Cortosis ore was a very rare, brittle, fibrous material whose conductive properties caused lightsabers to temporarily short out upon contact, although the wielder could solve this problem by turning the blade back on after a couple of seconds. This effect made cortosis a useful material for anti-lightsaber melee weapons, though with repeated strikes, a lightsaber could still cut through it. Cortosis, due to its heat and energy resistant properties, was also resistant to blaster fire.
This substance was used extensively in shadowtrooper armor, as well as the cortosis battle droids during the Clone Wars, and the Force-using group known as the Jensaarai. The cortosis used for this armor was smuggled out from Bespin's Cloud City. The walls of the Imperial Palace were also lined with cortosis ore. It was also used to stengthen starfighter and capital ship hulls, and was woven into body armor.
Cortosis was expensive to mine because it was so rare and it absolutely had to be refined. Pure, unrefined cortosis ore was for unexplained reasons energized, killing anyone who touched it with his/her bare skin, even Hutts, who had energy resistant enzymes in their sweat. Miners had to have filtering equipment, or else the cortosis particles would accumulate in their systems, causing hair loss, sickness, and eventually death. The substance was heat and energy resistant, meaning energy tools (such as plasma torches) were virtually useless. The brute force of hydraulic jacks were used to mine it, though it quickly wore the head of the jack to uselessness and its dust would clog the pistons.
The most valuable type of cortosis was the purified one. It is known as Cortosis-Shield, used by Roan Fel's Imperial Knights on their gauntlets. It can short out a lightsaber for a short period of time.
During the New Sith Wars, the Outer Rim Oreworks Company mined cortosis on Apatros. This was where future Dark Lord of the Sith Darth Bane was born and drilled cortosis for several years before fleeing to the Sith Army.
During the Clone Wars, the Jedi Council discovered that the Confederacy of Independent Systems was mining cortosis on Bal'demnic, and dispatched a task force led by Halagad Ventor and Sha Koon to sabotage the operation.
Some sources claim that cortosis is just resistant to lightsaber strikes, and doesn't cause any effect on the weapon itself. The position of the Star Wars RPG is that both are correct (see "External links" below). However, it is said that this is because it is a mix, and this has been proven to be said in RPGs such as Knights of the Old Republic.
In Star Wars EU, there are two types of cortosis—purified cortosis ore and cortosis alloy. Purified cortosis ore deactivates the lightsaber, and cortosis alloy simply blocks the blade, making cortosis something of a marvel of metallurgy, as nothing known about how the ore accounts for the relationship between the actions of circuit-interruption or energy-blade blocking. It should be noted, however, that cortosis is very brittle, and breaks easily. This is why it is mixed with other metals, to form cortosis alloy. However, the alloy loses the shut-down capability of the ore. Even when mixed, however, cortosis still makes the alloy weaker.
The length of time cortosis is effective seems to vary. In Vision of the Future, when Luke Skywalker first encounters it, it deactivates his lightsaber, but he is able to reignite the blade immediately. In other depictions, however, including Purge and the Legacy comic series, it renders lightsabers useless for several minutes. This may be explained by the cortosis alloy/ore difference and the amount of ore present in the alloy used.
|Combat||Duel · Dun Möch · Fast style · Medium style · Strong style · Form "Zero" · Mounted · Niman/Jar'Kai · Sokan · Three rings of defense · Trispzest · Tràkata|
|Forms||I: Shii-Cho · II: Makashi · III: Soresu · IV: Ataru · V: Shien / Djem So · VI: Niman · VII: Juyo / Vaapad|
|Techniques||Cho mai · Cho mok · Cho sun · Dulon · Faalo's cadences · Faalo's Will · Falling Leaf · Flowing Water · Jedi ready · Jung · Jung ma · Kai-kan · Lus-ma · Mou kei · Sai · Sai cha · Sai tok · Sequence · Shiak · Shiim · Shun · Su · Sun djem · Twin Suns · Velocities|
|Variations||Crossguard lightsaber · Curved-hilt lightsaber · Dual-phase lightsaber · Double-bladed lightsaber · Imperial Knight lightsaber · Lightclub · Lightfoil · Lightwhip · Long-handle lightsaber · Lightsaber pike · Protosaber · Shoto / Guard shoto · Training lightsaber / Sith training saber|
|Lightsaber-resistant materials||Armorweave · Cortosis · Darkswords · Force Weapon · Mandalorian iron · Neuranium · Orbalisks · Phrik · Sith alchemy · Ultrachrome|
|Technology||Blade emitter · Crystal · Diatium power cell · Emitter matrix · Focusing lens · Hilt · Inert power insulator · Pommel cap|
The Cortosis was a large, almost incomprehensible superweapon of a starship rumored to have been built at the Second Star Forge. It was 1,000 miles long, 500 miles tall, and had a beam width of 400 miles at the widest point.
Built at the Second Star Forge, The Cortosis rivaled in size the Death Star Three. The owner, Ordo Dreeno, had it built as a way to demoralize New Imperial troops, but also as a way to conquer the whole galaxy if required. He got his wish. 3D-R2, the 4,000 year old utility droid, activated the Second Star Forge's systems and built The Cortosis specifically to Ordo's specifications.
The Cortosis was built with eight megalasers capable of destroying planets, 1,000 Solar Torpedo tubes, and a Sector Subjugator. It also had numerous hangers for Destructive-class fighter-bombers, and a vast hyperdrive reactor.