An initial large area survey scan of 7x4 mm for raw and compost from Urban-3 or of 8x2 mm for raw and treated OWs from Agri-1 and Central-1 was collected at 15.8 keV to reveal the overall elemental distribution. Subsequently, a smaller area of interest (5x0.22 mm for raw and compost from Urban-3 or of 3x0.2 mm for raw and treated OWs from Agri-1 and Central-1) was chosen to conduct XANES imaging (XANES stack) consisting of 95 individual maps collected at increasing incident energies from 8900 eV to 9300 eV across the Cu K-edge. Energies were selected as follows: 8900-8960 eV in 10 eV increments, 8970-8975 eV in 1 eV increments, 8976-8999.5 eV in 0.5 eV in increments, 9000-9009 eV in 1 eV increments, 9010-9046 eV in 4 eV increments, 9050-9090 eV in 10 eV increments, and 9100-9300 in 25 eV increments. XANES maps were collected with a 1 ms dwell time and 2 µm steps using a motorised sample stage, and a micro-focussed X-ray beam to a spot size of 2 µm. XANES stack contained 275 000 pixels for raw and compost from Urban-3 or 150 000 pixels for raw and treated OWs from Agri-1 and Central-1 and 95 energies per pixel. Individual XANES maps were extracted as TIFF files from GeoPIXE™ and were imported into ImageJ v1.53 to be converted into a stack of TIFF images. This stack was then imported into Mantis 3.1.12 32 where PCA followed by cluster analysis were applied. 33, 34 PCA was used to find a reduced set of eigenspectra and cluster analysis was used to group spectroscopically similar pixels together. The average XANES spectra from each cluster were further analysed by LCF using the Athena software (SI-4).