Bog iron is a form of iron found in swamps. Bog Iron is generally found in a spring.
Smelting bog iron has existed since pre-Roman times. Most iron smelted during the Viking era came from bog iron. In Russia, bog iron was the main source of iron until the sixteenth century.
Iron was produced by Vikings around 1000 AD.
Mining Bog Iron had been done in Virginia as early as 1608, and more bog iron has been mined in New Jersey and Maryland.