The fictional metal used for Frodo’s coat of mail in J.R.R. Tolkien’s The Lord of the Rings is mithril.
Bilbo receives the mithril coat from Thorin’s treasure hoard after the events of The Hobbit, and he later gives it to Frodo. The light, exceptionally strong armor protects Frodo during the quest, including when he is struck by an Orc spear in Moria. Gandalf explains that the coat is worth more than the entire Shire.
Mithril is a Sindarin word meaning grey glitter. Tolkien describes it as a precious metal found especially in Moria, where the Dwarves mined it. Its value makes it both a practical material and a symbol of the lost wealth of Khazad-dûm.
Mithril is not the name of a person or smith. Telchar was a famous Dwarf craftsman, while Galvorn is a different fictional metal associated with Tolkien’s earlier First Age writings.