'Iron' in the Bible

And the LORD was with Judah; and he drave out the inhabitants of the mountain; but could not drive out the inhabitants of the valley, because they had chariots of iron.

And the children of Israel cried unto the LORD: for he had nine hundred chariots of iron; and twenty years he mightily oppressed the children of Israel.

And Sisera gathered together all his chariots, even nine hundred chariots of iron, and all the people that were with him, from Harosheth of the Gentiles unto the river of Kishon.