'Iron' in the Bible

"I will go before you and level mountains. Bronze doors I will shatter and iron bars I will hack through.

I did this because I know how stubborn you are. Your neck muscles are like iron and your forehead like bronze.

Shake off the dirt! Get up, captive Jerusalem! Take off the iron chains around your neck, O captive daughter Zion!

Instead of bronze, I will bring you gold, instead of iron, I will bring you silver, instead of wood, I will bring you bronze, instead of stones, I will bring you iron. I will make prosperity your overseer, and vindication your sovereign ruler.