Mithril is the fictional metal used to make Frodo’s mail-shirt in J.R.R. Tolkien’s works.
Bilbo receives the mithril coat from Thorin Oakenshield during The Hobbit, and later gives it to Frodo. The mail-shirt was made by the dwarves and is described as light, strong, and extremely valuable. It protects Frodo when he is stabbed by an Orc-chieftain on Amon Sûl, also called Weathertop.
Mithril is most famously associated with the mines of Moria, where the dwarves found the metal in abundance. Their mining eventually awakened the Balrog, an ancient being that had survived beneath the mountains. The metal’s value became so great that it was worth more than gold, and its scarcity contributed to Moria’s decline after the mines were abandoned.
Mithril is Tolkien’s term in the published English texts, although the material also has the Elvish name “mithril,” meaning “grey glitter” or “grey brilliance” in Sindarin-related interpretation.