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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS651
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:
ORIGINAL_DONOR: This sample was supplied by the U.S. EPA in 2005 and was labeled “Zonolite IV.”
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 size range from 1 – 7 mm (Fig. GDS651.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:
Rietveld refinement XRD analysis (limited quantities of sample and no internal standard) of the Cincinnati Method sink fraction indicates the presence of major quartz and talc (Fig. GDS627.XRD.1).
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
The sample was examined with probe microanalysis. Spot analyses on flakes from the sample plot in all but the lower left Enoree fields on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. GDS651.microprobe.1). This suggests the vermiculite is from Enoree and not Louisa. Six spot analyses plot in the Libby field and two others in the Palabora field. This distribution suggests a broader diversity in compositions among Enoree samples. No Libby amphiboles were found in this sample suggesting that it does not contain vermiculite from Libby (see EDS and SEM analyses below for more details).
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. Amphibole particles (some elongate) were detected in EDS and SEM analyses (e.g., Figs. GDS651.EDS.24, 26, and 29, and GDS.651.SEM.5; GDS.EDS.33 to 35, and GDS651.SEM.6). What is probably talc and not anthophyllite (based on XRD analysis) was also detected (e.g., Figs. GDS651.EDS.20 to 23, and GDS651.SEM.4). Apparently, the concentration of amphiboles is below the XRD detection limit in the sink fraction. No <93>Libby-like<94> amphibole bundles were found in the sink fraction.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum is spectrum typical for a sample with predominately 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 on the boarder of the Enoree/Jiangsu and Louisa fields (Fig. GDS651.spectrum.2) and Louisa/Enoree fields (Fig. GDS651.spectrum.3 and 4).
SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns