Thalmerite
Thalmerite was a highly explosive compound capable of destroying starships in sufficient quantities.

In 2369, the Klingon vessel  was destroyed by a thalmerite explosive device that Hon-Tihl placed near its reactor core shortly after its passage through the Bajoran wormhole. ()

In 2371, the  placed forty tons of thalmerite in a shuttle prior to its anticipated capture by a Numiri patrol vessel. Captain Kathryn Janeway threatened to detonate the explosive which would have destroyed the shuttle and Numiri vessel unless the shuttle was immediately released. ()

External link

de:Thalmerit

Chemical compounds
Explosives