## 3 Results and Discussion
### Chemical Composition  
Table 2 summarizes the major and trace elements contents in the different TSF tailings and salt precipitates. The concentrations of major element oxides, Fe\({}_{2}\)O\({}_{3}\), MgO and SiO\({}_{2}\) in all samples are high. Average Fe\({}_{2}\)O\({}_{3}\) contents in the tailings are 52.36%, 48.4% and 39.7% for TSF1, TSF2 and TSF3, respectively. These contents are related to the presence of manifold iron bearing minerals in the TSF tailings (magnetic, hematite, chalcopyrrite, pyrrhotite, arsenopyrrite, stembergite, lollingite, clinosafflorite skutterudite tenannatite, siderite, ankerite, clinochore, biotite, amphachite, actinolite, cummingtonite, anthophyllite). TSF2S and TSF3S also contain high amounts of Fe\({}_{2}\)O\({}_{3}\) (25.62% and 27.5%, respectively), which are held in lollingite, clinosafflorite, tenannatite, and anthophyllite. Even though all samples contain high concentrations of SiO\({}_{2}\) and MgO, their concentration is lower with respect to Fe\({}_{2}\)O\({}_{3}\). They come from silicates and carbonates. CaO (1.22-2.99%), Al\({}_{2}\)O\({}_{3}\) (0.41-4.99%), MnO (0.51-1.22%), Na\({}_{2}\)O (0.11-1.69%), and K\({}_{2}\)O (0.06-0.67%) are very rarely present in all TSF tailings. CaO comes from carbonates, silicates, sulfates and arsenates, Al\({}_{2}\)O\({}_{3}\) is derived from other major mineralogical sources such as aluminosilicates, while Mn mainly comes from ankerite. Other components such as TiO\({}_{2}\) (0.05-0.17%) and P\({}_{2}\)O\({}_{5}\) (0.005-0.15%) are highly depleted. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Content (\%)** & \multicolumn{3}{c}{**Mine Tailings**} & \multicolumn{3}{c}{**Salt Precipitates**} \\  & **TSF1** & **TSF2** & **TSF3** & **TSF2S** & **TSF32** & **UCC** \\ \hline CaO & 1.22 & 1.84 & 2.2 & 2.99 & 1.9 & \\ MgO & 12.57 & 12.78 & 13.55 & 15.45 & 18.55 & \\ SiO\({}_{2}\) & 8.86 & 11.66 & 15.58 & 17.1 & 9.37 & \\ Fe\({}_{2}\)O\({}_{3}\) & 52.36 & 48.4 & 39.57 & 25.62 & 27.5 & \\ Al\({}_{2}\)O\({}_{3}\) & 0.41 & 2.37 & 4.57 & 4.99 & 1.99 & \\ Na\({}_{2}\)O & 0.11 & 0.32 & 0.69 & 1.69 & 1.13 & \\ K\({}_{2}\)O & 0.06 & 0.13 & 0.24 & 0.67 & 0.27 & \\ MnO & 1.11 & 1.22 & 1 & 0.51 & 0.69 & \\ TiO\({}_{2}\) & 0.05 & 0.07 & 0.1 & 0.17 & 0.05 & \\ P\({}_{2}\)O\({}_{5}\) & 0.1 & 0.15 & 0.12 & \textless{}0.005 & \textless{}0.005 & \\ LOI & 23.15 & 21.05 & 22.38 & 30.78 & 38.53 & \\ Total & 100 & 99.99 & 100 & 99.97 & 99.98 & \\ S & 1.01 & 1 & 0.42 & NA & NA & \\ Elements (mg.kg\({}^{-1}\)) & & & & & \\ Au & 1.02 & 0.41 & 0.28 & NA & NA & \\ As & 1407 & 1577 & 1210 & 2114 & 2453 & 1.5 \\ Cu & 2600 & 1400 & 900 & 896 & 700 & 25 \\ Th & 410 & 724 & 570 & 407 & 328 & 10.7 \\ V & 400 & 647 & 561 & 695 & 216 & 60 \\ Ni & 380 & 493 & 459 & 267 & 577 & 20 \\ Co & 270 & 270 & 240 & 400 & 450 & 10 \\ Se & 123 & 148 & 141 & 131 & 98 & 0.05 \\ Zn & 140 & 124 & 103 & 73 & 72 & 71 \\ Pb & 100 & 86 & 72 & 47 & 41 & 20 \\ Sb & 35 & 35 & 29 & 17 & 16 & 0.2 \\ Cd & 18 & 14 & 16 & 9 & 12 & 0.1 \\ Zr & 10 & 9 & 15 & 16 & 13 & 190 \\ Sr & 25 & 34 & 62 & 88 & 86 & 350 \\ Ba & 200 & 190 & 170 & NA & NA & 550 \\ Cr & 30 & 10 & \textless{}5 & \textless{}5 & \textless{}5 & \textless{}5 & 35 \\ Li & \textless{}5 & 2 & 3 & 3 & 3 & 20 \\ Mo & \textless{}5 & \textless{}5 & 25 & \textless{}5 & 2 & 1.5 \\ B & \textless{}5 & \textless{}5 & \textless{}5 & \textless{}5 & \textless{}5 & 15 \\ Be & \textless{}5 & \textless{}5 & \textless{}5 & \textless{}5 & \textless{}5 & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Chemical composition of the tailings and salt precipitates collected in the three TSFs (NA: Not Analyzed, LOI: Loss on Ignition). Table 2 and Figure 13 illustrate the metallic trace element (MTE) contents in the TSF tailings and in the salt precipitates (TSF2S, TSF3S) compared to their content in the upper continental crust (UCC). These samples are enriched in Cu, As, Th, V, Ni, Co, Se, Sb and Cd and, to a lesser degree, in Zn and Pb, even though they are significantly depleted in Zr, Sr and Ba.