite, NV. The original surface was perserved and spectrally measured in the lab.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Quartz (major), anorthite (minor), albite (minor), calcite (minor), orthoclase ( minor), muscovite (minor), montmorillonite (minor), kaolinite (trace), magnesiohornblende (trace).

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 52%. Spectral absorptions are weak with the strongest 1.917 microns due to adsorbed or structural water in hydrated phases. The 1st OH overtone is located at 1.4160 microns. There is a weak Fe-absorption at 0.9127 microns. The 6% band at 2.2094 microns is mostly due to montmorillonite with contributions from muscovite. A weak calcite band may be indicated by a 1.5% absorption at 2.347 microns.

See: Swayze, G.A., 1997, The hydrothermal and structural history of the Cuprite Mining District, southwestern Nevada: an integrated geological and geophysical approach: unpublished Ph.D. Dissertation, University of Colorado at Boulder, 399p.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_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 8657 0.2-3.0µm 200 g.s.=


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