Pergium

Pergium is a radioactive element used for power in 23rd century nuclear reactors such as the PXK. Pergium is used by thousands of worlds as a source of energy. One key source of pergium is the planet Janus VI, where it is mined by a Federation colony in conjunction with the Horta. (TOS: "The Devil in the Dark")

There were several pergium mines in operation in the Sappora system in the 24th century. One was owned by Yanas Tigan and one by the Ferengi. The Orion Syndicate was also working its way into the industry in 2375. (DS9: "Prodigal Daughter")

Pergium is considered a rare commodity in some areas of the Delta Quadrant. In 2373, the crew of the USS Voyager attempted to acquire pergium from Bahrat's trading station near the Nekrit Expanse, to regenerate the filters of their environmental control systems. Neelix's friend Wixiban helped to procure 20 of the 45 kilograms they needed. (VOY: "Fair Trade")