There are two very rare materials that can only be found in Constelation Octans and Constelation Ophiuchus: Uranium Vapor and Crystalline Fluoride.
These materials will only spawn in those areas, in the final tunnel traveling towards them or in the tunnel while traveling from them (to the previous area or haling materials to the Apex).
They activate no special ability but collecting and hauling them to the Apex is the goal of the game. See more information on the story page.
Unlike the other items, they only appear in your inventory in those two regions or in the Apex after you successfully hauled them there.
Different occurences of special materials.
Hauling takes you to a long tunnel with few resources except for warp tunnel stabilization matrix. Make sure you have enough fuel for your special abilities.
Check out this hauling run to get an idea of the process (youtube video)