Jinchang Cu Ag deposit is a super large scale porphyry Cu Au deposit in Northeastern China. No. J 0 is a typical porphyry Cu Au ore body in the deposit. There are three gold bearing minerals in the J 0 ore body: siegenite, pyrite and chalcopyrite. Major element of the siegenite are Ni, Co and S. Ni constitutes 19.005%～28.14%, Co constitutes 26.877%～34.971% and S constitutes 40.242%～44.076% in the Siegenite. The atomic mol ratio of Ni/Co is 0.55～1.03, close to the theoretical value (Ni/Co≈1). The atomic mol ratio of（Ni，Co）/S is 0.68～0.74, tallying with the theoretical value \[（Ni，Co）/S=0.75\], and the crystal chemical molecular formula is coincides with（Ni，Co） 3 S 4 . The purity of natural gold is high in the siegenite, between 830 and 955. As a gold bearing mineral, it was the first time to discover siegenite in the Jinchang mining areas and gold deposits in China. It is also a rare finding for gold deposits throughout the world. By far, there are no related reports. The discovery in the Jinchang gold area has important factual and geological meaning, and made the discovery that siegenite is a new gold bearing mineral，and it was found for the study and improvement of gold mineralization theory provides key evidence.