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. Alternatively, crude crystals might be used, though their unusual shapes could affect the energy flow in unpredictable and potentially catastrophic ways. (
TOS: "
The Alternative Factor", "
Elaan of Troyius")