Which tools did stonemasons from the Late Bronze Age use to carve stelae of hard rocks from the Iberian Peninsula?

This research will put emphasis on a multidisciplinary approach to examine the Iberian stelae of the Late Bronze Age (c. 1200-800 BC) involving petrographic, geochemical, and metallurgic analyses, complemented by experimental archaeology. The petrographic determination of the rock composition of 16 stelae provided evidence that hard magmatic, sedimentary, and meta-sedimentary rocks were used. The rocks were classified as quartz rich granite, leucocratic syenogranite-aplite, meta-arkose, quarzitic wacke, and silicate quartz-sandstone. Regarding the magmatic rocks, the finest available grain size was preferred. The sedimentary and meta-sedimentary rocks were carved on surfaces with a hard ground, a silicate – ferruginous cemented bed or on a joint wall.

For the archaeological experiment, a variety of lithic tools and bronze chisels with various alloys were replicated, based on original Late Bronze Age tools from Portugal and Spain. Some lithic tools were completely inapplicable, while others, for example an amoeboid diablastic and equigranular quartzite (99 % quartz), provided acceptable results. The carving results with bronze chisels were disillusioning, regardless of the alloy composition. A long-ignored iron chisel from the Late Bronze Age site of Rocha do Vigio (Portugal) was studied with metallography. It revealed a medium-high carbon content steel and the replication of this chisel resulted as the only effective tool, provided the edge was hardened. This would establish the introduction of iron technology as a terminus post quem for the group of silicate quartz-sandstone stelae in Extremadura. Indeed, many of Europe´s earliest irons were found in nearby Portugal.

*(DFG-project AR 1305/2-1), https://www.experimentalarchaeology.uni-freiburg.de/