DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: WS485
MINERAL_TYPE: Nesosilicate
MINERAL: Grossular (Grossularite) (Garnet group)
FORMULA: Ca3Al2(SiO4)3
FORMULA_HTML: Ca3Al2(SiO4)3
COLLECTION_LOCALITY: Asbestos, Quebec, Canada
ORIGINAL_DONOR: Ward's Minerals
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Forms series with Andradite, with Hydrogrossular, with Uvarovite.
See additional spectra of grossular garnets in library for comparison. This sample has been washed in HCl acid to remove carbonate contaminants.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
File: gros485.out, *_mdi (smear mount on quartz plate)
References: Borg and Smith (1969), JCPDS #39-368, DHZ, v. 1a (1982),
Huebner's reference patterns
Found: Garnet
Comment: Extremely sharp, well-formed peaks indicate excellent
crystallinity
and suggest compositional homogeneity. ao=11.84, consistent with
grossular-rich garnet.
J.S. Huebner, J.Pickrell, T. Schaefer, written communication 1994
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
Bimodal grain size distribution:
mode1: 240 µm @ 50 vol%
mode2: 30 µm @ 50 vol%
avg. grain size = 171 µm
Sample looks clean with larger garnet grains 70% coated with finer grained garnet. Most grains are isotropic with parting surfaces. Trace contaminant could be feldspar because of low interference color and possible twinning. Optical properties are consistent with this sample being nearly pure garnet. G. Swayze.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2b3b4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns