## 5 Discussion
### Mineral Chemistry of Stibnite and Nano-Scale Inclusions  
The trace elemental study of stibnite by means of LA-ICP-MS needs further development [16]. To our knowledge, this study presents for the first time the mineral chemistry of stibnite from epithermal veins found in the periphery of a porphyry system [16]. Stibnite (Stb1) at Gerakario is enriched in base metals (As, Cu, Pb) and bears weak to moderate contents of critical and rare metals (Ag, Bi, Ce, La, Re, Sm, Th, Ti, Tl) (Table 2, Figure 6). However, it is depleted in Au, Hg, Se, and Te with concentrations below detection limits (Table 2). The depletion of Hg in stibnite contrasts to the Hg enrichment in stibnite from SE China [16]. In addition, the depletion of Au\({}^{+1}\) as solid solutions in stibnite and the presence of native gold in interstices of the quartz-stibnite veins [45] indicate that Au precipitation slightly followed Sb precipitation. Thus, it could be suggested that the precipitation of massive stibnite depleted the HgS content of the mineralizing fluids, and enhanced the precipitation of native gold (Au\({}^{0}\)) in the quartz-epithermal veins [65].  
The concentrations of As, Cu, and Pb in stibnite can be attributed to the stoichiometric substitutions of Sb (2 Sb\({}^{34}\leftrightarrow\) Cu\({}^{++}\)Pb\({}^{2++}\)As\({}^{3+}\)), as well as, in some cases, to invisible nanoparticles or to higher incorporation of an element in a specific sector zone, as the LA-ICP-MS depth profiles locally consist of a series of peaks of slightly varying size (Figure 10a,b) [16]. In addition, Cu and Pb exhibit a more consistent distribution in stibnite relatively to the As distribution (Table 2).  
The depth profile of La exhibits a similar pattern to those of Sb, As, Cu, and Pb (Figure 10a,b). The crystal lattice of stibnite does not include proper sites for REE accommodation, especially for La [21]. Thus, following the suggestions of [PERSON] et al. [21], lanthanum in stibnite at Gerakario may occur in fluid inclusions or in lattice defects. The rest of the critical and rare metals, including Ag, Bi, Ce, Re, Th, Ti, and Tl, which are detected in stibnite, display depth profiles close to background values. Regarding Ce and  
Figure 10: Selected time-resolved laser ablation ICP-MS depth profiles of stibnite from the epithermal quartz-stibnite veins at Gerakario. (**a**) In Stb1, the distribution patterns of As, La, Pb, Cu, and Sb are similar, suggesting their affiliation with stibnite. (**b**) In Stb1, the spiky pattern for As shows the presence of nano-scale inclusions of arsenopyrite in stibnite or that As is incorporated in higher amounts in a specific stibnite sector zone.  
La contents, possible matrix-derived interferences (i.e., \({}^{121}\)Sb\({}^{18}\)O(\(\pm\)H) for La and Ce) could not be excluded and the distribution of these elements needs further investigation.  
The depletion of stibnite in Hg, Se, and Te, and the enrichment in La could suggest that it was deposited during the late stages of the mineralizing events in the porphyry-epithermal system at Gerakario. In addition, the other Fe-Cu-Pb-As vein mineralization found in the periphery of the porphyry system [39] (Figure 2), and the enrichment of As, Cu, and Pb in stibnite, indicate the predominance of base metals in the mineralizing fluids related to the epithermal stage.