1. Monuments Lab, Royal Institute for Cultural Heritage (KIK-IRPA), Brussels 1000, Belgium
2. Antwerp Cultural Heritage Sciences (ARCHES), University of Antwerp, Ghent 9000, Belgium
3. Department of Geology (PProGRess), Ghent University, Ghent 9000, Belgium
4. Department of Chemistry, University of Hamburg, Hamburg 20146, Germany
5. Institute for Sustainable Heritage, University College London (UCL), London WC1E 6BT, United Kingdom
6. Department of Earth Sciences, Utrecht University, Utrecht3584 CS, The Netherlands