Adamantium is a virtually indestructible steel alloy named after the fabled metal Adamantine of Greek mythology. The metal has its origins in the work of American metallurgist Dr. Myron MacLain during World War II when the U.S. government assigned him to military research and development. Through a metallurgic accident, MacLain created the indestructible Vibranium-steel compound that was used to create the shield used by the super-soldier Captain America. MacLain spent decades attempting to duplicate the process, and although unsuccessful, he instead created True Adamantium in the 1960s.

Extraordinarily expensive to produce, Adamantium is created through the mixing of certain chemical resins whose exact composition is a closely guarded government secret. For eight minutes after the resins are mixed, Adamantium can be molded if kept at a temperature of 1,500 degrees Fahrenheit. Its extremely stable molecular structure prevents it from being molded further, even if the temperature remains high enough to keep it in liquefied form. Hardened Adamantium can only be altered by rearrangement of its cellular structure. Given sufficient mass, Adamantium could survive a direct hit from a nuclear weapon or a blow from the most powerful superhuman. The only known substance able to pierce Adamantium is the compound known as Antarctic Vibranium, also called "anti-metal".

The U.S. government has shared the secret of Adamantium’s composition with certain allies, through the information has fallen into unauthorized hands. Attempts by the former Solviet Union to reproduce the metal resulted in the creation of Carbonadium, a weaker yet far more malleable form that was used to create retractable coils wielded by the Russian super-soldier Omega Red. Due to the prohibitive cost of Adamantium’s creation, many parties have resorted to the use of a somewhat weaker compound named Secondary Adamantium, which was once used to coat the sentient computer named F.A.U.S.T..

The Japanese scientist Lord Dark Wind was the first to propose a procedure by which Adamantium could be bonded to a human skeleton. Dark Wind's theory was practiced by the ClanDestine Weapon X Program who subjected their former mutant operative, Wolverine, to the procedure. Wolverine's mutant healing factor allowed him to survive the process and induced a molecular change in the metal, transforming it into a wholly new metal, named Adamantium Beta that does not inhibit the biological processes of bone.

Dark Wind himself performed a similar procedure on the assassin Bullseye to replace some of his bones, while Weapon X repeated their earlier success with the feral mutant Sabretooth. A similar process was performed on the mutant mercenary Cyber to lace his skin with Adamantium, and the cyborg Donald Pierce once used the metal to rebuild his then-shattered form. The metal has also been used to coat certain robots, such as the superhuman-hunting TESS-One and to forge others such as the megalomaniacal Ultrons.

The Adamatco company in New Jersey has developed a procedure to coat objects with a thin layer of Adamantium. As a result, the plant has been targeted by such costumed criminals as the Overrider and the Absorbing Man, who sought to obtain Adamantium for their personal use.

Take note, True Believer! This crowd-sourced content has not yet been verified for accuracy by our erudite editors!
- Marvel Editorial Staff