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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 RES-9 Summitv (400C) DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: RES-9

MINERAL_TYPE: Sulfate

MINERAL: Alunite (Alunite group)

FORMULA: (Na,K)Al3(SO4)2(OH)6

FORMULA_HTML: (Na,K)Al3(SO4)2(OH)6

COLLECTION_LOCALITY: Summitville, Colorado, USA

ORIGINAL_DONOR: Roger Stroffregen

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Alunite RES-9 (XNa=68 and XNa=23) Sample is from the Summitville Mine in SW Colorado, probably from drill core samples. Sample composition is 40 mole % Na from atomic absorption analysis, but X-ray diffraction analysis indicates two alunite phases of XNa=68 and 23. See: Stroffregen, R.E., and C.N. Alpers, Observations on the unit-cell dimensions, H2O contents, and δD values of natural and synthetic alunite, American Mineralogist, 77, 1092-1098, 1992.

IMAGE_OF_SAMPLE:
Photo of sample

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

X-ray analysis indicates two alunite phases present in sample. One has XNa=68 and the other XNa=23.

see: Stroffregen, R., and Alpers, C., 1992, Observations on the unit-cell dimensions, H2O contents and δD values of natural and synthetic alunite: American Mineralogist, v.77, p. 1092-1098.

Major components include alunite and quartz with trace amounts of kaolinite and rutile. B. Benzel.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Sample has relatively strong vibrational features between 1.4 - 1.5, 1.76, and 2.0 - 2.24, 2.32, and a composite absorption centered at 2.5 microns. The absorption at 1.395 microns may indicate the presence of trace kaolinite. G. Swayze.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns