This is cryolite

That's the material you use to make ice-type gear!!

Ah... So it's an fictional ore that found in games.

It is mainly used as a solvent in smelting aluminum. Discovered in western Greenland, it is a halogen mineral that has the appearance of ice, thus the name. Ice-stone

The index of refraction is low, almost the same as water, so if a transparent crystal is put into water, it's almost impossible to see.

Greenland