Mineralogy and mineral chemistry related to the Au mineralization in the Dunde Fe-Zn deposit, western Tianshan

•Au mineralization has a close relationship with bismuth minerals.•Au mineralization is dominated by invisible Au at higher temperatures.•Au mineralization is dominated by electrum at lower temperatures.•A decrease of oxygen fugacity results in the formation of Bi melt.•A decrease of temperature makes the precipitation of Bi-Au melt.