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: alunite.5+MuscCU91-250A AMX4 DESCRIPT

DOCUMENTATION_FORMAT: MIXTURE

SAMPLE_ID: AMX4

MIXTURE_TYPE: Areal

MIXTURE: Alunite, Muscovite

FORMULA: KAl3(SO4)2(OH)6 + KAl2[AlSi3O10](OH,F)2

FORMULA_HTML: KAl₃(SO₄)₂(OH)₆ + KAl₂[AlSi₃O₁₀] (OH,F)₂

COLLECTION_LOCALITY: Cuprite, Nevada.

ORIGINAL_DONOR: G. Hunt, Gregg Swayze

COLLECTION_LATITUDE: Not Available # degrees and decimal minutes (N or S)

COLLECTION_LONGITUDE: Not Available # degrees and decimal minutes (W or E)

DATUM: Not Available # coordinate datum

CURRENT_SAMPLE_LOCATION: USGS Spectral Library Denver, Colorado

ULTIMATE_SAMPLE_LOCATION: USGS Spectral Library Denver, Colorado

SAMPLE_DESCRIPTION:

Calculated areal (linear) mixture of Alunite 50% HS295.3B and Muscovite CU-250A.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

See HS295.3B For muscovite CU91-250A: quartz (major), muscovite (both 2M1 and 1M polytypes). Analysis by Steve Sutley.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EPMA # XRF, EPMA, ICP(Trace), WChem

See HS295.3B

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

See HS295.3B

END_COMPOSITION_DISCUSSION.

See HS295.3B MICROSCOPIC_EXAMINATION:

See HS295.3B

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Spectrum resembles that of Alunite HS295.3B at wavelengths shorter than 2.0 microns. Between 2 and 2.5 microns the alunite absorptions are modified by the muscovite so that the main 2.17 micron alunite band strongly resembles that of halloysite. The 1.76 and 2.32 micron alunite bands are still present. The presence of the 1.45 micron alunite OH stretch overtone doublet is still diagnostic of the presence of alunite.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
See HS295.3B , CU91-250A