Ice Rock

An Ice Rock is an ice-covered rock that enables Eevee to evolve into Glaceon. If an Eevee is leveled up in an area containing an Ice Rock, it will evolve into Glaceon. Even if Eevee has reached other evolutionary conditions, the Ice Rock will still cause it to evolve into Glaceon rather than Espeon, Umbreon, or Sylveon.

In the games
It is located in an area where the blizzard is very rough, on the easternmost part of the route. It actually appears that the rock is located in the backyard of a house that is near a female Skier. It is surrounded by long grass. of previous regions. Eevee must be leveled up in the room with the Ice Rock in order to evolve into Glaceon; it will not evolve into Glaceon by leveling up anywhere else in Twist Mountain. As the Ice Rock is not present in HeartGold and SoulSilver, Eevee cannot evolve into Glaceon at all unless it is traded to one of the other Generation IV games, Diamond, Pearl, and Platinum.
 * In Sinnoh, a small Ice Rock is located a short way south from Snowpoint City on Route 217.
 * In Unova, a large Ice Rock is located in the basement of Twist Mountain, just west of Icirrus City. It is located on the lowest floor, past an NPC who gives the player Fossils
 * In Kalos, a large Ice Rock is located deep within Frost Cavern. Surf is required to access it.
 * In Hoenn (in Omega Ruby and Alpha Sapphire only), a large Ice Rock is located on the lowest floor of Shoal Cave, accessible only when the tide is low.

In side games
Due to the Ice Rock's absence in Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness, Eevee evolves into Glaceon through the use of the Frozen Rock, and the same method in Gates to Infinity.