## 7 Discussion  
### Occurrence State of Trace Elements in Chalcopyrite and Its Indicating Significance  
Chalcopyrrite is the main carrier of Cu in the Shuangjianzishan deposit. Its ideal chemical formula is CuFeS\({}_{2}\), and the tetragonal variant is the most common in nature. [PERSON] and [PERSON] [PERSON] and [PERSON] (1958) thought that there was a strong covalent bond between Cu and Fe, and the valence states of Cu and Fe fluctuated between monovalent-divalent and divalent-trivalent, respectively. Compared with base metal sulfides such as galena and sphalerite, the situation of trace elements entering the chalcopyrite structure is often more complicated [PERSON] and [PERSON] (1958), and because of the existence of covalent bonds in chalcopyrite, it means that the GoldSchmidt rule [PERSON] (1958) cannot be used to predict the distribution trend of elements just like pure ionic structure minerals, but it still has certain reference significance. The content of trace elements in chalcopyrite is controlled by many factors, such as the chalcopyrite crystal structure, element partition with co-crystallization minerals, and magma/fluid composition [PERSON] and [PERSON] (1958); [PERSON] (1958). The content of Sn is highest in chalcopyrite in this test. Sn, Cu, and Fe have similar ionic radius, so Sn can enter chalcopyrite through isomorphism. [PERSON] (1958) thought that the migration and enrichment of high-concentration Sn were mainly formed under high-temperature and reduction conditions. [PERSON] et al. [PERSON] et al. (1958); [PERSON] et al. (1958) pointed out that chalcopyrite is not the \"first preferred host\" of trace elements when there are co-crystallization sulfides such as sphalerite, but it is also beneficial to enrich trace elements in minerals if the ore-forming fluid is rich, so the early hydrothermal solution of the Shuangjianzishan deposit may be rich in Sn, which makes the Sn content in chalcopyrite higher. In the -CPS signal diagram (Figure 7), some In and Sn signals are consistent. The ionic radii of In and Sn are similar, and there is a good positive correlation (Figure 8b). It is speculated that In and Sn enter chalcopyrite in the form of coupling instead of Fe at high temperature [PERSON] et al. (1958), forming CuInS\({}_{2}\) and Cu\({}_{2}\)FeSnS\({}_{4}\) solid solutions with the same structure as chalcopyrite. Although In and Zn also show a weak positive correlation (Figure 8c), the synchronous change in Zn and In is not observed in the signal diagram, which further proves that there may be a coupling substitution relationship between In and Sn. The positive correlation between Zn and Mn (Figure 8d) shows that Zn mainly exists in chalcopyrite in the form of inclusions. There is a positive correlation between Pb and Bi in chalcopyrite (Figure 8f), but Pb and Bi cannot exist in chalcopyrite in the form of solid solution, but mostly exist in chalcopyrite in the form of inclusions, due to the large difference between the ionic radius of Cu and Fe ions. The content of As is high, which may replace the S element in chalcopyrite. [PERSON] et al. [PERSON] et al. (2018) think that As can promote the entry of Au and Ag. There is a weak correlation between As and Sb (Figure 8e), and there may be As-rich inclusions. The content of Se in chalcopyrite is high (the average is 665.83 ppm), and the S element is primarily substituted by other elements through isomorphic replacement, which implies that the formation temperature of chalcopyrite is relatively high [PERSON] et al. (2018). The low content of medium- and low-temperature elements such as Ga and Sb