Niberum

Niberum is an isotope of Helium. On the planets where it is naturally occurring, it is found as a light, chalky solid due to the temperature and pressure conditions. However at X-Base STP, it is a gas.

This gas form is highly unstable and tends to decay rapidly into Protium, the common form of Helium.

However, if it is introduced into a fusion core before reverts to a gas, it can be used to generate massive amounts of energy.