Tricellite was a durable, long-lasting mineral used as a substitute for zelebium in the guidance systems of Erstwhile-type freighters. Some star systems, for instance Omega Sagitta, lacked this mineral.

In 2365, the guidance system aboard the Erstwhile, commanded by Captain Thadiun Okona, was repaired with tricellite. (TNG: "The Outrageous Okona")

Tri-, three, cell-, chamber, and -ite, mineral; combine, three chambered mineral.