The volcanic millstones from the archaeological site of Morgantina (Sicily): provenance and evolution of the milling techniques in the Mediterranean area

The Morgantina archaeological area, inhabited from the Early Bronze Age, had its widest expansion from the fifth to the first century BC. The volcanic millstones found at Morgantina fall into three different groups on the basis of the milling technique: (i) saddle querns (known from the Middle-Late Bronze Age and Iron Age); (ii) rectangular hopper-rubbers (Olynthian) millstones, the invention of which dates to the fifth century BC; and finally (iii) Morgantina-type rotary millstones (starting to be used from the fourth to the third century BC). In order to determine the provenance of the raw materials (lavas) used for all these millstone types, we collected 38 very small rock samples for thin-section modal mineralogy, petrography and major trace element composition. The results have contributed to classifying different lithotypes and distinguishing between provenance from Etna and the Hyblean Mountains, the two volcanic areas respectively north-east and south-east of Morgantina. Saddle querns are made of tholeiitic basaltic andesites from the Hyblean Mountains and transitional basalts, mugearites and hawaiites from Etna. The variety of sources of portable saddle querns, mostly used in households, indicate that there was no general preference for specific quarrying sites. By contrast, the rectangular hopper-rubber and the Morgantina-type millstones, which document the period of Morgantina’s greatest prosperity, are almost completely made of hawaiites from Etna. The use of a specific lithotype (i.e., Etna hawaiite) for the more efficient rectangular hopper-rubber and rotary millstones could be linked to the fact that these mills may have been operated in business establishments. It is worth noting that the Gornalunga river was, in antiquity, a waterway joining Morgantina to the final stretch of the Simeto river and then the Ionian coast. The best candidate areas for the millstone hawaiite quarrying sites from Etna are the far south-western sectors of the volcano, along the Simeto Valley (i.e., the ‘Piano Provenzana’ Formation) or the inner suburb of presentday Catania (i.e., the ‘Pietracannone’ Formation). The very efficient Morgantina-type rotary millstones spread during the reign of Hieron II of Syracuse (275–215 BC) in eastern Sicily and met the need for grinding large quantities of cereals during a relatively peaceful time and a period of agricultural development.