Naquadria

"It's a mineral substance found to have highly unstable radioactive properties."

- Tomis Lee

Naquadria, a highly unstable radioactive variation of naquadah, has the potential to be an enormously powerful energy source. Even a very small amount emits a pulse of energy far greater than weapons grade naquadah and when, used as a weapon, it has the potential to be as powerful as a naquadah-enhanced nuclear warhead.

Overview
Naquadria is a heavier, less stable isotope than naquadah, and it does not occur in nature. It was discovered on Kelowna, where ancient writings revealed that Thanos, the Goa'uld who had occupied the planet thousands of years ago, had been experimenting with the mineral. Thanos had managed to create a small amount of naquadria by developing a process to convert raw naquadah, but he had been killed in a cataclysmic event that nearly destroyed the planet 10,000 years ago. The resulting explosion released a massive bombardment of subatomic particles which triggered a chain reaction and catalyzed the conversion of a vein of naquadah near the planet's surface.

Kelownan use
In 20,000 years, the converted naquadria would have decayed back into naquadah, however the Kelownans mined the mineral and began to research its use for weapons technology. When Dr. Kieran and his team of scientists successfully tested a naquadria bomb, its destructive power exceeded all expectations. However, subatomic particles from the explosion penetrated the planet's crust and triggered the conversion of a second, deeper vein of naquadah. As the conversion process traveled deeper underground, the heat and pressure increased until the highly unstable nature of the resulting naquadria threatened to explode and obliterate Kelowna. The process could not be reversed, however SG-1 cooperated with the Kelownans and used a deep underground excavation vehicle to deposit a small nuclear device near a minor fault line crossing the vein of naquadah in order to trigger a shift along the fault and isolate the advancing naquadria. The mission was successful, and Kelowna was spared.

Long-term exposure to naquadria radiation can cause a unique form of brain damage with symptoms of paranoia, delusions, and hallucinations. The Kelownan scientists who worked on the Naquadria Project, including Tomis Lee and Jonas Quinn's mentor Dr. Kieran, all developed advanced schizophrenia due to improper shielding of naquadria during their research. There was also a lab accident involving the experimental naquadria weapon in Kelowna that exposed Daniel Jackson to lethal doses of radiation; which would have taken his life had he not ascended.

Tau'ri use
Several hundred pounds of the mined naquadria had been acquired from Kelowna by the SGC for use in developmental hyperspace technology. The experimental X-302 craft was designed with naquadria-powered hyperspace generators. However, the instability of naquadria increases exponentially as more energy is extracted from it, and the X-302 was unable to maintain a stable hyperspace window. A more successful buffered naquadria reactor module was designed for the X-303 Prometheus, enabling the ship to achieve limited hyperspace travel. However, the instability of the naquadria caused a power overload, and the reactor module had to be jettisoned, stranding the Prometheus near Tagrea until repairs could be made.

The SGC has thus far pursued naquadria research for use in hyperspace, shield, and weapons technology— the Mark IX naquadria-enhanced nuclear warhead being a prime example. However, the Tau'ri's interest in naquadria has, more recently, declined due to the extremely advanced technology gifted to them by the Asgard. Because of this, Tau'ri ships, notably Daedalus-class vessels, are outfitted with such technologies as Asgard hyperdrive systems, capable of propelling ships at far greater speeds than naquadria-fueled reactors have been capable of achieving.

Icarus Base
Originally it was believed that Naquadria could not exist naturally anywhere in the universe and that the instances on Kelowna were artificially produced as a side effect of Thanos experiments there. However, in 2007, the SGC found a world 21 light years from Earth that housed an entire core made of naturally occurring Naquadria, the only known natural occurrence of this element in the universe. This world later became the site of Icarus Base, a project designed to tap the unstable planetary core and use the Naquadria to power a Stargate dialling a 9 Chevron address found in the Atlantis database.

This world was destroyed in 2009 by a combined attack on Icarus base by the Lucian Alliance and an attempt to dial the 9 chevron address which introduced an uncontrolled instability in the planet's Naquadria core, resulting in the destruction of the planet.