Veridium
From Memory Alpha, the free Star Trek reference.
Veridium is a substance with a variety of uses, primarily to manufacture explosives. It has a half-life of 70 hours.
In the late 2140s and early 2150s, the Malurians had a secret veridium mine on a planet with a pre-warp civilization, the Akaali. (ENT: "Civilization")
The cloaking devices used by the Ba'neth leave traces of veridium isotopes. In 2376, Naroq was able to use his photolitic converter to illuminate them on the Delta Flyer, allowing a first glimpse into the morphology of a Ba'Neth. (VOY: "Riddles")
In 2377, Irina gave the Delta Flyer II a fuel converter rigged to leak veridium isotopes into the warp core. She intended for the resulting warp core breach to decimate those attenting the Antarian Trans-stellar Rally. (VOY: "Drive")
