Ice Crystal is a block that can be found on Ice Planets and Pirate Space Stations. They give off light and are thereby easily recognized. Mining Ice Crystals is a good way to earn credits early on in the game because they sell for 500 credits each, equal to five level 2 minerals. It is best advised to start mining beneath a planet by making holes and searching for a pile of Ice Crystals. Before being able to salvage Ice Crystals off of a Pirate Space Station, make sure to destroy the Faction Module first.
People often use Ice Crystals as decorations on their ships and structures to make them look fancy. Other than that, Ice Crystals do not serve any other purpose.