Historical building stones in the province of Limburg (NE Belgium): role of petrography in provenance and durability assessment

Over 35 different stone species have been inventoried in historical monuments of Limburg (N-Belgium) and described in great detail. The resulting petrographical atlas provides a powerful identification and decision tool in restoration. Most indigenous building stones are no longer available: the historical monuments witness therefore of the former richness in geological materials. The atlas deals with macroscopic and microscopic features of the natural stones and provides suggestions for their replacement. The geographical distribution of the stones in the monuments reflects local geology and delimits geographical provinces. Most inventoried stones are sedimentary in origin. Rare volcanic and low-grade metamorphic rocks have been imported from adjacent areas. Petrography is very helpful, especially in discriminating different varieties of ferruginous, quartzarenitic, litharenitic and subarkosic sandstones. Moreover, thin-section analysis helps in assessing provenance, weathering and bioreceptivity potential. Finally, recommendations are made for replacement stones, whose intrinsic characteristics often differ from those of the original stones.