## 3 Results and Discussion
### XRD Phase Analysis of the Obtained Products after Firing under Different Conditions
\begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{4}{c}{**Sample W6**} \\ \hline  & **1300 \({}^{\circ}\)C, 30 min** & \multicolumn{2}{c}{**1600 \({}^{\circ}\)C, 60 min**} \\ \hline Forsterite & 73.7\% \(\pm\) 5.2 & Forsterite & 93.3 \(\pm\) 6.6 \\ Enstatite & 26.3\% \(\pm\) 2.6 & Clinoenstatite & 2.2 \(\pm\) 0.6 \\ Stishovite & 1.9\% \(\pm\) 0.6 & Maghemite & 4.5 \(\pm\) 0.6 \\ \hline \multicolumn{4}{c}{**Sample W6-5\% Fe\({}_{2}\)O\({}_{3}\)**} \\ \hline  & **1300 \({}^{\circ}\)C, 30 min** & **1300 \({}^{\circ}\)C, 120 min** & **1600 \({}^{\circ}\)C, 60 min** \\ \hline Forsterite Ferroan & 70.1 \(\pm\) 5.2 & 69.8 \(\pm\) 5.2 & Forsterite Ferroan & 89.9 \(\pm\) 6.3 \\ Protoenstatite & 15.9 \(\pm\) 1.1 & 16.0 \(\pm\) 1.1 & Clinoenstatite & 2.1 \(\pm\) 0.6 \\ Magnesoiferrite & 14.0 \(\pm\) 1.5 & 14.1 \(\pm\) 1.5 & Magnesoiferrite & 8.0 \(\pm\) 0.9 \\ \hline \multicolumn{4}{c}{**Sample W6-10\% Fe\({}_{2}\)O\({}_{3}\)**} \\ \hline  & **1300 \({}^{\circ}\)C, 30 min** & **1300 \({}^{\circ}\)C, 120 min** & **1600 \({}^{\circ}\)C, 60 min** \\ \hline Forsterite Ferroan & 63.8 \(\pm\) 5.0 & 62.5 \(\pm\) 5.0 & Forsterite Ferroan & 91.6 \(\pm\) 6.5 \\ Protoenstatite & 15.7 \(\pm\) 1.1 & 17.1 \(\pm\) 1.2 & Clinoenstatite & 2.6 \(\pm\) 0.5 \\ Magnesoiferrite & 20.5 \(\pm\) 1.5 & 20.5 \(\pm\) 1.5 & Magnesoiferrite & 5.8 \(\pm\) 0.7 \\ \hline \end{tabular}
\end{table} 
Table 4: The mineralogical content (wt.%) of examined samples W6 and W6 PT with the addition of hematite and after the application of different firing conditions. Figure 8: XRD patterns of thermally obtained products from sample W6 under different firing conditions with and without the addition of hematite. Finally, Figure 10 shows the XRD patterns for the thermally treated sample W8, whereas the respective mineral content is presented in Table 6.
* These products with hematite addition were found to consist mainly of olivine (forsterite, forsterite ferroan), pyroxenes (clinoenstatite, protoenstatite, enstatite ferroan) and magnesioferrite. * The mineralogical content of the obtained products show a significantly higher percentage of pyroxenes' presence, as compared to samples W5, W5 PT, W6 and W7, due to the initial mineralogically different content of this sample (W8, see also Table S1, Supplementary Material), which contains a higher percentage of pyroxenes. \begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{4}{c}{**Sample W7**} \\ \hline \multicolumn{4}{c}{**1300 \({}^{\circ}\)C, 30 min**} & \multicolumn{2}{c}{**1300 \({}^{\circ}\)C, 120 min**} \\ \hline Forsterite & 62.2\% \(\pm\) 4.3 & Forsterite & 91.6 \(\pm\) 6.7 \\ Enstatite & 37.8\% \(\pm\) 3.1 & Clinoenstatite & 4.0 \(\pm\) 0.4 \\  & & Maghemite & 4.4 \(\pm\) 0.7 \\ \hline \multicolumn{4}{c}{**Sample W7-5\% Fe\({}_{2}\)O\({}_{3}\)**} \\ \hline \multicolumn{4}{c}{**1300 \({}^{\circ}\)C, 30 min**} & \multicolumn{2}{c}{**1300 \({}^{\circ}\)C, 120 min**} & \multicolumn{2}{c}{**1600 \({}^{\circ}\)C, 60 min**} \\ \hline Forsterite & 71.4 \(\pm\) 4.7 & Forsterite & 61.4 \(\pm\) 4.2 & Forsterite \\  & & Ferroan & Ferroan & 92.5 \(\pm\) 6.8 \\ Clinoenstatite & 11.0 \(\pm\) 1.0 & Protoenstatite & 22.3 \(\pm\) 1.4 & Clinoenstatite \\  & 17.6 \(\pm\) 1.2 & Magnesioferrite & 16.3 \(\pm\) 1.3 & Magnesioferrite \\ \hline \multicolumn{4}{c}{**Sample W7-10\% Fe\({}_{2}\)O\({}_{3}\)**} \\ \hline \multicolumn{4}{c}{**1300 \({}^{\circ}\)C, 30 min**} & \multicolumn{2}{c}{**1300 \({}^{\circ}\)C, 120 min**} & \multicolumn{2}{c}{**1600 \({}^{\circ}\)C, 60 min**} \\ \hline Forsterite & 66.2 \(\pm\) 4.6 & Forsterite & 56.0 \(\pm\) 4.3 & Forsterite \\  & & Ferroan & Ferroan & 88.7 \(\pm\) 6.5 \\ Clinoenstatite & 9.3 \(\pm\) 1.1 & Protoenstatite & 23.5 \(\pm\) 1.4 & Clinoenstatite \\  & 24.5 \(\pm\) 1.5 & Magnesioferrite & 20.5 \(\pm\) 1.5 & Magnesioferrite \\ \hline \end{tabular}
\end{table} 
Table 5: The mineralogical content (wt.%) of product obtained from the sample W7 with the addition of hematite after firing.