REE's to distinguish source origin of main white marble in the Mediterranean basin

Many investigations have been reported in the literature on the provenance of a number of stone materials used to manufacture artifacts of archaeological or historical interest, with special reference to marble. Some of these investigations deal with "geological" (i.e. geochemical, mineropetrographic) parameters or have a physical approach (Cathodoluminescence, ESR-EPR spectrometry, etc.). In other cases, a chemical approach is followed, involving the determination of the elemental composition with different techniques: X-ray fluorescence Spectrophotometry, Plasma Spectrometry, Atomic Absorption Spectrometry, or Neutron Activation Analysis (NAA), as in the present case. Attention was then addressed to the rare-earth elements (REE's), which usually are useful in a number of geochemical studies, such as those conceming the formation,evolution, and classification ofa number ofrocks and soils, as well as in archaeometric studies. REE's were determined by neutron activation analysis in the 250 Kw Triga Mark II reactor of the University of Pavia and radiochemical separations based on the precipitation and purification ofREE's fluorides. For ali samples showing a light REE (La-Eu) enrichment compared to the heavy ones (Gd-Lu); ali of them show al so the socalled Eu negative anomaly. The intensity ofthis anomaly is evaluated in terms of "depth", expressed as the ratio EulEu*, of the normalized Eu content to the one, Eu•, obtained as the geometrical mean ofthe normalized content ofthe adjacent elements, Sm and Gd. Discriminant power of REE's to distinguish the source origin of white marble in the Mediterranean basin had been evidentiated. The results are presented, discussed and compared.