Lava crystals were a type of crystal that could be found on the hellish world of Mustafar. The native fire rats were known to gnaw on lava crystals. While recounting a tale to the prisoner Thom Hudd about the exploits of the droid captain Spikewheel and her crew on Lotho Minor, the Sith attendant Vaneé likened the fear gnawing at the group to rats gnawing at lava crystals.
The Lava Kyber Crystal or Lava Crystal is one of the most feared Kyber crystal ever used by the Jedi Order. They were so terrified of it, that barely any of them used it.
in the time of the Jedi Order’s reign most of their combatants wieleded lightsabers with blades of pure plasma. These blades were powered by Kyber crystals which could be found in numerous places across the Galaxy, including on the icy world of Ilum, or later Starkiller base. These crystals would attune to the person who collected them when they were harvested, changing their colour to match their traits. For example, those strong in physical combat and offensive force powers would often find their crystals to be attuned to the color blue, while those who focussed on the cosmic force often had green.
Despite this, there was actually one type of Kyber crystal which was so much more dangerous and deadly, that most Jedi would probably never want to use. This crystal was known as the Lava Kyber crystal.