Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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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)₂Si₄O_{10(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 preserved 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, EPMA, 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history of the Cuprite Mining District, southwestern Nevada: an integrated geological and geophysical approach: unpublished Ph.D. Dissertation, University of Colorado at Boulder, 399p.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