Crystals of lava existed as a variety of crystal and were located on the infernal planet of Mustafar. The local fire rats had a reputation for chewing on these lava crystals. Vaneé, a Sith aide, compared the fear eating away at captain Spikewheel and her team on Lotho Minor (as he told a story about the droid's adventures to the prisoner Thom Hudd) to rats chewing on lava crystals.
The first canon reference to lava crystals occurred in Star Wars Adventures: Return to Vader's Castle 1. This comic book was written by Cavan Scott and released by IDW Publishing on October 2, 2019. Within the Star Wars Legends continuity, lava crystals made their debut in the 2005 Trials of Obi-Wan addition to the MMORPG Star Wars Galaxies: An Empire Divided, where gamers had the option to utilize them as lightsaber crystals.