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.
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