radans
Star Trek: The Original Series
Episode: TOS 057 - Elaan of Troyius
Troyian word for the dilithium mined on that planet, used as gemstones until its usefulness in warp drive was made known to their culture.
The leader of Troyius gave Elaan, the Dohlman of Elas, a necklace of radans as a wedding present in 2268. Elaan's necklace served as a source of emergency crystals for the U.S.S. Enterprise NCC-1701 when that ship was under attack by a Klingon vessel.
