Jupiter in The Fiction of Leigh Brackett - Io (Jupiter I)

Io (Jupiter I)

Io is the innermost and third largest of the four Galilean moons of Jupiter.

Other than a small amount found on Jupiter XI, Io is the only source of Jovium, a radioactive isotope that can trigger a progressive breakdown in metallic atoms. Jovium is extracted from certain blue-green "muds" found on the surface of Io, which also have the property of crystallizing carbon wherever they come into contact with it—including living flesh. It was used as a weapon in the Jovian War, but production of Jovium abruptly halted after the explosive destruction of the Jovians' primary extraction plant.

Due to the instability of its surface, Io is uninhabited by intelligent beings other than military personnel and others involved in mineral extraction. The only significant animal indigenous to Io is the indescribable quag.