Firkrann Firkrann crystals, sourced from the planet Rafa V, were a type of lightsaber crystal known for their relatively high density. This crystal gave the lightsaber using it an electrical property, making it particularly effective against droids. Records show that the Dark Lords of the Sith were known to utilize them.
A Firkrann crystal was discovered by Revan inside the tomb of Tulak Hord, a Sith Lord. It's possible Hord used it in his own lightsaber.
In Star Wars: The Force Unleashed, this crystal appears as a lightsaber crystal with a chance to imbue the lightsaber with Force lightning.