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 GDS97 K Syn (150C) DESCRIPT

DOCUMENTATION_FORMAT: Man Made

SAMPLE_ID: GDS97

MINERAL_TYPE: Sulfate

MINERAL: K_Alunite (Alunite Group)

FORMULA: KAl3(SO4)2(OH)6

FORMULA_HTML: KAl₃(SO₄)₂(OH)₆

COLLECTION_LOCALITY: Synthetic

ORIGINAL_DONOR: Roger Stoffregen

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Synthetically prepared pure K-endmember sample made at 150C. Sample is 100% mole fraction K.

See Stoffregen, R.E., and C.N. Alpers, Observations on the unit-cell dimensions, H2O contents, and delD values of natural and synthetic alunite, American Mineralogist, 77, 1092-1098, 1992.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

For sample (GDS97B) heated to 400C: 40 kV - 30 mA, 6.5-9.5 keV (kalunt.out) References: JCPDS #14-136, 23-767, 7-17 Found: alunite, KAI(SO4)21 trace K-alum, and four unidentified weak reflections Comment: The K-alum identification is based on 5 weak to very very weak reflections. The unidentified phase(s) has (d/l, as above) 4.60/20, 3.139/100, 3.095/80, 1.550/20. All reflections are sharp, indicating good crystallinity and compositional homogeneity.

see: Stoffregen, R.E., and C.N. Alpers, Observations on the unit-cell dimensions, H2O contents, and delD values of natural and synthetic alunite, American Mineralogist, 77, 1092-1098, 1992.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: NONE #XRF, EM(WDS), ICP(Trace),WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Sample has relatively weak vibrational features between 1.4 - 1.5, 1.76, and 2.17, and 2.32 microns. Other pure K-endmember alunites prepared at higher temperatures have much stronger vibrational features.

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:	splib05a r 513	1.3-5.3µm	200	g.s.=

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