While we consider the observed differences in, e.g. the goethite distribution in layer 6 or of the hematite and talc distributions in layer 3 and 5 to be genuine, it cannot be excluded that the apparent gradual changes in the crocoite distribution inside layer 7 are due to absorption of the primary or diffracted beams inside the material. Under the optical microscope, layers 3–6 indeed have a grainier appearance than the homogeneous layer 7. Up to now, no attempt to correct for these absorption phenomena has been undertaken in the framework of this work, even though the mathematical correction of this relatively weak effect would appear feasible. On the other hand, the distortion of the XRF sinograms and tomograms of Ti–K and Ba–L appears to be so significant that a similar mathematical correction would not result in distribution images reflecting reality.