Second planet of six in the system 12 255 Crux. Crucible was charted by the Pathfinders Ship Pegasus and Lexington Keeler in the Sapphirean Year 7371. The remains of a human colony were discovered. It was determined that the colony had been annihilated by aliens of unknown origin. The planet was distinguished by its turbulent atmosphere and the abundance of hydrocarbons in its air and water, necessitating breathing masks to be worn continuously on its surface. (Book 6: Crucible )