Archaeometric characterisation of one Tunisian and two Italian calcareous alabasters used in antiquity

The term alabaster is often applied only to compact, translucent gypsum, but sometimes it also denotes a variety of decorative rocks consisting essentially of calcium carbonate. Calcareous alabasters, often petrographically classified as travertines, were quarried in several provinces of the Roman Empire and widely used for architectural elements and small decorative objects. In spite of their considerable importance as ornamental stones, and their wide distribution, very little is known about their origin, and their positive identification often remains very difficult. This is due to their variability of colour and fabric, also within the same species, and to a lack of specific studies, especially of archaeometric characterisation. Hence our analyses – minero- petrographical (by XRD and OM on thin section) and geochemical (Sr isotopes by mass spectrometry, and chemical quantitative analysis by XRF) – of two important Italian alabasters, those of Iano di Montaione (Florence) and of Castelnuovo dell’Abate (Siena) and of a Tunisian variety/ example/specimen from Djebel Oust (Tunis), and comparison of the results obtained with other alabasters from Egypt, Thyatira (Turkey) and Oran (Algeria), all of which have already been studied and are sometimes very similar macroscopically.