Erchius is a form of anomalous mineral, commonly found on airless planets, moons, asteroids, and some oxygen. It is commonly used for starship fuel in its liquefied form and can be commonly harvested from its solid form and gaseous form, through its solid form is considered highly dangerous by most. The origin of this seemingly exotic material and its associated subtypes and allotropes is heavily disputed, ranging from simply being an unknown molecular compound, to being an exotic element that originated long ago from naturally occurring tunnels to alien dimensional planes and has since disseminated throughout the galaxy either through natural or other, less natural means.
Erchius is actually a class of anomalous minerals and substances. What most people refer as erchius is actually prime erchius, the primary material. Other substances similar to erchius are referred to as erchioids or sub-erchioids.