The Opal is a Superhardmode ore in Avalon. It can be sold for 1 Gold. At the time of this writing, it is only required in the Focus Beam. It is also dropped by the Man of War NPC.
In Exxo Avalon, Opal is a new Superhardmode gem. It is found underground in Superhardmode after killing the Armageddon Slime. It can be used to craft the Spectrum armor set and Opal staff, among other things.
- In the source mod, it has rainbow rarity, which very few items have without a good reforge on them. This probably due to the fact that the gem is simply rainbow-colored like the rainbow brick in vanilla.