TITLE: Spessartine NMNH14143 Garnet DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH114143

MINERAL_TYPE: Nesosilicate

MINERAL: Spessartine (Garnet group)

FORMULA: Mn3Al2(SiO4)3

FORMULA_HTML: Mn3Al2(SiO4)3

COLLECTION_LOCALITY: Rutherford #2 Mine, Amelia, Amelia County, Virginia

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 Almandine.

"Results of petrographic examination: A group of 3mm and smaller diameter reddish crystals. Seem to be a few clear crystals adhering to the grains that were picked off; otherwise appears pure. Under petrographic microscope, sample appears pure."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Pure spessartine.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Pure spessartine (Norma Vergo).

END_XRD_ANALYSIS.

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

COMPOSITION: SiO2 35.02 wt% SiO2
COMPOSITION: TiO2 0.07 wt% TiO2
COMPOSITION: Al2O3 20.74 wt% Al2O3
COMPOSITION: FeO 10.40 wt% FeO
COMPOSITION: MnO 30.82 wt% MnO
COMPOSITION: MgO 0.04 wt% MgO
COMPOSITION: CaO 1.61 wt% CaO
COMPOSITION: Na2O 0.09 wt% Na2O
COMPOSITION: K2O 0.03 wt% K2O
COMPOSITION: Total 98.81 wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

Microprobe analysis found one heterogeous area where all oxides, including silica, summed to only 27 wt% (this is probably a flaw in carbon coating). Otherwise, FeO varies from 7.5 to 12%, with inverse variation in MnO. Average of 10 analyses (other than anomalous point). Analyst: Lou Walter (done on Smithsonian microprobe using WDS?)

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

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 4499 0.2-3.0µm 200 g.s.=

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

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