Geological Expedition Four was a UNSC Engineering Corps unit assigned to research planet XF-063, later named Onyx. Their findings were that the planet was rich in granite and quartz; having a rich fossil history, in addition to limestone deposits.

The team recommended further surveys, and further assessments in the fields of paleobiology, xenobiology, and biochemistry. Their requests were presumably ignored after Rear Admiral Margaret Parangosky classified the planet's existence.[1]



  1. Halo: Ghosts of Onyx, page 123-124