One of the four planets formed when the Sartan sundered the Earth into four elemental realms in The Death Gate Cycle books by Margaret Weis and Tracy Hickman.
Abarrach is the realm of stone. The planet has no sun, and thus no source of energy outside of the lava flows deep in the core. It also has no atmosphere. It is essentially a dying world. The air is tainted with sulfur gas and the magma that was the last source of warmth for the realm is receding deeper into the core. Because of the lack of resources and radiation, the crops are dying. Originally, Abarrach’s energy was provided by Pryan, using the Death Gate as a conduit. Large stone structures distributed the energy throughout the populated sections of the planet. This allowed the inhabitants of the planet to live closer to the surface, where the air was more fresh.
There are no members of the three lesser races living in Abarrach because they cannot live in the harsh conditions. The only inhabitants are small populations of Sartan, and even these no longer have the magical skills necessary for anything other than survival. Most of the magical power goes towards allowing the people to breathe the foul air.
The only magic in use other than this is the forbidden art of necromancy. As the population slowly grew smaller, the Sartan found that in order to have enough workers to grow food and maintain buildings, they needed to rely on the dead (who were beginning to outnumber the living). The dead are used for any task seen to be below the attention of the living. These zombies require supervision and very specific orders to function, and they are often forgetful, but they do not require sleep, or healing.
It is theorized that the cause of the Sartan dying out on Arianus and Pryan is the necromancy on Abarrach. Bringing the dead back to life is said to untimely cause the death of another. Some seek to harness the power of the dead, not realizing the consequences.
Information taken from the novels themselves, and a summary at http://members.iquest.net/~jschatte/novels.html