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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS327
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 came from a bag of Scotts ® horticultural vermiculite purchased locally in Denver, Colorado in 2001.
ORIGINAL_DONOR:
CURRENT_SAMPLE_LOCATION: USGS Denver, CO
ULTIMATE_SAMPLE_LOCATION: USGS Denver, CO
SAMPLE_DESCRIPTION:
The sample has a mottled golden color and ranges in grain size from 2 - 8 mm (Fig. GDS327.photo.1). Grains are relatively free from dust.
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 the Palabora Mine, Phalaborwa, South Africa.
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 diopside and tridymite, minor calcite and quartz (Fig. GDS327.XRD.2). Qualitative XRD analysis of the bulk sample indicates the presence of hyrobiotite, vermiculite, phlogopite, and biotite (Fig. GDS327.XRD.3). Figures GDS327.XRD.5 to 10 show XRD analyses for this Scotts sample (labeled GDS624) mixed with amphibole from Libby, Montana.
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 plot in the Palabora field on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. GDS327.microprobe.1). A few probe spots plot in the nearby Enoree field suggesting possible mixing with minor amounts of ore from Enoree, South Carolina, USA.
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. An amphibole grain (non-elongate) was found (Figs. GDS327.EDS.13 and 14 and GDS327.SEM.5). Apatite and possible feldspar grains were also found. No elongate amphibole particles were found.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum is typical for a sample with predominately hydrobiotite and phlogopite/biotite. The 1.40/1.42 micron band depth ratio plots below the “no detectable amphibole, talc, and serpentine” line in Figures GDS327.spectrum.2 and 3. The reflectance spectrum of this sample does not have a detectable 2.24-micron band so there is no symbol on Fig. GDS327.spectrum.4. The spectral parameters plot in the Palabora field (Figs. GDS327.spectrum.2 and 3).
SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns