Tiberium is a fictional mutagenic crystalline material featured prominently in the Command & Conquer series of real-time strategy video games. In each Command and Conquer game of the Tiberian series (Command & Conquer, Tiberian Sun and Tiberium Wars), these crystals are both the tools and spoils of war; the crystals are used by the player to purchase new units and buildings, and each faction is battling for control of the crystals. Tiberium comes in many varieties, mostly the common green crystal, but also comes in the form of a more rare blue crystal.Tiberium, within the context of the storyline, is presented as a double-edged sword. While it is the greatest mineral resource ever encountered, conveniently gathering many elements into an easily harvestable form, it brings with it a great cost: Tiberium-rich areas are too toxic to support normal carbon-based life. In the context of the gameplay, Tiberium can also be seen this way with its obvious tactical advantage as a resource and its
Source:
http://en.wikipedia.org/wiki/Tiberium