During the early 1940s, a small amount of Wakandan vibranium came into the possession of the scientist Myron MacLain. He tried to combine vibranium with iron to form a new tank armor, but was unable to fuse the elements. One morning, he found that the two materials had bonded on their own in an unknown manner. The ultra-resilient alloy was used to create Captain America's shield. MacLain worked for decades (without success) to duplicate the accident. However, during an experiment in the 1960s, he developed the virtually indestructible metal adamantium.