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(For further information on spectroscopy, see:
http://speclab.cr.usgs.gov)
TITLE: Almandine WS476 Garnet DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: WS476
MINERAL_TYPE: Nesosilicate
MINERAL: Almandine (Garnet group)
FORMULA: (Fe+2)3Al2(SiO4)3
FORMULA_HTML: Fe+23Al2(SiO4)3
COLLECTION_LOCALITY: Gore Mountain, Warren County, New York
ORIGINAL_DONOR: Ward Science Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Forms series with Pyrope and with Spessartine.
IMAGE_OF_SAMPLE:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
40 kV - 30 mA, 7.3-9.5 keV
File: alma476.out, *_mdi (smear mount on quartz plate) v. 1a (1982)
References: Huebner's reference patterns
Found: Garnet; one weak reflection at 3.33 Angstroms alunite (trace)
Comment: Very well crystallized reflections indicating high degree of crystallinity and suggesting compositional homogeneity. The garnet ao=11.50 Angstroms, consistent with (but not proving) almandine-rich garnet. The reflection at 3.33 Angstroms could be due to the presence of a trace of orthoclase.
J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: EM # XRF, EM(WDS), ICP(Trace), WChem
| COMPOSITION KEYWORD |
Oxide ASCII |
Amount | Weight Percent, % |
Oxide html |
|---|---|---|---|---|
| COMPOSITION: | SiO2 | 39.84 | wt% | SiO2 |
| COMPOSITION: | TiO2 | 0.08 | wt% | TiO2 |
| COMPOSITION: | Al2O3 | 22.04 | wt% | Al2O3 |
| COMPOSITION: | Cr2O3 | 0.01 | wt% | Cr2O3 |
| COMPOSITION: | V2O3 | 0.01 | wt% | V2O3 |
| COMPOSITION: | FeO | 22.01 | wt% | FeO |
| COMPOSITION: | NiO | 0.01 | wt% | NiO |
| COMPOSITION: | MnO | 0.56 | wt% | MnO |
| COMPOSITION: | MgO | 10.69 | wt% | MgO |
| COMPOSITION: | CaO | 4.93 | wt% | CaO |
| COMPOSITION: | Total | 100.18 | wt% | |
| COMPOSITION: | O=Cl,F,S | wt% | #correction for Cl, F, S | |
| COMPOSITION: | New Total | 101.18 | wt% |
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
avg. grain size = 125µm Range = 5 - 200µm
Uniform grain size distribution. Trace limonite? Garnet isotropic under cross-polarized light. Conchoidally fractured grains. G. Swayze
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2b3b4b # 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 162 | 0.2-3.0µm | 200 | g.s.= 125 µm |
| LIB_SPECTRA: | splib05a r 221 | 0.2-3.0µm | 200 | g.s.= |
| LIB_SPECTRA: | splib06a r 743 | g.s.= | ||
| LIB_SPECTRA: | splib06a r 756 | g.s.= |