Crystal is one of the three resource types used to expand and supply your empire.
Crystal is the rarer and more valuable of the two resources that can be mined from asteroids, Metal being the more easily obtained counterpart. Ice Planets have only crystal asteroids in their orbit, as opposed to Volcanic Planets that only have metal. Crystal is also the rarer common element in other planets, Home Planets usually have two metal asteroids and one crystal asteroid. Each race has research that can be done to increase the efficiency of crystal extraction. Crystal is removed from asteroids by the fairly cheap Crystal Extractor.