Amphorae, stones ballast and stowage materials found in the roman harbour of Pisa (Italy).

During the excavation of the ancient Roman harbour of Pisa, numerous amphorae and stones used as ballast and stowage for the material transported by the ships have been collected. Most probably the amphorae were made near the centres of production of the transported materials and when reaching destination were no more utilised and left there. The ballast found in the excavation site is represented by large blocks, mainly rounded, of various sizes but with diameter not less than 10 cm. The amphorae found in the “Southern Extension” of the excavations have been analysed: Dressel 1A, Dressel 1B, Dressel 1C, Dressel 9, Will D, Will C and Will E have been recognised. The knowledge of the compositional and technological characteristics of the ceramic body allowed to acquire information about the provenance of the raw materials and on the production technology. Inside each archaeological typology, samples with the same chemical-mineralogical composition have been found. A total of 21 samples of rocks coming from the areas of the archaeological site defined as zone 3, zone 5 and “Southern Extension” have been analysed. Mineralogical-petrographical characterisation of the ballast stones give information in the search for the possible areas of origin of the rocks themselves. That could shed light on the routes taken by the ships, although it cannot be ruled out that the materials may have been re-utilised. The mineralogical-petrographical analyses performed on the rock samples revealed the existence of markedly different lithotypes, certainly deriving from a very broad area. Particularly interesting is the way of stowing used by Romans: the amphorae where settled on an incoherent groundmass incorporating blocks of stone, lumps of brick and plant matter, laid on the underbeck. The groundmass show a carbonatic composition and the framework is composed by magmatic rocks with pyroxenes badly preserved, leucite and carbonatic fragments. The comparison between the information obtained by the amphorae characterisation and by the stones classification allow to identify the following trade routes: - Provence and Ligurian coasts (metamorphic rocks ballast – wine and oil goods, volcanic sands, ochre and red pigments); - Tirrenian coast (carbonatic, metamorphic rocks and dressel amphorae). Moreover others typologies of rocks were found outcropping in many areas of Mediterranean basin which at present do not permit a sure identification of the trade routes.