Since a few years a French-Belgian team of archeologists and geologists work on the characterization of ancient quern stones and millstones (mainly from the Antique period) linked with the identification of their stratigraphical and geographical provenances. This fruitful collaboration aims at reconstructing the ancient commercial roads and economic organization of territories during that period. In addition to the better-known volcanic rocks from the Eifel area, our study revealed the frequent occurrence of particular Devonian conglomerates and sandstones from the Ardenne area, as raw materials for the manufacturing of querns and millstones. The latter sandstones as well as the related antique millstone quarries, form an important and until now undervalued geological and cultural heritage in Belgium. Near the Ardenne border between France and Belgium, the earliest Devonian (Lochkovian) sediments deposited on the Caledonian substrate are conglomerates, which are interpreted as continental alluvial fans. The first marine sediments are littoral sandstones/quartzites or shales/slates. A sandstone formation, formally defined as the “Arkose d’Haybes” is closely linked to the former Lochkovian conglomerates (called also the “Poudingue de Fépin”). The outcrops of this particular formation around the reference localities of Haybes, Fépin and Hargnies (Ardennes, France), show a partly recrystallized, well-sorted grey to greenish sandstone (turbidite facies) with wine-red coloured joints. Another important area displaying old quarries in the same formation is located between Hirson (Aisne, France) and Macquenoise (Hainaut, Belgium): here, a more homogenous grey coarse sandstone facies occurs, with a better consistency and small amounts of dark green tourmaline crystals. These detrital formations were locally quarried, not only for building stones but also for the production of querns and millstones. The huge Proto-historical and Roman millstone quarries in Lochkovian conglomerates and sandstones from Macquenoise are known since the 19th century. Even if the lack of recent archeological excavations do not allow yet to precise the exact age of their quarrying, the dating of the various products derived from these quarries allow to consider the duration of the active extraction and how far the millstones from Macquenoise area were transported into the northern Gallo-Roman provinces.