An archaeometric contribution to the study of ancient millstones from the Mulargia area (Sardinia, Italy) through new analytical data on volcanic raw material and archaeological items from Hellenistic and Roman North Africa

The main quarrying area of the Mulargia ignimbrite, used mainly to produce rotary millstones during the Hellenistic and Roman age, has been identified and sampled in order to update and complete the petrographic and geochemical database by employing standard analytical methods (optical microscopy and ICP-AES/MS spectrometry). The combination of petrographic and geochemical data concerning the Tertiary rhyodacitic to rhyolitic ignimbrites outcropping in central west Sardinia, previously very poor, form a helpful tool for future work on this important typology of volcanic millstones. The data bank obtained has been used to verify the geological source of eight millstones discovered in different rural settlements of Hellenistic Numidia and Roman Africa Proconsularis supposed by archaeologists to be made of ignimbrite from Mulargia. The results of the petro-archaeometric study confirmed a Sardinian origin for these millstones and represent one of the very few analytical proofs of their effective export to North Africa.