The fictional metal lighter than steel and prized by the Dwarves in Tolkien’s Middle-earth is mithril.
Mithril is described as a rare, exceptionally strong metal found most famously in Moria. Its name comes from Sindarin and is translated as “grey glitter.” In The Lord of the Rings, Bilbo’s coat of mithril mail becomes an important protective object, and Frodo later wears it.
Mithril is valuable not only because of its physical properties but also because it links several historical periods of Middle-earth. Dwarven miners extracted it in Khazad-dûm, while the Elves of Eregion used it in notable works. Tolkien’s fictional metal later influenced the names of substances and products in popular culture.