Gleamstone

Soft, easily worked stone that has absorbed magic from surrounding areas. Can be found near ancient dragon dens, sites of cataclysmic battles between avatars of deities, barrows of long dead sorcerer kings and the liches they left behind, areas where the separation between planes have worn thin.

notable uses:

enhanced spell focuses

cores for wands/rods

magic tattoo ink

masonry resistant to magic - though potentially more susceptible to siege attacks