Star Wars: Edge of the Empire
Cortosis ore is a very rare, brittle, and fibrous material with highly-conductive properties.
Cortosis is expensive to mine due to its rarity and its volatile natural state. Pure, unrefined, cortosis ore is energized, killing anyone who touches it with bare skin (even Hutts, who have energy resistant enzymes in their sweat). The exact nature of this energization is unknown. Miners must utilize filtering equipment, otherwise the cortosis particles will accumulate in their body systems, causing hair loss, blood cancers, blindness, bone degradation, and eventually death. The mineral is heat and energy resistant, meaning energy tools (such as plasma torches) are virtually useless. The brute force of hydraulic jacks are used to mine it, though it quickly wears the head of the jack to uselessness and its dust clogs the pistons. Pockets of highly-combustible lethane gas often forms near cortosis deposits.
Refined cortosis causes lightsabers and other energy weapons to temporarily short out upon contact, although the wielder can alleviate this problem by turning the power back on after a few seconds. This effect makes cortosis a useful material for anti-energy melee weapons, though with repeated strikes, a lightsaber or energy weapon could still cut through it. Cortosis, due to its heat and energy resistant properties, is also resistant to blaster fire.