The Crystal Caves of Ilum were a legendary pilgrimage site for the Jedi Order from the time of their discovery circa 22,800 BBY until the destruction of the Order in 19 BBY. Located deep within the side of Ilum's largest mountain range, the caves stretched untold kilometers into the planet and contained a wealth of precious crystals which were vital to the construction of the Order's lightsabers. Erecting a Temple at the mouth of the cave, Ilum's caves became a traditional journey point for many Jedi over the centuries.
Located within Ilum's largest mountain range, the Crystal Caves were a potentially tens of thousands of kilometers-deep labyrinth of winging tunnels, bottomless shafts, and narrow corridors that wended their way through the heart of the mountains and deep below the surface of the planet. Despite their importance to the Jedi Order during the millennia over which they were mined, the caves' total area remained unknown. The Jedi kept charts of the paths near the entrance, but beyond that was a series of dead-ends, crevasses, or a maze of confusing, winding passageways. The largest natural entrance to the caves is the site of the Order's primary Jedi Temple facility on the world. The interior of the caves were made of natural shiny black stone; a volcanic rock that swallowed light instead of reflecting it. As time progressed and the Jedi Order grew, the many Jedi that visited the cave recorded their histories on its walls. A variety of Adegan crystals grew unimpeded in the walls, floors, and ceilings of the tunnels, and could easily be removed by hand or with hand-held excavation equipment. In some areas the crystals were so common they littered the floor.
The caves themselves were a powerful nexus of Force energy, creating a vergence within the Force itself. Due to the potency of the Force within the close confines of the caves, the place had a disorienting effect that was high distressing to most who entered into the depths. Many who entered suffered from vivid hallucinations, and the occasional Jedi has been lost forever in the darkness. Another effect that the caves often created in the minds of the young Jedi searching for their first lightsaber crystal masked the presence of the crystals. Padawans would journey through the tunnels following the Force to the crystal that called to them, and only that one was visible to their eyes.
Discovered by scouts for the Jedi Order circa 22,800 BBY, the frozen world of Ilum was discovered to hold a number of hidden treasure troves where crystals grew naturally. These crystals, prized for their usage as a focus lens in the Order's symbolic weapon, the lightsaber, encouraged the Jedi to found a Temple and training ground at the mouth to these caves so that members of the Order could mine the rare kathracite, mephite, and pontite crystals.
During the Great Galactic War between the resurgent Sith Empire and the Republic the caves were taken by the Empire in a swift battle. As the Empire began to garrison troops on the world, the Temple was made inaccessible and, due to thinly-stretched resources, the Order was unable to reclaim it for over a decade. Following the destruction of the Sith Empire the Order restored their Temple on Ilum and once more maintained a small group of Jedi on the planet to protect their coveted crystals.
The Caves were once more made inaccessible several millennia later during the Clone Wars, a deadly conflict between the Republic and the Confederacy of Independent Systems. During a skirmish between Confederate probe droids and Jedi, several bombs were placed throughout the Temple and damaged the entrance to the caves. Following the attack, the Jedi High Council determined that the coordinates to the secret Jedi world were compromised, the Council ordered that all crystals be harvested and taken to the Coruscant Jedi Temple for safe keeping. Yet Jedi Initiates were still taken to the Crystal Caves to find their lightsaber crystals in the ritual known as The Gathering.
As Order 66 was executed by the Grand Army of the Republic and the Order systematically wiped out, Ilum's prized crystal caves were seized by the Galactic Empire. Blocking access to the Temple at the mouth of the caves, the subterranean depths were largely inaccessible. In the months following the Great Jedi Purge, two surviving Jedi, Fy-Tor-Ana and Garen Muln sought refuge from the in the Crystal Caves. Fy-Tor-Ana eventually left for Coruscant, while Muln remained behind. Ferus Olin rescued Muln a few months later.
- Star Wars: The Old Republic
- Jedi Quest: Path to Truth (First appearance)
- Jedi Quest 1
- Anakin: Apprentice
- I Am a Jedi Apprentice (Mentioned only)
- Star Wars: Clone Wars – "Chapter 14"
- Star Wars: Clone Wars – "Chapter 15"
- Star Wars: Clone Wars – "Chapter 16"
- Star Wars: The Clone Wars – "The Gathering"
- The Last of the Jedi: Dark Warning
- The Last of the Jedi: Underworld (Mentioned only)
- The Last of the Jedi: A Tangled Web (Mentioned only)
- Star Wars: Empire at War (Mentioned only)
- Star Wars: Empire at War: Forces of Corruption (Mentioned only)
- The New Essential Chronology
- "Order 66: Destroy All Jedi"—Star Wars Insider 87
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- The Essential Atlas
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- Star Wars: The Old Republic Explorer's Guide
- Star Wars: The Clone Wars Comic UK 6.47
- Nexus of Power
- "Jedi First Steps"—Star Wars Magazine 3