Describe the bug
Theurgy registers cinnabar sulfur as a metal and incorrectly expects a item with the forge:ingots/cinnabar tag

Expected behavior
Theurgy should register cinnabar sulfur as a gem and expect a item with the forge:gems/cinnabar tag

Is cinnabar usually seen as gem in MC?
Can you provide some references from mods?

Not doubting you, just making sure I'm not messing up a bunch of modpacks :D

Yep. Cinnabar is crystal composed by sulfur and mercury.
For example:

• Thermal Series Cinnabar
  https://teamcofh.com/docs/1.12/thermal-foundation/cinnabar/ (web wiki is a bit old but cinnabar didn't change)

• Spelunkery
  https://github.com/AstralOrdana/Spelunkery/wiki/Resources#gem-shards

• Real Cinnabar
  https://upload.wikimedia.org/wikipedia/commons/9/98/Cinnabar-d6a.jpg

thanks a lot!