'''Serpentium''' is a type of crystalline mineral native to the Mazes, with the unique property of being a source of energy. Serpentium may also be called '''power crystals''', '''electrocrystals''' or, in Youkai-go, '''電気晶''' (''denkishou''), which transliterates to "electric crystal".
Serpentium crystals are hexagonal crystals resembling beryls. They are known for their semi-transparent black color, with golden-colored facets sprawling from the center of each crystal, often found in rough, serpentine , or thunderbolt-like shapes (which have presumably inspired the "Serpentium" name). These golden elements are naturally electroluminescent, causing them to emit a faint amount of yellow light, making them easy to spot and recognize.
Individual Serpentium crystals form in various sizes and shapes, each of which carry carries a certain quantity of energy. When the outer layers of a crystal is are broken, all of the energy contained within is released in the form of electricity, in a manner reminiscent of a thunderstorm releasing thunderbolts. Once the power contained is completely released, the crystal "shell" vaporizes instantly, leaving nothing behind except heat. The exact amount of power generated depends on the individual size and mass of a crystal.
Every [[generator facilty facility]] in the Mazes runs on Serpentium crystals, which are designed to puncture the crystals and subsequently harness the energy released in a safe and controlled manner.
Miners and adventurers in possession of Serpentium crystals may sell them to generator facilities at face value. Serpentium has a value per kilogram of [[File:Parallar symbol.png|10px]]'''1225''' /kg.