Summary of OH-related mid-infrared (MIR) spectral features.

Summary of OH-related mid-infrared (MIR) spectral features of unexpanded and expanded vermiculite ores.

Detailed Description

Table 5.  Summary of OH-related mid-infrared (MIR) spectral features of unexpanded and expanded vermiculite ores.

Notes: Vibrational positions from spectra of handpicked, ground mica flakes from the unexpanded GDS469 ore sample from Libby, MT; the unexpanded ALB5SA00 ore sample from Palabora, S. Africa; and the expanded vermiculite ores as noted.  Vibrational assignments from Beran et al. (2002), Besson and Drits (1997), Farmer et al. (1971), Fechtelkord et al. (2003), Jenkins (1989), Papin et al. (1997), Serratosa et al. (1970), Vedder and Wilkins (1969), Wunder and Melzer (2002), and this study.  va = OH stretch, δa = out-of-plane cation-OH bend, and δa’ = in-plane cation-OH bend fundamental absorptions. [  ] = vacant octahedral cation site.  ---- = absorption not observed.  v1 and v3 absorptions observed in spectra of expanded vermiculite ore caused by heating (see Fig. 15b); v2 = absorption observed in unexpanded ore ALB5SA00 (see Fig. 15a), which has 37% of its Fe as Fe3+ in tetrahedral sites according to electron probe microanalysis and Mössbauer analysis.

a Wavelength positions of absorptions based on Gaussian-Lorentizian area (fixed shape, variable width) deconvolution using Peakfit® v4.12.  

b Collapsed = increased dehydration-induced repulsion of hydroxyl hydrogen by adjacent interlayer divalent cations that were water-coordinated prior to heating-induced expansion of vermiculite ore.

c Higher frequency shift of absorption likely due to Fe3+ in tetrahedral layer.  

d Repulsed = repulsion of hydroxyl hydrogen by positive charge of adjacent interlayer cations.

e Non-repulsed = no repulsion of hydroxyl hydrogen due to lack of adjacent interlayer cations.

f Assignment based on presence of this absorption in spectra of the expanded vermiculite ore samples ALB22SC00, South Carolina; GDS847, Louisa, Virginia; and GDS909, Libby, Montana (Figs. 15b and 19); and in the spectrum of an unexpanded Mg-vermiculite VTx-1 sample from Llano, Texas (see appendix discussion and Fig. A6).

g Assigned to MgFe3+[   ]OH vacancy cation clusters based on the absence of these absorptions in the Mg- and Al-rich, Fe-poor Llano, Texas, vermiculite sample (see appendix discussion and Fig. A6).

Details

Image Dimensions: 883 x 1217

Date Taken:

Location Taken: US