Vibranium was a rare metal. It was stronger than steel and a third of its weight and was completely vibration-absorbent. It was most commonly known as one of the materials used to construct Captain America's shield. Howard Stark stated that he used all the vibranium he had to built the shield. Tony Stark also unknowingly synthesized the vibranium as he attempted to create a new element, with the clues his father left on the diorama, to take the place of the palladium in the arc reactor that powered his armors and the electromagnet that protected his heart from the shrapnel embedded in his chest.