## 3 Results and Discussion  
### XRD Analysis of Tailings Samples  
Structural characteristics of the JKB, JOF and JHC samples were investigated by using XRD, and the obtained results are presented in Figure 2 and Table 1. As observed in Figure 2a, all three analyzed samples exhibit a well-defined crystalline and a distinct mineralogical composition. Notably, the samples contain the following minerals: quartz, clinochlore, albite, biotite, pyrite and calcite [17; 18; 19; 20; 21; 22; 23]. From Figure 2b and Table 1, it is indisputable that the JKB and JOF samples possessed very similar compositions, and the most abundant minerals were quartz (\(\sim\)21-25%), clinochlore (\(\sim\)20-27%), albite (\(\sim\)28-31%) and calcite (\(\sim\)13-14%), while the presence of other minerals was in lower amounts (pyrite  
Figure 1: Sampling locations.  
(-1-5%); biotite (-6-8%)). A detailed description of the unit cell parameters of the minerals present is given in the Supplementary Material in the form of Table S1.  
In the crystal phase of the JHC sample, clinochore was largely present (-45%), while the contents of other minerals were: -18% calcite, -14% albite and quartz, -8% biotite and -1% pyrite. Although not all Miller indices were visible in the diffractograms due to overlapping reflections, good crystallinity was evident in all samples. Micrographs presented in the inset of Figure 2 showed that particle size was the highest for JKB sample,  
\begin{table}
\begin{tabular}{c c c c} \hline
**Phase** & **JKB** & **JOF** & **JPH** \\ \hline Quartz; SiO\({}_{2}\) & \(f\) = 25.24 & \(f\) = 21.01 & \(f\) = 14.29 \\ Pyrite; FeS\({}_{2}\) & \(f\) = 4.62 & \(f\) = 1.26 & \(f\) = 0.59 \\ Clinochore; & \(f\) = 20.49 & \(f\) = 27.30 & \(f\) = 45.33 \\ \(\mathrm{Calcite}\); CaCO\({}_{3}\) & \(f\) = 12.89 & \(f\) = 14.19 & \(f\) = 17.96 \\ \(\mathrm{Albite}\); Na (Al \(\mathrm{Si}_{3}\) O\({}_{8}\)) & \(f\) = 31.08 & \(f\) = 28.15 & \(f\) = 13.96 \\ \(\mathrm{Biotite}\) & \(f\) = 5.69 & \(f\) = 8.08 & \(f\) = 7.87 \\ \hline \end{tabular}
\end{table}
Table 1: The percentages of individual crystal phases (f/%), obtained using the software package Powder Cell, for examined samples.  
Figure 2: (**a**) XRD patterns and microphotography of examined samples; inset samples images obtained by optical microscopy; (**b**) Estimated mass percentages for the mineral composition of examined samples.  
and lowest for the JHC sample. Results give information that in the waste materials taken from different parts of tailings are present minerals which possess properties for practical application, such as albite (in manufacturing of glass or ceramic) [19; 20], calcite (in lime production and the construction industry) [21] and biotite (a filler and extender in paints, an additive to drilling muds, an inert filler and mold-release agent in rubber products) [22; 23], and thus, waste material taken from the tailings may be used as a source for their extraction. In this way, by applying appropriate technologies, the extraction of useful minerals from the tailings may lead to the reduction of waste in nature and its environmental impact, while at the same time, natural resources would be fully utilized.