Lava-Gem

"Except have something I wanted – an intact lava-gem, a rare find on the Tren Krom Peninsula," Vultraz replied. "They didn't want to give it up... thought it appeased the volcano or some such thing, kept it from erupting... a few well-timed explosions and one sea of lava later, and they found out how wrong they were."

- Vultraz to Mazeka, Brothers in Arms

A Lava-Gem is a very rare gemstone that has the ability to absorb the pressure of magma from the inside of volcanoes and keeping them from erupting.

Properties
Lava-Gems tend to glisten a red hue and have swirling effects inside of them, giving them the appearance of being alive. The gem is created with a distinct crystalline structure that is able to keep magma in check and the gases inside of volcanic chambers from forcing the magma outwards. They only have to be within a few miles of a volcano for this effect to work, otherwise they are too far away and cannot be used.