'Iron' in the Bible

And he shall cut down the thickets of the forest with iron, and Lebanon shall fall by a mighty one.

I will go before thee, and make the crooked places straight: I will break in pieces the gates of brass, and cut in sunder the bars of iron:

Because I knew that thou art obstinate, and thy neck is an iron sinew, and thy brow brass;

For brass I will bring gold, and for iron I will bring silver, and for wood brass, and for stones iron: I will also make thy officers peace, and thine exactors righteousness.