What fictional substance does Mithril refer to in J.R.R. Tolkien’s Middle-earth?

Mithril refers to a precious metal in J.R.R. Tolkien’s Middle-earth.

The metal is exceptionally light, strong, and valuable. Its name comes from Tolkien’s invented Sindarin language: mith means “grey” and ril means “glitter.” The most famous source is the Dwarven mine of Khazad-dûm, later called Moria.

Bilbo receives a mithril coat from Thorin’s company in The Hobbit, and Frodo wears it during The Lord of the Rings. The coat protects him from a spear thrust in the chamber of Moria, making the metal’s unusual strength important to the story.

Mithril is sometimes described as if it were simply “magic silver,” but Tolkien treats it as a rare mineral with remarkable physical properties. It is not the same as the fictional metal galvorn, nor is it a gemstone or a plant. The term later became widely used in fantasy games and other fiction.