Seen through a millstone. Geology and archaeology of quarries and mills. Bryggens Museum, Bergen, Norway 19 – 21 October 2011 International audience The dressing of grinding surfaces of millstones to maintain their “sharpness” is a technique known since ancient times. This wasfor the most part carried out by randomly pecking the grinding surface. More complex dressing patterns, requiring technicalknowledge of the progress of the grain through the stones, is observed on Olynthian hopper-rubbers in the Mediterranean since theClassical Period. Intricate dressing patterns were also applied in Antiquity to rotary querns in Germania, in northern and easternGaul, and in certain areas of the southeastern Narbonnese Gaul. Although millstone dressing appears to wane after Antiquity,it was widely adapted in Modern Times and was, in fact, a fundamental aspect of milling as late as the 20th century. Millstonedressing with intricate patterns in Antiquity in the Paris Basin seems to have been common. The study of a collection of millstonesfrom Antiquity allows us to offer a typology of dressing techniques regardless of their means of traction. The recurrence of certainpatterns of furrows and their symmetry on both the upper and lower grinding surfaces allows us, based on comparison with patternson modern millstones, to suggest the direction of rotation. The reasons behind dressing millstones in Antiquity remain still largelyunknown.