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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Almandine WS477 Garnet DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: WS477
MINERAL_TYPE: Nesosilicate
MINERAL: Almandine (Garnet group)
FORMULA: (Fe+2)3Al2(SiO4)3
FORMULA_HTML: Fe+23Al2(SiO4)3
COLLECTION_LOCALITY: Roxbury, Connecticut
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: alma477.out, alma477b.out, *_mdi
References: Borg and Smith (1969), JCPDS #9-427, DHZ, v. 1a(1982),
Huebner's reference patterns
Found: Garnet; very weak un indexed reflection at 3.32 angstroms
Comment: The garnet reflections are very sharp, indicating excellent crystallinity
and suggesting compositional heterogeneity. The garnet ao=11.51+/-3 angstroms,
consistent with (but not proving) almandine-rich composition.
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
Mineral mode:
85 vol% Almandine
15 vol% limonite stained almandine grains
avg. grain size = 50µm Range = 5 - 200µm
Trace amphibole? All other grains isotropic under cross-polarized light. Conchoidal fracture in almandine. Limonite staining and limonite grains embedded in almandine grains. G. Swayze
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2_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 172 | 0.2-3.0µm | 200 | g.s.= 50 µm |
| LIB_SPECTRA: | splib05a r 233 | 0.2-3.0µm | 200 | g.s.= |
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