The mineralogical, geochemical, and thermophysical characterization of healing saline mud for use in pelotherapy

Abstract With a rich spa and wellness heritage, Slovenia now boasts fifteen registered natural health resorts and spas. Certain locations feature the traditional use of the Secovlje Salina mud, or “fango.” This study represents the first investigation of the mineralogical, geochemical and thermophysical characteristics of this mud. The healing saline mud samples were characterized by very fine, sandy, medium silt in which the mud fraction greatly dominated over the sand fraction. The mineral fraction was predominantly composed of an amorphous phase, followed by quartz, calcite, illite/muscovite, gypsum and halite, albite, and clinochlore and pyrite. The results of XRD analysis with oriented preparation identified smectite, chlorite, interstratified layers of smectite/illite, and kaolinite mineral components. The contents of the major and trace elements of saline muds were comparable to their mean concentrations in surface sediment from the Central Adriatic Sea. The samples had a high cation exchange capacity, yet low total organic carbon, total nitrogen, and total sulphur content. The concentrations of select trace metals were in the range of that found in other healing saline muds. Additionally, the physical properties of the mud (i.e., density, specific heat, thermal conductivity, and viscosity) were measured. This study contributes new knowledge about natural peloid characteristics and their quality criteria related to wellness and therapeutic purposes.