The Collaborative International Dictionary
Crystallomancy
Crystallomancy \Crys"tal*lo*man`cy\ (-l?-m?n`s?), n. [Gr. kry`stallos crystal + -mancy.] Divination by means of a crystal or other transparent body, especially a beryl.
Wiktionary
crystallomancy
n. 1 The use of a crystal or other transparent solid for the purpose of divination. 2 Divination by a crystal ball.