Mineralogical phase analysis in monumental tuffeau limestone by x-ray powder diffraction

摘要

A non-destructive method allows to study the mineralogical evolution from surface to deph stone of monumental tuffeau limestone. The diffraction patterns obtained by a depth scanning of the sample showed concentration variations and calcite dissolution close to the surface, concurrently to gypsum formation. This one permits to define precisely the patina depth. X-ray anaysis of powder samples obtained by scraphing of the stone assuming that there are 2:1 layer silicates in small quantity in the atian. Their swelling properties have been studied and none smectite has been found in the limestone.