Toranium was a strong metal used in Cardassian construction. Toranium was used in the structure of Terok Nor (DS9 episode: "The Forsaken") and Sentok Nor. (TNG novel: The Battle of Betazed)
Federation Starbase Deep Space 10, which incorporated a number of Cardassian ideas into its design, had eleven toranium hull layers. This was fewer than the thirteen layers used in Terok Nor (and presumably all Nor-class stations), but used the same amount by having thicker hull layers. (CoE eBook: Troubleshooting)
External link[]
- Toranium article at Memory Alpha, the wiki for canon Star Trek.