Triadium

From Memory Alpha, the free Star Trek reference

Triadium is a type of metallic alloy. The Etanian Order used triadium to construct the control nodes for the guidance system hidden inside their artificial asteroids, which they used to simulate natural disasters on target planets. The presence of triadium in the asteroids allowed the USS Voyager to determine that the asteroids were not of natural origin. (VOY: "Rise")