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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, 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.

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: 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 162 0.2-3.0µm 200 g.s.= 125 µm
LIB_SPECTRA: splib05a r 221 0.2-3.0µm 200 g.s.=


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