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 AL706 Na100 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: AL706

MINERAL_TYPE: Sulfate

MINERAL: Alunite (Alunite group)

FORMULA: NaAl3(SO4)2(OH)6

FORMULA_HTML: NaAl₃(SO₄)₂(OH)₆

COLLECTION_LOCALITY: Sulfur, Nevada

ORIGINAL_DONOR: Ron Lyon, Stanford University

CURRENT_SAMPLE_LOCATION: CSES/CIRES, Univ. of CO, Boulder

ULTIMATE_SAMPLE_LOCATION: CSES/CIRES, Univ. of CO, Boulder

SAMPLE_DESCRIPTION: Composition determined to be natroalunite (Na=100) endmember based on position of the 1.496 micron OH overtone absorption using Swayze and other (2014) wavelength correlation method. See: Swayze, G.A., Clark, R.N., Goetz, A.F.H., Livo, K.E., Breit, G.N., Kruse, F.A., Sutly, S.J., Snee, L.W., Lowers, H.A., Post, J.L., Stoffregen, R.E., and Ashley, R.P., 2014, Mapping advanced argillic alteration at Cuprite, Nevada, using imaging spectroscopy: Economic Geology, v. 109, p. 1179-1221.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Alunite
Contaminant phases: smectite, quartz, minor amounts.

Kruse, F.A., and P.L. Hauff, eds., 1992, The IGCP-264 Spectral Properties Database. IUSG/UNESCO, Special Publication, 211p., (in press).

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

avg. grain size = 15 µm
Length fast, 1st order gray, sample looks pure but small grain size prevents determination of optical sign. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns