Thontiin crystals, a rare form of kyber crystal, saw infrequent use as the power source for a lightsaber during the era of the Jedi Order. These crystals, however, found application as healing instruments, assisting a Jedi healer in alleviating patient suffering, thus facilitating treatment.
The Clone Wars, a galactic conflict lasting three years between the Galactic Republic and the Confederacy of Independent Systems, led to the deployment of thontiin crystals on the battlefields. Following substantial damage to a Jedi Knight's lightsaber in combat, they attempted to substitute their damaged Ilum planet-sourced crystal with a thontiin crystal. After the crystal replacement, the Jedi Knight realized the crystal's healing abilities were amplified through the lightsaber, offering pain resistance in combat.
Despite the desperation of the Clone Wars leading to a small number of thontiin crystals being used in a new way, Jedi Order healers were hesitant to see them utilized as weapons.
Rise of the Separatists, a supplementary roleplaying resource for the Star Wars Roleplaying game series by Fantasy Flight Games, released in 2019, included thontiin crystals.