Mjölnir means lightning, and Thor’s hammer indicates the god’s power over thunder and lightning. Thor, ancient god of war is one of the most prominent figures in Norse mythology. Thor who was the storm-weather god of sky and thunder and also a fertility god, was the son of Odin and Fyorgyn, the earth goddess.
Thor’s hammer, Mjölnir is depicted in Norse mythology as one of the most fearsome weapons, capable of leveling mountains. Mjölnir, was a magical weapon that always came back to Thor when he threw it. Wearing Thor’s hammer as an amulet of protection was quite common as this was probably the most popular of all the pagan Viking symbols. Even during Christian times, from A.D. 1000 on, Vikings wore Thor’s Mjölnir as well as a cross on a chain or thong around their necks.
Mark Beré Peterson: Hauntings, Urban Legends, History, Folklore, Mythology and Witchcraft 