The same spring is said to turn wood into iron.

He hadn't attempted to turn any more cold iron into black iron.

Rather he was stout timber that had hardened into iron.

When going back in time trying to warn the world, he is turned into iron by a magnetic field.

Belief and magic forged as one, layered into iron, then shattered.

Among them was a radioactive form of cobalt, which rapidly transforms itself into iron.

There he jerked to a stop as though he had ran into white hot iron.

He found it, muscles turning into iron beneath the necessity to grip or fall.

The liquid warmth that had been spreading through her hardened into iron will.

Then the wood had changed back into iron.