Smartphone application for ancient mortars identification developed by a multi-analytical approach

The present work shows the results of the chemical, mineralogical and colorimetric characterisation of the ancient mortars from Silla Islamic Tower (Valencia, Spain) and Fuengirola Castle (Malaga, Spain). The samples were characterised from the mineralogical point of view by X-ray diffractometry and mid-infrared attenuated total reflection spectroscopy, while portable energy dispersive X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry were employed to obtain the concentrations of major and trace elements, including rare earth elements. Data analysis through multivariate statistics was used to evaluate features to discriminate among the mortars from the different construction phases and to classify undated samples. Finally, colour features of powdered and intact samples were characterised by smartphone photo processing and with a Vis-spectrophotometer as reference technique to evaluate the effectiveness of smartphones for archaeometric studies of historic mortars. The analytical results permitted the classification of most undated samples from Silla and evidenced the presence of peculiar chemical characteristics in some samples from Fuengirola. Imaging data for powdered samples showed a good potential as a reliable, cheap and non-destructive fast method to characterise mortars and carry out the study of construction phases in historical complexes.