Zortron energy

Zortron Energy was a type of power source that was powerful but bulkly. The Quarsian pirate ship that attacked Sartor were powered by Zortron Energy and was stored in huge amounts in the ship's engine rooms. Diamonds (or at least the ones on Sartor) were known to harness this energy, which was why the Quarsian pirates intended to raid the colony planet of Sartor and plunder its diamonds. (DWBIT: The Diamonds of Sartor, Quarsian Mission)