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. Author manuscript; available in PMC: 2020 Aug 14.
Published in final edited form as: Geochim Cosmochim Acta. 2017 Oct 13;220:248–260. doi: 10.1016/j.gca.2017.10.004

Table 2.

Smectite characterization data obtained by XRD and VNIR.

pH14d Smectite XRD
d-spacing, Å		 VNIR
combination band position, μm
02l 060 Al(Fe(III), Fe(II), Mg)OHb (Mg, Fe(II), Fe(III))3OHb (Mg, Fe(II), Fe(III))3OHc
3.12 ± 0.03 dioctahedral smectite 4.48 1.50 nda nd nd
3.72 ± 0.34 saponite 4.55 1.53 2.239 2.319 nd
7.17 ± 0.38 saponite 4.58 1.53 2.246 2.319 2.403
8.38 ± 0.20 saponite 4.57 1.53 2.243 2.300 2.408
a

nd-not detected;

b

Combination stretching and bending vibration (Neumann et al., 2011; Treiman et al., 2014);

c

Combination stretching and translation vibration (Frost et al., 2002; Chemtob et al., 2015).