Which fictional metal is used to make the sword Anglachel in Tolkien’s legendarium?

In Tolkien’s legendarium, Anglachel is forged from meteoritic iron. The sword was made by Eöl the Dark Elf from a black iron that fell from the sky, and it was one of two weapons created from that unusual material.

Anglachel was given to Thingol, King of Doriath, as payment for Eöl’s permission to live in Nan Elmoth. Thingol later lent it to Beleg Strongbow, who carried it while searching for Túrin Turambar. After Beleg’s death, Túrin had the blade reforged and renamed it Gurthang.

The sword’s changing names and dark history make it easy to confuse with other famous weapons. Mithril is a valuable silver-like metal used for armor and objects, but it is not the substance of Anglachel. Anguirel, the other sword made from the same fallen iron, was taken by Maeglin and has a separate history in the First Age.