A spark stone is a dark speckled stone that can ignite anything flammable it is swiped against without aid from another stone. Spark stones are formed at the bottom of lava lakes. Roglama will trade a spark stone for something in return, especially food.
The metal which gives spark stones their special properties is Flamium, although spark stones themselves are not made of pure flamium. Spark stones also contain oxygen, silicon, and trace amounts of other elements in their structure.