DF2014:Iron - Dwarf Fortress Wiki
The three ores of iron, which are Hematite, Magnetite, and Limonite, can only be found in sedimentary layers, with the exception of hematite, which can occasionally be found in igneous extrusive layers. Note that iron does not rust, so there's no harm in leaving iron objects out in the rain or submerging them in water. Uses. Melee weapons.