Adamantium is a virtually indestructible man-made steel alloy which does not occur in nature and whose exact chemical composition is a United States government classified secret. It is created by mixing certain chemical resins together. When these resins are mixed and kept at a temperature of 1,500 degrees Fahrenheit, the resulting liquid can be cast or worked into a particular shape. After an eight minute 'flux period', the mixture sets and becomes solid making it unchangeable after.

A sufficient amount is capable of surviving multiple nuclear explosions or a blow from the most powerful superhuman with no damage. A blade of pure, primary Adamantium is capable of cutting almost any known substance, with the known exception of Captain America's shield.