Iron

Tubal-Cain is the first-mentioned worker in iron (Gen 4:22 ). The Egyptians wrought it at Sinai before the Exodus. David prepared it in great abundance for the temple (1Chr 22:3; 29:7). The merchants of Dan and Javan brought it to the market of Tyre (Ezek 27:19 ). Various instruments are mentioned as made of iron (Deut 27:5 ; 19:5; Josh 17:16; 17:18; 1Sam 17:7 ; 2Sam 12:31 ; 2Kings 6:5; 6:6; 1Chr 22:3; Isa 10:34).

Figuratively, a yoke of iron (Deut 28:48 ) denotes hard service; a rod of iron (Ps 2:9), a stern government; a pillar of iron (Jer 1:18 ), a strong support; a furnace of iron (Deut 4:20 ), severe labour; a bar of iron (Job 40:18 ), strength; fetters of iron (Ps 107:10), affliction; giving silver for iron (Isa 60:17), prosperity.

EBD - Easton's Bible Dictionary