RESEARCH ARTICLE Combination of in situ spectroscopy and chemometric techniques to discriminate different types of Roman bricks and the influence of microclimate environment Claudia Scatigno 1,2 & Nagore Prieto-Taboada 2 & Cristina García-Florentino 2 & Silvia Fdez-Ortiz de Vallejuelo 2 & Maite Maguregui 2 & Juan Manuel Madariaga 2 Received: 6 March 2017 /Accepted: 4 December 2017 /Published online: 15 December 2017 # Springer-Verlag GmbH Germany, part of Springer Nature 2017 Abstract Red and yellow bricks are the wall-building materials generally used in Roman masonries. The reasons for the different coloration are not always understood, causing loss of crucial information both for the conservation and for the archaeological knowledge of the cultural sites. In this work, a combination of in situ analyses, employing portable Raman spectroscopy and handheld energy dispersive X-ray fluorescence (HH-ED-XRF) spectroscopy along with chemometric analysis, was carried out on ancient Roman bricks of the BCasa di Diana^ building (Ostia Antica, Italy-130 CE). Specifically, the compounds and the characteristic elements, which describe each type of brick (red and yellow), were studied avoiding destructive or invasive sampling. The molecular analysis allowed us to identify the major and minor compounds that characterise the bricks (anatase, hematite, quartz, calcite and silicates). However, the elemental analysis gave more useful information. Thus, the complex HH- ED-XRF data matrix generated was treated by a specific principal component analysis (PCA) to identify behavioural differences of the coloured bricks. The results revealed that Ca and Fe are the discriminatory elements for the two types of bricks. The PCA outcomes suggest that the contribution of certain elements is different in the bricks (mainly Ca, P, Sr, As and S, for yellow bricks), which could indicate different raw materials. Even among bricks with the same red colour (Al, Si, Ti, K, Fe, Cr, Mn, Ni, Zn, Cu, Rb and Zr, seemed to be the elements linked to raw materials), as a function of the surface impacts (orientation and microclimate affect the salts’ formation), a distinction was made. Furthermore, the PCA pointed out that the yellow bricks are those more affected by decaying processes (related with Ca, P and S), complying with the Raman spectroscopy results in which the efflorescences (gypsum) affect especially the surface of these types of bricks. Highlights • A combined approach with portable Raman and handheld HH-ED-XRF spectroscopy to study the Roman coloured bricks • An in situ screening to distinguish among different types of Roman bricks: reds and yellows • A PCA step procedure to perform a discriminant analysis using the data matrix obtained by HH-ED-XRF spectroscopy • The microclimate as an important issue in materials’ conservation Responsible editor: Michel Sablier Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-017-0938-6) contains supplementary material, which is available to authorized users. * Claudia Scatigno claudia.scatigno@uniroma2.it 1 Department of Physics, University of Rome BTor Vergata^, Via della Ricerca Scientifica 1, 00133 Rome, Italy 2 Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country, (UPV/EHU), Barrio Sarriena s/n, 48940 Leioa, Spain Environmental Science and Pollution Research (2018) 25:6285–6299 https://doi.org/10.1007/s11356-017-0938-6