From Ripoli (Teramo). Obsidian lamellae, mid-recent Neolithic. (photo Scarpelli). Obsidian is one of the most frequently traded products during the Neolithic. It is a volcanic glass whose main sources in the Mediterranean are found in Melos in the Aegean, in Lipari in the Aeolian Islands, on Monte Arci in Sardinia, in Palmarola in the Pontine islands and in Pantelleria.