Kelbonite
From Tardis Wiki, the free Doctor Who reference
Kelbonite was an element found on Naia VII. Along with dilithium and bilitrium, it was highly sought after by Starfleet, which maintained an underwater mining facility on the planet. (IDW: Assimilation²)
Behind the scenes
Assimilation² marks the first appearance of the Star Trek franchise's kelbonite in a Doctor Who story.