Opal

Opal is a new ore being added in Alpha 8 as a part of the Unobtainium Mines expansion. It gives 500 XP, and is rainbow colored.

Trivia

 * Opal was originally going to be similar to Azure Mines' Garnet, but was cut out due to complications. It was instead shifted to the Unobtainium Mines expansion.
 * Opal is the only item in the game besides Stone to have at least one variation. However, unlike all versions of Stone, Black Opal is it's own item.