Source: The Official Handbook Of The Marvel Universe: Deluxe Edition #1, Wolverine Saga #1
First Appearance: Avengers (1st series) #66

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. Adamantium is not an element; its properties do not qualify it for any known space on the Periodic Table of Elements. Rather, Adamantium is a series of closely related compounds of iron created through a secret process discovered by the American metallurgist Doctor Myron MacLain. It is the second strongest metal known to humanity.

MacLain began experimenting with the process that created Adamantium as a young scientist in the employ of the United States government in the June 1940. Assigned to create a super-metal with which to build tanks, MacLain laboured for months, experimenting with various iron alloys.

One of his experiments utilised the rare meteoric ore now known as Wakandan Vibranium. He tried to fuse the Vibranium to the iron alloy numerous times without success. Then one night when he dozed off, some as yet unknown factor entered the process, and permitted the fusion to occur. Upon discovering this success, MacLain poured the molten metal into a disc-shaped mold. The disc, once solidified, has proven to be the most impervious object ever created on Earth.

MacLain turned the disc over to the government and it was given to Captain America to use as his shield in June 1941 (Captain America v1 #255). Neither MacLain nor anyone else has ever been able to discover what was the x-factor that entered the process, or has been able to fuse Vibranium with another metal. (The unknown iron-Vibranium alloy of which Captain America`s shield is composed resembles True Adamantium, although Adamantium itself contains no Vibranium.)

Adamantium is created through the mixing of certain chemical resins whose composition is a United States government secret. For eight minutes after the resins are mixed, the Adamantium can be molded into a particular shape so long as it is kept zat a temperature of 1,500 degrees Fahrenheit. After this brief period the proces of creating Adamantium is completed. The extremely stable molecular structure of the Adamantium prevents it from being molded further, even if the temperature remains high enough to keep it in liquefied form. Only a device called a Molecular Rearranger can alter the form of hardened Adamantium.

The US Government commissioned the construction of an immense robot, code-named Tess-One, as a potential means of defense against renegade recipients of the "super-soldier serum." This serum enabled people to reach the heights pf physical perfection. Since only Captain America used the serum before the serum was lost, Tess-One was not put into operation for many years.

Somehow, though, the formula for the creation of adamantium fell into the hands of Japanese scientist Kenji Oyama, known as Lord Dark Wind. Kenji Oyama was released from an American prison camp in late 1945 and allowed to return to Japan. His injuries had left him permanently scarred, and to hide his disfigurement Oyama began wearing a full face mask. Oyama wrote a book about his experiences which was a huge success, and he used the proceeds from the book sales to purchase a small island off of the coast of Japan. Oyama, wishing to restore Japan's honor, eventually began attracting followers and began going by the name Lord Dark Wind. Years later Lord Dark Wind learned of the American government's attempts to recreate adamantium, and he arranged for the theft of notes for the formula. Dark Wind eventually began experimenting on a process to bond adamantium to bone in order to create a race of super-warriors who would avenge the defeat of imperial Japan in World War 2. But then Dark Wind's records of the process were stolen, and he was never able to implement the plan. (Alpha Flight #34, Daredevil #198)

Over the following decades MacLain experimented, Adamantium has been bonded to Wolverine`s skeleton and claws attempting to duplicate the process that created the shield.

Lord Dark Wind's daughter, who calls herself Lady Deathstrike, has alleged that Wolverine's adamantium-laced skeleton is the work of someone who has stolen her father's secrets - though she has no proof.

There is evidence that James MacDonald Hudson, a scientist working for the Canadian government, knew about the process that Lord Dark Wind had created. Yet, whether Hudson knew exactly how the process worked is unknown.

Finally, in recent years, he succeeded in developing the process by which the substance known as True Adamantium is created. True Adamantium is nearly as strong as Captain America's shield, and is, for all practical purposes, indestructible. The degree of impermeability varies directly with the thickness of the Adamantium. A direct blow from Thor`s hammer, conveyed with the thunder god`s full strength, will only slightly dent a solid cylinder of True Adamantium. A sufficient mass of Adamantium could survive a direct hit from a nuclear weapon.

The United States government has shared the secret of Adamantium`s composition with certain allies, and the secret has also fallen into the hands of various criminals, such as the Constrictor, who has made special weaponry from the Adamantium in the form of coils. Wolverine's skeleton has been fused with True Adamantium so as to greatly increase its tensile strength. The outer portion of the robotic body of Ultron is also composed entirely of True Adamantium, although Ultron`s inner mechanisms are not.

Adamantium is extraordinarily expensive to produce. Therefore, certain parties who wish to use Adamantium on a alrge scale have resorted to utilising a similar but somewhat weaker compound called Secondary Adamantium. Although Secondary Adamantium is still far stronger than even titanium steel, it can be destroyed by sufficiently great amounts of force. The sentient computer known as F.A.U.S.T. had a casing made of Secondary Adamantium which Thor and Iron Man managed to destroy. The Red Skull and the original Hate-Monger had a dome of Secondary Adamantium constructed to protect their island fortress, but the dome was destroyed by the vibratory force of Hydra's Overkill Horn and by powerful incendiary bombs.