Microchemistry and stable isotope systematics of gold mineralization in a gabbro-diorite complex, SE Egypt

► Microanalyses show dissolved Au in pyrrhotite and sulfarsenide in the Um Eleiga ore. ► Late, free-milling gold grains are associated with pyrite, or along micro-fractures. ► A magmatic source of gold is most likely, yet endowment by metasomatism was crucial. ► Stable isotope data of ore and gangue minerals indicate a generally light source. ► O and C isotope data of the lodes argue for a typical intrusion-related system.