What fictional metal makes up Captain America's shield?

Vibranium is the fictional metal that makes up Captain America’s shield.

In Marvel Comics, the circular shield is made from a unique vibranium-based alloy created by metallurgist Myron MacLain. He was attempting to develop an extremely strong material for the U.S. government when an unexplained accident fused vibranium with an experimental steel alloy. The exact process could not be reproduced.

Vibranium gives the shield its remarkable ability to absorb and redirect kinetic energy. That property helps explain how Captain America can block bullets, survive powerful impacts, and throw the shield without it shattering. The shield is often described as a vibranium-steel alloy rather than a simple slab of pure vibranium.

Vibranium first appeared in Daredevil #13 in February 1966. It is closely associated with Wakanda and Black Panther, whose suit is also made from the metal. Adamantium is a separate Marvel material, while carbonadium and unobtainium are not the canonical answer for Captain America’s primary shield.