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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: Uvarovite NMNH106661 Garnet DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH106661

MINERAL_TYPE: Nesosilicate

MINERAL: Uvarovite (Garnet group)

FORMULA: Ca3Cr(+3)2(SiO4)3

FORMULA_HTML: Ca3Cr+32(SiO4)3

COLLECTION_LOCALITY: Unknown

ORIGINAL_DONOR: National Museum of Natural History

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Grossular.

The garnet group includes a series of isostructural subspecies with space group Ia3d; the crystallize in the hexoctahedral class of the isometric system and are similar in crystal habit. Garnet compositions can be expressed by the general structural formula A3B2(SiO4) where the A site houses Ca, Mg, Fe+2 or Mn+2 and the B site incorporates Al, Fe+3, and Cr+3.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: uvarv106.out, *.mdi (smear mount on quartz plate)
References: JCPDS #11-696, Huebner's reference patterns
Found: garnet, talc, minor additional phase

Comment: Talc based on three strong basal reflections. There were three unindexed reflections at 2.940, 2.510, and 1.495 angstroms. The garnet has a=11.90 angstroms, between that of uvarovite (12.00 angstroms) or andradite (angstroms) and grossular (11.85 angstroms) or other garnet components with smaller cell dimensions. Based on the intense green color, this garnet contains significant uvarovite component, but the identity and proportions of other components is not known.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EM(WDS) # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 35.9700 wt% SiO2
COMPOSITION: TiO2 0.0744 wt% TiO2
COMPOSITION: Al2O3 5.7720 wt% Al2O3
COMPOSITION: Cr2O3 19.9300 wt% Cr2O3
COMPOSITION: V2O3 0.2657 wt% V2O3
COMPOSITION: FeO 1.0750 wt% FeO
COMPOSITION: NiO 0.0099 wt% NiO
COMPOSITION: MnO 0.7153 wt% MnO
COMPOSITION: MgO 0.4420 wt% MgO
COMPOSITION: CaO 32.5200 wt% CaO
COMPOSITION: Total 96.7743 wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

Microprobe by G. Swayze, average of several points

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

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 5096 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 6957 0.2-3.0µm 200 g.s.=


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