'Iron' in the Bible

and Jehovah is with Judah, and he occupieth the hill-country, but not to dispossess the inhabitants of the valley, for they have chariots of iron.

and the sons of Israel cry unto Jehovah, for he hath nine hundred chariots of iron, and he hath oppressed the sons of Israel mightily twenty years.

and Sisera calleth all his chariots, nine hundred chariots of iron, and all the people who are with him, from Harosheth of the Goyim, unto the brook Kishon.