Naquadria

A variant of naquadah, naquadria is very unstable, but holds much more energy. It powers the hyperspace engines of the Prometheus, and can only be found on Kelowna of Langara. This is because it is believed to have been created by the Goa'uld Thanos 3,000 years ago. (SG1: Meridian, Redemption, Part 1, Fallout)