The bentonites in pelotherapy: chemical, mineralogical and technological properties of materials from Sardinia deposits (Italy)

Bentonite muds are suited for use in pelotherapy due to their typical properties of high swelling (>25 ml/2 g), specific heat ( C _p ) and ease of handling, generally obtained at a material viscosity of 400 cps. This paper reports chemical, mineralogical and technological properties of Sardinia bentonites, to identify the most suitable materials for pelotherapy pastes. Their characteristics have been compared to the peloid properties commonly used in the spa of Benetutti (Northern Sardinia). On the basis of the mineralogical, chemical and technological characterization of the samples, besides their proximity to the most important regional spas and/or thermal sources, Costa Paradiso, Pedroseddu, Laconi, Busachi, Siurgus-Donigala and Giba bentonites are the most suitable Sardinia materials for pelotherapy. The results of this study also show that a complete characterization of clay materials is necessary in pelotherapy paste preparation. The utilization and/or addition of bentonites, largely available in Sardinia at relatively low cost, can improve the thermal mud quality for curative purposes.