Vibranium

Vibranium is the name of a rare element.

Iron Man 2
Tony Stark rediscovered the element after decoding a hidden message containing the structure of the element left in the diorama of the 1974 Stark Expo by his father, Howard.

Although unnamed in the film itself, the novelization identifies the element as vibranium.

Captain America: The First Avenger
Captain America's shield was constructed using vibranium.

X-Men Origins: Wolverine
An unnamed element is recovered by William Stryker and Team X from Lagos, Nigeria. The element had come from space in the form of a meteor and was thought to be sacred by the local villagers. Stryker eventually used the element to create the metal compound, Adamantium.