(a) TEM bright field image of an NAu-1 aggregate suspended in 25% Ml medium. The sample was embedded in hydrophilic resin, which was then cured and sliced into ultrathin sections, (b) SAED pattern of the aggregate, exhibiting well-defined smectite diffraction rings. The corresponding d-spacing values (nm) are indicated. (c) EDXS spectrum taken from the aggregate, showing that the aggregate is primarily composed of Si, Al, Fe, and Ca. Note that the Cu signals in this and all other EDXS spectra in this study are from the sample mounting material.