XRD pattern for a Fe2+–Fe3+ LDH preparation with x = 0.83 (upper pattern) compared with a pattern for feroxyhite. The data for feroxyhite were extracted from Fig. 1 of Drits et al. (1993) and those for the LDH preparation were extracted from Fig. 10b of Mills et al. (2012). The pattern for the latter does not appear noisy when compared with the original because it is a plot of the peaks with averaged noise. The data for feroxyhite were converted from Cu Kα radiation to Co Kα to facilitate comparison.