Toranium
From Star Trek : Freedom's Wiki
Toranium was an extremely strong metal used in Cardassian construction. Toranium was used on Deep Space 9. Standard phasers are ineffective at cutting through toranium inlays and a Bipolar Torch is recommended. (DS9: "The Forsaken")
When the USS Defiant posed as the Kobheerian freighter Rak-Miunis, Benjamin Sisko claimed that they were carrying Kobheerian toranium intended for military use on Cardassia. (DS9: "Second Skin")
