The use of pelitic raw materials in thermal centres: Mineralogy, geochemistry, grain size and leaching tests. Examples from the Lucania area (southern Italy)

The pelitic materials used in two important thermal centres of southern Italy have been studied from mineralogical, geochemical and granulometrical points of view, both in natural conditions and after maturation. These data can be used as an inorganic compositional reference compared with a wider database of pelitic sediments cropping out in the area. Prospecting criteria matching the compositional data of raw materials, mineralogic considerations and geochemical data concerning the amount of hazardous trace elements, have been proposed. Besides the traditional criteria, the role of toxic elements was also considered. Reproducing the active mechanism during therapeutic treatments, the leaching tests were performed, and the mobility of the same element, regarded as dangerous, was emphasised. The release of the toxic elements and some important therapeutic properties depend mainly on clay mineralogy. Therefore, the contribution of mineralogy and geochemistry in the development of thermal medicine is underlined.