Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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TITLE: Vermiculite GDS914 expanded DESCRIPT

DOCUMENTATION_FORMAT: Man_Made

SAMPLE_ID: GDS914

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 labeled “Miracle Grow®” and was supplied by the U.S. EPA in 2005.

ORIGINAL_DONOR: U.S. EPA

CURRENT_SAMPLE_LOCATION: USGS Denver, CO

ULTIMATE_SAMPLE_LOCATION: USGS Denver, CO

SAMPLE_DESCRIPTION:

The sample has a mottled golden color with numerous dark grains that range in size from 0.5 – 5 mm (Fig. GDS914.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:

No XRD analysis is available for this sample.

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 the central Enoree fields and rightmost Enoree field on the Al/Ti versus Al/[Mg/(Mg+Fe)] diagram (Fig. GDS914.microprobe.1). Two spot analyses out of 14 plot in the Palabora field.

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. Blocky amphibole particles were detected based on EDS and SEM analyses (i.e., Figs. GDS914.EDS.11 and 12 and GDS914.SEM.5; GDS914.EDS.25 and 26 and GDS914.SEM.7). Apatite was detected (GDS914.EDS.25 and 28 and GDS914.SEM.7). No talc was detected.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

This spectrum is 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 in the Enoree/Jiangsu field (Fig. GDS914.spectrum.2) and Louisa/Enoree fields (Fig. GDS914.spectrum.3 and 4).

SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns