Diamide

From Memory Alpha, the free Star Trek reference

Diamide is a 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")