(a) Random powder XRD patterns of samples KL-2 (pure vermiculite), Ver-18 (vermiculite, minor chlorite), and Phl-3 (pure phlogopite). Arrows show positions of chlorite 003 and 004 peaks in Ver-18, and insert expands this region for comparison of Ver-18 to KL-2. (b) Random powder XRD patterns of samples Ver-2 (vermiculite, hydrobiotite, phlogopite), MK-1 (vermiculite, hydrobiotite) and PB (hydrobiotite, phlogopite). Quantitative mineralogical compositions are given in Table 1.
Particles mapped for K distribution; bright areas indicate greater concentrations of K. (a) and (b) sample Ver-2, (c) and (d) sample MK-1, (e) and (f) sample PB. In all cases the field of view is ∼2 mm.
Particles mapped for Cs (purple and magenta (b), (d), (f)) and Mg distribution (light blue (f)). (a) Secondary electron (SE) image of particle from sample KL-2, (b) Cs map of same particle showing uniform distribution of Cs throughout the particle volume, (c) SE image of particle from sample Ver-18, (d) Cs map of same particle showing patchy mosaic distribution of Cs indicating that some areas of this particle cannot exchange Cs. (e) SE image of particle from sample Ver-18, (f) same particle showing combined maps for Cs (magenta) and Mg (blue), areas which do not exchange Cs are correspondingly richer in Mg.
Photomicrographs of samples before exfoliation (column 1) and after thermal (column 2) and H2O2 (column 3) exfoliation. Row A: KL-2, row B: Ver-18, row C: Ver-2, row D: MK-1, row E: PB, row F: Phl-3. Samples KL-2 and Phl-3 show no visible exfoliation; all other samples show ready exfoliation with both thermal and H2O2 treatment.
Mechanism of exfoliation: (a) particle variously consisting of intergrown mosaic of vermiculite, hydrobiotite and mica domains (or vermiculite and chlorite domains). Gas phases produced by shock thermal treatment, or breakdown of hydrogen peroxide are trapped in dead ends at phase boundaries causing pressure build up. The result (b) is exfoliation of the layers.
Quantitative mineralogical composition of the six samples (<2–>1mm sized) by full pattern fitting. Analytical uncertainties at 95% confidence are given following the method described in Hillier (2003).
Electron microprobe analyses from different samples and their classification. V = vermiculite, HB = hydrobiotite and P = phlogopite.
Data for changes in bulk density and mass loss at different temperatures (20, 400, 900°C) along with calculated coefficient of expansion (K), and volume ratios VT/V20 = volume at temperature/volume at 20°C. Values with standard error (n = 3).