Toranium
From Memory Alpha, the free Star Trek reference.
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 Prime. (DS9: "Second Skin")
