Please correct me if I'm wrong but didn't Tony Stark and the gang all know about Vibranium in AoU?

We know, from Civil War, that Wakanda has a seat at the United Nations. And, since the father was one of the speakers for the United Nations in the events of Civil War, it leads one to believe that Wakanda has been a member of the United Nations for quite some time.

We also know from Black Panther that Wakanda purposely hides the existence and location of their ultra-modern city, presenting their nation as a backward, sheep herding, third world nation to the rest of the outside world. This would explain why Everett Ross (and the world in general) has the view of Wakanda that he does... so effective is the Wakandan subterfuge that the world at large thinks Wakanda is nothing but a bunch of poverty stricken, third world, sheep herders.

Let's also remember that Ross also thought that Klaue had stolen Wakanda's ENTIRE supply of Vibranium (leading to the scene where he tells Ross otherwise). So Wakanda has also VERY successfully controlled the mining, sale, and world-wide distribution of Vibranium... so much so that the other nations of the world have no idea of how much of the stuff exists.

So, it is safe to say that Wakanda has been controlling the world-wide distribution of Vibranium for generations. Most likely releasing a few pounds here and there, every so often, in order to raise capital for trade of other materials and services needed for the Wakandan's to build their society. The rest of the world thinks Vibranium is exceedingly rare (which is why Stark and others went to the lengths they did to get a hold of it), while Wakanda prevents the true nature of their society and the availability of Vibranum from becoming known.