Hiridiu crystals were a form of light blue-colored crystal with an unusual property: mere proximity to the crystals could boost the strength of communications signals. Consequently, the crystals were utilized in many communications systems in the period of the Galactic Republic, and by the time of the New Republic, signals from modern communications technology could be boosted by as much as 30 percent.
A large deposit of hiridiu crystals was located on the southern pole of the planet Generis, located in the Atrivis sector of the Outer Rim Territories. During the Clone Wars fought between the Galactic Republic and the Confederacy of Independent Systems, hiridiu crystals were used in the construction of various technological items. The Alliance to Restore the Republic took advantage of this outcrop by constructing their secret Outer Rim Communications Center, under the control of the Atrivis Communications Group, near to the outcrop. This base remained under control of the Alliance's successor, the New Republic, up until the Imperial resurgence under Grand Admiral Thrawn. During the Fall of Generis, the facility was captured by Imperial forces, with the loss of the uniquely efficient communications center a significant blow to the New Republic.
Hiridiu crystals were created by Eric S. Trautmann for West End Games' The Last Command Sourcebook (1994). This book provided roleplaying statistics for Timothy Zahn's novel, The Last Command. This information was later reprinted in The Thrawn Trilogy Sourcebook, which collected the three sourcebooks written to support the Thrawn Trilogy. Crystal-aided communications systems had previously been mentioned in Star Wars canon in Han Solo and the Lost Legacy, which described mytag crystalline vertices as used in ancient subspace communications. In 2013, hiridiu crystals were added as a common crafting material in Star Wars: Clone Wars Adventures, an MMORPG produced by Sony Online Entertainment.
- The Last Command Sourcebook
- The Thrawn Trilogy Sourcebook