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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Alunite SUSTDA-20 DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: SUSTDA-20
MINERAL_TYPE: Sulfate
MINERAL: Alunite (Alunite group)
FORMULA: NaAl3(SO4)2(OH)6
FORMULA_HTML: NaAl3(SO4)2(OH)6
COLLECTION_LOCALITY: Sulfur, NV
ORIGINAL_DONOR: Ron Lyon at Stanford University
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
The sample was sieved to the grain size interval less than 250 µm.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
File: alun20_mdi, *.out (smear mount on quartz plate)
References: JCPDS #41-1467; Huebner's reference patterns
Found: Natroalunite and weak, unidentified reflections at 3.33,
2.90, 1.912, 1.719, 1.606, and 1.475 angstroms
Comment: Moderately sharp and well-formed peaks suggest only
moderate crystallinity and compositional heterogeneity. Some
alunite peak intensities do match the relative intensities of the
reference patterns.
J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
Pure sample. Clear elongated grains with parallel extinction along cleavage traces. Also length fast, and of low birefringence. This is all consistent with alunite.
Avg. grain size = 19µm
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 261 | 0.2-3.0µm | 200 | g.s.= 19 µm |
| LIB_SPECTRA: | splib05a r 817 | 0.2-3.0µm | 200 | g.s.= |
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