Cyranite is an energy source that affects long-range communications of Colonial Vipers, and is in use by the Colonials (The Law of Volahd, Part 1). Technology using cyranite as an energy source requires that it must flow continously from a main source; disruption to this source would cause devastating effects (The Law of Volahd, Part 2).
The Acmarans' homeworld contains a high volume of this material, which is critical for the survival of the Fleet (The Law of Volahd, Part 1).
Cyranite is the primary power source for both Salis and the force field, a column of cyranite-fed energy is in the center chamber of the city. Taron disrupts this field after discovering, much to his horror and anger, that he himself was turned into a cyborg construct without his knowledge by Cylon hands (The Law of Volahd, Part 2).