A wall of Cryolite located under the sea
Cryolite is a rare and valuable mineral with tremendous properties, appearing in the television series Thunderbirds 2086. Originally found deep below the Earth's crust (and in extreme cases along the rims of tectonic plates), the mineral can serve numerous uses once mined and refined, though is sought primarily as a vital element for starship fuel.
As technology and space travel advanced over the decades, Earth's Cryolite levels were rapidly depleted, despite only a minuscule amount required for processing. By 2086, the mineral was virtually mined to extinction, requiring the Federation to search elsewhere for the elusive fuel source. While traces have been located on asteroids in the outer solar system, the majority of Cryolite deposits originated from Earth.
Due to its rareness, the Federation have placed restrictions on the mining and exportation of Cryolite. This resulted in the mineral becoming extremely valuable and can sell for exponential amounts on the intergalactic black market. Among the many forces seeking Cryolite are the enigmatic Shadow Axis organisation, led by General Starcrusher. The mineral is vital to his plans of universal domination.