Iron (Fe) is one of the most abundant rock-forming elements. It makes up about 5% of the Earth's crust. It is the second most abundant and widely distributed metal (Aluminium is the most common). People have used it for more than 3,000 years. However, its use only became widespread in the 14th century, when smelting furnaces (the forerunner of blast furnaces) began to replace forges.
- Ramanaidou E.R. & Wells M.A. 2014. 13.13 - Sedimentary hosted iron ores. In: Holland H.D. & Turekian K.K. (eds) Treatise on Geochemistry. 2nd ed, Oxford: Elsevier. 313-355.