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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS850
MATERIAL_TYPE: Expanded Phyllosilicates
MATERIAL: Expanded Vermiculite Ore
FORMULA: (Mg,Fe2+,Al)3(Si,Al)4O10(OH)2.4H2O
FORMULA_HTML: (Mg,Fe2+,Al)3(Si,Al)4O10(OH)2.4H2O
COLLECTION_LOCALITY: This sample was collected from the expansion Grace ® expansion facility in Enoree, South Carolina in 2008 (courtesy of Chris Findlay, MSHA and W.R. Grace & Co.).
ORIGINAL_DONOR:
CURRENT_SAMPLE_LOCATION: USGS Denver, CO
ULTIMATE_SAMPLE_LOCATION: USGS Denver, CO
SAMPLE_DESCRIPTION:
The sample has a mottled golden color with equal numbers of gold and dark grains with a grain sizes that range from 1– 2 mm with occasional grains up to 5 mm (Fig. GDS850.photo.1).
A modified Cincinnati floation method was carried out on this sample. The sink fraction consists of mica flakes and small particles that were mounted on a stub for SEM examination.
The sample has a spectral signature similar to that of expanded vermiculite ore from Enoree, South Carolina, USA.
Original spectrum published in:
IMAGE_OF_SAMPLE:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Qualitative XRD analysis of the Cincinnati Method sink fraction indicates the presence of amphibole, talc, and biotite (Fig. GDS850.XRD.2).
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
The sample was examined with probe microanalysis. Spot analyses on flakes from the sample plot in the central and rightmost Enoree fields on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. GDS850.microprobe.1).
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
The sample was examined with SEM and Energy dispersive spectroscopy. Particles from the sink fraction were placed on an SEM stub, which was coated with carbon, and examined under high magnification. Points analyzed with EDS are shown in color on SEM micrographs that accompany the EDS spectra. Rounded amphibole particles were detected based on EDS and SEM analyses (i.e., Figs. GDS850.EDS.3 and 4 and GDS850.SEM.3; GDS850.EDS.9 to 12). One amphibole particle is somewhat elongate (Fig. GDS850.EDS.13 and 14, and GDS850.SEM.8). Rounded talc particles were also detected (e.g., Figs. GDS850.EDS.1 and 2, and GDS850.SEM.2). There were no highly elongate amphibole particles detected.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum is typical for a sample with vermiculite. The 1.40/1.42 micron band depth ratio indicates the presence of amphibole, talc, or serpentine probably at the few weight percent level. The shape of the grains of these contaminants cannot be discerned by spectroscopy. The spectral parameters plot in the Enoree/Jiangsu field (Fig. GDS850.spectrum.2) and Louisa/Enoree fields (Fig. GDS850.spectrum.3 and 4).
SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns