Control crystal

Control crystals are crystals used in controlling technology. They are used by the technologies of a variety of cultures, mainly the technologies of the Alterans and the Goa'uld. It is unknown who first made them, but the Alterans are the most likely candidates.

Ancients
"Do you have any idea how many crystal placement combinations there are?"

- Dr. Rodney McKay

The Ancient's control crystals range from colored jewel-like crystals to clear, fat, square crystals. They are found in almost all technology, including the Stargates, Puddle jumpers, Dial Home Devices and doors in Atlantis. Reordering crystal arrangements will produce different results from the device, or stop it working altogeather.

DHDs have control crystals which contain information on which planets a Stargate can link to, and where not to link to. They also send out new locations on the DHD's information update system. The DHD in Atlantis is the only one in the Pegasus galaxy which can achieve an extragalactic wormhole, via a special control crystal.

The latest Ancient computers appear to be able to store more information than the counterparts of other races. The Repository of knowledge contained all their knowledge and could precess it all in a matter of seconds, but was a lot smaller than the computer cores of the Asgard and other races. However, it is unknown if it used crystals, it may be a different technology altogether.

Three large vertically placed crystals are located at the side of most doors in Atlantis. The doors are opened by waving one's hand in front of the crystals, and the door closes automatically or by waving in front of them again.

Asgard
The Asgard use control crystals in some of their advanced technology such as the Asgard computer core for data storage. Alternate information can be stored on the reverse side of an Asgard crystal to hide it, but the computer will only read one side.

Eurondan
The Eurondans use crystals in atleast their Data storage canister which was a cylindrical shapped device used to encode information. Those devices are shaped like a large metal cylinder with differently colored crystals projecting from the top. They are apparently highly efficient, as the one seen contained data on almost every facet of Eurondan technology.

Goa'uld
Control crystals, called delmac in Goa'uld are also extensively used for Goa'uld technology. Long cylinders which contain information and data storage, they are required to access and power a great deal of their technology, including the Hyperdrives and weapons on Ha'taks. Blue indicates power regulation. They are also used to store information on research that has been conducted.

Ori
Like the Ancients, the Ori use control crystals to store information in the Supergate. In an attempt to stop the Ori from dialing into the Milky Way, the Asgard formed a control crystal to dial the Ori Home Galaxy. However, the Ori dialed in before they could dial out. Subsequent attempts to dial out were unsuccessful. Their power crystals are also compatible with Ancient technology, unsurprising, as the Ancients and Ori were once a single society.

Tau'ri
The Tau'ri also use control crystals, which are clear and either cylindrical or flat, reminiscent of Goa'uld and Ancient design. They are both manufactured by them and are also included with the technology given by aliens such as the Asgard. In function, they appear to have been taken out right from the Goa'uld control crystals, controlling such functions as the Asgard-built hyperdrives and shields.

Tok'ra
Like the Goa'uld, the Tok'ra use control crystals for their technology. The Tok'ra also use crystals to form their tunnels, which they use when they use to hide in. Small square crystals are used to form short tunnels, while long rectangles make longer passageways. Tok'ra crystals can also store data information like the Goa'uld crystals.