Psynergy Stone

Psynergy Stones are purple colored rocks that restore the Psynergy Points of the entire party. They can be found on the ground in various locations throughout both Golden Sun games. They are very distinguishable amongst other things. The small ones will disappear after being used but will return when players leave the area. They are often placed just before a boss or at strategic locations, such as the entrance to the insides of the numerous Elemental Rocks. The bigger ones, such as those in Vale and the Elemental Rocks, will not disappear (these are sometimes referred to as Psynergy Crystals.)

Story
In the original Golden Sun, when Isaac and the others acidentally caused the eruption of Mt. Aleph, the mountain rained Psynergy Stones across the land. The most obvious effect of these was to turn simple wildlife into fearsome monsters that the party had to battle (this also included raising the dead and producing numerous other creatures); this also caused several geographical features to change, including the temporary destruction of the Kalay Bridge and the transformation of Mogall Prarie into Mogall Forest. More importantly, several people around Weyard were exposed to the Psynergy Stones, and as a result several of them gained certain Psynergy powers.

In the Sequel, this is expanded upon when the party visit the town of Garoh, where it is speculated that Psynergy Stones could be the cause of the inhabitants of that town becoming werewolves.