From Scratchpad

Xyvors are the most powerful defensive metals. These metals are alloys of highly durable, corrosion-resistant substances that are combined into a substance that provides armor impenetrable by all but the strongest laser blasts. Since xyvors are often mined from the same ores as vananium, they can be found on vananium-rich planets such as UGAS, the chief exporter of xyvors.

Xyvors are utilized in most large capital ships of powerful empires such as the Hudnar Empire, the Xamileurata League, and the Andetarivo Union.