Impervium

Impervium was a tremendously resilient alloy frequently used for the armor on capital ships. It was stronger than duranium, another type of protective metal.

Behind the scenes
Impervium was first mentioned in the Star Wars Legends article Soldiers of the Empire! in 1978. Its first known canonical appearance was in the mobile-game Star Wars: Galactic Defense after a 2015 update.

Appearances

 * Star Wars: Galactic Defense