## 5 Discussion
### Diamagnetic Sub-Samples  
Concerning the diamagnetic fractions obtained through the two steps of gravity separation and magnetic separation, from the perspective of the major oxides' composition, they exhibited strong differences compared to the starting material. These sub-samples were significantly depleted in TiO\({}_{2}\) (approximately \(-92.7\%\)), MgO (approximately \(-86.5\%\)), and Fe\({}_{2}\)O\({}_{3}\) (approximately \(-82.4\%\)) because of magnetic separation (Figure 10). As expected, due to the similar physical properties of quartz and feldspar, gravity separation did not produced significantly impactful effects on the composition among these fractions. The only notable compositional differences among the three fractions related to P\({}_{2}\)O\({}_{5}\), which, however, in this case, were related to a P\({}_{2}\)O\({}_{5}\) abundance that was less than 0.05 wt.%. Regarding REEs composition, the differences were also substantial compared to the starting material. Specifically, all fractions were depleted in REEs, effects attributable to magnetic separation. In this case, unlike the oxide composition, the effects of gravity separation were also identifiable. It was possible to observe (Figure 11) how the light sub-samples were the most depleted in REEs, while lesser depletions were observed in the heavy sub-samples. Furthermore, it was noticeable how the main differences between the sub-samples were more pronounced in HREEs compared to LREEs. In all fractions, moreover, a marked positive anomaly in europium was observable. This positive anomaly is probably due to the fact that part of calcium present in plagioclase is replaced by europium. In fact, europium is a multivalent element that is divalent under reducing conditions and trivalent under oxidizing conditions in geological systems. Since Eu\({}^{2+}\) has an ionic radius similar to that of Ca\({}^{2+}\), europium readily replaces the calcium site in the plagioclase structure under reducing conditions ([PERSON] et al., 2016; [PERSON] et al., 2017). Overall, compared to the initial material, the light sub-samples exhibited an 80% decrease in \(\Sigma\)REE, the intermediate ones 75%, and the heavy ones 72%. These differences were also reflected in the concentrations of thorium (\(-84\%\) in light fractions; \(-74\%\) in intermediate fractions; \(-56\%\) in heavy fractions). The effects of gravity separation in terms of uranium concentration were essentially negligible in all the fractions. Figure 9: Comparison of the composition of granite waste used in the studies of [PERSON] et al. (2016), [PERSON] et al. (2019), [PERSON] et al. (2020), and the crushing powders obtained in this study. Missing data were not provided in the consulted studies. In relation to the quartz and feldspar content calculated through the CIPW norm, no substantial differences were observed in these sub-samples. All were found to be constituted by approximately 98.0 wt% of these minerals, representing an increase of about 11% compared to the initial granite waste. Specifically, quartz ranged between 38.7 wt.% and 39.6 wt.%, while feldspar between 58.6 wt.% and 59.7 wt.%. Based on the aforementioned, it can be stated that among the diamagnetic sub-samples obtained through the process of gravity separation and magnetic separation, there were no compositional differences significant enough to consider them as distinct materials. Therefore, within the context of research for potential reuse or recycling, it would be feasible to treat all such material uniformly. Figure 10: Comparison of major oxides composition of whole rock and light, intermediate, and heavy diamagnetic fractions (on the top)—bars represent standard deviation; mean whole-rock-normalized major oxides patterns of diamagnetic fractions. As observed from the results, following the applied processing method, the diamagnetic fractions represented 70.0 \(\pm\) 6.8 wt.% of the obtained material, making it the largest fraction.