Fig. 1

Four correlated images of exemplary nuisance dust sample: a LOM, b SEM-BSE, c PARC groups (phase map), d grain populations. Keys show colour coding for c PARC groups in Table 1 and d PARC grain populations in Table 3. Area proportions (area %) are for the whole analysed area as shown. The {empty spectra} count for image c includes the background pixels of the sample holder. Area percentages for d are normalised to 100% excluding the background shown in black. Note, a small number of loosely mounted particles visible in a had physically moved prior to acquisition of images b–d. Full resolution images and accompanying tabulated data given in Additional file 1: D