Mjölnir (from Old Norse Mjǫllnir) is the hammer of the thunder god Thor in Norse mythology, used both as a devastating weapon and as a divine instrument to provide blessings. The hammer is attested in numerous sources, including the 11th century runic Kvinneby amulet, the Poetic Edda, a collection of eddic poetry compiled in the 13th century, and the Prose Edda, a collection of prose and poetry compiled in the 13th century. The hammer was commonly worn as a pendant during the Viking Age in the Scandinavian cultural sphere, and Thor and his hammer occur depicted on a variety of objects from the archaeological record. Today the symbol appears in a wide variety of media and is again worn as a pendant by various groups, including adherents of modern Heathenry.
Etymology
The etymology of the hammer's name, Mjǫllnir, is disputed among historical linguists. Old Norse Mjǫllnir developed from Proto-Norse *melluniaR and one proposed derivation connects this form to Old Church Slavonic mlunuji and Russian molnija meaning 'lightning' (either borrowed from a Slavic source or both stemming from a common source) and subsequently yielding the meaning 'lightning-maker'. Another proposal connects Mjǫllnir to Old Norse mjǫll meaning 'new snow' and modern Icelandic mjalli meaning 'the color white', rendering Mjǫllnir as 'shining lightning weapon'. Finally, another proposal connects Old Norse Mjǫllnir to Old Norse mala meaning 'to grind' and Gothic malwjan 'to grind', yielding Mjǫllnir as meaning 'the grinder'.
Attestations
Kvinneby amulet
Likely worn around the neck, the Kvinneby amulet is a small copper amulet found in Öland, Sweden that dates from the 11th century and features an Old Norse Younger futhark inscription that invokes Thor and his hammer. Runologists Mindy MacLeod and Bernard Mees translate the amulet as follows: 'Here I carve for you (runes of) help, Bofi. Help me! Knowledge (?) is certain for you. And may the lightning hold all evil away from Bofi. May Thor protect him with his hammer which came from out of the sea. Flee from evil! It (?) gets nothing from Bofi. The gods are under him and over him.' The amulet inscription references narratives recorded hundreds of years later in both the Poetic Edda and Prose Edda (see discussion regarding Hymiskviða and Gylfaginning below).
Poetic Edda
In the Poetic Edda, Mjölnir is mentioned in the eddic poems Vafþrúðnismál, Hymiskviða, Lokasenna, and Þrymskviða. In a stanza from Vafþrúðnismál, the wise jötunn Vafþrúðnir tells the disguised god Odin that after the events of Ragnarök, Móði and Magni, sons of Thor, will wield Mjölnir:
In Hymiskviða, after gaining a tremendous cauldron that the jötunn (and personified ocean) Ægir has requested so that he may brew the gods ale, Thor battles malicious jötnar with the hammer (referred to here as whales as a poetic device):
In Lokasenna, in which the deity Loki and other gods trade insults (see flyting). In the poem, the gods threaten Loki with Mjölnir as part of a refrain repeated in all four stanzas in which he speaks.
The hammer is a focal point of the eddic poem Þrymskviða. In the poem, Thor wakes one day to find that his hammer is missing. Furious, the god pulls his beard, shakes his head, and searches for the absent weapon. Thor consults with Loki, informing him that only he knows that his hammer is missing.
Thor and Loki go to the goddess Freyja, and Loki asks her if he might use her feather garment. Freyja readily agrees, Loki puts on the cloak, and flies to Jötunheimr. There he finds the jötunn Þrymr sitting on a burial mound and caring for his animals.
The two speak, and Þrymr confirms to Loki that he has stolen the hammer. Þrymr says that he has buried it deep in the ground and no one will ever get it back unless they bring him Freyja to be his wife. Loki flies back to Asgard and meets with Thor. Thor asks Loki if he has any news, and Loki tells Thor Þrymr's ultimatum.
Thor and Loki go to Freyja. One of the two asks Freyja to put on a bridal head-dress and come with them to Jötunheim. Freyja is so enraged by this request that the hall shakes, and her necklace, Brísingamen, breaks off. The goddess refuses.