Much of alien technology is based on the use of crystals which can function as a power source as well as a means of storing and transmitting information.
The Ancients used crystal technology in building the stargate network. The stargate relies on control crystals both as a means of storing power and for storing the vast amounts of information required to convert matter into energy and then to reconvert those energy patterns back into matter. The DHD also contains a series of power crystals which coordinate with the much larger master control crystal. Other examples of Ancient technology, such as the weapon discovered on Velona or the inter-dimensional device brought back from P9X-391, have also been based on a crystal power core. Merlin's weapon, capable of destroying ascended beings, is crystal-based technology, and the Sangreal itself, the key to the weapon, is a red crystal, spherical in shape. While Ancient power crystals often take the shape of long pointed prisms, crystals used in certain Ancient technologies for programming specific functions are clear, colorless, and shaped as flat panels with markings etched into them. The Ancient control console, the Ancient transporter, the Sodan Eye of the Gods, and even the Ori supergate rely on these etched crystals which can hold programming information and can be replaced to change the programming of the device. The most significant power source discovered by the SGC, the zero point module, is an Ancient crystal power source that draws its energy from subspace.
The Goa'uld, as scavengers, have also relied on crystal power sources for much of their technology, including the control systems, defense shields, cloaking systems, sub-light engines, and hyperdrive for their motherships, alkesh, and teltacs. The ring transporter is also crystal-based technology, as are a number of Goa'uld weapons including the staff weapon and ribbon device, and the naquadah bomb which had been activated in Sekhmet's ark.
Crystals are also used for data storage and retrieval. A data crystal left behind on Kelowna held the key to the early naquadria research conducted by Thanos three thousand years ago. The Goa'uld probe encountered on P3X-666 had a similar function to a MALP, and also used memory crystals to store and to transmit vast amounts of information. When Anubis used a mind probe to extract the knowledge of the Asgard from Thor's mind, Thor's consciousness remained intact within the crystals of the computer core of Anubis's ship, and SG-1 was able to retrieve the data crystals and transfer Thor's consciousness into a new cloned body.
The Tok'ra use crystal technology to grow tunnels, similar to a geode, and individual crystals are programmed with the specific layout of a given passageway, allowing for the structuring of the tunnel system as is seen fit.
The SGC has begun to incorporate much of the alien technology they have encountered into new Earth technologies. The Prometheus spacecraft was constructed using a number of key systems that relied on crystal technology rather than wires and chips, and the crystals were capable of linking the computers to the alien systems. The Prometheus's hyperdrive, contributed by the Asgard, as well as its sub-light engines, also relied on control crystals. The more advanced Odyssey was also designed using the prism-shaped power and control crystals as well as the etched flat crystals which can be specifically programmed.
Typically, crystals of different colors have different functions. Blue crystals are often used for power regulation, whereas red crystals may control a timer. Goa'uld hyperdrive engines require a series of multi-colored crystals while the Prometheus's hyperdrive crystals were entirely clear. Normally, the crystals glow when activated and dim when they are removed or no longer functioning.
Crystals are an efficient and reliable source of power and can be used to transfer many different kinds of energy or to store a variety of data, however, once they have been burned out or destroyed, they cannot be repaired, and must be replaced.
Cross Reference: Alkesh, Ancient Control Console, Ancient Transporter, DHD, Eye of the Gods, Force Field, Ha'tak, Hyperspace, Inter-Dimensional Device, Merlin's Weapon, Odyssey, Probe, Prometheus, Ribbon Device, Ring Transporter, Sangreal, Sekhmet's Ark, Staff Weapon, Stargate, Supergate, Teltac, Thor, Tok'ra Tunnels, Velona, Zero Point Module
First Introduced: The Torment of Tantalus
Significant Episode Reference: The Tok'ra, 48 Hours, Last Stand, Descent, Sight Unseen, Resurrection, Lost City, Prometheus Unbound, Arthur's Mantle, Camelot, The Quest, The Shroud, Unending