XANES cluster map (400 µm × 100 µm) (bottom left), cluster Ca K-edge XANES spectra (top left), optical microscope image (top right) and XRD map (400 µm × 100 µm) (bottom right) for granule Mg1 produced in 500 p.p.m. Mg-amended artificial soil. The XANES map colours represent clusters denoted by the same colour in the XANES spectral image. In the optical micrograph the solid line denotes the area of the XANES map, while the dotted line denotes the area of the XRD map. In the XRD map red represents calcite and green vaterite.