The Horned Lands are unique in having very rare deposits of a unique magical gem: dweornite. Small clusters of dweornite gems, tear-shaped, semi-opaque, blue-white stones, are found in totally unpredictable subterranean locations. The gems have diverse magical powers. Those which have been documented include spell gems, gems which yield magical potions when crushed and dissolved, gems with empathic effects, gems with teleport, dimension door or extra-planar travel properties, and gems of a divinatory nature. Of special note are the spell gems, which when crushed in the hand of a mage allows memorized and already-cast spells to be regained. These are similar to the dweomerstones of the Cairn Hills, and some sages suggest a common origin for both these and the reputed ioun stones Rary seeks in the Bright Desert.