Xp Gems give 176 Experience Points when broken with an iron or superior pickaxe.
Xp Gems can be harvest with Silk Touch Pickaxes to craft Xp Bottle for Storage.
Xp Gems spawn in a Y range of 40-1. They are fairly rare.
Future Improvements (hopefully)
Xp Gem item drop.
Xp Gem breaks and gives xp upon right click.
Xp Gem Hardening/compression recipe for higher Xp values upon break.
Possible xp re-balancing or editable config.
I admit to not knowing how to do any of this currently. (aside from Xp value editing)
Animated Texture Preview Link:
Version 1.0 - Added Xp Ore and recipe to craft Xp Bottles. Xp Ore gives 176 experience points.
Version 1.1 - Updated animated texture for Xp Gem. Title changed to Wombatty's Xp Gems (previously ores)