Farcyte is a material with a unique biplanar nature that can be used to peer into the Khert and is also a key component of burners for loading spellwork into First Materials.
Rahm the Raptor has quite a large one in his underground workshop.
"And that Farcyte geode up there - I've never seen one that size. No surprise lizards built a temple around it." Quigley, Chapter 11. Page 10.