adamantium is a virtually indestructible man made iron alloy which does not occur in nature and whose exact chemical composition is a united states government classified secret adamantium is not an element its properties do not qualify it for any known space on the periodic table of elementshe unknown iron vibranium alloy of which the shield is composed resembles true adamantium although adamantium itself contains no vibranium over the following decades maclain experimented attempting to duplicate the process that create the shield