Samples of orange surface patinas 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 Scanning Electron M icroscop y coupled with Energy Dispersive Spectromet ry (LV SEM + EDS) EDS). Aim of the study was to assess whether the orange layers have been intentionally applied or were resulting from stone weathering Preliminary results suggest that the orange layer on the surface is mainly consisted of gypsum and hematite with halite and weddellite as minor compon ents This discovery implies the possibility that such orange patina s were applied intentionally instead of having been formed naturally by decay . A comparison was made between this patina and the “scialbatura ”, a protective coating often applied by conservators on limestones and marbles in monuments.