Crystal Magic refers to all magical spells and abilities which involve channeling/focusing energy through crystals.

An example:

Crystals Positioning System (CPS)

These are large towers placed at semi-regular intervals around the Shasnian globe. They all have a large crystal array which can see to the next ones. They broadcast a magical radiowave of sorts.

The minimum tower transmits a standardized ping; more information if a more complex crystal. These large crystals were originally found artifacts, but are more commonly grown now. They can capture many incoming signals as well, though it is difficult to locate them other than a distance away from the crystal. each personal unit can locate itself on the world by triangulation.