Cortosis
Cortosis is a rare mineral from the Star Wars Universe. It is a somewhat fragile light grey, chalky rock that has the strange property of being resistant to the energy blade generated by a lightsaber, the only known mineral to do so. The first mention of it is in Star Wars: Jedi Knight II: Jedi Outcast. It is later mentioned in Star Wars Episode III: Revenge of the Sith.
Cortosis is common in the Star Wars universe in weaponry. Many weapons are made from cortosis in order to fight lightsaber wielders. In the ancient times of the Old Republic, during times of war with the Sith, it was common for fighters to carry cortosis weaponry. Most commonly were varieties of cortosis vibroblades and vibroswords, which could be used to fight Jedi and Dark Jedi in close ranged combat. It was common for some Sith in ancient times to wield a vibrosword rather than a lightsaber for the purpose that it would wound opponents in a way that was more painful, due to the dicing way the vibroblades would cut.
Galak Fyyar processes cortosis ore to become a black armour that is used by his Shadow troopers. He also builds a suit of power armor he uses himself. It is unknown whether all cortosis ore deposits are capable of such processing; the ore Fyyar used was smuggled from Cloud City.
Cortosis has also been described as causing a feedback loop with a lightsaber which was described as "shorting out" the Lightsaber blade, requiring it to be reactivated (but not damaging it permamently). Many fans dispute which definition is the canon as both definitions have been included in established canon literature numerous times. The sources that describe it as "shorting out" the lightsaber blade also describe it as a brittle mineral. Some thus propose that ancient cortosis weapons were actually an alloy of cortosis and some other material. This would possibly allow them to resist but not actually short out lightsaber blades, and at the same time remain strong enough to hit things without shattering.
References
- Star Wars: I, Jedi, 1st edition, 1998. Michael A. Stackpole, ISBN 0-553-57873-1
- Star Wars: Vision of the Future, 1st printing, 1998. Timothy Zahn, ISBN 0-553-10035-1