There are several special metals in the Marvel universe that can have a place in the World of Darkness. These metals are usually very hard; much harder than mere steel, and they are not very ablative. They are also very rare, in general. One or two of them have special properties.
Adamantium - Adamantium is the hardest metal known to man, though it has not been made clear how dense it is. One would suspect that its density is roughly the same as that of normal steel, though a Storyteller can rule that it is as heavy as lead or as light as magnesium. At any rate, it would appear that no force on earth is sufficient to break or bend adamantium when it is at a normal temperature. Wolverine has used his adamantium-coated claws in Arctic climes as well as steamy jungles, so there is no reason to suppose that the metal becomes brittle at low temperatures. Judging from the number of times Wolverine’s flesh has been roasted or vaporized right off of his skeleton in the comics, with no visible effect on the metal, we must assume that adamantium has a relatively high melting point. In any case, to be nice to Logan, it also seems likely that it has a fairly high specific heat capacity, at least for a metal. It may or may not be one of the magnetic metals- as seen in X-Men 25- because Magneto has enough raw power to reach down and repel protons in the raw, if he wants to.
There is a special process that allows adamantium in ionic (salt) form to be bonded to human bones- as in Wolverine’s skeleton- or even human skin- as in Cyber’s case. This process was developed by a Japanese scientist and villain called Dark Wind, and stolen (or sold) for the benefit of Department H, a branch of the Canadian Ministry of Defense. The following characters have some sort of connection to the metal, or are actually running around wearing it: Wolverine, Cyber, Dark Wind, Apocalypse, the Professor (not Xavier), Ultron, Lady Deathstrike.
Carbonadium - Carbonadium is a resilient, unstable metal that is much tougher than steel but more flexible than adamantium. It would seem as though it is a difficult and extremely expensive process to make carbonadium, which is probably an alloy of some kind, since there is apparently only one carbonadium synthesizer in the entire world. Carbonadium, like its more resilient counterpart adamantium, would appear to have a high specific heat capacity and melting point.
Carbonadium may or may not have one unique property: it may serve to stabilize a life-force vampire’s condition, which would keep the mutant from having to drain the life force of others to survive. This may be a simple fact of Omega Red’s condition, rather than something general to life-force vampirism.
Omega Red’s tentacles are composed of carbonadium, and it is possible that his skeleton is also laced with the stuff. Other characters with a link to carbonadium include Wolverine, Sabretooth, Maverick, and John Wraith.
Omnium - Omnium is an extremely hard, extremely rigid metal that is likely to be second in resilience only to adamantium. In any case, it would seem that it is even less likely to bend without snapping than that metal. Omnium is not a commonly used or mentioned metal, but it has appeared on rare occasion in Marvel comics.
There was an acolyte of Magneto that had the power to change either himself or another person into an aware omnium statue. Other characters that have been seen using or testing the metal include Penance and the White Queen.
Uru- Uru metal is a mystical element that is so stupefyingly rare that it might be restricted to Asgard in its ore form. Thor’s hammer, Mjolnir, is made of Uru metal, and it is likely that the weapons of the other Norse Gods are also Uru in composition. It is magically strong, though not strong enough to break adamantium or Cap’s shield, and cannot be melted in any forge that Earth is capable of producing.
Vibranium - Vibranium is a special metal with unique properties. The largest and best known deposits of it are found in the African nation of Wakanda. It is much harder than normal steel, though certainly not as hard as adamantium. Vibranium is almost as valuable as that metal, though, because it has the special property of diffusing vibrations across its mass and thus disrupting them. This makes vibranium the ideal armour against blunt-force trauma and sonic attacks, and the ideal building material in an earthquake-prone area.
Captain America’s shield, which is even more resilient than normal adamantium, is actually a special alloy of adamantium and vibranium. Other characters that have some connection to the metal are the Black Panther, Klaw (Master of Sound), and the Fantastic Four. [/sub]