Is created when heavy metals fall into the Burner anomaly. This artifact eliminates radiation wonderfully. It is highly valued by stalkers and hard to find. - In-game description
The Crystal provides a -30% in radiation, in exchange of -18% in endurance. This makes the Crystal a valuable artifact as it can slowly purge the player from the radiation they accumulated while walking through irradiated areas. When combined, Crystals can make the use of vodka/anti-rads nearly redundant as they can quickly remove radiation. However, considering they lower the player's endurance, it is advised to use a Flash or a Moonlight to counter the Crystal's downside.
Crystals are a very good choice paired with an Exoskeleton for the Sarcophagus and other final levels. Since the player, while wearing the Exoskeleton, is not able to run, the endurance downside is nearly irrelevant, and considering most of the inside of the Chernobyl Nuclear Power Plant is irradiated, the player could use Crystal artifacts to eliminate radiation without having to rely on anti-rads or vodka.
The player will be rewarded with this artifact by Skinflint after completing the Kill the bloodsuckers in the village mission that can be taken either from Skinflint or Murk. This artifact can be found in few locations, including Lab X-18, sometimes hidden in a random box or near the Vortex anomaly. Another can be found in a box in the Monolith Control Center or the Sarcophagus, but one may get another artifact instead as this is a random spawn. Several stashes contain this artifact, usually later in the game, such as one in the Army Warehouses. It is possible to find this artifact out in the open near the tunnel entrance at Freedom's base in the Army Warehouses.
This artifact is formed in anomalous zones with intense thermal activity. Actively consumes excessive heat, remaining cool to the touch throughout. Emits radiation.In-game description
The Crystal returns in S.T.A.L.K.E.R.: Call of Pripyat, providing a +3 in fire protection and a +1 in radiation. Again, the protection granted by the Crystal is nearly insignificant unless combined - the very low radiation penalty mean one could combine max. four of these resulting in a +12 in fire protection and contain the radiation with a single Bubble.