Tricobalt

From Memory Alpha, the free Star Trek reference.

Tricobalt is a type of powerful explosive.

In 2267, the Eminian Union classified the USS Enterprise as 'destroyed' when it was attacked by virtual tricobalt satellites while in orbit of Eminiar VII. (TOS: "A Taste of Armageddon")

The same year, time traveling Klingon operative Arne Darvin planted a tricobalt explosive in a fake tribble, with the intent of assassinating James T. Kirk, who would have revealed Darvin's true identity otherwise. (DS9: "Trials and Tribble-ations")

During the 24th century it was used in weapon manufacturing, such as Starfleet's tricobalt devices. (VOY: "Caretaker", "Blink of an Eye", "The Voyager Conspiracy") The Maquis also had access to tricobalt explosives. (DS9: "Blaze of Glory")

This substance may be related to dicobalt.