Yurium

Yurium was a chemical compound with the chemical formula YU2. This compound was capable of storing large amounts of energy and was usually used as a an explosive. A radioisotope by-product, Jakmanite 632, was created artificially from the decay of high-energy yurium. 

Bela Tyken used anicium and yurium from his cargo to create a massive explosion. This kind of anomaly would later be named Tyken's Rift to his honor. 

In 2365, a planetary scan by the USS Enterprise (NCC-1701-D) detected 2% of yurium in the atmospheric composition of Theta VIII. 

Yurium ユリウム