Not to be confused with duridium ore.
In 2369, the Federation cargo ship Norkova was transporting a shipment of deuridium to Deep Space 9 from the Gamma Quadrant en route to the Kobliad homeworld. After exiting the wormhole, Rao Vantika (in the body of Doctor Bashir) took control of the Norkova and tried to steal the shipment but was stopped when Doctor Bashir's mind was able to regain dominance of his body.
Free deuridium was probably hazardous. Benjamin Sisko considered that if Norkova was destroyed and deuridium was released in the Bajoran system, every populated area would have to be evacuated. (DS9: "The Passenger")