Spark rocks are tools used by Earth Kingdom citizens to start fires. They are mined from cliffs found south of Ba Sing Se, known as the Fighting Cliffs. The cliffs, one white and one red, face each other with a wide ravine between them, and early Earth Kingdom peoples noticed that the ground of the ravine was charred and black. Legend says that the cliffs were created in an ancient battle between earthbenders and firebenders, and that the conflict was so "awesome" that the ground on which they fought soaked up their power and animosity. The rocks are small enough to hold with just the thumb and index finger, are rather jagged, and have a green coloration.
When Jet was on his mission to expose Iroh and Zuko as firebenders, he stole their spark rocks out of their apartment when they were staying in Ba Sing Se as refugees. He hoped to bait them to use their firebending, but his plan failed as Iroh just borrowed the spark rocks of their neighbors.
- They seem to be a common household item, as seen when Iroh went to another villager's home to borrow some.
- Spark rocks are similar to flint, a real world mineral that can be used for lighting fires.