*2.1. Materials*

Two pharmaceutical grade clays granted by TOLSA company (Madrid, Spain)—magnesium aluminum silicate (PS9) and attapulgite (G30)—with mineralogical identification previously evaluated (Table 1) were used [63].


**Table 1.** Fibrous clay (PS9 and G30) mineralogical composition (modified from [63]).

Two medicinal waters from Graena (GR) and Alicún De Las Torres (ALI) thermal stations were used. Both spring sources are located in Granada (Andalusia, Spain) and are classified as hypothermal (ALI) and hyperthermal (GR), both of them having a strong mineralization [64,65]. Their pH, conductivity and elemental compositions have been determined in a previous study, and results are summarized in Table 2.

**Table 2.** Medicinal water characteristics and elemental composition determined by means of ICP-OES and ICP-MS (modified from [63]).


According to previous studies and characterizations [63], hydrogels were prepared mixing 10% *w*/*w* of each clay mineral with the corresponding spring water, by means of a turbine high-speed agitator (Silverson LT, Chesham, UK) at 8000 rpm for 10 min. The obtained hydrogels are summarized in Table 3.

**Table 3.** Thermal muds tested, identification codes and composition.

