Abacomancy
Abacomancy (Latin abacus) is divination by reading patterns in dust, sand or ashes on a flat surface. Ancient practice attested in Mesopotamia, Egypt and Greece. Variant: throwing seeds or stones on dust and interpreting their position.
Related practices
Connected with geomancy (marks on the earth) and with alomancy (salt patterns). Original Arabic geomancy may have derived from primitive abacomancy.