Le argille di Venosa (PZ): Utilizzazione nel settore delle ceramiche antiche e moderne, nell'industria cosmetica e nei centri termali

The Plio-Pleistocene «argille subappennine» Formation outcropping on the five quarries localized on the Apennine margin of the «Fossa Bradanica», near Venosa (Basilicata), have been studied. This study was carried out to get information relative both to the composition and the utilization of Venosa clays in the ancient and modern ceramic, cosmetic and pelotherapy fields. These deposits are mostly clayey silt containing calcite, quartz, feldspar and dolomite. The clays are chemically homogeneous, except for the samples richer in the sand fraction that have higher SiO2 and Na2O contents. If one compares the mineralogical, petrographycal and chemical composition of the ancient ceramics from Venosa excavations to the Venosa clays, it should be deduced that to manufacture both black ceramics and bricks the Venosa clays were used. To produce the bricks the clays were mixed with the volcanoclastic materials of the Vulture. The Italian tile classification (Fiori et al., 1989) suggests that, with the addition of 10%-15% quartz and feldspar, the Venosa clays can be used for the production of red bodies and porous single-fired bodies. On the basis of their chemical composition the Venosa clays can be compared with the clays utilized in the pelotherapy and in the cosmetic industry. However, in order to use the Venosa clays in the cosmetic field it is necessary to reduce the particle size according to each specific cosmetic product.