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.
Lava crystals were first mentioned in canon in Star Wars Adventures: Return to Vader's Castle 1, a comic issue written by Cavan Scott and published by IDW Publishing on October 2, 2019. In the Star Wars Legends continuity, lava crystals were first introduced in the 2005 Trials of Obi-Wan expansion of the MMORPG Star Wars Galaxies: An Empire Divided, where players could use them as lightsaber crystals.