Iron is a key to life-playing a key part in hemoglobin and chlorophyll. Of course trace amounts of iron (enough for life to survive) remain on Athas today-but there are not refining processes powerful enough to take advantage. As I see it, iron is key to Athasian magic as well as psionics. Sorcerers use it to channel life energy from plants, and ascendant wizards channel it from animals as well-through the iron in the blood.
The Pristine Tower is made of living steel, and was the first thing on Athas to exhibit powers of psionics. The Gods turned Athas' iron core into molten glass and obsidian, and destroyed most of the iron reserves, to prevent mortals from making such a thing again. The lost magnetic field allowed psionics to flourish among mortals, and Green age people continued to mine surface iron until they suddenly and unexpectedly depleted it in the middle of the cleansing wars. 750 more years of wear and tear reduced most usable iron to scattered dust.
It was the Pristine Tower that disfigured a baby pyreen's body, and later, his adult mind, gradually eroding his personality away in self-hatred until he became Rajaat, or in other words Wiped Clean. The spirit of that tormented pyreen passed long ago into the Grey, while the spirit of the Pristine Tower raged across Athas in the twisted Pyreen's body, seeking to wipe Athas clean of everyone except for the Tower's original creators. Most of the Pristine Tower‘s power and all of its consciousness passed with its spirit into the hollow - this is why Rajaat could not get out by himself, but was quite powerful once he was out. The whole labor of the inhabitants of the Pristine Tower is to bring back the spirit of their most powerful creation. Only the Makers, the most powerful and ancient of the shadow-halfings know the secret of Rajaat's true connection to the tower-and these may be said to be Rajaat's masters, although personally they are weak in every way but knowledge and cunning.
Ironically (pun intended), Rajaat/ Pristine Tower are the sources of the changes in Athas that he/it most despises. The Brown Tide. The changing of the sun. New races. The changing of the sun (again) The Desiccation. The impoverishment and fragmentation of the surviving halfings. The dominance of the human race. The Changing of the sun (yet again!) Perhaps the terrified gods fled in fear, leaving the Grey to hopefully, eventually finish Rajaat off. Perhaps the pyreen are the ones who wait to tell the old gods-it is done; Rajaat is dead; you can spare this poor planet. Meanwhile, Everything Rajaat/ Pristine Tower does to undo its last blunder, makes things worse, its self-hatred more intense: