Chromium crucible steel was first made in Persia

For more than a century, evidence for the production of crucible steel in Central and Southern Asia, prior to European Industrial Revolution, has fascinated challenged material scientists, historians archaeologists. At same time, chromium-alloyed stainless was developed early 20th building upon 19th century experiments with low chromium steel. Here we demonstrate new intentional addition nearly millennium earlier, as part Persian (pulad) tradition including low-chromium 2nd CE Persia. We analysed archaeological finds from 11th c. site Chahak Iran showing regular mineral charge, resulting containing around 1 wt% chromium. A contemporaneous flint striker held Tanavoli Collection is reported also contain chromium, suggesting its origin Chahak. argue that mysterious compound ‘rusakhtaj’ Biruni's (10th – CE) recipe making refers chromite. Additional historical sources up mid-2nd refer being particularly brittle, consistent increased phosphorus content.