The presence of rotative grindstones have been frequently reported in the ancient mines and métallurgie centres round the Mediterranean. On the Roman iron and steel site at the Martys, two types of grindstones have been discovered in the mounds of slag dating from the first century BC : Pompeian type millstones carved out of tephritic leucite-loaded phonolite from the Orvieto area {Volsinii, Central Italy) and much smaller arm-propelled millstones carved out of basalt from the Agde area or out of granit from the Martys site itself. The mineralogical and geochimical results of this study show that the Pompeian millstones would have been used for the crushing of slag produced by low furnaces during the direct reduction of iron ores into an ir...