Orantium is a substance that explodes when exposed to air or water, making it a very useful weapon. It is normally contained in a glass orb. Orantium was mined anciently in Mount Allowat. After miners uncovered a vein that was too large to remove, production stopped and the mines were closed. Orantium globes come in two varieties: the smaller, softball-sized kind, and the larger, soccerball-sized ones known as "Gate-Crashers". It also can act as valuable currency due to the rarity of the spheres, as Galloran attempted to use them as a reason for potential allies to join the fight against Maldor.
Galloran gives Rachel an orantium globe after sending her and Jason off to find The Word. She later gives her globe to Jason to destroy a mangler during the battle encuring while Jasher made an appearance.
Jasher had many globes given to him by Galloran, one of which he strapped to his chest while battling Kimp, the others he used to destroy manglers when he saved Jason and Rachel from a conscriptor. At the battle after Jason and others escaped from Harthenham Castle, the orantium that he wore on his chest's glass casing was shattered by one of Kimp's attacks, blowing them apart and winning the battle.
In Seeds of Rebellion, the group must replenish their orantium supply. They go to Orruck, who is now a hideous monster and is in possession of a very large stockpile of orantium. Orruck is very angry to find that Galloran still hasn't defeated Maldor with the previous supply that he gave him. Galloran states that Rachel is a gifted wizard, which piques Orruck's curiosity. He teaches her two spells and then proceeds to try and kill them. Before he has his chance, Rachel utters The Word, which causes Orruck to disintegrate. The group then loots his orantium supply and leaves.
Later in the story, the oracle states that "Our hope is red, like the blood of heroes; black as the bowels of the earth; and white, like a flash of orantium." This is foreshadowing the downfall of Felrook.
In Chasing the Prophecy, Jason's group must get past the Maumet, which can turn into anything it touches, to enter the Celestine Library. Jason conceives a plan to make the Maumet take the form of orantium, which ultimately kills it.
In a later scene, Nedwin uses orantium to interrupt Copernum's dinner party and kill him, along with others at a feast.
The remaining members of Jason's group come across the Wanderer, one of Zokar's creations, and (unsuccessfully) try to use orantium to subdue him. He is later conquered and defeated.
After defeating the Wanderer, Jason continues and finds (the corpse of) Darian the Seer. Darian reveals that Maldor's stronghold was built atop Mount Allowat, the mountain where orantium was originally mined. After this information is relayed to Rachel's team, Tark and Ferrin uncover the lost vein under Felrook and destroy Felrook and all of Maldor's minions, unfortunately taking their lives with them.
- A special, cork-like substance was used to cover up the lost vein under Felrook.
- Because of how rare and precious orantium is, Aram was very weary of using them as weapons.