DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: WS478
MINERAL_TYPE: Nesosilicate
MINERAL: Almandine (Garnet group)
FORMULA: (Fe+2)3Al2(SiO4)3
FORMULA_HTML: Fe+23Al2(SiO4)3
COLLECTION_LOCALITY: Wrangell, Alaska
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.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 7.3- 9.5 keV
File:alma478.out,*.mdi (smear mount on quartz plate)
References: Borg and Smith (1969), JCPDS #9-427, DHZ, v. 1a (1982),
Huebner's reference patterns
Found: Garnet; weak reflection at 2.71 angstroms.
Comment: Very sharp reflections indicate good crystallinity and suggest compositional homogeneity. Garnet unit cell range is 11.47+/-3 angstroms indicating a pyrope-rich solid solution. The unidentified reflection is anomalously sharp (one grain??)
J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: EM # XRF, EM(WDS), ICP(Trace), WChem
| COMPOSITION: | SiO2 | 39.09 | wt% | SiO2 |
| COMPOSITION: | TiO2 | 0.00 | wt% | TiO2 |
| COMPOSITION: | Al2O3 | 22.05 | wt% | Al2O3 |
| COMPOSITION: | Cr2O3 | 0.02 | wt% | Cr2O3 |
| COMPOSITION: | V2O3 | 0.01 | wt% | V2O3 |
| COMPOSITION: | FeO | 33.10 | wt% | FeO |
| COMPOSITION: | NiO | 0.01 | wt% | NiO |
| COMPOSITION: | MnO | 1.73 | wt% | MnO |
| COMPOSITION: | MgO | 5.74 | wt% | MgO |
| COMPOSITION: | CaO | 0.57 | wt% | CaO |
| COMPOSITION: | Total | 101.32 | wt% | |
| COMPOSITION: | O=Cl,F,S | wt% | #correction for Cl, F, S | |
| COMPOSITION: | New Total | 101.32 | wt% |
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
av gr sz = 125µm Range = 5-325µm
Smaller grains adhere to larger ones. Trace of limonite staining and individual limonite grains. Garnet has conchoidal fractured surfaces, and is mostly isotropic under cross-polarized light. G. Swayze
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1_2_3_4_
LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 183 0.2-3.0µm 200 g.s.= 125 µm
LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=