Vertag crystal

Vertag crystal was a rare form of crystal. The three land masses of the planet Shownar were composed of Vertag crystals that grew in spires that were kilometers tall. At night, they glowed with a faint blue light. The wind blowing through the crystal spires at high altitudes resulted in a beautiful and soothing harmonic wave that was known as the Shownar Lullaby.

Sources

• Galaxy Guide 9: Fragments from the Rim