Adamantine (metal)

You may be looking for adamantium or some other meaning for "adamantine".

In a section of the World of Fiction devoted to Greek mythology, adamantine was "the strongest metal in the universe", which could cut through "anything". The War Master wondered aloud if it could damage bonded polycarbide armour (ie. a Dalek casing).

Zeus gifted an adamantine blade to Perseus, which Athena passed on with an assortment of other gifts from the gods, including Hades's Helm of Darkness. The Master had him bring these artefacts aboard his TARDIS, intending to use them against the Daleks. (AUDIO: The Wrath of Medusa)

Behind the scenes

Adamantine is a literary form of "adamant", often used to describe legendarily hard metal, stones or minerals, going back as far as the 16th century.

It does not seem to have any origins in Greek mythology, but the Master notes in the story that much of this world is tarnished by modern retellings.