Crystals, also known as Tiberium Vinifera, are in the matured stage of Tiberium. In Tiberium Alliances, it can be harvested by harvesters and is used as a resource to pay for units and their upgrades. Crystals can also be found in large amounts in crates in Forgotten camps and outposts and looted from raiding enemy bases.
Crystals are used for building and upgrading units on the offensive and defensive field. They are also used to repair damaged defending units after an attack.