ORGANIC AND INORGANIC-COMPOUNDS IN LIMESTONE WEATHERING CRUSTS FROM CATHEDRALS IN SOUTHERN AND WESTERN-EUROPE

Limestone and weathering crusts have been studied at the major cathedr als of Sevilla, in southwestern Spain, and Mechelen, in northern Belgi um. These cities have very different climatic and environmental condit ions. The deterioration characteristics of the limestone in both local ities have been compared. Detailed petrographical characterization was carried out for the different building stones, including restoration materials. The bulk and trace inorganic composition of the stones and crusts was assessed, and the leachable ions were analyzed, while eleme ntal concentration profiles with depth were studied with electron micr oprobe analysis. The organic compounds in the black weathering crusts have also been studied and compared. In the different types of limesto ne, the deterioration is largely influenced by the petrographic charac teristics of the stone. Gypsum crusts from Mechelen and Sevilla show v ariable textures, even on the same stone types. Sulfatation of calcite provides Ca for the gypsum crusts. Except for a part of the Sr and Fe fractions in the crust, all other elements may be of external origin. Concentrations of the various elements are more or less comparable in crusts from Mechelen and Sevilla. External inorganic particles consis t of fly ash, quartz, clay, and glauconite. Most of the organic materi al appeared to be of anthropogenic origin, due to combustion processes , while a minor fraction originated from cuticular waxes of higher pla nts.