ECLOGITES AND JADES AS PREHISTORIC IMPLEMENTS IN EUROPE - A CASE OF PETROLOGY APPLIED TO CULTURAL-HERITAGE

Eclogites and jades (Na-pyroxenites) are the raw-material of many preh istoric polished axes of the Neolithic-to-Bronze age. These tools are very abundant in northern Italy and south eastern France, and are more sporadically present in a great part of the rest of Europe. The petro graphy of north italian eclogites and jades of the axes is fully consi stent with a provenance in the eclogitic rocks from the Piemonte zone of the western Alps. They show a wide variety of petrographic types in terms of texture (fine-to-medium grained, homo- to heteroblastic, mas sive or schistose, blastic or sheared and mylonitic), metamorphic over prints, mineralogical composition (e.g. various Na- and Na-Ca-Px phase s coexisting in the same stone) and accessory mineralogy. Both geologi cal and archaeological reasons suggest that eclogite/jade axes have th eir source in the western Alps and foothills. Geologically, the rare c ombination of alpine-type eclogites plus jade are well-known in the we stern Alps. On the archaeological side, it is impressive that about 70 to > 90% of all axes found in regions near the western Alps (northern Italy and Provence) are made of eclogite and jade, whereas this perce ntage falls sharply away from the Alps, in favour of different stone m aterials. Single eclogite/jade finds are known in many european countr ies, up to 1000-1500 km from the western Alps, e.g. northern Scotland, Scandinavia, Moravia and Sicily. This bears witness to the export, ex change or gift of axes in prehistoric societes. In sites near the west ern Alps, eclogites prevail over jades, whereas outside this region, j ades become dominant; a selection of jades with long distance transpor t is thus suggested. The petrography of a number of european axes is s imilar to that of the north-italian axes and they probably derive from the same source. Only a few ceremonial jade axes of high quality in N W Europe do not fully correspond to a NW-alpine provenance.