Relationship between Fine Structure and Cell Parameters of Pyrite and Their Typomorphic Significance

Pyrite is the main gold bearing mineral in endogenetic gold deposits, and its typomorphic characteristics have important implications for gold mineralization. At present, the typomorphic characteristics of pyrite are mainly focused on the morphology and physicochemical properties, while the microstructure characteristics of pyrite, such as unit cell parameters, bond length & bond angle, are less studied. Moreover, the existing studies mainly focus on the influence of composition on cell parameters. Few people have analyzed the relationship between fine structure of pyrite characterized by bond length & bond angle and cell parameters.The experimental samples were collected from Sanshandao Gold Deposit in Laizhou, Shandong Province. The crystal structure data of pyrite were collected by single crystal X-ray diffraction, and the fine structure data were obtained by analytical software. The influence of bond length&bond angle on the lattice parameters of pyrite was analyzed by spatial geometric relationship and partial derivative. It was found that the lattice parameters of pyrite were mainly affected by the internal coordination octahedron.The effect of the size of the ligands is less affected by the gap between the ligands. The size of the octahedron is closely related to the length of the Fe-S bond in the octahedron, and the size of the space between the coordination bodies can be characterized by the Fe-S-Fe bond angle or the S-S bond length.The reason for the change of Fe-S bond length is related to the isomorphism of Co, Ni, Cu replacing Fe and As replacing S. This provides a theoretical basis for the change of unit cell parameters, and is of great significance for guiding gold production with the typomorphic characteristics of unit cell parameters.