Neolithic celt, Mopti, Mali. Many of these celts are found while cultivating and the explanation that was told to me by a villager in Essikro, is that they are the result of lightning hitting the ground. Many believe these "thunderstones" have magical, protective properties and can be found in shrines and bought in local fetish markets as a magical material.
In Material Culture and Indigenous Spiritism:
the Katamansu Archaeological “Otutu” (Shrine) by Wazi Apoh & Kodzo Gavua write "Some scholars have documented that these axe-heads were exploited for their assumed medicinal and magical properties (Field 1940; Ozanne 1962; Rattray 1923; Reade 1874; Shaw 1944; Wild 1927). They have pointed out that, having invested the “thunderbolts” or “God axes” (Nyu ηmo te/Nyame Akuma) with supernatural origins, most followers and priests of indigenous religions and herbalists assign them with various medicinal and magical properties. Some of the stones were ground and mixed with water and other concoctions and given out to cure cough and digestive ailments (Wild 1927). They were also sometimes fastened against the body to cure diseases (Rattray 1923)."