The Seventh Element is a manifestation of the three Prime Sources, using starlight from the sixth unmapped star, and it can be found in a quarry hidden by illusions in Elysian. While the Council is aware of its existence, they have kept it as a secret due to its great power. It has something to do with Stellarlune. It is also possible the secret of its use is in one of the caches. It was first mentioned in Stellarlune when Sophie, Tam, Maruca, Wylie, Sandor, and Rayni met with Vespera and Trix.