Steel is a Resource and the final metal that can be acquired. It becomes available after researching the Steel knowledgeKnowledge.
Steel is an alloy consisting primarily of iron and carbon, with other trace elements. It is produced in the Steel mill and requires Iron and Charcoal or Coke. It can be used as a replacement for all other metals used to produce resources, at a relatively low steel cost per unit produced.
Steel is produced relatively slowly in the steel mill, at a rate of about .1 steel per steel mill.