The gold deposits in Cambrian silicolite formation of western Qinling mountain are a new unique type of stratabound gold deposit which were discovered in China’s territory. The evidence of sulfur isotopic composition in silicolite formation of the deposits shows that the δ 34 S values vary in a wide range but they are characterized by enrichment in heavy sulfur. It is clear that the sulfur of sedimentary pyrite in ore-forming silicolite formation is meanly derived from sea-water sulfate by bacterium fra...