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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS649
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 is from the attic of a house in Lansing, Michigan.
ORIGINAL_DONOR:
CURRENT_SAMPLE_LOCATION: USGS Denver, CO
ULTIMATE_SAMPLE_LOCATION: USGS Denver, CO
SAMPLE_DESCRIPTION:
Expanded vermiculite mixed with nearly an equal amount of cellulose. The sample has a mottled golden color with occasional dark grains and grains range in size from 1 - 8 mm. The gray particle (Fig. GDS649.photo.1) is a fragment of building material likely incorporated into the vermiculite by subsequent construction.
A modified Cincinnati floation method was carried out on this sample. The sink fraction consists of mica flakes and small elongate amphibole bundles, the later of which were mounted on a stub for SEM examination.
The sample has a spectral signature similar to that of expanded vermiculite ore from Libby, Montana, 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, dolomite, and minor phases listed in Fig. GDS649.XRD.2. Elongate amphibole bundles were removed from the sink fraction for SEM examination prior to XRD analyses.
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
ELECTRON_PROBE_MICROANALYSIS: The sample was examined with probe microanalysis. Spot analyses plot in the Libby field on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. GDS649.microprobe.1).
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
The sample was examined with SEM and Energy dispersive spectroscopy. Elongate amphibole bundles were placed on stubs, coated with carbon, and examined under high magnification. Points analyzed with EDS are shown in color on SEM micrographs that accompany the EDS spectra. Bundles consist of individual elongate mineral particles (Fig. GDS649.SEM.1) and their EDS-derived composition is consistent with Libby amphibole (Figs. GDS649.EDS.1 and 2).
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum is typical for a sample with predominately vermiculite with minor hydrobiotite and a trace biotite. The 1.40/1.42 micron band depth ratio indicates the presence of amphibole, talc, or serpentine probably at relatively low levels (i.e., less than a few weight percent). The shapes of the grains of these contaminants cannot be discerned by spectroscopy. The spectral parameters plot in the Libby, MT fields (Figs. GDS649.spectrum.2 to 4). Samples were spectrally measured with cellulose uniformly mixed with vermiculite.
SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns