Polonium

Polonium is the rarest isotope you will mine.

Polonium is available as three different isotopes.

Polonium 1 : $5000 / unit

Polonium 2 : $200,000 / unit

Polonium 3 : $50,000,000 / unit

You will need Polonium 1? for: Fission Engine(500)?, Enormous Cargo(500)? and King Cargo(50,000)?