Notalium crystals are "sound energy [stored] in minerals", according to the Appendix entry for Journey. They have multiple uses such as:
- Powering mechanisms (such as the Mysterious stone pillars of Chapter 2).
- Temporarily protecting people from the effects of Al Niente, when worn as accessories (such as Fisica's pendant, Rossa's earrings).
- Restoring color, weather, plant life and animal life to an area affected by Al Niente once tuned by a Notalium Tuner.
Notalium also exist in one of two states: ordered and disordered. When disordered, the power inside a crystal becomes inactive, which is why places in the game can have these minerals in them yet still be under Al Niente's effects. Disordered Notalium is also unusable for any of the purposes above, but ordered crystals aren't always safe to be around. Some Notalium (such as those in the Clock Tower in Chapter 1) have way too much energy in them to be stable and require further tuning in order to be quieted. If this kind of Notalium isn't stabilized, structures surrounding them may collapse. This is also seen in the device in cyanine and the Pipe Organ.
Regular Notalium - such as the ones in the picture above - are collected through playing songs and completing challenges. However, in Chapter F's "Special Specimen Room" in the Notalium Administration headquarters, there are spherical pieces of Notalium whose "shape, brightness and formation are all different from the typical pieces" according to Fisica. She also wonders if there are more crystals like these waiting to be discovered somewhere.
Notalium dates back centuries, before the disaster of Al Niente began. Its inventor was a woman named Ena, the fabled "Mother of Notalium". An entire field of science was created around these crystals, seeing as there is a Notalium Administration and a National Institute of Notalium (whose tunnel is the main setting of Chapter 3). People also used to know how to make more Notalium, but this method has been forgotten over the ages. Still, scientists like Fisica can still come across these minerals easily in order to do research, and things such as Notalium Tuners can still be manufactured seeing as Fisica built one using documents from the Notalium Administration.
The Notalium Administration has tasked Fisica and Ritmo with restoring the world from the effects of Al Niente, but their true intentions are unknown.
Currently, the Notalium Administration is in charge of storing and distributing these crystals.