Dilithium, also known as radan, was an element, a member of the hypersonic series, mostly occurring as crystalline mineral. It was used to power the warp drive systems of many starships. Dilithium regulated the matter/antimatter reaction in a ship's warp core because of its ability to be rendered porous to light-element antimatter when exposed to high temperatures and electro-magnetic pressures. It controls the amount of power generated in the reaction chamber, channeling the energy released by mutual annihilation into a stream of electro-plasma.
Dilithium could be found on only a few planets in the galaxy, and was therefore a rare and valuable substance. Notable sources of dilithium included the Halkan homeworld, Coridan, and Elas in the Federation, as well as Rura Penthe in the Klingon Empire and Remus in the Romulan Star Empire. (TOS: "Journey to Babel", "Mirror, Mirror", "Elaan of Troyius"; Star Trek VI: The Undiscovered Country; DS9: "One Little Ship"; Star Trek Nemesis) It could also be found on Troyius, where it was known as radan, and had a variety of different uses, including jewelry. (TOS: "Elaan of Troyius") In 2267, the Federation attempted to open negotiations with the Halkans to allow the Federation to mine dilithium from their planet, but they refused out of fear that the Federation would one day use their materials for acts of violence. (TOS: "Mirror, Mirror")
Under certain rare circumstances, dilithium deposits could form in such a way that the crystals grow into perfectly aligned lattices. If enough dilithium is present, it begins to form "generator strata". A piezoelectric effect occurred when the crystals took the radiant heat of the planet and converted it into mechanical energy.
One method of detecting the potential presence of dilithium deposits during a geological survey was by studying UV absorption patterns. Certain characteristic patterns tended to indicate the presence of traker deposits, which were commonly formed along with the dilithium ore. An ico-spectrogram could then be run to confirm the ore's presence. (TNG: "Pen Pals")
While the early Earth starships of the NX-class utilized a dilithium matrix in their warp core, (ENT: "Affliction") Constitution-class starships used crystallized lithium until the mid-2260s, before switching to dilithium. Housed in a dilithium crystal converter assembly, the crystals were used as a power source as well as a regulator. Dependency on that power meant the starships risked losing the ability to maintain an orbit, let alone use of their warp drive, when a number of dilithium crystals were drained of their power or became fused in their assembly. In some circumstances, crystals could be re-amplified to provide continued service, rather than replaced. (TOS: "Mudd's Women", "The Alternative Factor", "Elaan of Troyius")
One of the reasons why dilithium was so valuable before the late 23rd century was because dilithium gradually decrystalizes during use, and there existed no practical means of inducing recrystallization. However, during a time travel mission to 1986, Spock and Scotty developed a method of recrystallizing dilithium through exposure to gamma radiation.
By the 2360s, it was possible to recrystallize dilithium while it was still enclosed in the warp core's dilithium articulation frame using a theta-matrix compositor. (Star Trek IV: The Voyage Home; TNG: "Relics"; VOY: "Innocence")
Dozaria was rich in dilithium, which attracted the Breen to the planet. In 2366, they forced the Ravinok to crash on the planet and put the survivors to work in the dilithium mine. (DS9: "Indiscretion")
In 2372, the USS Voyager discovered a new form of dilithium in the Delta Quadrant that remained stable at much higher reaction rates, allowing a vessel to travel more efficiently at much higher speeds. This dilithium was installed aboard the shuttlecraft Cochrane to test an experimental warp 10 flight. (VOY: "Threshold")
Dukat and Damar were able to trick Captain K'Temang into believing the Groumall was carrying refined dilithium crystals by modifying the Cardassian freighter's subspace transceiver array to emit a false dilithium signal. (DS9: "Return to Grace")
Lyndsay Ballard said that dilithium extraction was always one of B'Elanna Torres' specialties. (VOY: "Ashes to Ashes") Torres helped Neelix prepare for a mining operation by giving him material to study on dilithium geophysics. (VOY: "Phage")
|Elements:||Kryptonite • Stoogeium • Stoogeian • Purseronite • Princessium • Tngonian • Estonianium • Dilithium • Curly • Poi|
|Other series:||Gamma series • Omega series • World series • Transonic series • Mega series|
Scientifically, use of the prefix "di-" denotes two atoms, suggesting dilithium consists of two atoms of lithium. However, lithium, being a metal, should not be able to exist in this state, as metals cannot form diatomic molecules. "Real" dilithium (two lithium atoms in a covalent bond) is only currently known to exist as a gas.
According to Star Trek Encyclopedia, originally, lithium was said to be used to control the warp reaction, but it was quickly realized that since lithium was a real element, with known properties, it would not be able to do some of the things the writers wanted it to do.
Star Trek Online introduced dilithium as a currency in its fifth season, "Call to Arms".