The Firium Z (Japanese: ホノオZFlame Z) is a type of Z-Crystal introduced in Pokémon Sun and Moon. It is the type-specific Z-Crystal associated with the Fire type and allows Pokémon to upgrade their Fire-type moves to Z-Moves.
Unaffected by item negating effects (such as Embargo and Klutz). Item manipulating effects (such as Trick and Fling) cannot remove a Z-Crystal from a Pokémon.
The Firium Z debuted in PASM11. Sun received one from Kiawe after the latter found it inside the fur of Sun's Litten, En. Sun uses it to perform Inferno Overdrive with En.