"Psitanium is a very rare, psychoreactive mineral that crashed here on a meteorite hundreds of years ago. It responds to psychic waves. Focuses them, amplifies them. It can make psychics more psychic, but it can also make unstable people more unstable. Not everyone can handle that much activity in that part of their brain. It can drive them completely out of their gourd. Gives this valley an interesting history." — Ford Cruller, explaining Psitanium to Raz
Psitanium is a rare, psychoreactive mineral that may have extra-terrestrial origins and probability is not native to Earth. Prolonged exposure to it may cause insanity, paranormal hysteria, or even the development of Psychic abilities.
Psitanium has several properties that can be very beneficial for psychics, but also can have negative effects on normal people.
As a psychoreactive substance, Psitanium responds to psychic waves, focuses them, amplifies them. Prolonged exposure to it may cause insanity and paranormal hysteria in ordinary people, making those how are mentally unstable more unstable, as many cannot handle that much activity in that part of their brain.
However Psitanium also furthers development of Psychic abilities, amplifying their power for those gifted with psychic power or have the potential to have psychic powers. Psitanium can also be use to unlock psychic powers within people, however this is not guaranty and may ending up driving them insane. Also those who already insane have a higher chance of developing psychic powers that others, but due their mental instability leaves them incapable of using them or use them correctly.
Psitanium also has mutagenic properties, which can have very unpredictable and random results depending on levels of exposure. The Psitanium residue in the food chain in the Lake Oblongata and surrounding area has caused psychically mutated the local wildlife, causing them either to grow bigger, gaining psychic abilities or become highly intelligence.
Pyrokinetic Cougars, Telekinetic Bears, Hyper-Intelligent Squirrels, Brain Sucking Suckerfish, Giant Crayfish, Confusion Inducing Explosive Rats, Telepathic Lungfish with Psychic Shields and a Sapient Talking Turtle capable of Psi-Blasts are just few examples of Psitanium induced mutants.
500 years before the events of Psychonauts, a meteorite bearing an enormous amount of Psitanium crashed to earth. Much later, the natives of the area started making arrowheads out of the material, calling it "whispering rock" (rough translation).
When settlers founded a town called Shaky Claim in the area, many soon lapsed into madness, leading Houston Thorney to build an asylum to house the victims of the hysteria. The asylum finally closed when the government evicted the last residents of Shaky Claim, flooding the area into what is now Lake Oblongata.
Many years later, Whispering Rock Psychic Summer Camp was created in the vicinity of the lake. Deposits of Psitanium arrowheads buried by the natives are used as currency there. It is also the home of the largest Psitanium deposit in the world, located in Ford's Sanctuary.
While largest known Psitanium deposit in world can be found at Whispering Rock Psychic Summer Camp, which means that Whispering Rock is not only place where Psitanium can be found, as fossil evidence proving the existence of Levitating Velociraptors and other psychic dinosaurs, suggesting that there were many Psitanium bearing meteorite impacts happened throughout earth’s history, spanning across the planet, with varying size and energy.
In Rhombus of Ruin it is revealed that Psitanium has a negative counterpart, Psilirium. Psilirium has the ability to greatly inhibit psychic powers and make psychics hallucinate and become deliirious.
- Psitanium is the only thing keeping Ford Cruller's shattered psyche together, when not near it, he lapses into one of his alternate personalities. Ford had to carry a Psitanium backpack when he went out of the Sanctuary to stop him from changing into an alternate personality in the cutscene at the end of the game.