You must make your Eevee level up while near the rock. You can do it by battle or using a Rare Candy.
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level it up near strange icy rock (route 216 or 217)
I think if you take an eevee to it, it will evolve into an ice tipe Pokemon. Same with a moss rock. it will evolve into a grass tipe Pokemon
There is no physical ice stone that you can use on a Pokemon in this game. However, if you wish to evolve Eevee into Glaceon then you can evolve it at an icy covered rock somewhere around the Snowpoint area. But you do have to level up when you are around this rock in order for Eevee to evolve. there is also a item called icy rock. it does some special boost for the TM hail.
The icy rock is to the left of snowpoint city and below lake acuity. This stone is almost exactly the same as the mossy rock in eterna forest. If you level up an eevee around this rock, it will evolve into Glaceon.
The moss rock in Pinwheel Forest is to evolve Eevee into Leafeon. Just level up eevee beside that rock and it will evolve.