Stellanium

Stellanium (ステラリウム Suterariumu) is a Magic mineral, which appears in Fairy Tail: Dragon Cry.

Appearance
Stellanium are rainbow-colored crystals which resonates when starlight is absorbed into the minerals.

Description
Stellanium is a Magic crystal that was originally stated to absorb starlight which causes it to radiate but when too much was absorb they would become explosives. However it was proven false with the crystal just being used for magical purposes such as Swan's leg gauntlets.