Provenance of Obsidians Artefacts from different Archaeological Layers of Pahistos and Haghia Triada

26 obsidian artefacts from different archaeological layers (dated back from Neolithic to Middle Minoan period) of Phaistos and Haghia Triada sites have been analysed by using non-destructive methods and portable instruments.The results indicate that all the samples can be clustered into two groups. A comparison of our data with existing ones indicates that the two groups correspond to the Sta Nychia and the Dhemenegaki quarries of Melos. The obsidian artefacts from Neolithic layers were found to came only from the Dhemenegaki quarry, those from Early Minoan (EMI, EMII, EMIIB, EMIII) layers from the Sta Nychia quarry (with the exception of the sample labelled Fes09) and those from Middle Minoan (MM1A/B) layers from both quarries.