Chemical and mineralogical characteristics of peloids in Turkey

To investigate the physical, chemical, and mineralogical characteristics of peloids, which are being used traditionally and historically across Turkey, and evaluate their suitability and potential for use in peloidotherapy. Five peloid samples were gathered from their places of origin, namely Gölemezli, Dalyan, Köprüköy, Gökçeada, and Dikili. Mineral analysis and physical and chemical analyses including electrical conductivity, density, cations, anions, trace elements, organic matters, and water retention capacity at 105 °C were performed. The peloids contained a combination of clay minerals (mainly montmorillonite, kaolinite, and muscovite) and non-clay minerals (mainly quartz, calcite, dolomite, and albite) except for Gölemezli peloid, which was dominated by calcite. The other minerals (i.e., chloride-serpentine, sphalerite, pyrite, magnesium calcite, cristobalite) were also found in some peloids. Gölemezli, Dalyan, and Köprüköy peloids had high total organic matters, mainly humic substances. The water retention capacity was high in Dalyan, Köprüköy, and Dikili peloids. All peloids had a pH value slightly greater than 7 (range 7.93–8.69). Dalyan, Köprüköy, and Dikili peloids had a high water retention capacity. Dalyan and Gökçeada peloids had a high electrical conductivity, 22.040 and 9.020 μS/cm, respectively. The density of peloids was ranged between 1.240 (Gölemezli) and 1.450 (Gökçeada) g/cm³. Total mineralization of investigated peloids was greater than 1000 mg/L: Köprüköy, 2754.8 mg/L; Gölemezli, 3092.8 mg/L; Dikili, 4044.6 mg/L; Gökçeada, 6576.6 mg/L; and Dalyan, 11782.9 mg/L, mainly sodium, magnesium, calcium, chloride, sulfate, bicarbonate, and metasilicic acid. The levels of trace elements were low (≤ 2.0 mg/L) in all peloids. The peloids contained various amounts of clay minerals (mainly montmorillonite, kaolinite, and muscovite), non-clay minerals (mainly quartz, calcite, dolomite, and albite), organic matters (mainly humic acid), cations (mainly sodium, magnesium, and calcium), anions (mainly chloride, sulfate, and bicarbonate), and insoluble compounds (mainly metasilicic acid). The physical, chemical, and mineralogical properties of peloids suggest their suitability and potential for use in peloidotherapeutic applications.