Beritium
From Star Trek : Freedom's Wiki
Beritium is a valuble metallic alloy used in the construction of Cardassian skimmers.
Kira Nerys' earring was made of Diamide-laced beritium, from the wreckage of a skimmer she destroyed in her first battle with the Cardassians. (DS9: "The Search, Part I", "The Darkness and the Light")
