Hellenium

An extremely common metallic element, Hellenium as it is known in the Aleph Cluster, is a material prized for its capability to produce a stable molecular chain with strong bonds and low density. This material is used in many civilian, industrial, and military applications where it's unique combination of traits make it a regular pick for inexpensive, high durability applications.

The Balance Coalition recognizes the metal by an entirely different name, dating back to one of their earliest wars in which a Saint named the material 'Seraphium' in honor of their god's most noble servants for its strength and light weight befitting the glory of holy warriors. While the original religious context has faded to the point of being a historical footnote known to few in everyday life among the populace the name remains in common use among Balance citizens.

This material was unknown to the Matriarchy prior to their exodus and was newly discovered during the first mining operation performed by the Matriarchy in local space. Discovered to be useful as well as astoundingly common despite its valuable traits, the material has since been named Vuliarium or Vuliararium, with no clear consensus on which name was first applied to the material resulting in a begrudging acceptance of both names within Matriarchy documentation.

Chelti call the stuff Opfirum. But they're chelti so what can you expect?