Leconomancy

Leconomancy, it is a form of hydromancy developed by the ancient Assyrians consisting of divination by interpreting the patterns and ripples left on the surface of water from a basin when precious stones are dropped in. A special bowl was used, where the water was covered by a thin layer of animal oil or fat. After a question was asked, the diviner dropped a consecrated stone, usually marked with mystical symbols. Whether or not the oil separated determined the final prognostication. For meditation, the water was gazed upon, invoking a self-hypnotic state for divination.

http://www.crystalinks.com/lecanomancy.html