Sky Gold, also known as Blue Aurum (ブルーオーラム Burū Ōramu), is a valuable source of fuel found on the planets, Earth and Jung.
Sky Gold is a rare material seen in Jaco the Galactic Patrolman. It also exists outside of Earth as it is the fuel for Jaco's Spaceship and is known as Blue Aurum. It is used to power all sorts of machines.
The Macareni Gang attempted to steal a trainload of Blue Aurum but was stopped by the Galactic Patrol. Upon escaping from the prison, they return to Jung and successfully steal it then head to Earth where it is known as Sky Gold to steal more.
During the Granolah the Survivor Saga, when Chi-Chi notes that space money is worthless to the Heeter Macki who unbeknownst to her had come to Earth to trick Goku and Vegeta into taking on Granolah, Macki is able to convince her that they will pay Goku in Sky Gold which Chi-Chi accepts as Sky Gold is valuable material on Earth.