Technically speaking, I am correct, Never is correct, and wolverex84
is also (sort of) correct.
Here is the entry on Adamantium in the MarvelDirectory.Com website
(which re-prints the entry in the Marvel Universe Handbook, more
or less):
"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 know 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 Dr. Myron MacLain.
MacLain began experimenting with the process that created Adamantium as a young scientist in the employ of the United States government in the early 1940s. Assigned to create a super-metal with which to build tanks, MacLain labored for month, experimenting with various iron alloys. One of his experiments utilized 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 his 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 discover to the government and it was given to Captain America to use as his shield. 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 the shield is composed resembles True Adamantium, although Adamantium itself contains no Vibranium,)."
So wolverex84 is correct that Cap's Shield is a mixture of Vibranium
and a form of Iron, though he is wrong in saying that true Adamantium
is as hard as the Shield, which it isn't (the Shield is stronger still), as
the following paragraph confirms.
Also from the same entry:
"Over the following decades MacLain experimented, attempting to duplicate the process that create the shield. 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 purpose, 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 slightly dent a solid cylinder of True Adamantium. A sufficient mass of Adamantium could survive a direct hit from a nuclear weapon."
So Never is correct that if Adamantium was created "decades" after
the Shield, then how can the Shield have had Adamantium in it?
BUT here is the entry on Captain America from the Marvel Universe
handbook comic (issue #2, 1985), in the section on his Shield:
"Captain America's only weapon is his shield, a concave disk 2.5 feet in diameter, wighing 12 pounds. It is made of a unique Vibranium-Adamantium allow that has never been dupilicated. The shield was cast by American metallurgist Dr. Myron Maclain, who was contracted by the U.S. government to create an impenetrable substance to use for tanks during World War II. During his experiments, Maclain combined Vibranium with an Adamntium-steel alloy he was working with and created the disc-shaped shield. Maclain was never able to duplicate the process due to his inability to indentify a still unknown factor that played a role in it."
So I was right, the Shield is a mixture of both Vibranium and
Adamantium.
(My Bolds.)
The only resolution to this mix-up, is that the "iron alloy" refered to in
the first quotation, was adamantium (which, as the first quotation points
out, is made up of Iron compounds), or atleast an early experimental
version of Adamantium. So that the Shield is techinically made up
of both these elements (as I said), but that the final version of
Adamantium (True Adamantium) was only developed many years
later.