The Baria Crystal, known as Variarite (バリアライト Bariaraito) in the Japanese version, is a substance native to the Barian World.
At some point, Kite Tenjo acquired a Baria Crystal, which he used as a new power source for Orbital 7. Later, after he and Orbital 7 stole Yuma's key and found that no substance native to Earth could affect it, Kite suggested they try using the Baria Crystal on it. Using it, they successfully opened a portal, allowing Kite to enter the world inside the Key.
Within the chamber where Dumon, Girag, Mizar and Alito meet in the Barian World, many of these crystals are present. Before leaving for Earth, Girag crushes one with only his fist. The crystals serve as devices that can be used to monitor Earth. Using them, Dumon witnessed Girag's failures, prompting his decision to send Alit to Earth too.
The crystals also have healing properties, seen when Girag and Alito were resting inside them to heal after being defeated by Yuma.