'Iron' in the Bible

"As for me, today I'm making you a fortified city, an iron pillar, and a bronze wall against the whole land against the kings of Judah, against its princes, against its priests, and against the people of the land.

All of them are very rebellious, going around as slanderers. They're bronze and iron, and all of them are corrupt.

which I commanded to your ancestors on the day I brought them out of the land of Egypt, from the iron furnace. I said, "Obey me and do everything that I commanded you. Then you will be my people and I'll be your God.'

"Can anyone break iron iron from the north or bronze?

The sin of Judah is engraved with an iron stylus. It is inscribed with a diamond point on the tablet of their heart and on the horns of their altars.

"Go and say to Hananiah, "This is what the LORD says: "You have broken wooden yokes, but you have made iron yokes in their place."

For this is what the LORD of the Heavenly Armies, the God of Israel, says: "I've put an iron yoke on the necks of all these nations to serve Nebuchadnezzar king of Babylon. They'll serve him, and I've even given the wild animals to him."'"