The Icium Z (Japanese: コオリZIce Z) is a type of Z-Crystal introduced in Pokémon Sun and Moon. It is the type-specific Z-Crystal associated with the Ice type and allows Pokémon to upgrade their Ice-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.
An Icium Z was first seen in SM080, where it was given to Lillie by an AlolanSandslash after she had helped driving off a wild Tyranitar that had tried to take over the cave inhabited by Sandslash and a group of Alolan Sandshrew.