They found a steel chisel from the time period, "This was backed up by metallographic analyses of an iron chisel from the same period and region (Rocha do Vigio

They found a steel chisel from the time period, "This was backed up by metallographic analyses of an iron chisel from the same period and region (Rocha do Vigio, Portugal, ca. 900 BCE) that showed the necessary carbon content to be proper steel."