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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: Alunite HS295 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS295

MINERAL_TYPE: Sulfate

MINERAL: Alunite (Alunite group)

FORMULA: KAl3(SO4)2(OH)6

FORMULA_HTML: KAl3(SO4)2(OH)6

COLLECTION_LOCALITY: Utah

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Original spectrum published in:

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: IV. Sulphide's and sulphate's. Modern Geology, vol. 3, pp 1-14.

With the following comment: "Alunite is white when pure. This particular sample is pink, presumably because of a small amount of iron which causes the fall-off in reflectivity toward the blue. No iron bands are seen in the near-infrared."

A spectrum for this sample is also published in:

Clark, R.N., T.V.V. King, M. Klejwa, G. Swayze, and N. Vergo, 1990, High spectral resolution reflectance spectroscopy of minerals: J. Geophys Res. 12653-12680.

The only sample measured was HS295.3B which was dry sieved to the grain size interval 74-250 µm.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Analysis by Norma Vergo indicates pure Alunite

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: XRF # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 0.17 wt% SiO2
COMPOSITION: TiO2 0.02 wt% TiO2
COMPOSITION: Al2O3 35.6 wt% Al2O3
COMPOSITION: Fe2O3 0.14 wt% Fe2O3
COMPOSITION: MnO 0.02 wt% MnO
COMPOSITION: MgO less than 0.1 wt% MgO
COMPOSITION: CaO less than 0.02 wt% CaO
COMPOSITION: Na2O 0.34 wt% Na2O
COMPOSITION: K2O 10.2 wt% K2O
COMPOSITION: P2O5 0.75 wt% P2O5
COMPOSITION: LOI 44.2 wt% LOI
COMPOSITION: Total 91.56 wt%
COMPOSITION: O=Cl,F,S wt%
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

XRF analysis by Foggert, Bartel, and Stewart USGS Branch of Analytic Chemistry, Denver from:

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Sulfur was not included in analysis and probably accounts for the missing 8%.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

This reference notes that the sample is slightly pink in color, appears pure.

avg. grain size = 300µm

Grains have straight extinction, length fast, uniaxial (+). G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_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: splib04a r 251 0.2-3.0µm 200 g.s.= 300 µm
LIB_SPECTRA: splib05a r 554 0.2-3.0µm 200 g.s.= 300 µm
LIB_SPECTRA: splib05a r 577 0.3-2.5µm 200 g.s.= 300 µm


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