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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: ALB006CH01
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 Al Bush vermiculite collection housed at the U.S. Geological Survey in Denver. It apparently originates from Jiangsu, China based on the sample label.
ORIGINAL_DONOR: Al Bush vermiculite collection
CURRENT_SAMPLE_LOCATION: USGS Denver, CO
ULTIMATE_SAMPLE_LOCATION: USGS Denver, CO
SAMPLE_DESCRIPTION:
The sample has a red to golden color and its grains range in size from 0.5 - 3 mm (Fig. ALB006CH01.photo.1).
Because of the limited volume of this sample (< 200 cm3) the modified Cincinnati Method was not performed. Instead, a sample container dab from the bulk sample was collected on a stub for SEM examination.
The sample has a spectral signature similar to that of expanded vermiculite ore from Enoree, South Carolina, though its elemental composition is unique relative to the four others.
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 bulk sample indicates major biotite and phlogopite, with minor vermiculite (Fig. ALB006CH01.XRD.2). It is worth noting that expansion of vermiculite may destroy long-range crystallographic order and that unexpandable phases like biotite and phlogopite may dominate in x-ray diffraction measurements in expanded vermiculite ore. Talc was sought but not found even after attempts to enhance the intensity of the {001} reflection (but it was successfully found by SEM/EDS). There may also be some montmorillonite, however, there was not enough sample for a clay separation to better substantiate its presence.
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 are scattered between Enoree, Palabora, and Libby fields on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. ALB006CH01.microprobe.1). A Jiangsu specific compositional field was not defined for this study of expanded vermiculites.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
The sample was examined with SEM and Energy dispersive spectroscopy. One very large 216 x 20 µm elongate mineral particle was found (Fig. ALB006CH01.SEM.2). Points analyzed with EDS are shown in color on SEM micrographs that accompany the EDS spectra. The stoichiometry from EDS analyses (Figs. ALB006CH01.EDS.3 and 4) suggests the large elongate particle is serpentine. A talc particle was found as well as additional serpentines (e.g., Figs. ALB006CH01.EDS.12 and 15). Other minerals found include calcite, gypsum and clay with the majority of the sample being vermiculite/phlogopite/biotite. No elongate amphibole particles were observed.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum is typical for a sample with predominately vermiculite and hydrobiotite with a minor phlogopite and biotite. The 1.40/1.42 micron band depth ratio indicates the presence of serpentine, talc, or amphibole (see SEM/EDS summary below) probably at the few weight percent level. The shape of these contaminants cannot be discerned by spectroscopy. The spectral parameters plot in the Enoree/Jiangsu combined field (Fig. ALB006CH01.spectrum.2) and Jiangsu fields (Figs. ALB006CH01.spectrum.3 and 4).
SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns