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 unindexed reflection at 3.32 angstroms

Comment: The garnet reflections are very sharp, indicationg 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

av gr sz = 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: 1_2_3_4_

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 ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=