Dragonstone

Dragonstone is the name given to opalescent geodes that tend to form in places that have had long-term exposure to draconic magic. Similar to aether crystals (but much, much smaller), these stones are potent magical catalysts with a core of pure magical energy at its center. When cracked open, this core is released, often to unpredictable effect-- making working with Dragonstone a very dangerous but occasionally fruitful endeavor. Dragonstone is even harder to work with than aether crystals are, and frequently flake apart into thin scale-like fragments; it is very rare to find a solid piece of Dragonstone larger than the size of an apricot. As a result, most Dragonstone ends up being either refined and worked into pieces of stronger material or ground into dust.