Lithomancy is a form of divination

Divination

Divination is the attempt to gain insight into a question or situation by way of an occultic standardized process or ritual...

 by which the future is told using stones or the reflected light from said stones. The practice is most popular in the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

.

History

The earliest verified account of lithomancy comes from Photius, the patriarch of Constantinople

Constantinople

Constantinople was the capital of the Roman, Eastern Roman, Byzantine, Latin, and Ottoman Empires. Throughout most of the Middle Ages, Constantinople was Europe's largest and wealthiest city.-Names:...

, who describes using a stone called the baetulum to perform the ritual. However, some writers also claim that Helenus predicted the destruction of Troy

Troy

Troy was a city, both factual and legendary, located in northwest Anatolia in what is now Turkey, southeast of the Dardanelles and beside Mount Ida...

using the ritual.