Northern European folklore is replete with information and stories about Thunderstones or to use the German term, Donnerkeile. Our ancestors believed that they were the physical remnants of thunderbolts where the core had become spent. Often farmers would collect them and take them home, siting them in their houses and barns as protection against lightning. Sometimes beer was poured upon them as an offering to the Thunder God. Hag Stones, Holey Stones or Odin Stones also served a similar process. When an oncoming storm was detected the householder would swing it three times around his head and then throw it at the door. Odin Stones made this easy as they were naturally perforated with a hole to allow the thread to pass through. I have in my possession an Odin Stone of good size which is threaded with a red thread; red representing the colour of Thunor's beard. I also have a Donnekeil amulet which is inscribed in Runes on its wooden mount. Another smaller Odin Stone is attached to the head of a runic wand which I have crafted.
Donnerkeile and Odin Stones again remind us of the link with our Neolithic past when our ancestors were far more in touch with their environment and its numinous qualities. They understood that stone was not lifeless as assumed by modern man but vibrated with a different and lower frequency but nevertheless were alive and were repositories of energy and power.
"In Germany, Stone Age celts known as Donnerkeil ('Donar's wedges') were supposedly thrown to earth by the thunder god. Similar ceraunia were also treasured in Viking-period Scandinavia, as well as elsewhere in Europe into the nineteenth century." (The Divine Thunderbolt. Missile of the Gods, J.T. Sibley)
Donnerkeile could of course also be carried on the person as a general means of protection, especially in warfare as J.T. Sibley states:
"Until about 1870, a German soldier would carry a Donnerkeil (cerauniam, especially a Stone Age arrowhead) in his pocket as a protective ward against rifle fire."
This ancient tradition has not died out. Indeed a cursory look on the Internet is sufficient to indicate that their use is enjoying a revival as our folk rediscover their ancient spiritual and magical pathways.
In England these ceraunia have been interpreted as elfshot or arrows, causing sickness and so have a malevolent interpretation but this may be a later Christian interpretation as most of our lore was of course demonised and a contrary interpretation applied. However people still wore them as protection against disease! If mixed with or dipped into water they could effect a cure.
"'Fairies,' says Grose, 'sometimes shoot at cattle with arrows headed with flint stones; these are often found and are called elfshots. In order to effect the cure of an animal so injured, it is to be touched with one of these elfshots, or to be made to drink the water in which one is dipped." (Curiosities of Indo-European Tradition and Folk-lore, Walter Keating Kelly)
It should be remembered that before the introduction of the thunder axe or hammer the Thunder God would cast down thunderbolts to the earth in the form of these stones and thus they were much highly prized. There is a possibility that these stones at times did literally fall from the sky as fragments of meteorites or a remembrance of such events. It is conjectured by some that Thor's Hammer may indeed have been forged from meteorite stone or iron from the stone.