A large-area correlated SXDM-XFM image of a small vein in a freestanding thin section of shale. (a) An XFM image of the entire 800 µm × 440 µm scan area is shown in cyan, magenta and yellow for Cu, Fe and Mn, respectively. (b) An enlargement of the region of interest (ROI) of the 100 µm × 100 µm area indicated by the dashed square in panel (a). (c) An SXDM phase-contrast reconstruction in the same ROI, revealing high-resolution high-contrast structural information. For explanation, see main text.