Every source on Zosimos, his own treatises and the later Byzantine and Arabic writers who cite him, fixes only the period in which he was demonstrably active, around 300 CE in Greco-Roman Egypt, and none supplies a birth year.
What would resolve this A dated document, inscription or external biographical notice about Zosimos independent of his own writings, naming a birth year rather than only his working period.
OpenHistory of alchemy, papyrology, late antique Egyptian historyLawrence M. Principe, The Secrets of Alchemy