Representative photomicrographs of samples from the Tangjiagou and Dengezhuang gold deposits. (a) Assemblage of pyrite (Py1+Py2) (RPPL); (b) Pyrrhotite (Po) was cut by pyrite (Py3) (RPPL); (c) Sphalerite (Sp) contained pyrite (Py1) and chalcopyrite (Ccp) blebs were distributed along the pyrite (Py1) boundaries and fractures (RPPL); (d) Quartz (Qtz1) was cut by an aggregate of quartz (Qtz2) and calcite (Cal) filling fractures (TXPL); (e) Assemblage of pyrite (Py1+Py4) (RPPL); (f) Calcite (Cal) and quartz (Qtz4) filling fractures (TXPL); (g) Cube pyrite (Py1) and pyritohedron pyrite (Py2) (RPPL); (h) Quartz (Qtz2) was distributed along the quartz (Qtz1) boundaries and fractures (TXPL); (i) and (j) Large pyrite crystal (Py1) (RPPL); (k) Pyrrhotite (Po) is replaced by chalcopyrite (Ccp) (RPPL); (l) Euhedral cube pyrite (Py4) (RPPL); (m) Py1 was cut by Py2 (RPPL); (n) Quartz (Qtz2) was distributed along the quartz (Qtz1) boundaries and fractures (TXPL); (o) Assemblage of quartz (Qtz4) and calcite (Cal) (TXPL). Red circle points show the locations of in situ sulphur isotope spots. The orange dotted frame show the locations of EPMA mapping. RPPL: reflected plane-polar ised light, TXPL: transmitted crossed-polar ised light.