A thunderstone is a prehistoric hand axe, stone tool, or fossil which was later used as an amulet to protect a person or a building. The name derives from the ancient belief that the object was found at a place where lightning had struck. They were also called ceraunia (a Latin word, derived from the Greek word κεραυνός, both of which mean 'thunderbolt').

Albanians believed in the supreme powers of thunderstones (kokrra e rrufesë or guri i rejës), which were believed to be formed during lightning strikes and to fall from the sky. Thunderstones were preserved in family life as important cult objects. It was believed that bringing them inside the house would bring good fortune, prosperity, and progress to people, especially in livestock and agriculture, or that rifle bullets would not hit the owners of thunderstones. Thunderstone pendants were believed to have protective powers against the negative effects of the evil eye and were used as talismans for both cattle and pregnant women.

The Greeks and Romans, at least from the Hellenistic period onward, used Neolithic stone axeheads for the apotropaic protection of buildings. A 1985 survey of the use of prehistoric axes in Romano-British contexts found forty examples, of which twenty-nine were associated with buildings including villas, military structures such as barracks, temples, and kilns.

During the Middle Ages many of these well-wrought stones were venerated as weapons, which during the "war in heaven" had been used in driving forth Satan and his hosts. Hence, in the 11th century the Byzantine emperor sent to the Holy Roman emperor a "heaven axe"; and in the 12th century, a Bishop of Rennes asserted the value of thunderstones as a divinely appointed means of securing success in battle, safety on the sea, security against thunder, and immunity from unpleasant dreams.

In Scandinavia thunderstones were frequently worshiped as family gods who kept off spells and witchcraft. Beer was poured over them as an offering, and they were sometimes anointed with butter. In Switzerland the owner of a thunderstone whirls it, on the end of a thong, three times around his head, and throws it at the door of his dwelling at the approach of a storm to prevent lightning from striking the house. In Italy they are hung around children's necks to protect them from illness and to ward off the Evil eye. In Roman times, they were sewn inside dog collars along with a little piece of coral to keep the dogs from going mad. In Sweden they offer protection from elves. Up until the 19th century it was common practice in Limburg to sew thunderstones into cloth bags and carried over the chest, in the belief that it would soothe stomach ailments. In some parts of Spain for example the province of Salamanca it was believed that by rubbing the thunderstones on the joints it would help prevent rheumatic diseases. In the French Alps they protect sheep, while elsewhere in France they are thought to ease childbirth. Among the Slavs they cure warts on man and beast, and during Passion Week they have the property to reveal hidden treasure.

In Burma they are used as a cure and preventative for appendicitis. In Japan they cure boils and ulcers. In Malaysia and Sumatra they are used to sharpen the kris, are considered very lucky objects, and have been credited with being touchstones for gold.

In North Carolina and Alabama there is a belief that flint stones placed in the fire will keep hawks from molesting the chickens, a belief which probably stems from the European idea that elf arrows protects domestic animals. In Brazil, flint is used as a divining stone for gold, treasure and water.

The flint was an object of veneration by most American Indian tribes. According to the Pawnee origin myth, stone weapons and implements were given to man by the Morning Star. Among the K'iche' people of Guatemala, there is a myth that a flint fell from the sky and broke into 1600 pieces, each of which became a god. Tohil, the god who gave them fire, is still represented as flint. This myth provides a parallel to the almost universal belief in the thunderstone, and is reminiscent of how the Roman god Jupiter was worshipped in the form of a flint stone. The Cherokee shaman invokes a flint when he is about to scarify a patient prior to applying his medicine. Among the Pueblos there were flint societies which, in most tribes, were primarily concerned with weather and witchcraft, but sometimes had to do with war and medicine.