Admantinum I believe, sorry if I misspelled
Vibranium, technically. (and it's spelled adamantium)
BTW is the GA shield version diecast? just wondering. The only thing that is a downside to the new shields in this set is the weight and the lack of grip that comes with the grip hands.
The GA shield is diecast. I have one of the knockoff diecast shields, and I was planning to give it to my FA figure, but it kept dragging his arm down. It's a nice bonus (compared to the old plastic shields), but that extra weight is kind of annoying.