Mineralogical and chemical characterization of surfa ce orange layers on the limestone of the Monastery of Batalha, Central Portugal.

Abstract

Abstract Samples of orange surface patina s found on the limestone balustr ade and sculpture s of the Batalha Monastery in Portugal, have been investigated by X ray micro diffract ometry (µ XRD) and Low Vacuum S canning E lectron M icroscop y coupled with E nergy D ispers ive S pectromet ry (LV SEM + EDS) EDS). Aim of t he study was to asse ss wh ethe r the orange layers ha ve been i ntentionally applied or were resulting from stone weathering Preliminary r esult s suggest that the orange layer on the surface is mainly consisted of gypsum and hematite with halite and weddellite as minor compon ents This di scovery i mplies the possibility that such orange patina s were applied intentionally instead of having been formed naturally by decay . A comparison was made between thi s patina and the “scialbatura ””, a protective c oating often applied by conserva tors on lim estone s an d marbles in monuments.