Mithril

Mithril was a precious, silvery metal, very lightweight but immensely strong, that was mined by the Dwarves in Khazad-dûm.
== Description ==
Mithril in its pure form was rather soft and malleable. It could be used in various alloys to produce extremely lightweight, hard and durable armour. It was also used as a type of inlay called ithildin. The Elves loved it for its beauty and presumably used it for jewelry and attire rather than weapons or armour.
== History ==
Mithril was extremely rare by the end of the Third Age, as it was found only in Khazad-dûm. The Dwarves of Moria mined for mithril too greedily and too deep, ultimately releasing a Balrog, Durin's Bane. Once it destroyed the kingdom of the Dwarves at Khazad-dûm, Middle-earth's only source of new Mithril ore was cut off.
Before the Dwarves abandoned Moria, mithril was worth ten times its own volume in gold. However, once the Dwarves abandoned Moria and the excavation of mithril ore stopped entirely, it became priceless, as the presence of the Balrog prevented the Orcs in Moria from mining for it. The only way to obtain a mithril object at the end of the Third Age was to either use heirloom mithril weapons and armour that were produced before the fall of Moria, or to melt down these existing objects to forge new ones. However, most of the mithril produced by the Dwarves before the fall of Moria was gathered by Orcs and paid as tribute to Sauron, who was said to covet it.
The Ñoldor of Eregion discovered how to make an alloy out of it called ithildin ("star moon"), which was often used to decorate gateways and portals, and was visible only by starlight or moonlight. The West-gate of Moria bore inlaid ithildin etchings and runes.
The helmets of the Guard of the Citadel were made of mithril, heirlooms of Gondor's past wealth. After the War of the Ring the Great Gate of Minas Tirith was rebuilt by the Dwarves of Aglarond out of mithril and steel.
While Moria was the only known source of mithril, there are inconclusive indications that it may also have been found in Númenor and Aman in smaller quantities.
== The mithril coat ==
Of all items made of mithril, the most famous is the "small shirt of mail" retrieved from the hoard of the dragon Smaug, and given to Bilbo Baggins by Thorin Oakenshield. "It was close-woven of many rings, as supple almost as linen, cold as ice, and harder than steel..." and studded with white gems of unknown variety.
Bilbo donated the shirt to the Shire 's mathom museum in Michel Delving, but reclaimed it before he left the Shire. Later in Rivendell, Bilbo passed it on to his nephew Frodo, who wore it during the Quest to Mount Doom. It saved Frodo's life when he was nearly skewered by an Uruk captain (in the book) in the Mines of Moria. Aragorn said the thrust was strong enough to skewer a wild boar, but the spear point could not penetrate the mithril-alloy mail. However, the leather shirt beneath the mithril was punctured with the force of the blow and Frodo was bruised and in pain.
Described by Gimli as having been a kingly gift, Gandalf states that the mithril-coat was worth more than the entire Shire and everything in it (though Gandalf says that he never told Bilbo, Frodo suspects Bilbo knew to some extent). Its value seems to have been even greater, however.  After leaving Moria, the Fellowship has a chance to examine the shirt, and Gimli says of it, "I have never seen or heard tell of one so fair" and that Gandalf "undervalued it."
The Mithril mail-shirt was later taken by the Orcs who captured Frodo in the pass above Cirith Ungol, and passed on to the Dark Lord's servants at Barad-dûr. When the coat was displayed before the hosts of Aragorn at the Gates of Mordor many despaired, thinking Frodo had been captured or killed, and the Ring taken. Gandalf reclaimed it from Sauron's lieutenant, the Mouth of Sauron, and was later able to return it to Frodo after the battles were won.
== Other mentions in Tolkien's works ==
* Galadriel possesses one of the three Elven Rings, Nenya. It is wrought of mithril with a white stone.
* Searching Orthanc, King Elessar and his aides found the long lost Elendilmir, a white star of Elvish crystal affixed to a fillet of mithril. Once owned by Elendil, the first King of Arnor, it is an emblem of royalty in the North Kingdom.
* The Guards of the Citadel of Minas Tirith wear helmets of mithril, "heirlooms from the glory of old days."
* As Aragorn's ships sail up the Anduin to relieve the besieged Minas Tirith during the War of the Ring, the standard flying on his ship shows a crown made of mithril and gold.
* After Gimli became lord of Aglarond, he and his Dwarves forged great gates of mithril to replace the gates of Minas Tirith which were broken by the Witch-king of Angmar during the Battle of the Pelennor Fields.
* The doors of Moria are inscribed with ithildin, an alloy of unknown composition that contains mithril.
=== The Hobbit trilogy ===
In The Hobbit: The Battle of the Five Armies, Thorin gives Bilbo the mithril vest while the dwarves are arming themselves for the upcoming battle, stating that it is a gift and a token of their friendship. Thorin states that it is made of silver-steel but does not mention its value or rarity.
=== The Lord of the Rings trilogy ===
: "Here's a pretty thing...light as a feather, and hard as dragon's scales."
: —Bilbo Baggins (Peter Jackson Movie Trilogy)
In Peter Jackson's film adaptation of The Fellowship of the Ring, Frodo was stabbed by a boar spear wielded by a Cave-troll rather than an Orc-chieftain.
While it is never explicitly stated where the mithril shirt originally came from, in the extended edition, Gandalf tells the Fellowship that Bilbo had a set of mithril rings given to him by Thorin. Gimli states that it was a kingly gift and Gandalf agrees but admits he never told Bilbo exactly how valuable the rings were.