# Mineral Powder Extraction by the Natural Drying of Water from the Public Springs in Borsec
## Results
### Mineral Crystallization Assessment
Figure 3: XRD patterns of the crystals formed from the drying of the water samples collected in (**a**) the first campaign and (**b**) the second campaign. The increased levels of Mg\({}^{2+}\) and Na\({}^{+}\) reported for springs 6 and 10 facilitate the crystallization of pseudo-dolomite along with halite and natron. Therefore, samples S6 and S10 have calcite as the dominant mineral but it is situated in the range of 29-31%, while the amounts of the other minerals, mainly dolomite and aragonite, significantly increase. The pseudo-dolomite crystallization is well sustained by the rich magnesia mineralization of these two springs facilitating the strong development of the peaks for (104) and (202). This indicates a particular growth of the crystals on these crystallographic planes. The relatively increased level of Na facilitates the precipitation of natron and halite. Both XRD patterns feature a strong peak for (200) of halite. It corresponds to the development of large and thin square-based crystals with the height variable on the surface topography [20; 21]. Natron crystals are sustained by less intense and relatively broad peaks corresponding to relatively thin crystals. The formed crystals are investigated under cross-polarized light using the optical mineralogical microscope allowing for their correlation with the XRD data. The POM results for the samples from the first campaign are presented in Figure 4 and the results from the second campaign in Figure 5.  
The specific crystal lattice of each mineral influences the polarized light in a unique manner exhibiting a specific color range that allows for proper identification. Aragonite \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Characteristics**} & \multicolumn{5}{c}{**Mineral Composition**} \\ \cline{2-6}  & **Aragonite** & **Calcite** & **Pseudo-Dolomite** & **Halite** & **Natron** \\ \hline Chemical formula & CaCO\({}_{3}\) & CaCO\({}_{5}\) & CaMg(CO\({}_{3}\))\({}_{2}\) & NaCl & Na\({}_{2}\)CO\({}_{3}\)-10H\({}_{2}\)O \\ Crystal system & Orthorhombic & Trigonal & Trigonal & Cubic & Monoclinic \\ Habit & rhombic & rhombic & columnar & rectangular & prismatic \\ granular & granular & granular & plates & columnar \\ POM colors & violet-blue & yellow white & yellow white & transparent & yellow– \\ –brown & –brown & –brown & pale blue–gray & yellow gray \\ \hline \hline \multicolumn{6}{c}{Campaign 1} \\ \hline \multirow{2}{*}{Spring 3} & Amount, wt.\% & 11 & 65 & 13 & 6 & 5 \\  & Size range, \(\mu\)m & 3–5 & 5–8 & 5–10 & * & 5–12 \\ \hline \multirow{2}{*}{Spring 5} & Amount, wt.\% & 9 & 68 & 17 & 3 & 3 \\  & Size range, \(\mu\)m & 2.5–5 & 3–8 & 5–10 & * & 5–15 \\ \hline \multirow{2}{*}{Spring 6} & Amount, wt.\% & 19 & 48 & 20 & 8 & 5 \\  & Size range, \(\mu\)m & 3–10 & 5–15 & 5–18 & * & 5–20 \\ \hline \multirow{2}{*}{Spring 10} & Amount, wt.\% & 15 & 53 & 21 & 7 & 4 \\  & Size range, \(\mu\)m & 2–15 & 5–12 & 5–18 & * & 5–10 \\ \hline \multirow{2}{*}{Spring 11} & Amount, wt.\% & 7 & 78 & 9 & 3 & 3 \\  & Size range, \(\mu\)m & 5–10 & 5–10 & 5–12 & * & 5–10 \\ \hline \multirow{2}{*}{Spring 3} & Amount, wt.\% & 13 & 57 & 17 & 8 & 5 \\  & Size range, \(\mu\)m & 2.5–5 & 3–5 & 3–6 & * & 5–10 \\ \hline \multirow{2}{*}{Spring 5} & Amount, wt.\% & 10 & 62 & 15 & 8 & 5 \\  & Size range, \(\mu\)m & 3–10 & 3–12 & 5–15 & * & 5–10 \\ \hline \multirow{2}{*}{Spring 6} & Amount, wt.\% & 26 & 32 & 21 & 14 & 7 \\  & Size range, \(\mu\)m & 5–10 & 5–25 & 5–20 & * & 5–15 \\ \hline \multirow{2}{*}{Spring 10} & Amount, wt.\% & 25 & 31 & 18 & 17 & 9 \\  & Size range, \(\mu\)m & 3–12 & 5–15 & 5–18 & 1.5–2 & 3–10 \\ \hline \multirow{2}{*}{Spring 11} & Amount, wt.\% & 14 & 67 & 16 & 3 & below detection \\  & Size range, \(\mu\)m & 5–13 & 5–15 & 5–15 & * & - \\ \hline \hline \end{tabular}  
* The halite amount is embedded in the rectangular plates within the formed crystalline crust.  
\end{table} 
Table 3: The XRD information correlated with POM observations. crystals are colored in violet-blue depending on their position regarding the microscope optical axis.