Characterization of nanostructured calcium carbonate found in two ancient Etruscan tombs

In this work, we have analyzed and characterized a white patina, that covers the walls and frescoes of two Etruscan tombs located in the Monterozzi’s necropolis of Tarquinia: the Tomba degli Scudi and the Tomba Bartoccini. The powders have been retrieved from these areas before and during the intervention of the restorers and then SEMEDX, FT-IR and XRD have been performed for the characterization. These white powders are formed by rod-like and crystalline calcium carbonate, the length of which is a few micrometers, while the thickness has an average value of about 400 nm. This particular structure can be traced back to the moonmilk, a particular form of calcium carbonate, normally found in karst caves or other underground environments. Besides, the presence of some microorganisms in close connection with this material provides an important clue of its biological origin.