Structural Characterization of Stone Flooring “Calçada Marble”, in Lisbon, Portugal

Abstract

Abstract. The Lisbon "Calçada" sidewalks have a traditional style made of small flat and irregular cobblestones, representing magnificent mosaics. This work presents the characterization and identification of the mineralogical phases of sidewalk stones, originating from Lisbon, Portugal. Samples referenced MEKPBL (white) and MEKPNL (grey-black) were studied by means of Raman spectroscopy, ATR-FTIR and XRD. All Raman spectra show a strong band around 1089 cm-1 which can be attributed to the v1-symmetric stretching mode of (CO3)2-, indicating that calcite is the main crystal phase in both samples. All Raman spectra of MEKPNL show also graphite fingerprints localized around 1329 cm-1 and 1607 cm-1, which are characteristic respectively of the D and G peaks of the carbonaceous material. These carbonaceous materials are the substance responsible of the grey-black color to these stones. Furthermore, the Raman spectra of the MEKPNL sample show also a weak Raman band located at 460 cm-1 which can be attributed to the symmetrical stretching of Si-O-Si, characteristic of the α-quartz. Furthermore, ATR-FTIR and XRD analyses supported the Raman results.