Evidence of layering at macro-scale. The mineral content of each layer is given in the inset. Dominant elements in each layer are shown in bold: (1) photograph of NR 94 sample. Layering is defined by alternating bluish (a) and yellow-orange layers (b), characterized by various grain sizes and by slightly different mineral compositions (see Supplementary material SM2 for a complete description); (2) thin section photograph of sample Momo 1. A layering is underlined by red dotted lines.