'Bronze' in the Bible

"I myself will go before you, and I will level [the] {mountains}. I will break [the] doors of bronze and cut through[the] bars of iron.

because {I know} that you [are] obstinate, and your neck an iron sinew, and your forehead bronze.

Instead of bronze I will bring gold, and instead of iron I will bring silver, and instead of wood, bronze, and instead of stones, iron. And I will {appoint} peace [as] your overseer, and righteousness [as] {your ruling body}.