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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Alunite GDS83 Na63 DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: GDS83
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: Komatsuga, Japan
ORIGINAL_DONOR: Roger Stoffregen, SMU
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
this alunite sample is from a high temperature, coarse vein deposit. Sample composition is 63 mole % Na from atomic absorption analysis 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:
GDS83 Na-(65) alunite 40 kV - 30 mA, 6.5-9.5 keV (n65aint.out) References: JCPDS #41-1467; Parker (1962) Found: alunite and a major unidentified phase Comment: The alunite closely matches natroalunite; its sharp reflections indicate good crystallinity and compositional homogeneity. The additional phase(s) has some strong lines (d in A / intensity): 2.81/100, 2.253/100, 2.002/2, 1.877/50, 1.575110, 1.4731100. 1 have been unable to identify this phase. Where not obscured by the alunite, peaks of this unidentified phase "tail off' toward larger d, suggesting compositional zoning.
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
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
Standard used by Stoffregen et al. Stoffregen, R., and Alpers, C., 1992, Observations on the unit-cell dimensions, H2O contents and del D values of natural and synthetic alunite: American Mineralogist, v.77, p. 1092-1098.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
avg. grain size = 35 microns, Uniaxial (+), low birefrigence, length fast, basal cleavage, all consistent with alunite. Very little contamination. G. Swayze.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
Sample has relatively strong vibrational features between 1.4 - 1.5, 1.76, and 2.0 - 2.24, 2.33, and a complex centered at 2.5 microns.
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 215 | 0.2-3.0µm | 200 | g.s.= 35µm |
| LIB_SPECTRA: | splib05a r 335 | 1.3-5.3µm | 200 | g.s.= |
| LIB_SPECTRA: | splib05a r 374 | 0.2-3.0µm | 200 | g.s.= |
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