Duralinium

Duralinium was a mineral used in the construction of buildings and other structures, such as the armoury doors on Peladon. (TV: The Monster of Peladon) By the 25th century, Earth was desperate for it and needed it for the construction of residential complexes. Like most minerals, it was found in rock veins. It was highly abundant on the planet Uxarieus, the biggest find in IMC history. (TV: Colony in Space) According to General Fesk, not even a Dalek was able to break out of pure duralinium chains. (AUDIO: The Eternity Cage)

The bodies of the detective robots were made of duralinium. (COMIC: Gangster's Paradise)

The spade in the Twelfth Doctor's confession dial was made of an amalgam of duralinium and dwarf star alloy, a combination theoretically strong enough to cut azbantium. (PROSE: The Veil)