Clancium oxide was one of many explosive materials available to the crew of the USS Enterprise-D in 2367 when they were trapped in a Tyken's Rift.

According to the database, this material is a "Medium-yield explosive used for high-volume heat generation in emergency situations. This compound is preferred to conventional sarium krellide explosives because of superior thermal dispersion characteristics in low-pressure atmospheres." (TNG: "Night Terrors")