Vibranium was never mentioned in "X-Men Origins: Wolverine" for the reasons mentioned above.
This is what the wikipedia entry for Vibrainium says about it for it's appearance in "Iron Man 2".
"In the feature film Iron Man 2
, Tony Stark
synthesizes a new element to take the place of the palladium
that powers his armor. Although unnamed in the film itself, the movie's novelization identifies the element as vibranium, so named by Stark because it shares characteristics with uranium
and has similar transgenic properties to another fictional element named "vibernum". Its molecular structure is that of a triangular buckyball
During the movie, it is first shown using a polygon mesh
of squares and then with a mesh that uses more than the 110 points (the number of points in a 'triangular buckyball')"
It also goes on to say that the element was first named in "Captain America: The First Avenger".