Milling--the grinding of grains to produce flour--is an interesting technological study in and of itself. Rudimentary mills are known from the Neolithic; and by the Roman Empire of the last centuries BC and first centuries AD, grinding grain was an art. Recent studies using geochemical analysis of the raw material used in the millstones have highlighted the breadth of the trade network used by the Roman empire.
One popular style of milling during Roman times was the hour-glass-shaped mill (also called "Pompeiian"), and illustrated in the photo below. The earliest date of the use of the hour-glass methodology is from the 4th century BC at the Etruscan village of Orvieto.
Millstones at Pompeii. Photo by Tyler Bell
Pompeian millers balanced two cone-shaped blocks of volcanic rock at their points. A collar fit around the stones to capture grain and flour as it was ground. The top cone was then rotated against the bottom one by means of a bar pushed either by a slave or by a donkey. The best material for a millstone was volcanic material, because it was wear-resistant, hard enough so that bits wouldn't break off and contaminate the flour, and maintained a rough-enough surface to allow a certain level of grinding.
Known and hypothesized quarries for the millstones have been located in northeast Spain, central France, eastern Germany, and Libya and Morocco in north Africa, as well as Italy and various islands in the Mediterranean: Sicily, Pantelleria, Sardinia, Ustica, and the Aeolian Islands; some identified millstones on Roman sites come from as far away as 1500 kilometers.
Volcanic Raw Material Sources of the Roman Empire. Each red dot represents at least one known location where Romans are known to have quarried volcanic rock for millstones. Base map: Geuiwogbil, data: (see sources)
Getting those millstones to far-flung local places throughout the Roman empire took ships, and thus the tracing of the origins of the igneous rocks by petrology and chemical analysis has the effect of tracking important trade routes throughout the Roman empire.
More on Trade
- Parthians as Intermediaries on the Silk Road
- Baltic Amber and Trade
- Along the Silk Road: Trade Networks
- Viking Trade Networks
Sources
Antonelli F, and Lazzarini L. 2010. Mediterranean trade of the most widespread Roman volcanic millstones from Italy and petrochemical markers of their raw materials. Journal of Archaeological Science 37(9):2081-2092.
Antonelli F, Lazzarini L, and Luni M. 2005. Preliminary study on the import of lavic millstones in Tripolitania and Cyrenaica (Libya). Journal of Cultural Heritage 6(2):137-145.
Antonelli F, Nappi G, and Lazzarini L. 2001. Roman Millstones from Orvieto (Italy): Petrographic and Geochemical Data for A New Archaeometric Contribution. Archaeometry 43(2):167-189.
Gluhak TM, and Hofmeister W. 2009. Roman lava quarries in the Eifel region (Germany): geochemical data for millstone provenance studies. Journal of Archaeological Science 36(8):1774-1782.
Peacock DPS. 1980. The Roman Millstone trade: a petrological sketch. World Archaeology 12(1):43-53.
Williams-Thorpe O. 1988. Provenancing and archaeology of roman millstones from the Mediterranean area. Journal of Archaeological Science 15(3):253-305.
Williams-Thorpe O, and Thorpe RS. 1989. Provenancing and Archaeology Of Roman Millstones From Sardinia (Italy). Oxford Journal Of Archaeology 8(1):89-113.
Comments