Eclogites and jades as prehistoric implements in Europe. A case of petrology applied to Cultural Heritage
D'amico, Claudio; Ana, Raffaellamaria Camp; Felice, Gianluigi; Ghedini, Massimo
published: Feb 8, 1995
manuscript accepted: May 3, 1994
manuscript received: Oct 30, 1993
ArtNo. ESP147050701003, Price: 29.00 €
Abstract Eclogites and jades (Na-pyroxenites) are the raw-material of many prehistoric 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 petrography of north italian eclogites and jades of the axes is fully consistent 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, massive or schistose, blastic or sheared and mylonitic), metamorphic overprints, mineralogical composition (e.g. various Na- and Na-Ca-Px phases coexisting in the same stone) and accessory mineralogy. Both geological and archaeological reasons suggest that eclogite/jade axes have their source in the western Alps and foothills. Geologically, the rare combination of alpine-type eclogites plus jade are well-known in the western 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 percentage falls sharply away from the Alps, in favour of different stone materials. Single eclogite/jade finds are known in many european countries, up to 1000-1500 km from the western Alps, e.g. northern Scotland, Scandinavia, Moravia and Sicily. This bears witness to the export, exchange or gift of axes in prehistoric societes. In sites near the western Alps, eclogites prevail over jades, whereas outside this region, jades become dominant; a selection of jades with long distance transport is thus suggested. The petrography of a number of european axes is similar 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 NW Europe do not fully correspond to a NW-alpine provenance.