Mineralogical characteristics of telluride and their precipitation mechanism in the Jinqingding gold deposit, eastern Shandong, China

Optical microscope and electron microscope analysis with EDX indicate that calaverite is first discovered in this research, in addition, there are hessite, petzite and pilsenite in the deep No.Ⅱore vein, which not only further proves previous assumption, but also defines the traditional understanding there is no petzite in the deep area. These telluride minerals appear as intergrowth or veinlet in the fractures of sulfides and quartz. The content of gold in hessite and petzite varies dramatically but tellurium has a small variation. Gold is negatively correlated with silver. In addition, Au seems to have a positive correlation with bismuth. The paragenetic association of Au-Ag tellurides in Jinqingding gold deposits has been studied based on the experimental results in Au-Ag-Te ternary system. The experiments show that Te always give priority to combine with Ag to form hessite or petzite, and Te combines with Au to form calaverite after Ag of magmatic hydrothermal consumed, there remains a lot of gold in ore solution, forming a natural gold. Gold gradually enriches in ore-forming hydrothermal with the evolution of ore-forming process, which displayed mainly precipitation order of Au-Ag telluride: hessite-petzite-calaverite-Au.