# Mineral Powder Extraction by the Natural Drying of Water from the Public Springs in Borsec
## Results  
### Water Sample Properties  
Physicochemical properties of the water samples are very important for understanding the minerals' germination and their subsequent growth forming well-developed crystals. pH plays a key role regarding the water stability and the investigated samples have almost the same pH, as seen in Figure 2a. It is situated in a close range of 7.16 to 7.38 in the first campaign and 6.99 to 7.38 in the second campaign. Thus, the statistical analysis reveals that the pH values indicate a single representative group including all investigated samples. It clearly reveals that the measured pH is independent of the source aquifer and of the seasonality. It proves to be a constant characteristic of the Borsec mineral water established by the stable equilibrium between alkaline ions and the presence of carbonic acid induced by CO32- ions. This fact is of great importance for crystallization chemistry. Electrical conductivity and resistivity are complementary properties of the water samples evidencing their ability to conduct electrical currents. Electrical conductivity is facilitated by the ions' presence while the resistivity is negatively influenced. In other words, the high mineral content induces high electrical conductivity and low resistivity. Thus, Figure 2b,c reveal two statistically relevant groups: the first includes S3, S5, and S11 characterized by relatively low electrical conductivity and relatively high resistivity. On the other hand, the springs S6 and S10 have high conductivity and low resistivity. We also observed some significant statistical differences between the measuring campaigns. The electrical conductivity significantly increases in the second campaign compared to  
Figure 2: Mean values of water sample properties: (**a**) pH, (**b**) electrical conductivity, (**c**) electrical resistivity, (**d**) total dissolved solids, (**e**) salinity, (**f**) total Cl, (**g**) turbidity with CO2 bubbles, and (**h**) turbidity without CO2 bubbles. the first one, and the electrical resistivity decreases in the second campaign. This strongly indicates that the mineralization is stronger in the samples collected during March 2024 and relatively weaker in the samples collected during November 2023. The electrical properties' variation is explained by the total dissolved solids (TDS) and salinity of the samples. Both the TDS and the salinity are weaker in the samples collected in the first campaign and considerably increased for the second campaign, evidenced by the relevant statistical differences in Figure 2d,e. The statistical analysis reveals two relevant groups: the first is characterized by low TDS and salinity (S3, S5, and S11) and the second group has high values of TDS and salinity (S6 and S10). The samples' salinity is strongly influenced by the total chloride, shown in Figure 2f, which is low in samples S3, S5, and S11 and high in the S6 and S10 samples. Turbidity is an important physical parameter of water showing the dispersed particulate matter. It is based on the nephelometric measuring method [14; 15]. The CO\({}_{2}\) bubbles' presence in the sparkling mineral water represents a physical problem due to their interference with the light scattering within the nephelometer system generating erroneously high values for the samples' turbidity; this fact was previously reported in the literature [16; 17]. The turbidity measured in our freshwater samples generates bigger values (especially for S6 and S10); see Figure 2g. The value range is situated between 24.62 and 93.27 NTU (Nephelometric Turbidity Units), being too high for drinking water. Therefore, it was necessary to let the water sample lose the gaseous CO\({}_{2}\) prior to re-effectuating the turbidity measurements, as shown in Figure 2h. All samples have zero turbidity after the gas bubbles' removal, except for spring 10 which has remnant turbidity. The values are significantly lower after the gas loss than in the initial samples but still are high. They are related to suspended micro-particles.