title: Renaissance patinas in Ubeda (Spain): mineralogic, petrographic and spectroscopic study.
abstract: Different analytical techniques were used for microstructural and compositional analysis of the ochre-coloured patinas that appear on the calcarenite substrate of monuments in the historical settings of Ubeda and Baeza (Spain). Optical microscopy, scanning electron microscopy-energy dispersive x-ray spectrometry (SEM-EDX), x-ray diffraction, Raman spectroscopy and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) were employed and a critical comparison of their experimental requirements, strengths and weaknesses is presented. The study focussed on two churches in Ubeda where patinas were widespread in ornamental elements. These films contained calcite as the principal component, and traces of dolomite and feldspars. Clear identification of calcium oxalate, mainly in the form of whewellite, was achieved by infrared and Raman spectroscopic studies. Results from texture, distribution and composition of the patinas in ornamental elements suggest that ancient treatments were applied for protection of Renaissance façades and consolidation of weathered older façades. The patinas were seldom found on supporting elements. Their different composition, apatite was found together with oxalates, and location may suggest a biogenic origin here. Gypsum crusts were sometimes found over the patinas.
authors.affiliation: Department of Geology, University of Jaén, Paraje Las Lagunillas s/n, 23071, Jaén, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Campos-Suñol
authors.forename: A
authors.initials: A
authors.lastname: Domínguez-Vidal
authors.forename: M J
authors.initials: MJ
authors.lastname: Ayora-Cañada
authors.forename: M J
authors.initials: MJ
authors.lastname: De la Torre-López